I found that I had to redrill the threaded holes in the wheelhead arms in order to attach the guide block when building my Bonelle – It seems that there are various cumulative errors that eventually don't quite add up! I had real trouble trying to find out why the thing didn't fit!! Additionally I had the problem that my 2" square iron bar for the wheelhead block (C4) was metric i.e. 50 mm square (rather than 2" or 50.8mm) and had also been cleaned up on all four sides making the actual dimensions even less by a few thou all round. Not really surprising that it did not fit off the drawings.
So far this is the only part that has not fitted after being machined straight from the drawings. I am currently building the toolholder and have worked through the drawing in more or less the order that they are set-out.
The only modification I have done is with the bellows and their attachments. I will be using commercial rubber bellows and have designed and machined a set of attachments to allow the bellows to rotate as the front bar is rotated – otherwise the bellows would twist and prevent free movement of the bar.
Just to add – Don't alter the guide block. Just reposition the threaded holes used to secure it. You will have problems if you alter the block. There are two positions for the leadscrew in the wheelhead guide (C8) that can be used and both will fit if you simply reposition the holes for the block.
Edited By Bizibilder on 03/04/2023 15:35:17