Best bits for cutting 2-1/2 holes in MDF

[Tom Henderson2]

I need to cut some 2-1/2 inch diam holes in 1/4" MDF for a router pattern.

This is larger than most traditional bits (spade, forstner, etc) can handle. So my options are to use a single-point circle cutter, or a hole saw.

Anybody out there have any experience using a single-point circle cutter like this?

http://www.woodcraft.com/product.aspx?ProductID=16N41&FamilyID=799

Since this is for router pattern usage, I'd like to have pretty clean, smooth edges. Not sure how well those circle cutters work.

The other option is a hole saw; my experience with most of them has been mediocre at best so I thought I'd consider a circle-cutter....

Thanks in advance.

-Tom in Ventura

[Mike Null]

They work pretty well but can be dangerous.

Secure your material well; reduce the rpm on your drill press to the lowest setting, use gentle pressure and keep your hands out of the way.

Do not consider using this unless you have a drill press.

A hole saw will work but I view them as a bit of a nuisance. But you can use them in a hand held drill.

[Tom Adger]

I recently had to drill a hole about that size in 3/4" MDF. I used a hole cutter with a cordless drill. Use the hole cutter with the twist drill pilot in the center, and after the pilot goes thru, cut in from the other side so you don't get tearout.

[Todd Hoppe]

single point circle cutter will work great in a drill press

[Matt Meiser]

Woodcraft has a 2-1/2" Forstner bit as does MLCS

http://www.woodcraft.com/product.aspx?ProductID=125947&FamilyID=1071
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/forsbit.htm

[Gary Herrmann]

I've seen 2 1/2" Irwin forstners at the blue borg

[Tom Henderson2]

Thanks for your thoughts everyone.

I'll take another look at the Forstner situation; when I looked online previously I didn't see any, but might have missed one.

I should have mentioned that I do have a DP. Just never used a "circle cutter" before so wasn't sure about the surface finish, etc. But I the comments about securing the work are good ones, and that may be an issue here. So a hole saw may be the alternate if I can't find a Forstner.

Thanks again everyone.

-Tom in Ventura

[Prashun Patel]

Use a hole saw. MDF will be killer on the teeth, though, and since there's no place to eject, you can burn wicked easy.

This method works extremely well for alleviating the dust buildup in the kerf

http://www.woodworkingtips.com/etips/etip031010ws.html

You don't need a forstner. Cut 1/8" deep with the hole saw. Then use a brad point or twist bit to drill just a shade inside the plug all the way through. Wiggle the bit a little so it contacts the hole's cut line - just take care not to hit the outside perimeter of the hole. Then complete your hole. I agree about drilling from 2 sides to avoid tear out. You'll be amazed how much quicker and burnfree yr hole will be....

[Greg Crawford]

Can you use a router? I use a plunge router on a trammel and the MDF isn't nearly as hard on the carbide bits, and the holes are pretty clean.

[john bateman]

There is a device called a Jasper Jig that attaches to your router, and will cut circles very precisely...and you don't need a new one for every sized hole.
Use a 1/4" carbide plunging bit with it.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=365-255
http://www.parts-express.com/images/item_large/365-255_L.jpg

[Chris Padilla]

Mr. Bateman took my suggestion. I have several of Jasper's circle cutting jigs and they work beautifully! You just have to get it in your head if you are making a disc or making a hole! :) A router in MDF will cut like butter, produce flour like dust clouds, but leave a very clean finish.

I wonder if that No. 400 Jasper jig will fit a Bosch Colt router? Yoy really want a smaller router like that to cut small holes with small diameter bits. :)

[Chris Tsutsui]

I have the Jasper Jig which will probably make the cleanest holes of any method since it uses a router. It's a bit time consuming to do a lot of holes though so I would use the jig to make a template if you've got a lot of holes to make. If the holes were bigger, I'd use a jig saw to remove most of the material before using the router + template to clean it up.

If you need to make a ton of rough holes, I use a hole saw bit and drill press.

Cut down from one side most of the way, then flip the wood over and finish the cut.

Keep the teeth clean and don't burn the MDF.

[glenn bradley]

single point circle cutter will work great in a drill press

+1 with Todd. I use them all the time. A forstner is fine as well but the better ones will yield a cleaner exit hole. 2-1/2" is not hard to find in a forstner-like (http://www.leevalley.com/wood/page.aspx?c=2&p=42245&cat=1,180,42240) bit if that is your preference.

[Todd Hoppe]

Thanks, Glenn. Also, the single point cutter will not shoot dust in clouds like the router, is infinitely adjustable (e.g., if you have a vacuum hose a hair under 2.5"), and does not tear out on the back side if supported

[Tom Henderson2]

Good evening everyone.

Thanks again for your thoughts. In this case, I'm using the holes as corners for a router guide template. Sho'nuff, the local Woodcraft had a 2-1/2 house-brand Forstner in stock. So I picked it up after work, bored the holes cut out the remaining webs and sanded the remains flush and tangent.

While the Jasper hole jig wasn't the answer for me, this time, it sure looks handy so I'll have to look into those further.

Thanks again.

-Tom in Ventura