Routing and Drilling: What Order?


I am trying to make a custom half-round molding on the router table, and then drill and counterbore holes for 1/4-20 bolts. I am wondering what order I should do it in: do I drill first and then rout, risking tearout on the inside of the holes (their about 5/8" dia) or rout the half round and then drill, with the holes possibly shifting from side to side. The holes need to be fairly precise as the bolt connects to a metal bar that doesn't have much leeway, and the wood has to be fairly smooth. Any ideas or comments?
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woodworker88 wrote:

Try drilling the holes first, then fill with a piece of dowel and sand smooth, then run piece thru router.
Finally, remove remaining dowel piece with a gimlet exposing counter bores.
HTH
Lew
PS: You can always use some varnish as glue to hold dowel in place while machining, if necessary.
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Bolts in a molding? I'd probably use biscuits, glue and clamp the molding for a day. Or if you are fastening it to metal use epoxy. Anyway, one choice would be to drill small holes first, route the half-round, then countersink.
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The wood is basically a bumper for a metal object, so it needs to be strong. On the other hand, the general consensus seems to be the same: drill pilot holes, then route, then counterbore. I'll try it on a piece of scrap before I run 8 feet of it. Thanks everyone for your advice
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Chances are good for no tearout over the countersinks. Test on scrap first. If you're using bearing and a bearing might roll over a hole you have no choice but to drill after routing. Notwithstanding, drilling after routing may be a necessity as sanding and such may reduce the pre countersink diameter. And to be sure, if your pre drill 1/4" pilots only and follow with countersinks after routing, (requires piloted countersinks) you will clean up any tearout created during the rout. More on routing and drilling? http://www.patwarner.com
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how about drilling the holes first, and "pinning" them to a piece of scrap with dowels or toothpicks... run them through the router using the stock as a jig, then countersink the holes before mounting?
mac
Please remove splinters before emailing
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Anyone interested in the project this is related to should check out either: www.lahsrobotics.org or http://www.eecs.berkeley.edu/~mseeman/photos/robotics/pages/_DSC0108.html The wood will be a bumper underneath the outside metal frame. The frame is 1" aluminum square tubing, 1/8" wall.
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