I don't use a router often but recently I dusted both of mine off and
got a surprise. I was using a 1-1/4-inch x 1/4-inch shank flush trim
bit and I thought my router was broken.
But after some routing and closer inspection I found that the bit just
isn't stiff enough at top speed to remain straight. It is easy to see
it and when I tried to use it it was easy to feel it and hear it. It
caused the whole router to vibrate and caused a lot of chatter. I tried
in the other router and the same thing but to a lesser amount. I've got
a bit that has a 1/2-inch shank and finished what I needed.
Two things occurred to me.
1 the bit has two bearings and they both need to rest on the material
i wasn't doing that because the bit's longer than the material's
thick But even so a router bit needs to remain straight and stiff
and this doesn't at ~23,000/rpm
2 1/4-inch shank is not the way to go for a flush trim bit, needs
to be a 1/2-inch shank to maintain proper stiffness and avoid
the horrible deflection.
maybe it'd be ok at lower rpm but both routers are full on or
off
On Saturday, February 14, 2015 at 6:23:49 PM UTC-6, Electric Comet wrote:
>=20
> But after some routing and closer inspection I found that the bit just
> isn't stiff enough at top speed to remain straight.=20
> Two things occurred to me.
>=20
But even so a router bit needs to remain straight and stiff
> and this doesn't at ~23,000/rpm
>=20
At the point the shaft is no longer straight, i.e., where it meets the bit =
aspect, there is a slight curved "lip". If you sink your shaft all the wa=
y down to the collet, the collet will/may catch on that lip, rather than fu=
lly grasping onto the straight part of the shaft. If this happens, the re=
sults will/could be a misaligned bit and, hence, vibration. When this hap=
pens, your bit could possibly become loose from the collet's grasp, sending=
your bit flying.
Try not to sink your bit's shaft all the way down to the collet, hence avoi=
ding the collet grabbing onto that lip.
Sonny
On 2/14/2015 8:26 PM, Sonny wrote:
> On Saturday, February 14, 2015 at 6:23:49 PM UTC-6, Electric Comet wrote:
>>
>> But after some routing and closer inspection I found that the bit just
>> isn't stiff enough at top speed to remain straight.
>> Two things occurred to me.
>>
> But even so a router bit needs to remain straight and stiff
>> and this doesn't at ~23,000/rpm
>>
>
> At the point the shaft is no longer straight, i.e., where it meets the bit aspect, there is a slight curved "lip". If you sink your shaft all the way down to the collet, the collet will/may catch on that lip, rather than fully grasping onto the straight part of the shaft. If this happens, the results will/could be a misaligned bit and, hence, vibration. When this happens, your bit could possibly become loose from the collet's grasp, sending your bit flying.
>
> Try not to sink your bit's shaft all the way down to the collet, hence avoiding the collet grabbing onto that lip.
>
> Sonny
>
+2
--
Jeff
On 2/16/2015 10:53 AM, Electric Comet wrote:
> On Mon, 16 Feb 2015 10:40:19 -0600
> Leon <lcb11211@swbelldotnet> wrote:
>
>> A two bearing bit, top and bottom, is a convenience thing. It is
>> some times easier to use one or the other depending on the
>> orientation of the bit to the work and or pattern.
>> Typically a straight cut bit with a bearing is a flush cut bit.
>
> I've not seen a straight cut bit with a bearing at top only so
> the definition should be a straight cut bit with a bottom bearing
> and may also have a top bearing with a collar to secure it.
Great cor cutting dado,s with a router and template/straight edge guide.
http://www.cabinetmakerwarehouse.com/amana-tool-flush-pattern-plunge-45464?gclid=CjwKEAiAx4anBRDz6JLYjMDxoQYSJAA4loRm_4pJw-l8Xuvkz0ZQpWKG2C4HijvPaR1aGf0FVu6hQRoCu9Tw_wcB
>
>> Well that is not entirely true. If you are flush cutting veneer or
>
> true doesn't have gradations
Not always true.
>
>> laminate a 1/4" flush cut bit is more than adequate. and those are
>
> a laminate 1/4-inch shank flush cut bit that doesn't deflect under
> no load is adequate
>
> more adequate or more better
Look, I am only trying to help you out. If yo want to get into a
pissing contest, you win.
>
>> The smaller the diameter of the cutter portion of the bit the faster
>> you need to run. Once you start using bits that have a 1" or greater
>> cutter you need to slow down the router speed.
>
> or once you start using bits that deflect under no load
Then you have a defective bit or it is not properly mounted in the router.
Electric Comet <[email protected]> wrote in news:mbqihi$pl8$3
@dont-email.me:
> That's deflection. I can see it happen as the router comes up to
> max speed. lower revs it spins straight and true then it goes bad
> at full rev on both routers the problem's inherent in the design
> and going slower is the only solution
This doesn't seem to make sense, so I must be reading it
wrong. If the bit is actually deflecting (and is not
permanently bent, or the router collet is what's actually
flexing) then it would flex more at slower rpm because
the loading per unit time is higher.
In general 1/4 shank bits are only suitable for light
cuts (and 1/8th, which is half the shank diameter, is
probably not "light"). Also, small routers (aka palm
routers or laminate trimmers) are only suitable for very
light cuts (not sure what sort of router you're using).
John
Electric Comet <[email protected]> wrote in news:mbt6cc$1k0$2
@dont-email.me:
> On Sun, 15 Feb 2015 17:15:58 +0000 (UTC)
> John McCoy <[email protected]> wrote:
>
>> In general 1/4 shank bits are only suitable for light
>> cuts (and 1/8th, which is half the shank diameter, is
>> probably not "light"). Also, small routers (aka palm
>
> it's a flush trim bit so what you're saying doesn't apply
How the hell not? If you're cutting material off, how much
you're cutting always makes a difference, regardless of
whether you're flush-trimming or cutting a profile.
> load or not the bit deflects
Then either your bit is bent or your router is bad. If
it happens unloaded then it's not deflecting.
John
Electric Comet <[email protected]> wrote in news:mc22gu$k7o$2
@dont-email.me:
> On Mon, 16 Feb 2015 17:19:37 +0000 (UTC)
> John McCoy <[email protected]> wrote:
>>> load or not the bit deflects
>> Then either your bit is bent or your router is bad. If
>> it happens unloaded then it's not deflecting.
>
> no to both I tried in two routers I still need to try it with
> the end bearing and allen screw removed
After reading Bodger's comment, I realized what the problem
is here: you don't know what the word "deflection" means.
from thefreedictionary.com: "deflection - the movement of a
structure or structural member when subjected to a load"
(the "structural element" in this case being the router bit).
What you are talking about is (as Bodger said) runout.
He explained the causes of runout. If it changes with the
speed of the router, it could be an unbalanced bit, or it
could be bad bearings - more likely the latter. If it
doesn't change with speed, it's most likely a bent bit.
John
> ... Possibilities...
>
> 1. Bent bit
>
> 2. As sonny said, bit isn't properly seated in the collet
>
> 3. Collet is worn or not properly seated
>
> 4. The bearings - the router bearings, not the bit bearings - are worn.
If neither the bit nor router is damaged, and the bit is seated properly, there is another possibility: The shaft flexes enough to produce a poor cut.
How big a bite is the bit taking? It might be too much for the router/bit combination.
Typically, machinists will make a "spring cut" or "spring pass" to compensate for any deflection of the cutting tool. They do this by using the same setting make a cut. Some will use a climb cut for this last pass.
You may want to test this on a sample and see what results you get.
Joel
On 2/14/2015 6:19 PM, Electric Comet wrote:
> I don't use a router often but recently I dusted both of mine off and
> got a surprise. I was using a 1-1/4-inch x 1/4-inch shank flush trim
> bit and I thought my router was broken.
>
>
> But after some routing and closer inspection I found that the bit just
> isn't stiff enough at top speed to remain straight. It is easy to see
> it and when I tried to use it it was easy to feel it and hear it. It
> caused the whole router to vibrate and caused a lot of chatter. I tried
> in the other router and the same thing but to a lesser amount. I've got
> a bit that has a 1/2-inch shank and finished what I needed.
>
> Two things occurred to me.
>
> 1 the bit has two bearings and they both need to rest on the material
> i wasn't doing that because the bit's longer than the material's
> thick But even so a router bit needs to remain straight and stiff
> and this doesn't at ~23,000/rpm
A two bearing bit, top and bottom, is a convenience thing. It is some
times easier to use one or the other depending on the orientation of the
bit to the work and or pattern.
Typically a straight cut bit with a bearing is a flush cut bit.
>
> 2 1/4-inch shank is not the way to go for a flush trim bit, needs
> to be a 1/2-inch shank to maintain proper stiffness and avoid
> the horrible deflection.
Well that is not entirely true. If you are flush cutting veneer or
laminate a 1/4" flush cut bit is more than adequate. and those are
typically bottom bearing bits. In thicker cuts if is best to not cut so
much in a pass that you hear the chatter. At that point your bit is
over loaded with what it can easily handle and does not deliver the
smoothest cut.
>
> maybe it'd be ok at lower rpm but both routers are full on or
> off
The smaller the diameter of the cutter portion of the bit the faster you
need to run. Once you start using bits that have a 1" or greater cutter
you need to slow down the router speed.
A 1/2" shank bit will typically deliver less chatter however it does not
prevent you from removing too much material. You can still over load a
small diameter cutter on a 1/2" shank bit.
On Sun, 15 Feb 2015 06:41:23 -0500, "dadiOH" <[email protected]>
wrote:
>"Electric Comet" <[email protected]> wrote in message
>news:[email protected]
>> I don't use a router often but recently I dusted both of mine off and
>> got a surprise. I was using a 1-1/4-inch x 1/4-inch shank flush trim
>> bit and I thought my router was broken.
>>
>>
>> But after some routing and closer inspection I found that the bit just
>> isn't stiff enough at top speed to remain straight. It is easy to see
>> it and when I tried to use it it was easy to feel it and hear it. It
>> caused the whole router to vibrate and caused a lot of chatter. I tried
>> in the other router and the same thing but to a lesser amount. I've got
>> a bit that has a 1/2-inch shank and finished what I needed.
>>
>> Two things occurred to me.
>>
>> 1 the bit has two bearings and they both need to rest on the material
>> i wasn't doing that because the bit's longer than the material's
>> thick But even so a router bit needs to remain straight and stiff
>> and this doesn't at ~23,000/rpm
>>
>> 2 1/4-inch shank is not the way to go for a flush trim bit, needs
>> to be a 1/2-inch shank to maintain proper stiffness and avoid
>> the horrible deflection.
>>
>>
>> maybe it'd be ok at lower rpm but both routers are full on or
>> off
>
>1/4" shank bits are fine. Possibilities...
I wouldn't use them for any major material removal. In fact, I don't
have any (that I use, anyway).
>1. Bent bit
My bet. At some point, the bit got too hot.
>2. As sonny said, bit isn't properly seated in the collet
>
>3. Collet is worn or not properly seated
>
>4. The bearings - the router bearings, not the bit bearings - are worn.
"Electric Comet" <[email protected]> wrote in message
news:[email protected]
> I don't use a router often but recently I dusted both of mine off and
> got a surprise. I was using a 1-1/4-inch x 1/4-inch shank flush trim
> bit and I thought my router was broken.
>
>
> But after some routing and closer inspection I found that the bit just
> isn't stiff enough at top speed to remain straight. It is easy to see
> it and when I tried to use it it was easy to feel it and hear it. It
> caused the whole router to vibrate and caused a lot of chatter. I tried
> in the other router and the same thing but to a lesser amount. I've got
> a bit that has a 1/2-inch shank and finished what I needed.
>
> Two things occurred to me.
>
> 1 the bit has two bearings and they both need to rest on the material
> i wasn't doing that because the bit's longer than the material's
> thick But even so a router bit needs to remain straight and stiff
> and this doesn't at ~23,000/rpm
>
> 2 1/4-inch shank is not the way to go for a flush trim bit, needs
> to be a 1/2-inch shank to maintain proper stiffness and avoid
> the horrible deflection.
>
>
> maybe it'd be ok at lower rpm but both routers are full on or
> off
1/4" shank bits are fine. Possibilities...
1. Bent bit
2. As sonny said, bit isn't properly seated in the collet
3. Collet is worn or not properly seated
4. The bearings - the router bearings, not the bit bearings - are worn.
--
dadiOH
____________________________
Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net
On Sat, 14 Feb 2015 17:26:02 -0800 (PST)
Sonny <[email protected]> wrote:
> Try not to sink your bit's shaft all the way down to the collet,
> hence avoiding the collet grabbing onto that lip.
No lip on the bit. It's pure deflection due to the length
of the bit, 1/4-inch shank and the bearing and allen screw at the
end.
On Sun, 15 Feb 2015 06:41:23 -0500
"dadiOH" <[email protected]> wrote:
> 1/4" shank bits are fine. Possibilities...
>
> 1. Bent bit
>
> 2. As sonny said, bit isn't properly seated in the collet
>
> 3. Collet is worn or not properly seated
>
> 4. The bearings - the router bearings, not the bit bearings - are
> worn.
No to all those, including 1-1/4-inch long, 1/4-inch shank bits
are not fine and I've found that some attach a rheostat so they
can lower the router rpm
On Sun, 15 Feb 2015 07:18:56 -0800 (PST)
"[email protected]" <[email protected]> wrote:
> properly, there is another possibility: The shaft flexes enough to
> produce a poor cut.
That's deflection. I can see it happen as the router comes up to
max speed. lower revs it spins straight and true then it goes bad
at full rev on both routers the problem's inherent in the design
and going slower is the only solution
Put a 6-inch long 1/4-inch shank metal shaft in your router to see
an exagerrated example of deflection. I wouldn't really do this but
you can imagine what happens
>
> How big a bite is the bit taking? It might be too much for the
> router/bit combination.
it's a flush trim bit so the amount of material can be variable
in my case it was 1/8-inch but this irrelevant
>
> Typically, machinists will make a "spring cut" or "spring pass" to
> compensate for any deflection of the cutting tool. They do this by
> using the same setting make a cut. Some will use a climb cut for this
> last pass.
>
> You may want to test this on a sample and see what results you get.
Not sure what this means
On Sun, 15 Feb 2015 11:14:40 -0500
[email protected] wrote:
> I wouldn't use them for any major material removal. In fact, I don't
> have any (that I use, anyway).
right, won't be buying any more long 1/4 shank bits, short ones are
fine if price is right
"Electric Comet" <[email protected]> wrote in message
news:[email protected]
> On Sun, 15 Feb 2015 06:41:23 -0500
> "dadiOH" <[email protected]> wrote:
>
> > 1/4" shank bits are fine. Possibilities...
> >
> > 1. Bent bit
> >
> > 2. As sonny said, bit isn't properly seated in the collet
> >
> > 3. Collet is worn or not properly seated
> >
> > 4. The bearings - the router bearings, not the bit bearings - are
> > worn.
>
> No to all those, including 1-1/4-inch long, 1/4-inch shank bits
> are not fine and I've found that some attach a rheostat so they
> can lower the router rpm
I can only say that I have been using 1/4" router bits since the late 60s
and I have never seen what you say is happening. (Half inch shanks are a
johnny come lately. In fact, I still have - and use - some 1/4" shanks
from the 60s and 70s. None of those have carbide, it wasn't available -
or at least not commonly so - back then.)
One of my favorite bits is a 1/4" x 2 1/2" (maybe 2 1/4) that I mostly use
with a mel board template for drilling shelf holes. I have drilled 100s
and 100s of holes, never deflected. Of course, there is no lateral push
when drilling holes but apparently you still get deflection even when
there is zero load.
'Tis a mystery but my money is still on one or more of the things I
mentioned.
--
dadiOH
____________________________
Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net
On Sun, 15 Feb 2015 15:50:46 -0500
"dadiOH" <[email protected]> wrote:
> One of my favorite bits is a 1/4" x 2 1/2" (maybe 2 1/4) that I
> mostly use with a mel board template for drilling shelf holes. I
So there's no bearing out at the end since it's a drill bit
this is significant
> have drilled 100s and 100s of holes, never deflected. Of course,
> there is no lateral push when drilling holes but apparently you still
> get deflection even when there is zero load.
correct zero-load
put a long 1/4-inch shank in a router, say 4-inch or more and you'll
get to see it
I'm going to take the end bearing and allen screw off and see how
it looks
On Sun, 15 Feb 2015 17:15:58 +0000 (UTC)
John McCoy <[email protected]> wrote:
> In general 1/4 shank bits are only suitable for light
> cuts (and 1/8th, which is half the shank diameter, is
> probably not "light"). Also, small routers (aka palm
it's a flush trim bit so what you're saying doesn't apply
the material thickness is not a factor either as said in original
post
load or not the bit deflects
On Mon, 16 Feb 2015 10:40:19 -0600
Leon <lcb11211@swbelldotnet> wrote:
> A two bearing bit, top and bottom, is a convenience thing. It is
> some times easier to use one or the other depending on the
> orientation of the bit to the work and or pattern.
> Typically a straight cut bit with a bearing is a flush cut bit.
I've not seen a straight cut bit with a bearing at top only so
the definition should be a straight cut bit with a bottom bearing
and may also have a top bearing with a collar to secure it.
> Well that is not entirely true. If you are flush cutting veneer or
true doesn't have gradations
i turned the light not entirely on
> laminate a 1/4" flush cut bit is more than adequate. and those are
a laminate 1/4-inch shank flush cut bit that doesn't deflect under
no load is adequate
more adequate or more better
> The smaller the diameter of the cutter portion of the bit the faster
> you need to run. Once you start using bits that have a 1" or greater
> cutter you need to slow down the router speed.
or once you start using bits that deflect under no load
On 2/14/2015 7:19 PM, Electric Comet wrote:
> I don't use a router often but recently I dusted both of mine off and
> got a surprise. I was using a 1-1/4-inch x 1/4-inch shank flush trim
> bit and I thought my router was broken.
>
>
> But after some routing and closer inspection I found that the bit just
> isn't stiff enough at top speed to remain straight. It is easy to see
> it and when I tried to use it it was easy to feel it and hear it. It
> caused the whole router to vibrate and caused a lot of chatter. I tried
> in the other router and the same thing but to a lesser amount. I've got
> a bit that has a 1/2-inch shank and finished what I needed.
>
> Two things occurred to me.
>
> 1 the bit has two bearings and they both need to rest on the material
> i wasn't doing that because the bit's longer than the material's
> thick But even so a router bit needs to remain straight and stiff
> and this doesn't at ~23,000/rpm
>
> 2 1/4-inch shank is not the way to go for a flush trim bit, needs
> to be a 1/2-inch shank to maintain proper stiffness and avoid
> the horrible deflection.
>
>
> maybe it'd be ok at lower rpm but both routers are full on or
> off
>
>
>
>
I'd just put a dial gauge on it and check for runout (powered off of
course). You could have anything from true bending of the bit, a slightly
dirty collet or sleeve, dodgy bearings, bad seating, or some combination.
2-1/4" for such a bit sounds more like a pattern cutting bit rather than a
standard flush-trim bit but I guess that the difference is more a matter of
degree. I've never seen flexing of even a 1/4"-shank router bit used at
normal loading.
"Electric Comet" <[email protected]> wrote in message
news:[email protected]
> On Sun, 15 Feb 2015 15:50:46 -0500
> "dadiOH" <[email protected]> wrote:
>
> > One of my favorite bits is a 1/4" x 2 1/2" (maybe 2 1/4) that I
> > mostly use with a mel board template for drilling shelf holes. I
>
> So there's no bearing out at the end since it's a drill bit
> this is significant
It is a plain old straight bit. The presence of a bearing is not
significant unless the bearing is unbalanced or loose.
> > have drilled 100s and 100s of holes, never deflected. Of course,
> > there is no lateral push when drilling holes but apparently you still
> > get deflection even when there is zero load.
>
> correct zero-load
> put a long 1/4-inch shank in a router, say 4-inch or more and you'll
> get to see it
I've never even heard of - let alone seen - a 4" router bit with a 1/4"
shank. If such exists, I sure wouldn't want to use it. For that matter,
the longest cutting edge on my 1/2" shank bits is maybe 3".
Even a bit that long (4") should run true if it is round and if properly
seated in a collet that isn't screwed up.
--
dadiOH
____________________________
Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net
"Electric Comet" <[email protected]> wrote in message
news:[email protected]
> On Mon, 16 Feb 2015 10:40:19 -0600
> Leon <lcb11211@swbelldotnet> wrote:
>
> > A two bearing bit, top and bottom, is a convenience thing. It is
> > some times easier to use one or the other depending on the
> > orientation of the bit to the work and or pattern.
> > Typically a straight cut bit with a bearing is a flush cut bit.
>
> I've not seen a straight cut bit with a bearing at top only
They are common, handy for routing around a template that is on top of
what is being cut.
--
dadiOH
____________________________
Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net
On Mon, 16 Feb 2015 17:19:37 +0000 (UTC)
John McCoy <[email protected]> wrote:
> How the hell not? If you're cutting material off, how much
> you're cutting always makes a difference, regardless of
> whether you're flush-trimming or cutting a profile.
the most wood you can cut is the diameter of the bit plus the depth
depth is limited by top and bottom bearings
material was 1/8x1/8 a smidgeon
> Then either your bit is bent or your router is bad. If
> it happens unloaded then it's not deflecting.
no to both I tried in two routers I still need to try it with
the end bearing and allen screw removed
On Mon, 16 Feb 2015 13:18:50 -0500
BenignBodger <[email protected]> wrote:
> I'd just put a dial gauge on it and check for runout (powered off of
> course). You could have anything from true bending of the bit, a
> slightly dirty collet or sleeve, dodgy bearings, bad seating, or some
> combination. 2-1/4" for such a bit sounds more like a pattern cutting
it's a 1-1/4-inch x 1/4-inch shank
> bit rather than a standard flush-trim bit but I guess that the
> difference is more a matter of degree. I've never seen flexing of
> even a 1/4"-shank router bit used at normal loading.
I've never used any bits longer than 3/4-inch with 1/4-inch shank
so first time I'd seen it
as mentioned will remove bottom bearing & allen screw just to
see of there's an imbalance
On Mon, 16 Feb 2015 14:19:48 -0500
"dadiOH" <[email protected]> wrote:
> It is a plain old straight bit. The presence of a bearing is not
> significant unless the bearing is unbalanced or loose.
right, that's the point
> I've never even heard of - let alone seen - a 4" router bit with a
> 1/4" shank. If such exists, I sure wouldn't want to use it. For
> that matter, the longest cutting edge on my 1/2" shank bits is maybe
> 3".
right that was the point, more an exercise or example that I
intentionally exagerrated to make the point
>
> Even a bit that long (4") should run true if it is round and if
> properly seated in a collet that isn't screwed up.
you say should but I say wouldn't
find some 4-inch x 1/4-inch diameter stiff rod and rev it up
On Mon, 16 Feb 2015 15:31:40 -0600
Leon <lcb11211@swbelldotnet> wrote:
> Great cor cutting dado,s with a router and template/straight edge
> guide.
now I know, just hadn't seen them as another poster pointed out too
> Not always true.
it is, a partial truth is a full lie but I just figured your reply
was meant to be polite instead saying I was full of it
> Look, I am only trying to help you out. If yo want to get into a
> pissing contest, you win.
Yay! wait what'd i win
settle down is rec.woodwroking
> Then you have a defective bit or it is not properly mounted in the
> router.
I'm leaning toward a poorly engineered bit but I still have a couple
of tests to do with it
so possibly defective by design but still a chance that it's defective
in materials although it appears fine
On 02/15/2015 11:15 AM, John McCoy wrote:
> Electric Comet<[email protected]> wrote in news:mbqihi$pl8$3
> @dont-email.me:
>
>> That's deflection. I can see it happen as the router comes up to
>> max speed. lower revs it spins straight and true then it goes bad
>> at full rev on both routers the problem's inherent in the design
>> and going slower is the only solution
>
> This doesn't seem to make sense, so I must be reading it
> wrong. If the bit is actually deflecting (and is not
> permanently bent, or the router collet is what's actually
> flexing) then it would flex more at slower rpm because
> the loading per unit time is higher.
I've stayed on the sidelines but this thread has gone on so long I
finally thought I'd see what was going on... :)
...
You're reading it wrong, yes methinks... :)
He's saying the shaft isn't stiff enough but what the mass on the end
causes flexure when at high speed. The case where he goes on to later
to mention the 6" long shaft is clearly what he's speaking of. Now
whether that's the actual mechanism can't tell w/o actually seeing it or
measurements, but seems clear what he thinks is happening.
Iff'en as he says it occurs in two separate routers I'd judge not the
collet/router runout but associated with the bit. It could be there's
sufficient imbalance to cause the problem if it were an inexpensive bit
that didn't muster quality control checks that a more expensive would
have failed at the manufacturer. Or, given the fact it has double
bearings it may just be that indeed the mass is too much for a 1/4"
shank and with _any_ imbalance is an issue. If this is an issue, I'd
put it back in the toolbox and never get it out again in anger--a flying
router bit head from a fractured shaft is too spooky to venture a chance...
I'd venture the solution would be to set the bit deeper into the collet
if have that much exposed shank that flexure is an issue and use the
router depth adjustment to control the depth. If the shank is so long
that even set a full depth it causes this, see above.
If it were a decent manufacturer and the bit is fully inserted in a
collet, I'd contact them with the symptoms; some Chinese import thru
eBay or whatever source, "not so much"...
ADDENDUM: Perhaps it's hitting a critical axial moment--at that point
bending resistance magically becomes much less and all kinds of bad
things can happen. Once't upon a time in a former life with centrifuges
for a casing of approx. tractor-trailer length and feet in diameter,
operating speed was at roughly router rpm's. To get up and down from
rest required passing through 5(yes, five, count 'em!!!) criticals;
early on the failure rates were quite the issue...
--
I would demand and expect my 1/4" drill bit to not wobble in my drill
press. I realize that the RPM is higher on the router, but the
principle holds true. Maybe I'm just lucky as I've not ever experienced
what you reference. I still suspect that the bit is bent as it doesn't
take much as you move the router around, lay it on its side, etc. I had
a buddy buy some cheap router bits - total waste of time and money. I
have mostly 1/4" shank carbide bits, I expect to pay $20 -- $30 per bit,
I have them resharpened, some are over 20 years old and still work fine.
On 2/18/2015 7:10 AM, Electric Comet wrote:
> On Mon, 16 Feb 2015 14:19:48 -0500
> "dadiOH" <[email protected]> wrote:
>
>> It is a plain old straight bit. The presence of a bearing is not
>> significant unless the bearing is unbalanced or loose.
>
> right, that's the point
>
>> I've never even heard of - let alone seen - a 4" router bit with a
>> 1/4" shank. If such exists, I sure wouldn't want to use it. For
>> that matter, the longest cutting edge on my 1/2" shank bits is maybe
>> 3".
>
> right that was the point, more an exercise or example that I
> intentionally exagerrated to make the point
>
>>
>> Even a bit that long (4") should run true if it is round and if
>> properly seated in a collet that isn't screwed up.
>
> you say should but I say wouldn't
> find some 4-inch x 1/4-inch diameter stiff rod and rev it up
>
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