Bearing location on stile/rail bits
I will be buying matched stile/rail router bits for cabinet doors (stand application). In shopping around, I noticed that there are several bit designs (not talking about the inside edge shape), but I have a question about two of them. The most common design has a bearing between two cutters on one of the bits and a bearing at the end of the cutters on the other bit. This design seems to control the depth of cut without using a fence. Companies like CMT and Eagle America sell this design of stile/rail bits.
My question concerns this other design: This design has the bearings located at the end of the cutters on both bits. Oldham, Rockland, Grizzly, and others sell this design of matched stile/rail bits. It’s clear from pictures at the Oldham web site that neither the stile nor the rail touches these bearings during the cut. It seems that the bearings are used only with templates (for curved edges), and that to cut straight edges, you have to use a fence with these bits. What advantage does this bit design have over the one with the bearings positioned to limit the depth of cut as described above? It can’t just be that it is cheaper to make these because the price difference seems to be about $10. Is one design more accurate that the other?
By the way, thanks again for helping with my Hitachi M12 questions. Great answers, and the referenced web site for modifying the router for table use was excellent.
Bert
Replies
Use of a router bearing is subject to every little bump in the wood, and so doesn't give as smooth a cut as a fence or edge guide. However for a curved top or other special shape they are a lifesaver.
The question becomes whether you have a separate smooth template to guide the router (the only way to go if you are making many of the same...), or if you are working one-off, and the work piece is both the product and the template (be sure to sand the edge smooth before routing).
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Charlie Plesums Austin, Texas
http://www.plesums.com/wood
Thank you, this is very helpful.
Atually the two piece sets with a bearing on the end of both bits have each bit made as one piece. The sets that have a bearing in the middle of one of the bits have each bit made from two pieces with shims between. The advantage of the ones that have a bearing between the cutters on one of the bits (like Freud) is that the fit is adjustable with shims so that you can have them sharpened and still maintain a proper joint. Even with the bearing you still use the fence for straight edges.
Freud, Inc.
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