In your article you touched briefly on a subject to plagues me every time I try to use a template. Recently I routed a base plate for a cabinet. The plate consisted of a large arc with small radii ( 1/2" radius) at the ends of the arc. To route the edge, I used a 1/2" diameter 1" long flush cut router bit. One end came out perfectly, but when routing the other radius the router bit always grabbed and split the part. It didn't seem to make any difference which way I moved the router i.e. from the large arc into the radius or the opposite direction into the radius first. I should also point out that I was only removing from 1/16" to 1/8" (closer to 1/16"). I had used my band saw to cut close to the pattern line. The surface was somewhat ragged because the band saw won't cut that tight a radius. I believe my problem is referred to as "climb routing".

My question of course is how do I avoid the router bit grabbing and splitting the part. And, of course there is the safety issue when the part is thrown half way across the shop.

-Joseph R.
Hemet, CA

Our Expert

When routing end grain the trailing edge will splinter or "blowout" as the bit exits the work. When routing around the perimeter of a board the solution is to start with an end; as you work aro

und the perimeter of the board the splinters will shape away as you route the long-grain edges. When this is not possible, as in your situation with the arch, I rip the piece oversized when milling. After routing, I rip the workpiece to final width which removes the splintered surface.

You're taking the right step by bandsawing close to the final surface. When template ro

uting I first saw the stock to within 1/16". This limits the amount of the stock to removed by the router and limits the possibility of having the router bit grab the workpiece. If your bandsaw blade is too wide for the small radius I suggest that you remove a little more stock in this area first with a rat-tail file.

Finally, for the smoothest possible surface I use a spiral flush-trim bit such as the Amana "Ultratrim".

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