I wanted to start this restoration a while ago, but the one thing that stoppped me was that I did not have a C-spanner to unscrew the chuck's holding nut.
End of last year I set out and asked on the Colchester group on groups.io for help in designing one. The response was quick and some valuable info came forth.
After some measurements (no not the bar type) and discussions on the group message I had what I needed.
It is interesting to note that the C-spanner works on friction and not on the front lip gripping. The lip is just to let the spanner lock into place to get the friction grip created.
I sat down and designed a new spanner on CAD. If you look at the drawing you can see the surfaces where the friction between spanner and nut is created.
This CAD design I then sent to a local shop to have it laser cut. I had to pay the minimum fee of a full R250 as the actual cost was a lot less than that. Still a bargain compared to buying and shipping one from overseas at a cost of about US$160.
After a few days I fetched it and deburred the edges. I also noted that the locking lip is in fact rounded at 90 degrees to the length of the spanner to ensure it fits correctly in the slot grinded into the nut.
Painted a nice red so that I do not loose the spanner.
A perfect fit! Job well done.
Onto restoration then as the chuck can now be removed!
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