Removing leadscrew from SB9a gearbox

[Skowinski]

Trying to get this leadscrew off the gearbox in preparation for dissasembly, cleaning/inspection and painting. I've removed the nut and locknut that hold the gear on the end of the leadscrew, but the gear itself won't budge. I think it's keyed to the shaft, so needs to come off along with the key so the leadscrew will pull out from the other side. How do I get this thing off without damaging anything? I've tried pulling, tapping gently, and soaking in liquid wrench, but so far - no go.

 

[Norseman C.B.]

It may be cross pinned, some times that can be hard to see after years of use, just a thought...................

 

[Skowinski]

Thanks, I'll check. But all the parts diagrams I can find, and the rebuild manual I have, only show/mention that the gear is keyed to the shaft. I presume a Woodruff key. Seems it should just slide off, or be able to come off with some gentle persuasion.

 

[Norseman C.B.]

Does the diagram show a tapered fit or straight ??
If it's not pinned a little heat and a love tap or two might do it .......

 

[jocat54]

It has been a while since I've had my 9A--but from what I remember the only thing holding the leadscrew is the nuts and a key--should come off with little persuasion.

 

[derf]

Mine was a little stubborn too. I made up some hardwood wedges to push from the end of the other shaft. After about 1/4" movement it popped right off.

 

[Skowinski]

Mine was a little stubborn too. I made up some hardwood wedges to push from the end of the other shaft. After about 1/4" movement it popped right off.

Ah, so you pushed on the threaded end of the lead screw shaft, hadn't thought of that. I've been trying to devise ways of driving the gear off to the left in the photo above, but it's hard to get anything on it without simply pushing on a few teeth.

One thing I did notice - if you rotate the lead screw gear and watch the gear stack behind it rotating there is one position where teeth on the adjacent gear to the left of the one it engages with line up*. I've been putting that position on the lead screw gear, it seems that has to be done to allow the lead screw gear to slide off to the left.

*edit - you can see this in the photo above, on the back side of the gear stack the teeth are completely misaligned

 

[Tim9]

My 9A was Keyed. It was stubborn also. That said I was able to remove the shaft with very limited tools which I brought with me to pick up the lathe. I'm pretty sure I used a brass hammer. I set the leadscrew on the bench with the QCGB hanging off side on the bench. This kept the QCGB from moving while I tapped the leadscrew. Afterwards I did have to clean the threads a bit.

 

[Skowinski]

Quick note - got it out, by removing all the other shafts and gears first. Once I'd removed the screw gear shaft (input) to the left of the lead screw in the original photo above, it was a simple job to insert a long punch through where that shaft went and knock the lead screw loose from it's keyed gear.