Screw cutting issues

[Lockwood1956]

I have a Churchill redman cub Mark 3a

Screw cutting shaft occasionally stops when cutting threads.

I initially thought half nuts might be badly worn, but stripped all that down, cleaned inspected and put back together, no real wear on half nuts.

There is a connector between gearbox and shaft, which turns by hand. I think it may be a clutch type mechanism, there is a hole where it looks like either a grub screw or a pin might go there (i can see no evidence of either)

It surfaces and slide cuts fine (but thats from the other shaft of course)



Anyone able to shed any light on this issue?

Thanks in anticipation

[Lockwood1956]

Pictures
   
   
   

[Vinny]

If that's the lead screw shaft in your picture, it shouldn't turn by hand unless there's something (knob, lever, ...) to disengage it, and it's in that position. To see if it's a pin or grub screw, put a paper clip in it and see if you feel threads or a hole going all the way thru. That's just my guess.

[Lockwood1956]

IThe collar moves, not the shaft

Apologies for not being clearer

[Lockwood1956]

There is a shear pin on the upper shaft which is inside the gearbox.

I stripped out the gearbox and replaced the pin, all working well now

Happy puppy