Drilling a mortise at an angle

[rhmercier]

I need to drill a stair banister into a log pole.  I don't know how to drill the mortise at the correct angel to accommodate a 2 1/8" diameter tendon.  Any suggestions?

Ron 

[Kevin]

A plunge router, bushing and template will work.
Double face tape the template to the log, drop the bushing into the template and router out the mortise.

[rhmercier]

Thanks Kevin,

This will be a 2 1/8" diameter about 1.5" to 2" deep hole.  Is the router motor strong enough for that size of hole?

[beenthere]

This will be a 2 1/8" diameter about 1.5" to 2" deep hole.  Is the router motor strong enough for that size of hole?

I was thinking Kevin meant to router out a small amount at a time... maybe your depth would be the biggest limitation for a router bit.

[chet]

A good sized plunge router would do the trick. I have done mortises with mine to 5'' already. It has to be done in multiple steps, and blow out the chips each time.

[m wood]

this probably sounds crazy, but when I'm drilling mortise's for stair banisters (log railing mind you) I get the angle grinder and nip away a shoulder until I can get the forstner bit to catch with the center bit.  Variable speed hole hawg and taker' slow.  Yes, I estimate and eye-ball that angle.  No matter how many guages and angle finders I've used on log railing...the best results have come from the good ol' eye-ball'in!  just my 2 cents.

I've had a bit or 2 (or more) walk out of that shoulder, but once you get the forstner to cut all the 360 degree, it'll go.
mark

[Kevin]

You can buy mortise chisels and clean out the drilled holes as well.

http://www.ptreeusa.com/edirect_100813.htm

[Axe Handle Hound]

If this is for an exterior staircase I would use an alternative method or make sure you drill your hole completely through the lower stringer.  Otherwise you're making a waterpocket that will rot your banister and stringer in no time. 

Another possible option for drilling those large diameter holes would be to build a solid wood jig that sits on your stringer and has a hole pre-drilled through it at the correct angle.  Clamp the jig to the stringer and the pre-drilled hole will guide your bit straight despite the center spur not being engaged at first.