making router subbase

[Robert Reece]

I've made a few router bases in the past, but now I want to make one that accepts PC template guides. The material will be 3/8" polycarbonate. What is the best way to guarantee the guide hole ends up perfectly concentric to the router collet?

[David DeCristoforo]

Whenever I need to hole in the sub-base to be concentric with the collet, I use a straight router bit or a "forstner" bit chucked in the collet to punch the hole in the base. I have one bit that is the correct size for the body of the PC style guides. A machinist friend shortened the shank and turned the end down to 1/4" so it can be mounted in the router. Then I use a rabbeting bit with the "right size" bearing to cut out for the flange on the guide collar. Sorry but I don't remember the exact OD of the bit... haven't used it in a while. Also, you almost have to have a VS router with the forstner bit. Otherwise the bit is spinning way too fast.

Even with that, there can still be some slight variation or "play" in the router itself. The plunge routers seem better for this than the ones where you rotate to motor in the base to adjust the depth.

[Steve Clardy]

I just purchase mine from Pat Warner.

Clear PC bases are about 10.00 or so.
Been a while since I have purchased one, so prices may be different.

[Bruce Wrenn]

Get hold of a copy of Bill Hylton's book, " Route Magic." He has a section on doing this very operation. I like to use a plunge router to make initial hole. Then using a centering bit in drill press, clamp base down. Then drill the two sized holes.

[Robert Reece]

Get hold of a copy of Bill Hylton's book, " Route Magic." He has a section on doing this very operation. I like to use a plunge router to make initial hole. Then using a centering bit in drill press, clamp base down. Then drill the two sized holes.

He uses an MDF template along with a template guide in his router to do the hole. I guess if you are very careful, it would line up well.

Will a forstner bit drill polycarbonate ok?

[Gary McKown]

Agree about just purchasing from Pat. Super-quality, no hassle, and a true gentleman (plus a router magician).

[glenn bradley]

+1 on Pat's bases; great quality. If you want to do it yourself, make the shouldered hole, install a template that comes with a precision machined centering pin, center the plate and drill your screw holes for the base a bit oversized (and counterbored). This assumes pan head baseplate screws as countersunk flathead ones will try to center to the cone and that will fight you.

[Rich Neighbarger]

Funny. I just made one last week using Glenn's method... It works great.

Yes, forstner bits cut polycarbonate just fine. Just make sure they are on slow speed so as to cut the plastic rather than melting it.

[Robert Reece]

One reason I have hesitated to order a base from Pat is because the website lists them as acrylic. I have several acrylic bases that have cracked. I know at least one was dropped w/o a router in it. So I was looking to use polycarbonate which I believe is tougher than acrylic.