[TheForge] OT: Deep hole spot facing

[Peter Fels & Phoebe Palmer]

Ummmm
1 drill hole pretty close to depth.
2 flatten end of bit in lathe with abrasives. relieve edges.
3 fake cutting flukes leaving flat cutting edges, and face bottom of hole.
4 lap with 1/4” brass rod and lapping compound.
?

On Dec 5, 2014, at 9:53 AM, Andrew Vida <osan at netlabs.net> wrote:

I need to produce a reasonably accurate spot face at the bottom of a deep (~ 2.5") 1/4" diameter hole.  Furthermore, I would very much like to relieve the corner in order that a precision ground facing shim (or washer) will seat solidly and precisely normal to the axis of the bore.  To wit:


________________________________________________________________
| |
|       __________________________________________________________|
|     C_ <--Relief
|_____|<.
|            \
|_____     \
|      _|<-Spot-faced surface
|    C___________________________________________________________
| |
|_______________________________________________________________|

The only spot-facing tools of which I am aware are for shallow holes and often have pilots.  What I would ideally like is a .250" reamer, face cutting, with the relief provision ground into the face. Single operation to ream, face, and relieve.

Anyone know who might make such cutters?  I know I can make a boring bar to do this, but for some reason I seem to welded myself to the idea of this approach.

Thanks.

   -Andy
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