How do I make driver holes??

[rtate]

I am about to start construction on a Rythmik 12" sub made from 3/4" mdf.
The driver cuttout is 11 3/16"
How do I go about making the hole so that it's perfectly round?
I don't own a router, should I be looking at purchasing one?

[craigwalsh]

You can also use a jigsaw, the way I've done it up until recently. In my experience, jigsaws make less than perfect round holes. Okay, it's not the jigsaw, it's the operator. There may be simple jigs one can use for making nice round holes with a jigsaw. But, routers are great for this stuff, esp. with MDF. I've just started using one for template and hole-cutting. Boy, it is very nice and quick and the edges made are really clean. I don't think I'll go back to using a jigsaw for this.

I'd look into getting a router and circle cutting jig if possible.

[Drew Eckhardt]

Originally posted by rtate
I am about to start construction on a Rythmik 12" sub made from 3/4" mdf.
The driver cuttout is 11 3/16"
How do I go about making the hole so that it's perfectly round?

Plunge router, circle jig, and spiral up-cut bit.

While you can buy a circle jig, making one is as simple as matching the router's mounting pattern in a piece of scrap plywood, driling holes at the radiuses you want, and making a bigger hole to clear the bit. You can screw the inside cutout to something behind it, or stop your cut short of going all the way through, finish with a jig saw, and clean it up with a flush trim or pattern bit. Make three passes. It'll stress the bit less (there's not much metal in a 1/4" spiral bit's web).

The other reason you want a router is that it makes it easier to make perfect cabinets. You start with four sides that are the same height, two of which are thinner than the intended width in that dimension by two material thicknesses (probably .750"). Rather than trying to make the top and bottom exactly match that width or sand (MDF Is horrid) you can cut it 1/8" oversized and trim to fit with a flush trim bit.

Routers are a lot of fun; mine has become my favorite power tool.

[rtate]

Thanks for the info!!
I was looking a a circle jig at Lee Valley but it only went up to
7 1/2" and i need 11 3/16"....

[SpeakerScott]

Originally posted by rtate
Thanks for the info!!
I was looking a a circle jig at Lee Valley but it only went up to
7 1/2" and i need 11 3/16"....

Jasper Tools...great stuff...
http://www.jaspertools.com/

[Drew Eckhardt]

Originally posted by SpeakerScott



Jasper Tools...great stuff...
http://www.jaspertools.com/

I own a set. While they're nice, I've also made my own circle jigs for larger radiuses around 1.5, 5, and 12'.

After doing that I decided that $40 to save 10 minutes the first time and a minute each time I needed new diameters wasn't worthwhile.

The 1/8" dowel pin as a pivot is nicer than a nail but shouldn't run you over $1 at a decent hardware store.

[littlemike]

A router and circle jig is my preferred way to speaker cutouts (at least larger ones)

I have the Jasper Jigs too, they are nice.

You can certainly make your own jig for a lot less $$$, it will work as well, but might be a little bit more work to set up initially.

[rtate]

The jasper jig looks good but $40 for 1 sub...
I'm not sure if it is cost effective...

Anybody want to sell a used jasper??

[MJL21193]

Originally posted by rtate

I'm not sure if it is cost effective...

It's not a big deal to make your own.
Gee, if you think you can build a speaker, you sure enough should be able to make a circle jig. It doesn't need to be fancy - a piece of thin hardboard will do. DIY.

[SpeakerScott]

Originally posted by MJL21193



It's not a big deal to make your own.
Gee, if you think you can build a speaker, you sure enough should be able to make a circle jig. It doesn't need to be fancy - a piece of thin hardboard will do. DIY.

Wow...a home made circle cutting jig, with a home made plunge router using a flush cut bit...

I'm impressed, and I feel inadequate since I just bought mine...and didn't build it...jeez..

-Scott