Really underground garage
Join Date: Aug 2010
Location: mnts of Va
If I had to do what OP proposes....on the cheap....would try a cpl different approaches.
A pc of steel tubing with an OD approx 1/16 less than cutting tool OD.And theres the rub,would probably start with a spade bit(cheap)but would be prepared to use a router bit or even a 2 flute end mill(they can be had with reduced shanks that would fit in tubing and yield the 1/16 "over" cut radius).And tig it to the end of tubing.Using sliding pillow blocks would get the alignment correct at the start.....moving them on a rail system or doing away with them as hole gets deeper.The notion is that the tubing OD keeps it cntrd,well as much as the 1/32 side clearence allowed.Chips may build up in tubing?They're deffinately gonna build up in hole so constant clearing is a givin(as mentioned by firehawkmph).
The things that would concern me most is:
Cutting action of tip on endgrain.....and would have to experiment with different forms.
Boring bar stiffness and straightness
And trying to come up with a cheaper better alternative(bust it,dado it,glue it back together.And how finished product could be made stiffer as a result......then compare that with the "hassle factor" of trying to bore it)than boring.
Best of luck,BW
On edit.......a bushing could be machined for end of tubing that would allow cutting tool to spin independently of outer tubing.......the reason would be for chip extraction during cut.Don't think it would work but a shop vac connected to a WYE in the azz end(so as to not interfere with drill motor)of tubing might work?Probably go with above welding a solid boring bar.
Last edited by BWSmith; 01-08-2011 at 09:15 AM.