I was milling 1/4" wide 3/8" deep mortises in 1-1/4" legs in a router
table with a 1/4" Whiteside solid carbide spiral upcut bit in a PC 7518
router -- nothing I haven't done a number of times before. I milled the
first mortise and was in the middle of the second when the piece
started vibrating and hopping. I turned the router off and found that
the bit had raised out of the router by a good 1/4". Not good. The
collet certainly wasn't easy to get off, and when I did I couldn't seen
any buildup inside or on the threads. The bid was exactly the same
diameter as all my other 1/4" bits to a few thousanths.
OK, next suspect was the collet. I had another identical one from a PC
690 router, so I installed it and gingerly started cutting mortises.
Same thing. Probably not the collet alone.
The last suspect was the router chuck. It appeared normal except that
the threads were rough rather than smooth. Maybe the threads on the
collet are binding against the rough threads of the chuck. I washed the
collet in mineral spirits, and put a drop of light oil on the chuck
threads, thinking that maybe a bit of lubrication would make the
problem disappear. Which it did. I milled the rest of the mortises
without the bit rising out of the collet.
A quick search through the wreck showed that this has happened a number
of times in the past. Always with a spiral upcut bit, which is not a
big surprise since the force on the bit wants to pull it out, unlike
most other bits.
Bay Area Dave and Swingman both had this happen to them, and both with
PC 7518 routers. If your interested search the wreck for a thread
titled "climbing bit" in Feb '04. Others have mentioned other PC
routers, and a few had the same problem with Craftsman routers.
My conclusion is that there is probably no single cause (unless
somebody doesn't tighten the collet enough. :-)
The causes mentioned include
- 1/4 in. spiral upcut bit
- a gunked-up collet.
- rough threads on the router chuck. I wonder if there was a bad batch
of chucks during a production run on 7518s.
- and no lubrication.
As Michael Conrad used to say on Hill Street, Let's be careful out
there.
--
Vince Heuring To email, remove the Vince.
Good post, Vince. There are things you know, things you should
remember, and you just don't. With your mentioning the previous
posts, I remember that scenario and fix.
Had that happened to me without reading today's post, I would have had
to go through all the gyrations just like you did. Now if it that
happens in the 6 months (OK... ninety days...) I will remember exactly
what to do.
Robert
On Aug 23, 7:57 pm, "[email protected]" <[email protected]>
wrote:
> Good post, Vince. There are things you know, things you should
> remember, and you just don't. With your mentioning the previous
> posts, I remember that scenario and fix.
>
> Had that happened to me without reading today's post, I would have had
> to go through all the gyrations just like you did. Now if it that
> happens in the 6 months (OK... ninety days...) I will remember exactly
> what to do.
>
> Robert
30 days?
You didn't say if the shank of the bit was also 1/4". If it was,
there's less gripping surface in a 1/4" collet than in a 1/2"
collet so that may be part of it.
Trying to hog out wood in a single pass, be it an upcut or down
cut spiral bit ain't a good idea given that the spiral shape doesn't
leave a whole lot of metal. Better to make a series of shallower
(say 1/8" for a 1/4" bit) passes and a really shallow pass for
the finish cut.
The other common source of "bit slip" is due to something
that isn't obvious. If, when you set the bit, you bottom it
out, you can get a hammering/bouncing effect while cutting.
This will tap the bit up out of the collet. Don't seat the
bit so that it bottoms out.
Feed rate can also contribute to the problem you described,
again, trying to hog out too much wood at one time will
cause you grief.
hope this helps
charlie b
Sun, Aug 26, 2007, 11:46am (EDT-3) [email protected] (charlieb)
doth adviseth:
<snip> The other common source of "bit slip" is due to something that
isn't obvious. If, when you set the bit, you bottom it out, you can get
a hammering/bouncing effect while cutting. This will tap the bit up out
of the collet. Don't seat the bit so that it bottoms out. <snip>
Perzackly. Happened two-three times to me. Now I bottom 'em out,
draw them up 1/16"+, and no more of that particular problem.
JOAT
I do things I don't know how to do, so that I might learn how to do
them.
- Picasso
I've actually had it happen on a PC 7529. Milling rabbets in a piece of 1/2"
Birch ply with a 3 flute straight carbide Freud bit. Climbed 3/8 of an inch
in 6". Put a nice gouge in my bench top.
I did the same as you. I cleaned everything and lubed, problem solved for 20
minutes. Replaced the bit, problem solved for good.
Allen
"Vince Heuring" <[email protected]> wrote in message
news:230820071732000356%[email protected]...
>
> I was milling 1/4" wide 3/8" deep mortises in 1-1/4" legs in a router
> table with a 1/4" Whiteside solid carbide spiral upcut bit in a PC 7518
> router -- nothing I haven't done a number of times before. I milled the
> first mortise and was in the middle of the second when the piece
> started vibrating and hopping. I turned the router off and found that
> the bit had raised out of the router by a good 1/4". Not good. The
> collet certainly wasn't easy to get off, and when I did I couldn't seen
> any buildup inside or on the threads. The bid was exactly the same
> diameter as all my other 1/4" bits to a few thousanths.
>
> OK, next suspect was the collet. I had another identical one from a PC
> 690 router, so I installed it and gingerly started cutting mortises.
> Same thing. Probably not the collet alone.
>
> The last suspect was the router chuck. It appeared normal except that
> the threads were rough rather than smooth. Maybe the threads on the
> collet are binding against the rough threads of the chuck. I washed the
> collet in mineral spirits, and put a drop of light oil on the chuck
> threads, thinking that maybe a bit of lubrication would make the
> problem disappear. Which it did. I milled the rest of the mortises
> without the bit rising out of the collet.
>
> A quick search through the wreck showed that this has happened a number
> of times in the past. Always with a spiral upcut bit, which is not a
> big surprise since the force on the bit wants to pull it out, unlike
> most other bits.
>
> Bay Area Dave and Swingman both had this happen to them, and both with
> PC 7518 routers. If your interested search the wreck for a thread
> titled "climbing bit" in Feb '04. Others have mentioned other PC
> routers, and a few had the same problem with Craftsman routers.
>
> My conclusion is that there is probably no single cause (unless
> somebody doesn't tighten the collet enough. :-)
>
> The causes mentioned include
>
> - 1/4 in. spiral upcut bit
>
> - a gunked-up collet.
>
> - rough threads on the router chuck. I wonder if there was a bad batch
> of chucks during a production run on 7518s.
>
> - and no lubrication.
>
> As Michael Conrad used to say on Hill Street, Let's be careful out
> there.
>
> --
> Vince Heuring To email, remove the Vince.
"Swingman" <[email protected]> wrote in message
news:[email protected]...
> "Vince Heuring" wrote in message \
>
>
> One reason my two Grrippers get so much use to this day ... if you don't
> have two, what are you waiting for??
>
> --
>> I agree. Got one then two. One has a dado blade mark in the
>> bottom....coulda been my hand. Hats off to however came up with it.
>
>
>
>
In article <230820071732000356%[email protected]>,
[email protected] says...
>
> The causes mentioned include
>
> - 1/4 in. spiral upcut bit
>
> - a gunked-up collet.
>
> - rough threads on the router chuck. I wonder if there was a bad batch
> of chucks during a production run on 7518s.
>
> - and no lubrication.
>
> As Michael Conrad used to say on Hill Street, Let's be careful out
> there.
Funny that. Happened to me last week with my Hitachi router. I just quietly put
it aside and knocked off for the day, haven't gone back to investigate 'cause
I've put my back out and had a bunch of other things come up for attention.
I shall have a durned good look a the threads, and assembly - my surmise at the
time was that I hadn't tightened things up sufficiently.
thanks for the tips, -Peter
--
=========================================
firstname dot lastname at gmail fullstop com
Vince Heuring <[email protected]> wrote in
news:230820071732000356%[email protected]:
<snip of a router bit climbing tale>
> Bay Area Dave and Swingman both had this happen to them, and both with
> PC 7518 routers. If your interested search the wreck for a thread
> titled "climbing bit" in Feb '04. Others have mentioned other PC
> routers, and a few had the same problem with Craftsman routers.
>
Did it to me cutting rabbets in soft maple. With a Freud FT2000e router
and a 1/2" upcut spiral bit. Figured it was my fault, but it tossed the
clock cabinet side maybe 25'.
It wasn't just the router that needed a break.
Glad you're OK.
Patriarch
"Vince Heuring" wrote in message \
> Bay Area Dave and Swingman both had this happen to them, and both with
> PC 7518 routers. If your interested search the wreck for a thread
> titled "climbing bit" in Feb '04. Others have mentioned other PC
> routers, and a few had the same problem with Craftsman routers.
>
> My conclusion is that there is probably no single cause (unless
> somebody doesn't tighten the collet enough. :-)
I see that drawer front, with the Dutchman I used to fix it, in our kitchen
every morning when I make my breakfast. It's a constant reminder to never
trust a router collet. The tendency to use bare hands atop a non-through cut
on the router table, or with a table saw/dado stack for that matter, should
always be resisted. I shudder every time I see Norm do it.
One reason my two Grrippers get so much use to this day ... if you don't
have two, what are you waiting for??
--
www.e-woodshop.net
Last update: 8/08/07
KarlC@ (the obvious)
On Thu, 23 Aug 2007 17:32:00 -0600, Vince Heuring
<[email protected]> wrote:
>
>As Michael Conrad used to say on Hill Street, Let's be careful out
>there.
Glad to hear that things didn't get too ugly and no injury ensued!
---------------------------------------------
** http://www.bburke.com/woodworking.html **
---------------------------------------------
That's a LOT of router and a very little router bit.
I would only use 1/4" bits on very tiny mortises.
Most of the bit guys carry a 1/4" bit with a 1/2" shank.
A 7518 has the power to overwhelm a small bit like that.
Vince Heuring wrote:
> I was milling 1/4" wide 3/8" deep mortises in 1-1/4" legs in a router
> table with a 1/4" Whiteside solid carbide spiral upcut bit in a PC 7518
> router -- nothing I haven't done a number of times before.