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?

woodworker88 wrote:
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?


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.

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.

On 14 Apr 2005 20:17:18 -0700, "woodworker88"
wrote:

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?

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

On 14 Apr 2005 20:17:18 -0700, "woodworker88" wrote:

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?

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

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

Anyone interested in the project this is related to should check out
either:
www.lahsrobotics.org or
http://www.eecs.berkeley.edu/~mseema.../_DSC0108.html
The wood will be a bumper underneath the outside metal frame. The
frame is 1" aluminum square tubing, 1/8" wall.