Tooling: What type of bits should I use to cut wood?

[winc]

Our company has just purchased a ShopBot, and I'm trying to get up to speed on tooling for the machine. Specifically, I'm looking for 1/16" and 1/8" diameter straight cutting plunge bits to cut slots in 3/4" oak and mdf. I'm much more familiar with cutting metals, and I've found end mills that may work, but I'm not sure how well they'll cut wood. Can anyone recommend the correct tooling for this application? Where can I purchase the best cutting bits? Thanks!

P.S. Thanks for all of the responses to my last post in which I was looking for a ShopBot in the Atlanta Area. Rob Williams of Furniture Unlimited was kind enough to demo his, and I purchased my own the same day!

[kerrazy]

www.onsrud.com is a good place to start. Their new online catalogue should make it a little easier for you.
You definatley will want a variety of upcut and single flute cutters for your wood material.
Dale

[bjwat@comcast.net]

Robert,
Onsrud does sell top notch bits...however save them for when you get your feeds and speeds dialed in. www.pricecutter.com is a great place to get discount carbide bits of all sorts.

Slotting 3/4" Oak with 1/16 and 1/8 is extremely tricky. I can tell you that you are going to break a lot of tools until you figure out what the right RPM, and cutting/feed speeds are. Plan on running very, very slowly through the material in multiple passes. I have broken 1/16" bits in wax moving at .5 IPS and .0625 cutting depth with a .2IPS Z plunge. I had better success with .03125 cut per pass with a 1/16" bit.

So...If I were to start experimenting with MDF and Oak with those bits, I would try PriceCutter and search for some other 'cheapies' before investing in the Onsrud cutters. I save the Onsrud stuff for special things like ballnose cutters and plastic cutting bits. I use the generic stuff for profile cutting.

Hope that helps,
Brady

[gerald_d]

Robert, the end mills that you are using for steel now, are a pretty good start - provided that they are solid carbide and not only HSS (High Speed Steel). The Onsrud type bits spoken of above are probably around 20% better than your good endmills. Do not expect a quantum leap in performance from the good bits that you are already using for cutting steel.

In your situation, I would be more concerned about how to spin those tiny bits fast enough. Let's hope you aren't going for the biggest (slowest) router that you can find.

[winc]

Thanks for all of the help. I've called Onsrud and I plan on purchasing their 1/8" bit #63763 for my MDF cutting, but they cannot even custom make a 1/16" bit that will cut through 3/4" material. I'll probably end up using an end mill for that.

Maybe if I give some more specifics on my application, you guys will have some ideas on how I can do it. I'm cutting slots in 3/4" quartersawn oak. The slots are 0.135" wide. The problem is getting square ends on the slot. I was planning to use a 1/16" bit to overcut the corners just enough so a squared off piece of 10 gage stainless will slide into the slot. Maybe I should try one of those mortising drill bits that combines a square chisel and a drill bit? Anybody have other ideas?

[rgbrown@itexas.net]

Robert,

There are general rules of how much cut one can do with a bit in a particular material. In wood, I use a depth/diameter of 3/1 MAXIMUM! That means I take a 3/4" cut with a 1/4" bit.

With a machine tool. and accuracy measured in "tenths of thousandts", one can keep a tool in the same slot and clear material to quite a depth. With a step-motor and gear driven system, there is a limit to what is repeatable.

3/4 inch and a 1/16 inch bit makes for a 12/1 cut/diameter ratio. This will cause a LOT of deflection. Carbide does not like flexing.

I think you are inviting a visit from Mr. Murphy and his laws. You may also find several laws of physics you are trying to violate.

I wish you luck. And, if you find a way, I hope you will share the process.

Ron

[pappy]

Brady,

For better prices on router bits try www.magnate.net ...3/8 2 flute upcut or downcut
spiral are only $29.00 each. I have been using them since I got my Legacy.

[gerald_d]

Robert, I wouldn't try to cut square corners with a router bit for your application. You seem to metalworking toolroom guy, so why not broach the ends after routing? With a file, or a self-made broach cutter? A big hacksaw blade, or a couple of stacked smaller ones?

If your stainless is laser cut, then change the design of the stainless part so that it has a narrower "tongue" and thus hides the radiuses at the end of the oak "groove".