...any chance of posting the design of our guide.... either in picture form or drawing so we can build our own...
I suspect the guide pilots off the snout of the crankshaft, and has a concentric hole drilled in it the size of the tap drill for the chosen bolt.
Then if you want a tap guide as well a second one is made with a hole to fit the major diameter of the tap.
Were I to make one for repeated use I'd use drill bushings. If planned right the two bushings would be interchangeable in the same body.
In fact the same body would work for multiple bushings to suit different drill sizes.
Look at
www.McMaster.com for these part numbers:
8493A263 bushing for 7/16-20 tap drill, 25/64"
8493A329 bushing for 1/2-20 tap drill, 29/64" As well as a bushing for 7/16" tap (~0.010" clearance),
8493A049 bushing for 1/2" tap, (~0.008" clearance)
Also need one of number
8496A13, a lock screw for the bushings.
The above parts would cost about $42, or half that if you only wanted two bushings (one tap size only) not sure what tap size is normal for this procedure?
I can also make some of these if there is interest, send me a PM.
Grigg
