It finally happend to me

[Vince Heuring]

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.

[B A R R Y]

Glad to hear that things didn't get too ugly and no injury ensued!

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[nailshooter41]

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

[Allen Roy]

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

[Swingman]

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??

[Lee]

[Patriarch]

Vince Heuring wrote in news:230820071732000356% [e-mail]:

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

[Peter Huebner]

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

[Neillarson]

30 days?

[charlieb]

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

[J T]

Sun, Aug 26, 2007, 11:46am (EDT-3) [e-mail] (charlieb) doth adviseth: 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.

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

[Pat Barber]

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.

V> I was milling 1/4" wide 3/8" deep mortises in 1-1/4" legs in a router