# Keyhole bit usage



## FreeTime (Dec 2, 2012)

I’m in the process of cutting about 20 keyholes. I was into the 3rd (1 inch long) keyhole and the bit basically fell out of the collet (on a Colt) almost converting the piece to scrap (it didn’t go through and I was able to repair it). 

I know I tightened it well and the collet “looked” clean and no, it wasn't bottomed out (I always double check this). Needless to say, I will be cleaning the collet and bit before the next attempt. I may try sharpening the bit, but it’s a small Freud bit and I have a replacement on the way. 

So my question is … the bit was too hot to touch at the time, was this (the heat) the reason the collet loosened? That has never happened on this router before and it’s a pain to check / re-tighten (I have to take the router out of the plunge base, and it fits tight).

I wasn’t forcing the feed but may not have had the RPMs high enough. I’m cutting mostly Red Oak, but I’m not looking forward to the couple pieces of White Oak and Maple. Any processing advice or things to check for would be appreciated – I’d rather not melt down my new Whiteside bit after 3 cuts.


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## CharleyL (Feb 28, 2009)

Was this a single cutter bit or double cutter? I'm asking, because I've had trouble with the single cutter bits vibrating excessively and causing movement in the collet. The double cutter bits don't seem to do this as bad and I haven't had any trouble with them. Bits do get hot when you use them hard. This could also cause possible problems with the bit shank expanding when it gets hot and then any temperature reduction causing the collet to become loose enough to allow bit movement.

My best thoughts at the moment. Hope it helps.

Charley


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## Cherryville Chuck (Sep 28, 2010)

Heat may have been the culprit. Something that will make a large difference is if you take a forstner (preferably) the size of the slot portion of the keyhole, or just slightly smaller, and drill a few holes where the slot is going. This gives the bit a chance to eject the chips and get some cooling air which will allow it to run much cooler and will require a lot less force to rout the slot then. That bit has the larger portion below the slot and that section produces the most chips so it's hard for the bit to get rid of them.


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## FreeTime (Dec 2, 2012)

Thanks for help, guys. It is a double sided cutter. I normally do rough out my slots but for some reason it never occurred to me on this one ... good idea. Its going to be a lot of drilling though - the slot is 3/16 wide so I have to get under that. I have some brad point bits that should work nicely. That should also cut down on the grabbing. The router is guided but there were a couple times the bit sounded like it was going to self-destruct.


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## harrysin (Jan 15, 2007)

Keyhole bits do create heat because the swarf cannot easily escape so it isn't unusual for the bit to become VERY hot routing multiple keyholes in quick succession.


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## 4DThinker (Feb 16, 2014)

I highly recommend running a straight bit the same diameter of the inner part of your keyhole bit first. Removes the center of all the keyhole slots before the winged bit can come through and do the undercut.


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## Cherryville Chuck (Sep 28, 2010)

Mark your profile says you have 2 618s so set one up with a straight bit like 4D suggests and put the keyhole bit in the other.


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## DesertRatTom (Jul 3, 2012)

Cherryville Chuck said:


> Mark your profile says you have 2 618s so set one up with a straight bit like 4D suggests and put the keyhole bit in the other.


This is one of the best reasons for owning two of the same routers. Add a jig to guide them--two parallel boards connected by cross pieces, and tasks like this are made pretty easy. You have to make sure the bases are identical and centered.


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## FreeTime (Dec 2, 2012)

DesertRatTom said:


> This is one of the best reasons for owning two of the same routers. Add a jig to guide them--two parallel boards connected by cross pieces, and tasks like this are made pretty easy. You have to make sure the bases are identical and centered.


I would love to own two Colts but I'm running out of room to store stuff. I do have a base dependent guide (similar to what you describe) for the operation ... so the DeWalt secondary is off the list. But I'm a little ahead of you on this one - I put a 1/4" base on it so I could maintain some path alignment and stop/start marks.

I did take Chuck's advice and drill out what I could - it took me a minute to figure out how to get a straight line with a manual alignment on the bench top drill press. (no straight edges on the part, just a centerline). The 2 pass route would have been an option but I don't have any bits that small (3/16")

As it turns out, the collet was toast - I'm not sure if this was cause or effect. So I ordered 3. I feel like things come to a stop without that router operating just like they did 2 weeks ago when my POS Ryobi drill press gave up its return spring ... thankfully Delta had a comparable part.


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## Cherryville Chuck (Sep 28, 2010)

FreeTime said:


> I feel like things come to a stop without that router operating just like they did 2 weeks ago when my POS Ryobi drill press gave up its return spring ... thankfully Delta had a comparable part.


The Delta might actually be a Ryobi. Delta`s cheapest models are/were made in Asia. Delta sold a 13" planer that was identical to my 16" King Canada except for the width. Same gear box, same 2 speeds, same columns, same motor, etc. Only very superficial differences.


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