Question about snug router plate

[Josh Kandiko]

I was looking at Rod Peterson's article on woodcentral and he recomends creating a template the same size as the router plate. He then goes on to say that one should use a guide bushing and straight bit. He recomends 1/4" bit and a 3/4" collar or a 1/2" bit and 1" collar. He says this will net 1/4" smaller hole than the plate on all sides, and that one could just use a 1/4" rabbeting bit to trim out the rest. I like the idea, but don't understand the math. If there there is a total of a 1/2" from the outside of the bushing to the bit, won't the hole be a 1/2" smaller on all sides? I've never used collars before so maybe I'm missing something. Anyone try this or have insight into the math?

Thanks
Josh

[Ralph Barhorst]

Either of those two collar and bit combinations will give a 1/4" clearance since the 1/2" bit is centered in the 1" collar leaving 1/4" between the OD of the collar and the edge of the bit.

[Steve Clardy]

I used a 1/2" rabbit bit after making my template 1" under size all away around. I just sawed the hole out with a jigsaw, smoothed with a wood rasp, then rabbited the lip for the plate to sit on.

[JayStPeter]

There was a thread on WoodCentral about that a month ago or so. He used a rabbeting bit after routing the initial hole so it left a lip for the plate to sit in.

Jay

[Richard Hash]

This is a bit off-topic, but if you are considering a rabbeted lip to sit your plate in, I would advise against it. Just make the hole walls flush, spend $15 on plate levelers, and you will never look back again! Then swapping plates in and out doesn't require paper shimming, etc. You just tweak a screw here and there, and it's dead flat.

My $.02 ;-)

[John Keane]

Outside diameter?

[Steve Clardy]

This is a bit off-topic, but if you are considering a rabbeted lip to sit your plate in, I would advise against it. Just make the hole walls flush, spend $15 on plate levelers, and you will never look back again! Then swapping plates in and out doesn't require paper shimming, etc. You just tweak a screw here and there, and it's dead flat.

My $.02 ;-)

Most plates come with leveling screws, to use after the lip is rabbited in.
So you can fine tune the plate.

[Richard Hash]

Most plates come with leveling screws, to use after the lip is rabbited in.
So you can fine tune the plate.

True enough for store-bought plates, but that's a hassle for home-made ones, and inevitably the dust & chips works their way between the plate and the lip and start messing with you. Flush cut sides and plate levelers make all that a thing of the past. It's cheap, easy, and fast. You can drop in a new plate, tweak a screw and you are good to go.

Made me a believer once I tried it :) ...