Best way to cut 1 in. MDF ?

[audiowood]

I need to cut many 3 in. and 6 in. holes in 1 inch MDF. I figure on using a template and cutting on a shaper or router table ( my shaper goes to 10K rpm) I am not sure what type of bit to use. It would have to be bearing guided. Any input would be welcome Thanks Woodman

[Andy]

My first thought is a router on a trammel - basically make a long skinny router sub-base out of 1/4" hardboard or something like that. Sink a little finish nail at the appropriate distance from the bit, and into your workpiece, plunge and spin (slowly). It would be much easier on the router if you cut pretty close with a jigsaw first.

A bearing would work with a template, but so would a template guide bushing if that's easier for you. Or a larger round template, and just use the edge of your stock sub-base as a guide (note - this might not be as accurate as a bearing or bushing). Good luck, Andy

[audiowood]

The guide bushing sounds good . Can you rec. a bit to use with that Thanks

[Andy]

I like a solid carbide spiral upcut bit, but they can be a little expensive. You can try a solid carbide end mill - same thing, cheaper price when it doesn't say "router bit". Check the archives for sources. A straight bit would work fine too, but most aren't intended for plunge cuts. You could start it with a hand-drilled pilot hole or something like that. Andy

[Robatoy]

If you start off with a large diameter bushing, you can cut the hole with a small bit, then leave the template in place and drop a rabbet in with a large diameter bit so can you flush mount your drivers.

[SWDeveloper]

The effort is making the template with a perfect round hole in it. I'd use a circle cutting bit in a drill press using hardboard. If you want to cut perfectly-spaced holes make at least two same-sized holes in your template--that way you can use one hole as an index. Use either clamps or double-sided tape to fasten to the MDF. A spiral-cutting bit with a bearing would be ideal. A straight-cutting bit would be my second choice. Use good DC, dust mask. MDF is rough on cutting tools and lungs.

[Pat Barber]

would also buy a spiral bit for the best cut...

This was designed by speaker cab> I need to cut many 3 in. and 6 in. holes in 1 inch MDF. I figure on

[pat]

[pat]

The templets can be made from router and subbase like the one at the link:

the templet is clamped and indexed to the work you can trim to templet wth bearing guided trimmers or collars & straight bits. Wasting 1" MDF can make the mess of the century on the router table or shaper. I'd clamp the work to the bench, fashion a bottom cover (with a hole in it for a vacuum connector) and clamp it to the underside of the panel. With the vac. running you stand a good chance of avoiding lung cancer. Without it, you will have dust, even in the attic, weeks later. PW

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[Pat Barber]