Thread: Al336d lathe crash

I can't really see the need for leadscrew covers - one purpose is to keep swarf off the leadscrew but because of the position of it there should not be too much getting on there. The other often quoted reason is "safety", but again because of the placement of a leadscrew I'm not really sure how it becomes a hazard - you'd have to be wearing something with lots of tassels and loose bits I think.

Michael

I've never seen any mention of a "safety" aspect - leadscrew turns so slowly it's hard to imagine an issue. Injury in slow motion ?

I do a lot of grinding on my lathe and I hate to think what would happen to the leadscrew and half nuts without covers - lots of residue gets dumped on the covers.

A great asset in my opinion, but to each their own.

Good point but I try (not always successful ) to cover everything when grinding.
Even other machines.

Phil

Originally Posted by Steamwhisperer

Good point but I try (not always successful ) to cover everything when grinding.
Even other machines.

Phil

Yes, so do I, but the leadscrew is a very sensitive area, and any amount of grit can cause serious grief throughout the system.

With the covers in place I only need lube the leadscrew every couple of years.

Even after that period the lube is as new, with no sign of bronze bleeding from the half nuts, so obviously no wear.

I use Loctite 767 on the leadscrew. I wouldn't recommend it for an uncovered leadscrew, as it makes a huge mess when handled.

In reference to the risk of uncovered leadscrews:

I was present when a shirt was ripped completely off the back of the operator due to having the shirt being worn loose outside the shorts and the shirt-tail being caught and wrapped around the leadscrew.

Even though there were many people present, it was only the tearing of the shirt material that prevented injury to the operator, it happened that quickly.

John

Originally Posted by electrosteam

it happened that quickly.

Leadscrew on what? you must thread was faster than I do....... then again, most people likely do

Stuart

Hi guys,
just a quick update, well today I managed to get it all disassembled. Identified the damaged parts- chipped gear tooth and bent shaft on the same part.Also a bent tooth on the rack that said gear meshes with. Am ordering parts tomorrow than just have to get it all back together !!. I was pleased to find that there was no casting sand or swarf in the apron
And it was clean inside. There doesn't seem to be anymore damage fingers crossed!. But I guess I'll find out when I get it all reassembled and back in action hopefully soon.

Cheers Clint

Originally Posted by Stustoys

... you must thread was faster than I do...

Stuart

I cannot be sure, but it may have been during a normal turning pass.
On many lathes, the leadscrew turns even when feeding is selected.

John

Originally Posted by CC555

Hi guys,
just a quick update, well today I managed to get it all disassembled. Identified the damaged parts- chipped gear tooth and bent shaft on the same part.Also a bent tooth on the rack that said gear meshes with.

Cheers Clint

Exactly what I expected. I've seen this done before and it usually bends the gear shaft and a few rack teeth.

Sometimes it even bends/bows the rack, depending on where the crash occured.

Check any shear pins, and you should be good to go.

A bit of an overdue update! .I've managed to get it all reassembled and back into full working condition. Although I've decided to leave the leadscrew cover off for a while to try to avoid a repeat crash!. Once again thanks to all you guys for giving me the confidence to give it a go, I'm now a lot more familiar with my machine, now to get on with some projects😃 thanks Clint.

Originally Posted by CC555

A bit of an overdue update! .I've managed to get it all reassembled and back into full working condition. Although I've decided to leave the leadscrew cover off for a while to try to avoid a repeat crash!. Once again thanks to all you guys for giving me the confidence to give it a go, I'm now a lot more familiar with my machine, now to get on with some projects thanks Clint.

Pictures, or it didn't happen.....





Or maybe it did happen and pictures won't help.....

Mate thanks for posting this up Clint! It would have been a frustrating experience I'm sure but lathes are pretty unfriendly in that regard. I have come very close on a few occasions over the years to doing the same thing. It's the reason I don't let anyone use mine...simply because I cannot afford to fix it if I bugger it up, let alone someone else.

How did it end up getting fixed? Was it a new rack and gear?

I'm going to look at my lathe today and make sure it has some shear pins on the auto feed and lead screw.

Hi Ben, I had to replace a gear shaft that meshes with the rack (was bent like a banana!). But I didn't end up having to replace the rack had to file a tooth or two back into shape but doesn't seem to have hurt it. Had to drill a hole in the gearshaft for a locating roll pin (new part had no hole pre-drilled). The shear pins in the feed shaft etc did not shear, I believe this was because I think I caused the damage when I manually disengaged the saddle with the handwheel rather than the damage being caused by the leadscrew cover jamming. Lesson learnt!! Will post some pics but not sure how I go about that!

We all have the moments mate! I would have done the same thing but because you shared your experience I now know better! When I crash mine...I will hand wind it back out.

Just before Xmas I cooked a relatively new gearbox on a slasher. Yep...I did not check the oil.

I just gave up a last week and I had to replace it. I was lucky it was a relatively cheap one but you add in the two days of stuffing around fixing it... That was a lesson learned! I ended up having to make a big gear puller to pull the cutter bar off the gearbox shaft. Not so bad as it's something I will need to do regularly anyway but that was $400 and two days I could have spend elsewhere!