Breaking keyhole bits left and right

[Steven Toomey]

I need to create some keyhole slots for a bunch of 12" squares and am running into issues with the bits breaking. The wood is 1/2" and 3/4" baltic Birchwood. I've tried both a 1/4"(http://www.amazon.com/gp/product/B00004T7JX) & 1/2" shank(http://www.amazon.com/gp/product/B000P4LQ6I). I was only able to get about 6 panels done before the brand new bit snapped. The router is brand new, Bosch 1617 and I have the speed set to Max setting of 6. I do notice that it seems the routed portion is clogged with the sawdust(see pic below) and it does seem to take a little force to push the panel through. So what am I doing wrong?

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[Brian Henderson]

Well, for one, you're trying to do a very long slot without clearing the sawdust. The sawdust catches in the channel and if you don't clear that sawdust regularly, the bit will clog and seize and snap. I have no idea what your dust collection is like under the table, but if you can get a vacuum hose under there close to the bit, then push a little, back off or pause for a bit, let the vacuum clear it out, then go again, you shouldn't have problems.

[Peter Quinn]

Plow the straight cut with a 1/4" straight bit first, then Change cutters and finish up with the key hole slots. Those bits have a very weak point just under the wide flat part, and Baltic birch is basically cross grain every other layer, actually pretty tough stuff to route. So lighten the load, do it in two passes.

[Larry Edgerton]

Plow the straight cut with a 1/4" straight bit first, then Change cutters and finish up with the key hole slots. Those bits have a very weak point just under the wide flat part, and Baltic birch is basically cross grain every other layer, actually pretty tough stuff to route. So lighten the load, do it in two passes.

This..........

[Steven Toomey]

Thanks for the tips. I was hoping there would be a more time efficient solution since I will be doing this to 100+ blanks. I will try straight cutting it first and getting the vacuum better underneath the router.

[Dan Hintz]

Plow the straight cut with a 1/4" straight bit first, then Change cutters and finish up with the key hole slots. Those bits have a very weak point just under the wide flat part, and Baltic birch is basically cross grain every other layer, actually pretty tough stuff to route. So lighten the load, do it in two passes.

Yep, this...

[Myk Rian]

Perfect use for 2 router tables. Or a dual one.

[Ed Aumiller]

Why do you need such a long cut... normally less than 1" is all needed ...

[Alan Wright]

Another issue to consider is the heat building up in the bit. Similar to dovetail bits, when they get overheated and you key them cool slowly the metal "crystallize" and they become brittle and break. I have broken many dovetail bits. It you immediately hit the bit with compressed air to cool the bit quickly you will get longer life. It's kind of a pain to do,but saves on bits. I don't know the physics of all this but I came across this tip on a similar site and it really seems to work.

[Yonak Hawkins]

Woodline sold some poorly designed ones awhile back. They only had one flute. I guess they figured they were lightweight enough that they wouldn't vibrate enough to cause problems. Well, the problem was that they kept breaking. I called Woodline who said they were aware of the problem and they replaced all the keyhole bits I had received.

This is a report of good customer care but poor warehouse management, as they were still on the shelf after they knew about of the problem.

[Dan Hintz]

Woodline sold some poorly designed ones awhile back. They only had one flute. I guess they figured they were lightweight enough that they wouldn't vibrate enough to cause problems. Well, the problem was that they kept breaking. I called Woodline who said they were aware of the problem and they replaced all the keyhole bits I had received.

This is a report of good customer care but poor warehouse management, as they were still on the shelf after they knew about of the problem.

Cheaper to sell and replace if/when they break, most likely. Many folks won't complain, they'll just eat the low cost and move on.

[glenn bradley]

Thanks for the tips. I was hoping there would be a more time efficient solution since I will be doing this to 100+ blanks. I will try straight cutting it first and getting the vacuum better underneath the router.

I do not pre-cut the slot. I broke one bit years ago and doubt that I have just been lucky ever since; I'm not lucky at much else . I use Whiteside 3050 or 3051 (1/4" and 1/2" shank respectively but, this is really a non-point since the narrow neck is the weak spot). I pre-drill the 3/8" hole to near depth. I lower the part onto the spinning bit via stop-blocks and fence for position and move right to left. I have good dust collection below the table and move at a reasonable rate of feed (listen to the cut). Like any delicate bit, making this cut is not a race. A good feed rate will save more time than stopping to change broken bits every time .