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Jim85IROC 26th January 2004 12:31 PM

Can somebody educate me on router rabbit bit usage?
I've got my speaker boxes almost finished for my TB W3-871s', and now I'm ready to use the rabbit bit to create the flush-mount for the speakers. I went to Home Depot last night and didn't exactly see what I was expecting. They only had a few sizes, and the way they measure them (diameter) makes it impossible for me to know what size groove it's going to cut, since none of them were thoughtful enough to provide the bearing diameter. The guy at Home Depot showed me a package of different bearing sizes that I could swap out, but the package only had 2 different sizes.

So anyway... what tool do I need to be able to route different size notches for my flush mounts? In this particular case, I need the notch to be 5/16".

Timn8ter 26th January 2004 12:46 PM

I use a router witha 1/4" straight bit and a Jasper Circle Jig. I cut the rabbet first then cut the hole.

pinkmouse 26th January 2004 12:56 PM

The easiest way is to use a collar guide fitted on the baseplate of your router, not bearing guided bits. First, make a test cut with your collar and say, a standard 1/2" bit, with a thin (1/8" or so) ply or MDF sheet resting on top, 1/2" or so in from the edge, Measure the ofset of the cut from the edge, and cut a template from this same wood oversize by the amount you measured over the driver diameter. Use this jig to cut the rebate for the driver. Make a smaller jig for the actual cut out. When you have been doing this for a while, you build up a nice collection of templates for different drivers, that can be used quickly and easily, again and again.

General routing advice, don't cut too deeply in any one cut, 1/8" to 1/2" in any pass gives the best results with a normal domestic grade router.

Good luck, :)

maylar 26th January 2004 03:27 PM

So, measure the bearing.

Rabbet depth = 1/2 (bit dia. - bearing dia)

Or just measure from the bearing to the outside of the cutter.

Timn8ter 26th January 2004 03:37 PM

Your explanations seem rather complicated. Is this somehow a better method than mine or am I missing something? Or perhaps you don't have a plunge router?

officeboy 26th January 2004 03:52 PM

I've been to home depot, and I didn't really have a problem finding what they had, part of the reason is that they have very little.
At best you will be able to find a 3/8 and a 1/2. Probably only a 3/8 and it will be about $30, quite a lot for a bit you will very seldom use.
And the bits that they had at my home depot all gave what the cutting depth was, not the diameter of the bit.

I would suggest looking somewhere online maybe and seeing what you can find there, something with adjustable bearing sizes would be good.

Jim85IROC 26th January 2004 04:08 PM

I did some searching online and found numerous companies that sell rabbet sets with multiple bearing sizes, to achieve a bunch of different cut widths. For $30, it doesn't seem like a bad setup, and will be versatile enough to be useful on a lot of future projects.

Unfortunately, nobody in my area sells it, so I guess I'll be putting my speaker project on hold until I can order one. :dunno:

Davey 26th January 2004 04:23 PM

IMHO the best way to cut holes is with a circle cutting jig. A Jaspar is nice, but you can make one yourself from a chunk of 1/4" hardboard. A small hole for a pin or screw at the required radius is the pivot and a one inch hole for the bits.

Two straight bits...3/4" and 1/4" are all that is collars or rabbeting bits. Use the 3/4" bit to cut the rebate first at the required depth...usually about 1/4". Since the center pin is still anchored solid for the full cut you're guaranteed a perfect circle.
Then switch to the 1/4" bit and cut the through-hole being careful at the end of the cut since the "circle" will come loose. There might be a little "nub" leftover, but it won't show and it's easily smoothed with some sandpaper.



NoTalent 26th January 2004 04:27 PM


Originally posted by Timn8ter
I use a router witha 1/4" straight bit and a Jasper Circle Jig. I cut the rabbet first then cut the hole.

I would do what Davey and Timn8ter said. All you would have to do is go purchase some more MDF (if that's what you are using). It probally would be cheaper than buying a rabbeting kit.

On another note--what types of bits do you use on MDF? I have a HSS bit that my dad gave me and it burns like crazy. Would a carbide bit not burn, or should I cut less at a time (was doing about 1/4").


Timn8ter 26th January 2004 04:37 PM

Seriously Jim, if you have a plunge router, a circle jig and a straight bit is all you need for making a large variety of rabbets and cut outs in 1/16" increments. Granted, it's $40 from Parts Express but if you're planning on continuing in this hobby it's money well spent.

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