# Router bit won’t fit after one use.



## WillcWBNC (May 25, 2021)

I recently purchased a router and put 1/4 bit into and used it once. I then took the bit out and when I went back to use another bit the collet will not loosen far enough for it to fit anymore. Any help?


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## kp91 (Sep 10, 2004)

If you put a router bit in a collet so far that it bottoms out against the shaft, then tighten it, the collet can deform the shank of the bit. Depending on how it deformed you might just have a burr that can b polished off.

Always make sure the bit isn't touching bottom before tightening.


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## old55 (Aug 11, 2013)

Welcome to the forum.


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## sreilly (May 22, 2018)

Any chance the bit is 3/8" shaft and not 1/4" or is it the same bit? BTW, welcome to the forum.


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## mgmine (Jan 16, 2012)

It doesn't sound right. Take the nut completely off and see if the bit goes in. If not then take the router back.


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## mgmine (Jan 16, 2012)

One other thing would be after taking the nut off try to use another bit. If neither fits then the collet is screwed up.


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## TenGees (Sep 12, 2012)

Just a reminder as posted on this forum many times... *Do not tighten a collet without a bit in it*. Doing that could deform the inner part of some collets. If this has happened, you have to be very careful when trying to pry it open. Over doing it could break or weaken the part. It would be safer to replace the collet. I wouldn't run a router without a bit because the collet would be loose, right?.

There's another common problem and that is bits that aren't the correct shaft size. Be aware that there are metric, imperial and poorly manufactured ones available. If you tighten a collet on one that's too small, it's similar to tightening a empty collet. Or if the bit is oversize it's obviously not going to go in. As @mgmine mentioned: Try different bits and see if they all have the problem. If you have a calliper, try measuring the shafts.

A different issue is people bottoming out the shaft of the bit. This can cause a collet to not tighten properly. I pull the bit out about 1/8" and then tighten it. Some people use O-rings either on the shaft or in the collet to prevent this (member Harry made bit storage with holes the right depth to set the position of the O-ring). Many have had bits wander in depth or come flying out. At around 20000 RPM this can be quite dangerous.

In your case I suspect either:

The collet has been over compressed
The bit isn't the correct size


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## DesertRatTom (Jul 3, 2012)

Just for clarity's sake, here is a diagram of a collet, nut and spincle. The collet is a very precise thing. The difference between tight and loose is a matter of a few thousandths of an inch. The nut pushes the collet down into a tapered spindle so deforming it is pretty easy to do, and I suspect a quarter inch collet is even more easily damaged. Once damaged, a collet can't be trusted for safety reasons Paul explained.








One other issue could be that you are using an Imperial bit in a metric collet, or vice versa. The difference is tiny, but then so are the tolerances.

I don't ever use a collet that is giving me any signs of problems. New collets for good brands are cheap compared to a hospital bill. For a few off brands that are more than a few years old, even finding a collet that fits is difficult to impossible. Another reason to buy a spare, several if it's a cheapo router or Crapsman.


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## Rev. A (Jan 29, 2021)

kp91 said:


> If you put a router bit in a collet so far that it bottoms out against the shaft, then tighten it, the collet can deform the shank of the bit. Depending on how it deformed you might just have a burr that can b polished off.
> 
> Always make sure the bit isn't touching bottom before tightening.


I've had burr issues sometimes. I take them off with a high grit diamond file. Just be careful not to get too aggressive a file a flat onto the shank, messing up the tool balance. An imbalanced tool at the usual 25,000 RPMs router's spin would eventually cause bearing damage.


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## mike 44 (Feb 6, 2021)

WillcWBNC said:


> I recently purchased a router and put 1/4 bit into and used it once. I then took the bit out and when I went back to use another bit the collet will not loosen far enough for it to fit anymore. Any help?


Have you tried to install the original cutter?. If that cutter will fit then the problem lies with the second one. If you have a micrometer or know someone who has one , have it checked to see the shaft diameter. I had a neighbor that received several brand new cutters, all slipped. I checked them with a micrometer and found they were metric. 
mike


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## Rev. A (Jan 29, 2021)

mike 44 said:


> Have you tried to install the original cutter?. If that cutter will fit then the problem lies with the second one. If you have a micrometer or know someone who has one , have it checked to see the shaft diameter. I had a neighbor that received several brand new cutters, all slipped. I checked them with a micrometer and found they were metric.
> mike


That's what happens when you buy from China or the EU. The collet should still work with a 6mm shank, it's only .014" smaller than a 1/4" The range of the collet should be greater than that but buying a 6mm collet would insure a good fit.

*Better yet - BUY AMERICAN. *


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## Rev. A (Jan 29, 2021)

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