Cutting circles on mdf

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Hi to everyone,

I would like to cutout two circles on mdf for a woofer and a tweeter. How can I do this. It seems I need a router, but it is expensive. Any suggestions?

Also for the interior sound insulation what is best?

Thank you

George Christofilopoulos
You can do it (slowly) with a jig saw. Make sure you have a very good circle drawn, and just trace it out with the saw. It's not going to be perfect, but as long as you take it slow, it'll work fine. I've been able to do it that way effectively, especially with some "cementing" compound to fill in any potential gaps, although if you have any gaps where you can see through, scrap it and start over. It may not be the BEST way, but it will work, and if properly sealed, you'll get the same fit.

A better way, if you have the patience, is with a hand saw. Since they're easy to control, you can make sure you get a perfect cut. You just want something with a thin blade, to allow you to carve out the corners. I don't know the specific names of the types of saws, but I have used a couple of them for smaller holes.
Retired diyAudio Moderator
Joined 2002
I just used a jigsaw, and I found some blades made by Bosch made for cutting curves in wood. They are much more narrow, and can pivot and turn much better. With using them, and then finishing up with some sandpaper, you can get a decent circle cut out.

If you have the cash though, I hear that the router jigs make perfect circles everytime.

That's the bit I'm using for cutting circles. I have a router mounted on a table. I drill the hole in a center of a circle in MDF with a small drill and measure the radius of a cutout. Now I measure the same distance on a table from edge of a router bit and drill the hole in a table and put the drill bit there. I mount the MDF on a table ( the drill bit goes through the hole I made previously). I can rotate the MDF piece on a table, while the router bit cuts the perfect circle from a bottom.


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A jigsaw is fine as long as you've got a steady hand. Make sure you test on a scrap piece of MDF first to convince yourself that you're going to screw it up when you do the real thing. Also, this might sound obvious, but get a small jigsaw blade which is designed for cutting small holes and not straight lines - it makes cutting even big holes much easier.

I have used a Jasper Circle Jig ( ) for a few years and it works great. Essentially, the jig is a machined piece of plastic that bolts to the bottom plate of most routers and enables the router to rotate around a pin placed at the center of the circle you are about to cut out. They have several different models that can cut nearly any size circle. While it may not be cost effective to purchase a router and a jig for only a few cutouts, you may be able to make a similar device for your own use by looking at what Jasper has on their site. If you only needed a couple of different diameter cutouts and could borrow a router, it would be pretty easy to make a jig similar to the unit Jasper sells.

On a recent sub project, where I used a series of nested Sonotubes and needed a bunch of end caps and bottom plates cut, I racked up nearly a hundred feet of MDF cutting with all of the cutouts and rabbets in material up to 1.5 inches thick, using the Jasper and a Bosch plunge router. All of the cuts were dimensionally very precise, thanks to the jig. Unfortunately, cutting that much MDF created what looked like an explosion in a flour factory.:yikes: But the results were much better and more quickly accomplished than if I had attempted doing it any other way that I had at my disposal.

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