Hi,
I never have any experience with Table Saw Molding Head, maybe the experts
in this forum could give their opinion.
I saw a tabl saw molding head with one blade. Is it good? Would it worth
buying? How does it compare to the typical 3 blade head?
Thanks in advance for any opinion given.
Best Regards,
Jo
--
Posted via a free Usenet account from http://www.teranews.com
"SWDeveloper" <[email protected]> wrote in message
news:[email protected]...
>
>
> Maybe not crazy, but not as safe as a perfectly balanced molding head.
> The more balanced the the cutter head, the less vibration. A
> well-balanced blade assembly will give you a cleaner cut too.
Ok, lets stop and think here for a moment. This single head cutter is not a
fluke, flash in the pan tool that was here today and gone tomorrow. I first
saw them some 25 years ago. I have heard of no incidents regarding problems
with the cutter, have you?
True they probably do not leave as smooth of a cut given the same feed rate
but as long as the cutter is balanced there should be no vibration. I
suspect that if there was significant vibration that the tool would have
never made it out of the R&D department.
Huge and heavy by comparison engine crank shafts are very irregular in shape
and when balanced can spin at speeds in excess of 12,000 rpms.
On Mar 27, 6:04 pm, "Leon" <[email protected]> wrote:
> "RonB" <[email protected]> wrote in message
>
> news:[email protected]...
>
> >> No, the tip speed on you TS is no where near a 30-06, or a 22 for that
> >> matter. The typical 10" blade turns at about 3600 rpm. The blade is
> >> 31.4 inches around or 2.61 feet around. 2.61' x 3600 + 9420' per minute.
> >> That comes out to about 107 MPH. IIRC the typical 22 has a muzzle
> >> velocity of around 1100 feet per second and that comes out to about 7
> >> times faster. A 30-06 with a 150 grain bullet travels at about 2700 feet
> >> per second or about 17 times faster than your saw blade. If you are
> >> spinning a smaller diameter dado or molding cutter the tip speed would be
> >> slower than the 10" blade.
>
> > It would still earn you a trip to the emergency room - or worse.
>
> If the whole cutter came loose and hit you I would agree. If a small
> fragment came loose, probably not.
>
>
>
> - Hide quoted text -
>
> - Show quoted text -
Hello,new here but seems strange that tommorow I will be using the
cutter head (3) again and yes I am afraid of it, the weird noise and
the wind it makes. Although have you tried it on a radial arm? Now
that is spooky but hey by the end of this year I will have the router
completely set up, and I feel fairly safe with the router. Have a good
evening
Jim in WI
Now maybe you should compare the energy of the 200 grain bullet with the
weight of the cutter and compare the total energy of both?
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Mike Marlow" <[email protected]> wrote in message
> news:[email protected]...
>>
>> Not even close to the same neighborhood. In fact, the table saw isn't
>> even
>> close to the lead sled speed of a .45ACP.
>>
>
> CORRECT. LOL And the 22 caliber is 7 times faster than a 10" TS blade
> tip and only 2/3's the muzzle velocity of a 45.
>
The thing is you might not have control over some nut with an 06 but you do
have control over what kind of tool you buy or how you use it.
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Mike Marlow" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Arvid Sorsdahl" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>> Now maybe you should compare the energy of the 200 grain bullet with the
>>> weight of the cutter and compare the total energy of both?
>>
>> That's not necessary. The comments you are replying to were simply in
>> response to the preceding comment which speculated that the speed of a
>> cutter coming off would approximate the speed of a 30-06 bullet.
>
> Still I would much rather be hit by that cutter then the 30-06 bullet .
>
Lesson to be learned here: don't stick your hand in the path of a moving
blade. Pretty universal
"RonB" <[email protected]> wrote in message
news:[email protected]...
> >>> I've had the 3 head unit from Craftsman for about 35 years and recall
> >>> that they sold the single head at that time as well. The three head
> >>> cutter (on a RAS, no less) ........
>
> Yeah -- Old memories. My cousin was cutting moulding with a Craftsman
> 3-blader many years ago on a RAS. He felt a thud on one hand and looked
> down at his shirt which was covered with blood, tissue and bone fragments.
> You can guess the rest. The damage was limited to the end of one finger
> above the joint.
>
> The surgery and recoup from trying to restore part of the fingertip was
> almost worse than the injury itself. Horrible looking mess. He was a
union
> utility worker at the time and had to have all of his digets in working
> order.
>
> He is a talented woodworker to this day but the old RAS, and moulding head
> is ancient history to him.
>
> RonB
>
> RonB
>
>
"CW" <[email protected]> wrote in message
news:[email protected]...
> Lesson to be learned here: don't stick your hand in the path of a moving
> blade. Pretty universal
;~) I was not gonna say it.
> No, the tip speed on you TS is no where near a 30-06, or a 22 for that
> matter. The typical 10" blade turns at about 3600 rpm. The blade is 31.4
> inches around or 2.61 feet around. 2.61' x 3600 + 9420' per minute. That
> comes out to about 107 MPH. IIRC the typical 22 has a muzzle velocity of
> around 1100 feet per second and that comes out to about 7 times faster. A
> 30-06 with a 150 grain bullet travels at about 2700 feet per second or
> about 17 times faster than your saw blade. If you are spinning a smaller
> diameter dado or molding cutter the tip speed would be slower than the
> 10" blade.
>
It would still earn you a trip to the emergency room - or worse.
"RonB" <[email protected]> wrote in message
news:[email protected]...
>
> "Charley" <[email protected]> wrote in message
> news:[email protected]...
> > ......... Even then, always stand well out of line of it when you turn
the
> > saw on, as these molding heads have been known to throw a knife
> > occasionally.
> >
>
> Yeah - I have occasionally been tempted to calculate the tip speed of the
> cutters running on my table saw and compare it to a 30-06. I'll bet they
> are in the same neighborhood if one came off. Like I said earlier, mine
is
> on the shelf but doesn't get a lot of use.
>
Not even close to the same neighborhood. In fact, the table saw isn't even
close to the lead sled speed of a .45ACP.
--
-Mike-
[email protected]
It is absolutely necessary that the molding head is balanced when it is
running. I've never heard of a one cutter molding head, so I suspect that
it's a 2 cutter molding head with one cutter missing. DON'T USE IT, until
you are absolutely sure that it's got all of the knives in place that it's
supposed to, and make absolutely sure that all of the knives are properly
secured in place before you even put it on your saw. Even then, always stand
well out of line of it when you turn the saw on, as these molding heads have
been known to throw a knife occasionally.
I have had a 3 knife Craftsman for over 30 years and I have used it quite a
few times, but less and less as I get older and less brave. I've always felt
very un-safe whenever I have used it, even after taking extra time to be
sure that all of the feather boards and necessary guards were in place. I
feel much safer doing the job with a router or shaper. These table saw
molding heads can get the job done, but they run much slower, cause more
chip-out, and are much less safe then doing the same job with a router or a
shaper. I have had pieces of molding completely shatter when cutting them
with one of these, sending large splinters all over the shop. They
definitely aren't for the timid or un-skilled user. I haven't trashed mine
yet, because every once in a while I still find a need for it, but I avoid
using it whenever possible.
--
Charley
"RonB" <[email protected]> wrote in message
news:[email protected]...
> Personally, I have never heard of a one-blade moulding head. I have had a
> three-blade cutter for 30 years. It used to get a fair amount of use but
> bigger, better routers and router bits seem to be replacing it,
>
> The three-blader can do a fairly good job if you feed slowly. Remember
that
> most routers are running in the 18,000 to 22,000 rpm range. A shaper
(which
> the moulding head is trying to simulate) also runs quite a bit faster than
> your table saw, which is in the 3,000-4,000 rpm range. If you start
> shallow, and work up to final cutting depth, and feed slowly then can do
the
> job - but not as well as the router or shaper. I would approach a one
head
> cutter with a fair amount of caution.
>
> RonB
>
> "Jo" <[email protected]> wrote in message
> news:[email protected]...
> > Hi,
> >
> > I never have any experience with Table Saw Molding Head, maybe the
experts
> > in this forum could give their opinion.
> >
> > I saw a tabl saw molding head with one blade. Is it good? Would it worth
> > buying? How does it compare to the typical 3 blade head?
> >
> > Thanks in advance for any opinion given.
> >
> > Best Regards,
> > Jo
> >
> > --
> > Posted via a free Usenet account from http://www.teranews.com
> >
>
>
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Unquestionably Confused" <[email protected]> wrote in message
> news:[email protected]...
>>
>> Not sure that it would necessarily be crazy but I think it might be a bit
>> more prone to get a bit too much material in there, a bit too quickly and
>> watch it (hopefully that's all) go flying.
>
> I have had the 3 head set for almost that long. LOL Since 1978 IIRC.
>
>
>> Three bits, means you're removing the material 3x faster. This makes for
>> a smoother finish. It also means that at a given feed rate it will
>> remove 3x the material.
>
> I agree with probably a smoother finish but at a given feed rate, the
> material removal would be the same on either the 1 or 3 cutter design.
> The single cutter would actually be removing more material at that given
> feed rate.
THe single cutter at a continuous feed rate would remove the same ammount
......BUT ... the 3 cutter removes it in 3 smaller chips as opposed to one
large one giving much better quality finish.
>
> Just seems that it would be more likely, with
>> one cutter, to be able to feed a bit much in and wind up with a big
>> ker-chunk and a load of splinters flying or the whole damn thing taking
>> off on you.
>
> Perhaps so but with the cutter tip speed being approximately 50 MPH (73'
> per "second") and your feed speed being say 5' per "minute", a double feed
> rate of 10' per "minute", the ratio of feed to spin speed is still quite
> steep.
> I think the feed rate would have to be much higher, 100 peet per minute
> before the 1 cutter design would be more likely to take a huge bite than
> the 3 cutter design.
At any given feed rate the single cutter is taking a larger bite.
>
>
>> I've had the 3 head unit from Craftsman for about 35 years and recall
>> that they sold the single head at that time as well. The three head
>> cutter (on a RAS, no less) and set up with proper guards, fencing,
>> feather boards, etc. is pretty scary.
>
> Yeah I had this set up on a RAS also.
>
>
>
>> It does a nice job if you take your time on setup and feed slow. One
>> thing you won't like get is complacency when using that puppy. It seems
>> to provide its own wake-up call every time you power up<g>
>>
> I absolutely agree. ;~)
>
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "RonB" <[email protected]> wrote in message
> news:[email protected]...
>>> No, the tip speed on you TS is no where near a 30-06, or a 22 for that
>>> matter. The typical 10" blade turns at about 3600 rpm. The blade is
>>> 31.4 inches around or 2.61 feet around. 2.61' x 3600 + 9420' per minute.
>>> That comes out to about 107 MPH. IIRC the typical 22 has a muzzle
>>> velocity of around 1100 feet per second and that comes out to about 7
>>> times faster. A 30-06 with a 150 grain bullet travels at about 2700
>>> feet per second or about 17 times faster than your saw blade. If you
>>> are spinning a smaller diameter dado or molding cutter the tip speed
>>> would be slower than the 10" blade.
>>>
>>
>> It would still earn you a trip to the emergency room - or worse.
>
> If the whole cutter came loose and hit you I would agree. If a small
> fragment came loose, probably not.
>>
>>
>
>
Although it would be a relativly small hole at those speeds it would go
straight throug you assuming you hit no bone. Assuming also you have hit no
major organs I hope you keep at least 2 band aids in your safety kit.
Having done a lot of moulding work over the years I would not touch a single
cutter cutter head on that type of setup. I would sit down and scrape the
mould by hand using no more than a blunt butter knife rather than use it. It
is possible that the head may be balanced with a counterweight opposite the
knife. The only problem with this theory is how do you compensate for
different size/shape/projection/weight knives? I can not imagine how but
maybe the head is designed with a depth limiter to limit feed rates. If it
is not you are talking a major risk of kickback at that diameter and speed.
Although not a recomended practice but an accepted practice is to use
different shaped cutters on the same head at times on spindals (shapers).
Occasionally for a one of run you might only grind 1 knife and just use a
blank on the opposite side. Whenever I do this I always have a rubber lined
1/4" plate guard between me and the cutters. The rubber is to catch the
chips of the end of the cutter when it hits the guard. Even the ammount of
knife projection has a marked effect on the inbalance.On a spindle we are
only talking about a 3" head running on very heavy bearings and shaft
compared to the 8" you are talking on a TS on relativly light bearings and
smaller shaft. A spindle running collars runs at around 4000rpm, 4500 is
the maximum recomended for that type of cutter. That gives a spindle cutter
a surface speed of 4,188'/Min (4,712'/Min at max) allowing 1/2" projection
for cutter. Assuming 8" moulding head on TS you are looking at
7,200'/Min.surface speed with no cutter projection. On a spindle even if the
knives are roughly the same size the ammount of vibration due to the
inbalance is incredible. And needless to say the risk of throwing a knife
and kickback increases dramaticly as well as lower quality finish. I used to
have the formula for working out the inbalance taking centrifigal force into
account but forget it now. Maybe someone else in here can shed dome light on
that subject. I know I for one would be interested in knowing it again.
--
Every hour, every day I am learning more.
The more I learn the less I know about before.
The less I know the more I want to look around.
Always digging deeper for clues on higher ground.
"Jo" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> I never have any experience with Table Saw Molding Head, maybe the experts
> in this forum could give their opinion.
>
> I saw a tabl saw molding head with one blade. Is it good? Would it worth
> buying? How does it compare to the typical 3 blade head?
>
> Thanks in advance for any opinion given.
>
> Best Regards,
> Jo
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Paul D" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Leon" <[email protected]> wrote in message
>> news:[email protected]...
>
>>>
>>> I agree with probably a smoother finish but at a given feed rate, the
>>> material removal would be the same on either the 1 or 3 cutter design.
>>> The single cutter would actually be removing more material at that given
>>> feed rate.
>>
>> THe single cutter at a continuous feed rate would remove the same ammount
>> ......BUT ... the 3 cutter removes it in 3 smaller chips as opposed to
>> one large one giving much better quality finish.
>
>
> What I was trying to get at was that the single cutter removes more "per
> cutter" than the 3 cutter design at any given rate.
>
>
>
>
>
>>> Just seems that it would be more likely, with
>>>> one cutter, to be able to feed a bit much in and wind up with a big
>>>> ker-chunk and a load of splinters flying or the whole damn thing taking
>>>> off on you.
>>>
>>> Perhaps so but with the cutter tip speed being approximately 50 MPH (73'
>>> per "second") and your feed speed being say 5' per "minute", a double
>>> feed rate of 10' per "minute", the ratio of feed to spin speed is still
>>> quite steep.
>>> I think the feed rate would have to be much higher, 100 peet per minute
>>> before the 1 cutter design would be more likely to take a huge bite than
>>> the 3 cutter design.
>>
>> At any given feed rate the single cutter is taking a larger bite.
>
> Which I do not dispute, given the cutter speed vs. feed rates the single
> cutter does remove more per revolution but certainly not 3 times
> "dangerous capacity". Regardless of which configuration is being used the
> cutters are not removing a large quantity of wood.
Leon, I think we are misinterperating each other somewhere.To hopefully make
things clearer we will exagerate things a bit. Material is being fed at a
constant rate. Keyword being constant, Regardless of that being 5" per hour
or 50mph. Lets say that the stock moves into the cutter 3/16" and the cutter
has done one revolotion. The 3 knife cutter has removed 3 X 1/16" chips
through this 1 revolution. The single knife has removed 1 X 3/16" chip. The
same amount of material is removed in either case. It is just the size of
the chip(s) that has varied.
>The feed rate would have to be close to the speed of the cutter head, "50
>mph" for the 3 to 1 capacity ratio to come into effect.
Regardless of the feed rate you still have one head cutting one chip per
revolution compared to the other cutting 3 small chips per revilution. You
can feed a 1000mph if you like the number of cuts per revolution does not
change. The one knife head will still cut one and the 3 knife head will
still cut 3 per revolution.
>More likely for each revolution and the typical feed rate, each triple
>cutter probably removes 1 or 2% of its capacity and the single probably
>removes 3 to 6% of its capacity
I'm sorry, maybe I am spinning in reverse, but i don't follow what you are
trying to say here. Per revolution each cutter should remove 100% of its
capacity. Three knife will revove 33.3% per cutter and the single tooth
100%. Either way you still get 100% cut. My previous 2 comments explain
this.
> I believe feed rate would have to be drastically increased before a
> significant increase in danger would be noticed between the 3 and single
> cutter head design.
Any increase in feedrate always generates larger cut regardless of number of
knives an thus increases risk of kickback. Refer previous comments on chip
size
> By comparison, a 30 tooth blade is not much more likely to cause a tragic
> problem than a 90 tooth blade.
>
That I agree with, but here you are talking a totally different cenario.
Thats like comparing a triangular or square wheel to a round wheel.There is
a major difference between 1 tooth going chunk, chunk, chunk compared to to
a 30 or 90 tooth saw blade running smoothly through a revolution.(once again
chip size) A 30 tooth blade is slightly more likely to cause kick back than
a 90 but it is a very very marginal ammount.
I hope that clears things up little.
In summary
Slower feed rate regardless of number of cutters means smaller chip size
which in turn means better finish and less danger.
Higher feedrate means larger chip size which means poorer finish and greater
danger.
More cutters at specific feedrate means smaller chip size which means better
quality finish and less danger of kickback.
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Paul D" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Leon" <[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Paul D" <[email protected]> wrote in message
>>> news:[email protected]...
>>>>
>>>> "Leon" <[email protected]> wrote in message
>>>> news:[email protected]...
>>>
>
>
> SNIP.
>
> LOL... I think we are probably on the same page here Paul. I am only
> trying to make the point that while a 3 cutter vs. a 1 cutter head
> probably makes a smoother cut, with a given constant recommended feed
> rate cutters on both units are most likely well within their capacity of
> making a safe cut.
> While your example of the amount removed ratio is correct, I suspect that
> the amount removed by either stile cutter head at operating rpm is in the
> low thousands of an inch per cutter pass. If the 3 cutter head is
> removing 10 thousandths per cutter the single cutter is removing 30
> thousandths.
I did say I was exagerating a bit. 3/16 was just a nice convenient figure to
work with. Maybe i shoul have went to 3/8 LOL
>
> That said, LOL, the single cutter is probably more likely to give a crisp
> clean cut than a 3 head cutter providing your feed rate is 1/3 that of the
> 3 cutter version.
I theory the single knife cutter head at 1/3 the feed rate should give
exactly the same quality of finish. I dont know about you but I am not
getting any younger and might not have enough time left to take 3 times as
long to do the same job
> I have the 3 head version and the cutters do not perfectly fit in
> alignment with each other. When I use the beading bit the resulting bead
> is not as perfectly formed as the profile on any single cutter. Because
> they do not register in perfect alignment on the head they each cut at a
> slightly different location resulting in a profile that is not exactly
> like any one cutter.
Any multi knife cutter suffers from the same problem. It is the combination
of the shape of the 2 or 3 knives whatever the case might be that determins
the final outcome. When hand grinding knives like I do it takes quite a
considerable number of years practice before you can grind a near perfect
set of knives so that they all do their fair share of work and are balanced.
Note I said near perfect. Although it is possible to make a perfectly
matched pair of knives freehand the time involved far outweighs the
benefits. I did do it once for a very special set of knives but you wouldn't
want to be paying me for the hours spent stoning / checking/ stoning /
checking .... and it goes on. At times this 'feature' is actually useful.
Lets say I am grinding a set of knives for a particular moulding to match
clients house and I accidently go a little deep in one spot .... woops ...
not to worry I just have to make sure that that particular spot on the other
knife is correct.
Just as a side point for anyone interested, grinding a set of knives to
match a particular moulding is not as simple as 'tracing' the shape onto the
cutter and grinding away. The shape has to be projected to take into account
the rake angle of the particular head you are using and the projection of
the knives. Set up those knives in the same head a second time but project
them out a little more or pull them back a bit and you will get a slightly
different shape on the moulding. Put those knives into another head with a
different rake angle and once again you get a slightly different shape
moulding. The difference is not that noticable to look at but don'y try to
mitre or butt join the two pieces together ... it will make you look like a
poor woodworker.
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Paul D" <[email protected]> wrote in message
> news:[email protected]...
>> Having done a lot of moulding work over the years I would not touch a
>> single cutter cutter head on that type of setup. I would sit down and
>> scrape the mould by hand using no more than a blunt butter knife rather
>> than use it.
>
> After doing that for several days on end, you might reconsider using the
> single cutter design. LOL
Doubt it I have lots of patients and besides if its achoice between somthing
taking a long time or having the hands to do it with, the hands wins hands
down
> If you have never seen one in operation, don't knock it.
Its asicly the same as set of collars with one knife and one blank except
larger.
>
>>It is possible that the head may be balanced with a counterweight opposite
>>the
> knife.
>
>
> Tthe counter ballance is more likely engenereed to be dynamically balanced
> like car tires are balanced. Counter balance weights are spread over an
> averaged out area in multiple spots so that minor variations are not so
> significant. Typical wheel weights on automobiles are placed in as many
> as 4 locations to off set the heavy spot when tires are staticly palanced.
> If a single weight is thrown off the unbalanced effect is much less
> dramatic than if a single weight is thrown off opposite the heavy spot.
>
>
> The only problem with this theory is how do you compensate for
>> different size/shape/projection/weight knives? I can not imagine how but
>> maybe the head is designed with a depth limiter to limit feed rates. If
>> it is not you are talking a major risk of kickback at that diameter and
>> speed.
The only practical option i see here that might wirk to allow for differing
weights/projections would be a fluid filled head working on the same
principle as an. automatic transmition torque converter,You must also
remember that increasing projection also upsets balance.
>
> Size and shape will not have any effect on balance if the cutter unit is
> balanced. Balance on a spinning object concerns weight, not shape or
> size.
I strongly disagree here. Change the weight or the amount of projection and
you affect balance considerably. For a spinning object to balance it must be
balanced at that particular configeration. Change that configeration and you
upset the balance.
> I strontly suspect that different shaped cutters made ofr a single head
> cutter will be shorter or longer so that different profiles each has equal
> mass regardless of shape.
Even at equal mass if one cutter projects further than another it will
affect balance.
> You would not want to run the cutter head with out a cutter in it or a 3
> cutter head with only 1 or 2 cutters in it.
>
>
>
>>
>> Although not a recomended practice but an accepted practice is to use
>> different shaped cutters on the same head at times on spindals (shapers).
>
> This would be a totally different situation and while it may be accepted,
> that is truely throwing the cutter head out of balance by introducing
> different weights in other locations.
So is changing the one cutter in a single cutter head
>
>> Occasionally for a one of run you might only grind 1 knife and just use a
>> blank on the opposite side. Whenever I do this I always have a rubber
>> lined 1/4" plate guard between me and the cutters. The rubber is to catch
>> the chips of the end of the cutter when it hits the guard. Even the
>> ammount of knife projection has a marked effect on the inbalance.On a
>> spindle we are only talking about a 3" head running on very heavy
>> bearings and shaft compared to the 8" you are talking on a TS on
>> relativly light bearings and smaller shaft.
>
> Again, if the single cutter is balanced the load on the bearings is a non
> issue.
that is true IF a single cutter is balanced.
>
>
> A spindle running collars runs at around 4000rpm, 4500 is
>> the maximum recomended for that type of cutter. That gives a spindle
>> cutter a surface speed of 4,188'/Min (4,712'/Min at max) allowing 1/2"
>> projection for cutter. Assuming 8" moulding head on TS you are looking at
>> 7,200'/Min.surface speed with no cutter projection. On a spindle even if
>> the knives are roughly the same size the ammount of vibration due to the
>> inbalance is incredible.
>
> Again, a single cutter head cutter will be balanced so vibration will not
> be as great as you make it out to be.
Unless it has some form of dynamic balancing that will 'adjust' itself on
the run it will not balance with varying knives
> A cutter does not have to be perfecetly symetrical to be balanced.
No it does not. I have some knives which are different but designed to run
as a pair. But the design of knives in this situation takes considerable
design considerations taking into account weight distribution in relation to
projection to compensate for varying shapes and centrifigal force.
>
> And needless to say the risk of throwing a knife
>> and kickback increases dramaticly as well as lower quality finish.
>
> While I'll bite at the possiblilty of a kick back providing your feed rate
> is "much faster" than recomended , the increase chance of throwing a knife
> is non existant when copmpared to a 3, 12 , or 90 tooth cutter.
Sorry I do not follow your point there. The increased risk of throwing a
knife is due to the inbalance, nothing to do with the number of knives
> Think about single flute router bits that spin at 25,000 rpm. It's all
> about balance when it comes to spinning irregular shaped objects.
>
Thats right ... weight is distributed equally in any direction from centre,
bit is balanced although oposing sides are different. Now lets take that
same router bit and grind or break half the carbide tip of ( simulating
changing cutter shape) ...... woops what happened to that perfectly balanced
bit.
>
>
>
>
"Paul D" <[email protected]> wrote in message
news:[email protected]...
>
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>
> Its asicly the same as set of collars with one knife and one blank except
> larger.
No, I would say that the cutter head is weighted to compensate for the
weight of a cutter and all cutters for that head are of the same weight.
>
> The only practical option i see here that might wirk to allow for
> differing weights/projections would be a fluid filled head working on the
> same principle as an. automatic transmition torque converter,You must also
> remember that increasing projection also upsets balance.
Increasing projection will up set balance if the changing
projection remains the same weight.
>> Size and shape will not have any effect on balance if the cutter unit
>> is balanced. Balance on a spinning object concerns weight, not shape or
>> size.
>
> I strongly disagree here. Change the weight or the amount of projection
> and you affect balance considerably. For a spinning object to balance it
> must be balanced at that particular configeration. Change that
> configeration and you upset the balance.
Correct if the projection changes after the balance has been made. Differnt
projections would have to be made heavier or lighter to compensate for their
changes.
>
>> I strontly suspect that different shaped cutters made ofr a single head
>> cutter will be shorter or longer so that different profiles each has
>> equal mass regardless of shape.
>
> Even at equal mass if one cutter projects further than another it will
> affect balance.
Correct. That is why the cutter with another projection would have to be
made lighter or heavier to maintain the blaance. Add or take away length.
>
>> You would not want to run the cutter head with out a cutter in it or a 3
>> cutter head with only 1 or 2 cutters in it.
>>
>>
>>
>>>
>>> Although not a recomended practice but an accepted practice is to use
>>> different shaped cutters on the same head at times on spindals
>>> (shapers).
>>
>> This would be a totally different situation and while it may be accepted,
>> that is truely throwing the cutter head out of balance by introducing
>> different weights in other locations.
>
> So is changing the one cutter in a single cutter head
Ok, you are assuming that all cutters for the single cutter head are not
tuned for that particular cutter head.
>
>>
>>> Occasionally for a one of run you might only grind 1 knife and just use
>>> a blank on the opposite side. Whenever I do this I always have a rubber
>>> lined 1/4" plate guard between me and the cutters. The rubber is to
>>> catch the chips of the end of the cutter when it hits the guard. Even
>>> the ammount of knife projection has a marked effect on the inbalance.On
>>> a spindle we are only talking about a 3" head running on very heavy
>>> bearings and shaft compared to the 8" you are talking on a TS on
>>> relativly light bearings and smaller shaft.
>>
>> Again, if the single cutter is balanced the load on the bearings is a non
>> issue.
>
> that is true IF a single cutter is balanced.
>
>>
>>
>> A spindle running collars runs at around 4000rpm, 4500 is
>>> the maximum recomended for that type of cutter. That gives a spindle
>>> cutter a surface speed of 4,188'/Min (4,712'/Min at max) allowing 1/2"
>>> projection for cutter. Assuming 8" moulding head on TS you are looking
>>> at 7,200'/Min.surface speed with no cutter projection. On a spindle even
>>> if the knives are roughly the same size the ammount of vibration due to
>>> the inbalance is incredible.
>>
>> Again, a single cutter head cutter will be balanced so vibration will not
>> be as great as you make it out to be.
>
> Unless it has some form of dynamic balancing that will 'adjust' itself on
> the run it will not balance with varying knives
>
>> A cutter does not have to be perfecetly symetrical to be balanced.
>
> No it does not. I have some knives which are different but designed to run
> as a pair. But the design of knives in this situation takes considerable
> design considerations taking into account weight distribution in relation
> to projection to compensate for varying shapes and centrifigal force.
>
>>
>> And needless to say the risk of throwing a knife
>>> and kickback increases dramaticly as well as lower quality finish.
>>
>> While I'll bite at the possiblilty of a kick back providing your feed
>> rate is "much faster" than recomended , the increase chance of throwing a
>> knife is non existant when copmpared to a 3, 12 , or 90 tooth cutter.
>
> Sorry I do not follow your point there. The increased risk of throwing a
> knife is due to the inbalance, nothing to do with the number of knives
This cutter head that we are discussing has been around for a long time.
There have been no complaints of there being a vibration or balance problem
that I have ever heard of. This is not all theory, the tools exist and run
with out exagerated vibration.
>
>> Think about single flute router bits that spin at 25,000 rpm. It's all
>> about balance when it comes to spinning irregular shaped objects.
>>
> Thats right ... weight is distributed equally in any direction from
> centre, bit is balanced although oposing sides are different. Now lets
> take that same router bit and grind or break half the carbide tip of (
> simulating changing cutter shape) ...... woops what happened to that
> perfectly balanced bit.
We are both beating our heads against a brick wall here. ;~)
The tool exists and has for many years. Apparently it works.
>>> I've had the 3 head unit from Craftsman for about 35 years and recall
>>> that they sold the single head at that time as well. The three head
>>> cutter (on a RAS, no less) ........
Yeah -- Old memories. My cousin was cutting moulding with a Craftsman
3-blader many years ago on a RAS. He felt a thud on one hand and looked
down at his shirt which was covered with blood, tissue and bone fragments.
You can guess the rest. The damage was limited to the end of one finger
above the joint.
The surgery and recoup from trying to restore part of the fingertip was
almost worse than the injury itself. Horrible looking mess. He was a union
utility worker at the time and had to have all of his digets in working
order.
He is a talented woodworker to this day but the old RAS, and moulding head
is ancient history to him.
RonB
RonB
"Arvid Sorsdahl" <[email protected]> wrote in message
news:[email protected]...
> Now maybe you should compare the energy of the 200 grain bullet with the
> weight of the cutter and compare the total energy of both?
That's not necessary. The comments you are replying to were simply in
response to the preceding comment which speculated that the speed of a
cutter coming off would approximate the speed of a 30-06 bullet.
--
-Mike-
[email protected]
"Arvid Sorsdahl" <[email protected]> wrote in message
news:[email protected]...
> Now maybe you should compare the energy of the 200 grain bullet with the
> weight of the cutter and compare the total energy of both?
Well you have probably 400 grain for the cutter. Its not brass and lead
like the bullet so it is going to be larger on the size to weight ratio.
Then a 200 grain bullet is probably going to be coming out of a more
powerful gun with a muzzle velocity of about 15 to 20 times more speed than
the molding head cutter.
What do you think? The object is 2 or 3 times heavier but 15 to 20 time
slower speed.
"Jim" <[email protected]> wrote in message
news:[email protected]...
> Hello,new here but seems strange that tommorow I will be using the
> cutter head (3) again and yes I am afraid of it, the weird noise and
> the wind it makes. Although have you tried it on a radial arm? Now
> that is spooky but hey by the end of this year I will have the router
> completely set up, and I feel fairly safe with the router. Have a good
> evening
I too would prefer a router or a shaper for the job, but that's because I
generally try to stay away from tools that have been adapted to a secondary
use. Having said that, if you think about the speed of your router and the
speed of your table saw, and you throw in the fact that routers have been
known to throw carbide (especially with cheap bits), you might be more
concerned about that router. It's typically somewhere near 3 to 6 times
faster than that table saw blade.
--
-Mike-
[email protected]
"Lew Hodgett" <[email protected]> wrote in message
> > buying? How does it compare to the typical 3 blade head?
>
> SFWIW, I threw my Craftsman set, unused, in the trash years ago.
Har! I never used the set I bought 30 years ago. I'm sure it's around here
somewhere, but damned if I know where.
"Charley" <[email protected]> wrote in message
news:[email protected]...
> It is absolutely necessary that the molding head is balanced when it is
> running. I've never heard of a one cutter molding head, so I suspect that
> it's a 2 cutter molding head with one cutter missing. DON'T USE IT, until
> you are absolutely sure that it's got all of the knives in place that it's
> supposed to, and make absolutely sure that all of the knives are properly
> secured in place before you even put it on your saw. Even then, always
> stand
> well out of line of it when you turn the saw on, as these molding heads
> have
> been known to throw a knife occasionally.
Craftsman had the 1 cutter version also. The cutter head that that cutter
fits into is not perfectly round and compensates of the single cutter.
"Jo" <[email protected]> wrote in message
news:[email protected]...
>>
>>
>
> Craftsman.
Not the best brand but it will do the job. Be very careful, use guards,
and feed very slowly with hold down and push sticks. Wear eye protection
and preferabley a face mask.
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>
"Mike Marlow" <[email protected]> wrote in message
news:[email protected]...
>
> "Arvid Sorsdahl" <[email protected]> wrote in message
> news:[email protected]...
>
>> Now maybe you should compare the energy of the 200 grain bullet with the
>> weight of the cutter and compare the total energy of both?
>
> That's not necessary. The comments you are replying to were simply in
> response to the preceding comment which speculated that the speed of a
> cutter coming off would approximate the speed of a 30-06 bullet.
Still I would much rather be hit by that cutter then the 30-06 bullet .
"Paul D" <[email protected]> wrote in message
news:[email protected]...
>
> Any multi knife cutter suffers from the same problem. It is the
> combination of the shape of the 2 or 3 knives whatever the case might be
> that determins the final outcome. When hand grinding knives like I do it
> takes quite a considerable number of years practice before you can grind a
> near perfect set of knives so that they all do their fair share of work
> and are balanced. Note I said near perfect. Although it is possible to
> make a perfectly matched pair of knives freehand the time involved far
> outweighs the benefits. I did do it once for a very special set of knives
> but you wouldn't want to be paying me for the hours spent stoning /
> checking/ stoning / checking .... and it goes on. At times this 'feature'
> is actually useful. Lets say I am grinding a set of knives for a
> particular moulding to match clients house and I accidently go a little
> deep in one spot .... woops ... not to worry I just have to make sure that
> that particular spot on the other knife is correct.
You know, I never really noticed whether the grind was identical on the 3
knife cutters that I have. I did notice however that none of the cutters
would seat in the same position on the cutter head. Tightening the set
screw would often nudge the cutter a bit. And now you throw in the fact
that cuter knives are not always perfect. LOL
Leon, wrote the following at or about 3/27/2007 3:46 PM:
> "Toller" <[email protected]> wrote in message
> news:[email protected]...
>> "Charley" <[email protected]> wrote in message
>> news:[email protected]...
>>> It is absolutely necessary that the molding head is balanced when it is
>>> running. I've never heard of a one cutter molding head, so I suspect that
>>> it's a 2 cutter molding head with one cutter missing.
>> No, they do make them. Presumably they are balanced more or less
>> properly.
>> But 3 cutter heads are dangerous enough; using a 1 cutter would be crazy.
>>
>
> Could you explain how 1 cutter would be crazy?
Not sure that it would necessarily be crazy but I think it might be a
bit more prone to get a bit too much material in there, a bit too
quickly and watch it (hopefully that's all) go flying.
Three bits, means you're removing the material 3x faster. This makes
for a smoother finish. It also means that at a given feed rate it will
remove 3x the material. Just seems that it would be more likely, with
one cutter, to be able to feed a bit much in and wind up with a big
ker-chunk and a load of splinters flying or the whole damn thing taking
off on you.
I've had the 3 head unit from Craftsman for about 35 years and recall
that they sold the single head at that time as well. The three head
cutter (on a RAS, no less) and set up with proper guards, fencing,
feather boards, etc. is pretty scary.
It does a nice job if you take your time on setup and feed slow. One
thing you won't like get is complacency when using that puppy. It seems
to provide its own wake-up call every time you power up<g>
You both have stated it somewhat differently but you both were saying the
same thing. All else being equal, the chip load on the single flute cutter
is greater.
"Leon" <[email protected]> wrote in message
news:[email protected]...
>
> "Paul D" <[email protected]> wrote in message
> news:[email protected]...
> >
> > "Leon" <[email protected]> wrote in message
> > news:[email protected]...
> >>
> >> "Paul D" <[email protected]> wrote in message
> >> news:[email protected]...
> >>>
> >>> "Leon" <[email protected]> wrote in message
> >>> news:[email protected]...
> >>
>
>
> SNIP.
>
> LOL... I think we are probably on the same page here Paul. I am only
trying
> to make the point that while a 3 cutter vs. a 1 cutter head probably makes
a
> smoother cut, with a given constant recommended feed rate cutters on both
> units are most likely well within their capacity of making a safe cut.
> While your example of the amount removed ratio is correct, I suspect that
> the amount removed by either stile cutter head at operating rpm is in the
> low thousands of an inch per cutter pass. If the 3 cutter head is
removing
> 10 thousandths per cutter the single cutter is removing 30 thousandths.
>
> That said, LOL, the single cutter is probably more likely to give a crisp
> clean cut than a 3 head cutter providing your feed rate is 1/3 that of the
3
> cutter version.
> I have the 3 head version and the cutters do not perfectly fit in
alignment
> with each other. When I use the beading bit the resulting bead is not as
> perfectly formed as the profile on any single cutter. Because they do
not
> register in perfect alignment on the head they each cut at a slightly
> different location resulting in a profile that is not exactly like any one
> cutter.
>
>
"Mike Marlow" <[email protected]> wrote in message
news:[email protected]...
>
> Not even close to the same neighborhood. In fact, the table saw isn't
> even
> close to the lead sled speed of a .45ACP.
>
CORRECT. LOL And the 22 caliber is 7 times faster than a 10" TS blade tip
and only 2/3's the muzzle velocity of a 45.
"Unquestionably Confused" <[email protected]> wrote in message
news:[email protected]...
>
> Not sure that it would necessarily be crazy but I think it might be a bit
> more prone to get a bit too much material in there, a bit too quickly and
> watch it (hopefully that's all) go flying.
I have had the 3 head set for almost that long. LOL Since 1978 IIRC.
> Three bits, means you're removing the material 3x faster. This makes for
> a smoother finish. It also means that at a given feed rate it will remove
> 3x the material.
I agree with probably a smoother finish but at a given feed rate, the
material removal would be the same on either the 1 or 3 cutter design. The
single cutter would actually be removing more material at that given feed
rate.
Just seems that it would be more likely, with
> one cutter, to be able to feed a bit much in and wind up with a big
> ker-chunk and a load of splinters flying or the whole damn thing taking
> off on you.
Perhaps so but with the cutter tip speed being approximately 50 MPH (73' per
"second") and your feed speed being say 5' per "minute", a double feed rate
of 10' per "minute", the ratio of feed to spin speed is still quite steep.
I think the feed rate would have to be much higher, 100 peet per minute
before the 1 cutter design would be more likely to take a huge bite than the
3 cutter design.
> I've had the 3 head unit from Craftsman for about 35 years and recall that
> they sold the single head at that time as well. The three head cutter (on
> a RAS, no less) and set up with proper guards, fencing, feather boards,
> etc. is pretty scary.
Yeah I had this set up on a RAS also.
> It does a nice job if you take your time on setup and feed slow. One
> thing you won't like get is complacency when using that puppy. It seems
> to provide its own wake-up call every time you power up<g>
>
I absolutely agree. ;~)
In article <[email protected]>, "Charley" <[email protected]> wrote:
>It is absolutely necessary that the molding head is balanced when it is
>running. I've never heard of a one cutter molding head, so I suspect that
>it's a 2 cutter molding head with one cutter missing.
Don't you think he'd notice if there was a cutter missing?
In fact, there is such a thing as a one-cutter head. Sears used to sell
one, but it seems they don't any more. It's not perfectly circular; there are
strategically-placed flat spots to keep it balanced.
Somebody sold one on eBay recently:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200086210874
Pic shows both 1-blade and 3-blade Sears molding heads.
FWIW... I've never heard of a 2-cutter molding head. All I've ever seen is 1-
and 3-cutter heads.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
"Paul D" <[email protected]> wrote in message
news:[email protected]...
>
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "Paul D" <[email protected]> wrote in message
>> news:[email protected]...
>>>
>>> "Leon" <[email protected]> wrote in message
>>> news:[email protected]...
>>
SNIP.
LOL... I think we are probably on the same page here Paul. I am only trying
to make the point that while a 3 cutter vs. a 1 cutter head probably makes a
smoother cut, with a given constant recommended feed rate cutters on both
units are most likely well within their capacity of making a safe cut.
While your example of the amount removed ratio is correct, I suspect that
the amount removed by either stile cutter head at operating rpm is in the
low thousands of an inch per cutter pass. If the 3 cutter head is removing
10 thousandths per cutter the single cutter is removing 30 thousandths.
That said, LOL, the single cutter is probably more likely to give a crisp
clean cut than a 3 head cutter providing your feed rate is 1/3 that of the 3
cutter version.
I have the 3 head version and the cutters do not perfectly fit in alignment
with each other. When I use the beading bit the resulting bead is not as
perfectly formed as the profile on any single cutter. Because they do not
register in perfect alignment on the head they each cut at a slightly
different location resulting in a profile that is not exactly like any one
cutter.
"Leon" <[email protected]> wrote in
news:[email protected]:
>
> "Jo" <[email protected]> wrote in message
> news:[email protected]...
>> Hi,
>>
>> I never have any experience with Table Saw Molding Head, maybe the
>> experts in this forum could give their opinion.
>>
>> I saw a tabl saw molding head with one blade. Is it good? Would it
>> worth buying? How does it compare to the typical 3 blade head?
>
> What brand? I saw a sewing machine that was electric, is it good?
>
> A 3 cutter head will last longer.
>
>
>
>
Craftsman.
--
Posted via a free Usenet account from http://www.teranews.com
"Toller" <[email protected]> wrote in message
news:[email protected]...
>
> "Charley" <[email protected]> wrote in message
> news:[email protected]...
>> It is absolutely necessary that the molding head is balanced when it is
>> running. I've never heard of a one cutter molding head, so I suspect that
>> it's a 2 cutter molding head with one cutter missing.
>
> No, they do make them. Presumably they are balanced more or less
> properly.
> But 3 cutter heads are dangerous enough; using a 1 cutter would be crazy.
>
Could you explain how 1 cutter would be crazy?
"Charley" <[email protected]> wrote in message
news:[email protected]...
> ......... Even then, always stand well out of line of it when you turn the
> saw on, as these molding heads have been known to throw a knife
> occasionally.
>
Yeah - I have occasionally been tempted to calculate the tip speed of the
cutters running on my table saw and compare it to a 30-06. I'll bet they
are in the same neighborhood if one came off. Like I said earlier, mine is
on the shelf but doesn't get a lot of use.
Of course you could say the same about other tools.
RonB
RonB
"Paul D" <[email protected]> wrote in message
news:[email protected]...
>
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>>
>> "RonB" <[email protected]> wrote in message
>> news:[email protected]...
>>>> No, the tip speed on you TS is no where near a 30-06, or a 22 for that
>>>> matter. The typical 10" blade turns at about 3600 rpm. The blade is
>>>> 31.4 inches around or 2.61 feet around. 2.61' x 3600 + 9420' per
>>>> minute. That comes out to about 107 MPH. IIRC the typical 22 has a
>>>> muzzle velocity of around 1100 feet per second and that comes out to
>>>> about 7 times faster. A 30-06 with a 150 grain bullet travels at about
>>>> 2700 feet per second or about 17 times faster than your saw blade. If
>>>> you are spinning a smaller diameter dado or molding cutter the tip
>>>> speed would be slower than the 10" blade.
>>>>
>>>
>>> It would still earn you a trip to the emergency room - or worse.
>>
>> If the whole cutter came loose and hit you I would agree. If a small
>> fragment came loose, probably not.
>>>
>>>
>>
>>
> Although it would be a relativly small hole at those speeds it would go
> straight throug you assuming you hit no bone. Assuming also you have hit
> no major organs I hope you keep at least 2 band aids in your safety kit.
Naw. The fragment might cut you cut certainly not go through you. I have
been hit by fragments of wood many times thought the years and they mostly
bounce off. And while that is only wood, I have also had fragments of
carbide go flying also and never see any signs of it hitting anything.
Do you think a pro baseball pitcher could throw a small fragment of carbide
hard enough to go through your arm or hand? Not likely and he can throw
pretty much as fast as the tip speed op a 10" blade on a TS.
I have had a fragment of a 22 bullet hit me and it did not penetrate
although I did receive a red spot.
There simply is not enough mass to overcome the resistance.
Now if a whole tooth or cutter came loose, that would be a different story,
still I don't think it would go through you as a 22 bullet seldom goes
through at speeds 7 time faster.
"Paul D" <[email protected]> wrote in message
news:[email protected]...
>
> "Leon" <[email protected]> wrote in message
> news:[email protected]...
>>
>> I agree with probably a smoother finish but at a given feed rate, the
>> material removal would be the same on either the 1 or 3 cutter design.
>> The single cutter would actually be removing more material at that given
>> feed rate.
>
> THe single cutter at a continuous feed rate would remove the same ammount
> ......BUT ... the 3 cutter removes it in 3 smaller chips as opposed to one
> large one giving much better quality finish.
What I was trying to get at was that the single cutter removes more "per
cutter" than the 3 cutter design at any given rate.
>> Just seems that it would be more likely, with
>>> one cutter, to be able to feed a bit much in and wind up with a big
>>> ker-chunk and a load of splinters flying or the whole damn thing taking
>>> off on you.
>>
>> Perhaps so but with the cutter tip speed being approximately 50 MPH (73'
>> per "second") and your feed speed being say 5' per "minute", a double
>> feed rate of 10' per "minute", the ratio of feed to spin speed is still
>> quite steep.
>> I think the feed rate would have to be much higher, 100 peet per minute
>> before the 1 cutter design would be more likely to take a huge bite than
>> the 3 cutter design.
>
> At any given feed rate the single cutter is taking a larger bite.
Which I do not dispute, given the cutter speed vs. feed rates the single
cutter does remove more per revolution but certainly not 3 times "dangerous
capacity". Regardless of which configuration is being used the cutters are
not removing a large quantity of wood. The feed rate would have to be close
to the speed of the cutter head, "50 mph" for the 3 to 1 capacity ratio to
come into effect. More likely for each revolution and the typical feed
rate, each triple cutter probably removes 1 or 2% of its capacity and the
single probably removes 3 to 6% of its capacity.
I believe feed rate would have to be drastically increased before a
significant increase in danger would be noticed between the 3 and single
cutter head design.
By comparison, a 30 tooth blade is not much more likely to cause a tragic
problem than a 90 tooth blade.
"RonB" <[email protected]> wrote in message
news:[email protected]...
>
> "Charley" <[email protected]> wrote in message
> news:[email protected]...
>> ......... Even then, always stand well out of line of it when you turn
>> the saw on, as these molding heads have been known to throw a knife
>> occasionally.
>>
>
> Yeah - I have occasionally been tempted to calculate the tip speed of the
> cutters running on my table saw and compare it to a 30-06. I'll bet they
> are in the same neighborhood if one came off. Like I said earlier, mine
> is on the shelf but doesn't get a lot of use.
No, the tip speed on you TS is no where near a 30-06, or a 22 for that
matter. The typical 10" blade turns at about 3600 rpm. The blade is 31.4
inches around or 2.61 feet around. 2.61' x 3600 + 9420' per minute. That
comes out to about 107 MPH. IIRC the typical 22 has a muzzle velocity of
around 1100 feet per second and that comes out to about 7 times faster. A
30-06 with a 150 grain bullet travels at about 2700 feet per second or about
17 times faster than your saw blade. If you are spinning a smaller diameter
dado or molding cutter the tip speed would be slower than the 10" blade.
"RonB" wrote
>
> Yeah - I have occasionally been tempted to calculate the tip speed of the
> cutters running on my table saw and compare it to a 30-06. I'll bet they
> are in the same neighborhood if one came off.
I had a safety freak shop teacher in high school who used ask questions on
his tests of how many times a tool could hit you or cut you before the
signal would reach the brain to react. The big damage is done long before
you pull the hand away.
Fast moving metal and flesh are not compatable.
"RonB" <[email protected]> wrote in message
news:[email protected]...
>> No, the tip speed on you TS is no where near a 30-06, or a 22 for that
>> matter. The typical 10" blade turns at about 3600 rpm. The blade is
>> 31.4 inches around or 2.61 feet around. 2.61' x 3600 + 9420' per minute.
>> That comes out to about 107 MPH. IIRC the typical 22 has a muzzle
>> velocity of around 1100 feet per second and that comes out to about 7
>> times faster. A 30-06 with a 150 grain bullet travels at about 2700 feet
>> per second or about 17 times faster than your saw blade. If you are
>> spinning a smaller diameter dado or molding cutter the tip speed would be
>> slower than the 10" blade.
>>
>
> It would still earn you a trip to the emergency room - or worse.
If the whole cutter came loose and hit you I would agree. If a small
fragment came loose, probably not.
>
>
On 27 Mar 2007 05:51:07 GMT, Jo <[email protected]> wrote:
>Hi,
>
>I never have any experience with Table Saw Molding Head, maybe the experts
>in this forum could give their opinion.
>
>I saw a tabl saw molding head with one blade. Is it good? Would it worth
>buying? How does it compare to the typical 3 blade head?
>
>Thanks in advance for any opinion given.
>
>Best Regards,
>Jo
Before I had a properly tooled shaper I used a three knife molding
cutterhead quite a bit with a great deal of success. never used , nor
even have seen, a single knife cutter.
The downside to molding cutterhead is low surface speed, I would say,
and because of it , controlling tearout is much more difficult. You
can get acceptable results, however if you are careful about backing
your cut and use slow feed rates. At least that was my experience.
---
In article <[email protected]>, RonB <[email protected]> wrote:
<...snipped...>
>
>Yeah - I have occasionally been tempted to calculate the tip speed of the
>cutters running on my table saw and compare it to a 30-06. I'll bet they
>are in the same neighborhood if one came off. Like I said earlier, mine is
>on the shelf but doesn't get a lot of use.
>
>Of course you could say the same about other tools.
>
If you do the math, you'll find that it's not even close. The speed at
the teeth of a sawblade at normal RPM is comparable to a car on freeway,
no where near even a handgun bullet speed, let alone a 30-06. Still,
plenty fast enough to cause serious injury.
--
There are no stupid questions, but there are lots of stupid answers.
Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
"Paul D" <[email protected]> wrote in message
news:[email protected]...
> Having done a lot of moulding work over the years I would not touch a
> single cutter cutter head on that type of setup. I would sit down and
> scrape the mould by hand using no more than a blunt butter knife rather
> than use it.
After doing that for several days on end, you might reconsider using the
single cutter design. LOL
If you have never seen one in operation, don't knock it.
>It is possible that the head may be balanced with a counterweight opposite
>the
knife.
Tthe counter ballance is more likely engenereed to be dynamically balanced
like car tires are balanced. Counter balance weights are spread over an
averaged out area in multiple spots so that minor variations are not so
significant. Typical wheel weights on automobiles are placed in as many as
4 locations to off set the heavy spot when tires are staticly palanced. If
a single weight is thrown off the unbalanced effect is much less dramatic
than if a single weight is thrown off opposite the heavy spot.
The only problem with this theory is how do you compensate for
> different size/shape/projection/weight knives? I can not imagine how but
> maybe the head is designed with a depth limiter to limit feed rates. If it
> is not you are talking a major risk of kickback at that diameter and
> speed.
Size and shape will not have any effect on balance if the cutter unit is
balanced. Balance on a spinning object concerns weight, not shape or size.
I strontly suspect that different shaped cutters made ofr a single head
cutter will be shorter or longer so that different profiles each has equal
mass regardless of shape.
You would not want to run the cutter head with out a cutter in it or a 3
cutter head with only 1 or 2 cutters in it.
>
> Although not a recomended practice but an accepted practice is to use
> different shaped cutters on the same head at times on spindals (shapers).
This would be a totally different situation and while it may be accepted,
that is truely throwing the cutter head out of balance by introducing
different weights in other locations.
> Occasionally for a one of run you might only grind 1 knife and just use a
> blank on the opposite side. Whenever I do this I always have a rubber
> lined 1/4" plate guard between me and the cutters. The rubber is to catch
> the chips of the end of the cutter when it hits the guard. Even the
> ammount of knife projection has a marked effect on the inbalance.On a
> spindle we are only talking about a 3" head running on very heavy bearings
> and shaft compared to the 8" you are talking on a TS on relativly light
> bearings and smaller shaft.
Again, if the single cutter is balanced the load on the bearings is a non
issue.
A spindle running collars runs at around 4000rpm, 4500 is
> the maximum recomended for that type of cutter. That gives a spindle
> cutter a surface speed of 4,188'/Min (4,712'/Min at max) allowing 1/2"
> projection for cutter. Assuming 8" moulding head on TS you are looking at
> 7,200'/Min.surface speed with no cutter projection. On a spindle even if
> the knives are roughly the same size the ammount of vibration due to the
> inbalance is incredible.
Again, a single cutter head cutter will be balanced so vibration will not be
as great as you make it out to be.
A cutter does not have to be perfecetly symetrical to be balanced.
And needless to say the risk of throwing a knife
> and kickback increases dramaticly as well as lower quality finish.
While I'll bite at the possiblilty of a kick back providing your feed rate
is "much faster" than recomended , the increase chance of throwing a knife
is non existant when copmpared to a 3, 12 , or 90 tooth cutter.
Think about single flute router bits that spin at 25,000 rpm. It's all
about balance when it comes to spinning irregular shaped objects.
Toller said this, remember.
"Leon" <[email protected]> wrote in message
news:[email protected]...
> >
>
> Could you explain how 1 cutter would be crazy?
>
>
On Tue, 27 Mar 2007 20:46:47 GMT, "Leon"
<[email protected]> wrote:
>
>"Toller" <[email protected]> wrote in message
>news:[email protected]...
>>
>> "Charley" <[email protected]> wrote in message
>> news:[email protected]...
>>> It is absolutely necessary that the molding head is balanced when it is
>>> running. I've never heard of a one cutter molding head, so I suspect that
>>> it's a 2 cutter molding head with one cutter missing.
>>
>> No, they do make them. Presumably they are balanced more or less
>> properly.
>> But 3 cutter heads are dangerous enough; using a 1 cutter would be crazy.
>>
>
>Could you explain how 1 cutter would be crazy?
>
Maybe not crazy, but not as safe as a perfectly balanced molding head.
The more balanced the the cutter head, the less vibration. A
well-balanced blade assembly will give you a cleaner cut too.
"Jo" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> I never have any experience with Table Saw Molding Head, maybe the experts
> in this forum could give their opinion.
>
> I saw a tabl saw molding head with one blade. Is it good? Would it worth
> buying? How does it compare to the typical 3 blade head?
What brand? I saw a sewing machine that was electric, is it good?
A 3 cutter head will last longer.
In article <[email protected]>, "RonB" <[email protected]> wrote:
>Yeah - I have occasionally been tempted to calculate the tip speed of the
>cutters running on my table saw and compare it to a 30-06. I'll bet they
>are in the same neighborhood if one came off.
Not even close, actually. Following is a very rough approximation:
Typical molding head has a diameter of 7 or 8 inches. Circumference then is
about two feet. 2' x 4500 rpm = 9000 fpm = 150 fps or about 100mph.
Much too fast to dodge, but nowhere near the muzzle velocity of any rifle.
--
Regards,
Doug Miller (alphageek at milmac dot com)
It's time to throw all their damned tea in the harbor again.
"Charley" <[email protected]> wrote in message
news:[email protected]...
> It is absolutely necessary that the molding head is balanced when it is
> running. I've never heard of a one cutter molding head, so I suspect that
> it's a 2 cutter molding head with one cutter missing.
No, they do make them. Presumably they are balanced more or less properly.
But 3 cutter heads are dangerous enough; using a 1 cutter would be crazy.
"Arvid Sorsdahl" <[email protected]> wrote in message
news:[email protected]...
> The thing is you might not have control over some nut with an 06 but you
> do have control over what kind of tool you buy or how you use it.
Huh?
Personally, I have never heard of a one-blade moulding head. I have had a
three-blade cutter for 30 years. It used to get a fair amount of use but
bigger, better routers and router bits seem to be replacing it,
The three-blader can do a fairly good job if you feed slowly. Remember that
most routers are running in the 18,000 to 22,000 rpm range. A shaper (which
the moulding head is trying to simulate) also runs quite a bit faster than
your table saw, which is in the 3,000-4,000 rpm range. If you start
shallow, and work up to final cutting depth, and feed slowly then can do the
job - but not as well as the router or shaper. I would approach a one head
cutter with a fair amount of caution.
RonB
"Jo" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> I never have any experience with Table Saw Molding Head, maybe the experts
> in this forum could give their opinion.
>
> I saw a tabl saw molding head with one blade. Is it good? Would it worth
> buying? How does it compare to the typical 3 blade head?
>
> Thanks in advance for any opinion given.
>
> Best Regards,
> Jo
>
> --
> Posted via a free Usenet account from http://www.teranews.com
>