johnsmachines

When I was making the triple expansion steam engine I turned the crankshaft from a piece of 50mm diameter stainless steel rod.   One centre for the main bearings, and 3 other eccentric centres for the big ends.  I spent a long time marking out the centres, then turned the bearings, gluing in a packing piece after turning each one, so that pressure on the ends of the crankshaft would not distort it.

After a whole day on the job, I was pretty pleased with the progress, and I lined up the almost finished crankshaft with the bearings on the bed, to see how it would look.

#%&*##

I had made a 3mm mistake with the position of one of the big ends.  It was a fatal mistake.

So I made another crankshaft the next day, and that one worked out fine, and is on the triple to this day.

The ruined crankshaft sits prominently on a shelf in my workshop, as a reminder.

Today I am making another confession, of another stupid mistake.

This was a beautifully smooth, accurate, keyless Rohm chuck which I used often in my mill, mounted on a quick release quality JT6 Japanese fitting.  I used it successfully on drills down to 1mm size for several years.

But lately it seemed to have a bit of runout.  Inspection appeared to show that the JT6 taper part of the chuck had dislodged a bit.  Not the taper itself, but the sleeve that the taper was machined into.

So, I put it in the press to snug it back home.

No movement, so I pushed a bit harder.  (stupid stupid stupid!)

BANG!

I don’t know what let go, but I think that I cracked the tapered sleeve.  The chuck was seized solid.  Would not move despite heavy persuasion.  I had really buggered it.

O well, you live and learn.  I figured that I would remove the chuck, buy a new one, and install it on the expensive Japanese JT6 spindle.

So I applied a gear remover, one of those double C shaped ones, with the hardened steel jaws, and tightened the bolts.  But it would not move.  Tightened the bolts further, and further, until I was not game to apply more pressure for fear of breaking the gear remover or the Sidchrome spanner.   Considered applying heat with oxyacetylene, but I really did not want to wreck the Japanese fitting as well, so I put the question to a colleague at the model engineering club today.  As a result of that conversation, this is what I did…..with an angle grinder.

As you can see.

I considered putting it on the shelf next to the crankshaft, but you know what…. I don’t think that I can bear to look at it, so it is going out with the rubbish to be forgotten as quickly as possible.  (ps.  now sitting next to the crankshaft)

The JT6 spindle seems to survived unscathed.

The other side of the chuck and the spindle, after separation.

In retrospect, I wonder if I should have tried some heat, but the chuck was busted, so it would not have made much difference.

End of confession.  But I dont feel any better.