Power feed problem

[larry phelan 1Participant @larryphelan1]

Good morning all,

I have a problem with the powerfeed on my Craftsman lathe. What happened was this; I was parting off under power when the cutter became stuck and the feed stopped. I switched off at once, disengaged the feed and backed out the blade, right out ! When I tried to engage the feed again, it just did not want to know. It made a feeble attempt to engage, but I could stop it by just holding the handwheel, not good !

I dismantled the unit holding the change levers to see if any damage had been done to the spline or the rack, but both are fine so the problem seems to be behind the front panel. My question is, how do I get access to this area and what should I expect to find ? [I dread to think }

I,m sure this has happened to someone else, so any help or advice will be more than appreciated. While I can still use the machine, the loss of powerfeed is a right P-I-T-A. Perhaps trying to fix it might be another one, but it has to be done.

Any ideas ????

[DiogenesParticipant @diogenes]

Sounds like a shear pin has done it’s job?

Is there a ‘socket’ that the L/H end of the PF drive shaft fits into? – check the pin there..?

[SillyOldDufferModerator @sillyoldduffer]

Agree with Diogenes.  When it happened to me, the shear pin snapped but the ragged end had enough friction to turn a lightly loaded power feed.  Above a certain load, it slipped, causing symptoms as described by Larry.

On my lathe, the shear pin was under a sleeve at the headstock end of the leadscrew.   The pin connects the leadscrew to the gearbox shaft.

Larry’s lathe may have more than one sheer pin, or it’s located somewhere else in the drive train.   I located mine by running the motor and loading the lathe enough to cause slippage.  Though the sleeve hid it, I quickly noticed that that the gearbox output shaft was rotating correctly, whilst the leadscrew stuttered.

Sheer pins are usually positioned obviously where shafts connect, not inside gearboxes etc, so trace through the drive train to find where the breakage is.  With luck an easy fix once the pin is found.

Dave

 

[larry phelan 1Participant @larryphelan1]

Hi Diogenes,

I presume that the driveshaft is the one with the keyway running the length of the machine ? It is revolving alright  whether the drive is engaged or not. There is another shaft running from front to back, the one with a rack which engages with the splines when the lever is operated. What,s at the other end of that, I dont know.

That driveshaft is pinned to a socket as it enters the headstock, but the pin does not seem to be sheared. In fact it looks more like a roll pin.

[larry phelan 1Participant @larryphelan1]

Good morning Dave,

My leadscrew seems to be working OK, just the carrage an cross slide feeds.

I will take another good look at it to see if I can find a damaged pin.

Thank you both for your quick replies.

Why is nothing ever simple ????

[Robert ButlerParticipant @robertbutler92161]

Larry

it may not be obvious the roll pin is sheared as either end would remain in place. Does the Headstock end of the leadscrew transmit drive to the leadscrew through the sleeve?

Robert Butler

[larry phelan 1Participant @larryphelan1]

Good morning Robert,

Yes, I see what you mean !, in fact when I knocked out the pin, I think it was in two pieces. I replaced it with a brass one, just to try it, but it made no difference to the feeds.

My leadscrew has its own connection to the headstock and seems to be working OK. If, as Dave said, there may be another pin somewhere else, I cannot see any. One other thing which may be a factor, is that when I tighten up the screws holding the change lever box in place, the lever movement becomes locked. That,s why I thought there may be a problem at the other end of that small shaft which moves in and out to engage the different feeds. I was not able to remove it in order to check.

Looks like I will have to spend a bit more time on it.

I still appreciate all advice, since I have much to learn, so keep it coming please.

[Dave HalfordParticipant @davehalford22513]

Larry ,

Does power sliding not work either?

If you have the modern Chester one there a clutch in the apron according to the manual, items numbering from 440 to 449 in the Chester manual.

Clutches are normally adjustable, on my Rockwell for instance there is an allen screw to increase the grip inside the ‘engage drive’ lever.

[DiogenesParticipant @diogenes]

I’m guessing that it’ll take some while to wade through the drawings in the manual that Dave linked to.. ..there are a few possibilities to check there, I think..

..please do let us know how you get on..

[larry phelan 1Participant @larryphelan1]

No Dave, my machine is some 20 years old, but still working well, apart from this issue. No clutch, as far as I know, unless it be the small allen screw with the ball bearing on the left hand side of the change lever ? I suppose that could be a clutch. I did try adjusting it but it made no difference. The lever does click into position but the feed still does not engage, or only sort of !

Back to the drawing board !

[Dave HalfordParticipant @davehalford22513]

Larry,

A sprung ball is just a detent to hold the lever.

To be honest it’s difficult to see how anyone can help. Craftsman’s have been made in the US and now the far east. Without pictures or a model number we don’t even know if it’s 12″ or 31/2″

[larry phelan 1Participant @larryphelan1]

Just had a look at that manual that Dave linked to, heavy stuff !

There seem to be a few differences to my machine ,maybe nothing major but the change box looks different. I was trying to see if I could make out what happens behind the wall, not easy !

,In all fairness, I must say it is an improvement on Chester`s usual manual!

[larry phelan 1Participant @larryphelan1]

So Dave, no clutch !

[Dave HalfordParticipant @davehalford22513]

In which case try the bit that engages with the slot in the shaft it’s likely snapped off

[larry phelan 1Participant @larryphelan1]

My thoughts exactly ! That,s  why I was asking how to get at that part.

[larry phelan 1Participant @larryphelan1]

Just wading through that manual [heavy going ] and I think the model shown has a clutch, mine does not, as far as I can  see.

That may be a later model, but since it came from Chester, I doubt if it is American, I believe their stuff comes from China. The drawings are very good [up on the usual Chester ones ], but thy still dont show how to get at these parts. I am fairly sure at this point that the problem lies at the inside end of that racked bar, but I cannot see how to remove it. I hope I dont need to separate the front plate from the top one, that might be messy. but at least it would show a bit more. Will let you know what I find, if anything, and again, my thanks to all.

Watch this space !

BTW, I did check for any more shear pins, but found none anywhere.

[BazyleParticipant @bazyle]

You have been confusing people by talking about a Craftsman which is a very popular low end  American lathe maker rather than what I think you have namely a Chester Craftsman which is just one of the Chester models (far Eastern) It is the same as the Warco BH600 and a few others and is a development of the generic “12×24”.
It was sold in the ‘states by Grizzly as the G9249. If you can find the manual for that is is by far the best and way more than the uk importers. Some of the electrical wiring changes but the mechanicals are the same. Several people on here have these lathes.

If the feed shaft is rotating check if it will autofeed or slide lengthways. If it does it is something in the apron. I suspect the lever that selects between slide and traverse is out of register on its shaft and did not properly engage the dog clutch inside the apron and the edges of the dog teeth have given way a bit. About 10 years ago on here someone did a strip of the apron with pictures that might help.

Also join the Groups.io 12×24 import lathes forum. Lots of back reading to do.

 

[larry phelan 1Participant @larryphelan1]

Hi Bazyle,

It was not my intention to confuse anyone, that would serve no purpose. The machine cam from China, via Chester, as did any of the spare parts I ever needed for it.

I think you are correct in saying that the problem lies with the lever selection, that,s what I thought, but I still dont know how to get at it.

I am surprised that no-one has encountered this before, since it is a very simple mistake to make. SOD did mention shearpins, but I found only, and replaced that anyway, not that it made any difference.

I will continue to try resolving this, although at this point, I dont really know what else to try.

[Dave HalfordParticipant @davehalford22513]

That grizzly can’t be Larry’s it has a clutch. Must be an even older one still.

[BazyleParticipant @bazyle]

Sorry I didn’t mean to imply it was deliberate. The linked manual is similar but the apron might be a mirror image.
This link shows some pictures of an equivalent lathe. It is actually a Jet 10×24 but emphasises how all these lathes are clones with small variations for size and cost reduction over time. The part No 445 is a dog-clutch that either engages with 443 for traverse or 447 for feed.
Another possible fault is that the circlip 446 has broken. I assume you can see how to check this.

[BazyleParticipant @bazyle]

Forgot the link.

https://www.hobby-machinist.com/threads/missing-and-broken-gears-for-lathe.17649/

Here is a helpful thread but what happened to the photos of Oubaillie? (Geoff Halstead)
https://www.model-engineer.co.uk/forums/topic/i-screwed-up/

and Geoff himself showing the apron details
https://www.youtube.com/watch?v=NdHEYhceCew

[Michael GilliganParticipant @michaelgilligan61133]

If a picture is worth a thousand words, Geoff’s video is worth a million !

MichaelG.

[Howard LewisParticipant @howardlewis46836]

Assuming that the power shaft rotates steadily, the failed drive will be within the Apron.

Within the Apron, the gear driving the shaft with the integral pinion that engages with the rack is pinned to the 16mm dia shaft.

It might be that this pin has sheared.

The shaft, with its integral pinion is not the strongest of material, and bends easily.

My lathe , like the Craftsman and Warco BH600, is an Engineers ToolRoom BL12-24, all to the same design as a generic Taiwanese lathe.

When I had problems, Geoff Halstead (Oubaillie) kindly gave instructions on how to remove the Apron (It is heavy)

If you want, PM me with an E mail Address, and I will send you some details.

Having driven out the rollpins in the drive to the power shaft, and the Leadscrew, replace them with brass shearpins, 5 mm diameter with a 2.5 central drilling. This will be quite strong enough to provide a drive, but weak enough to shear in the event of any crash.

To rewmove the power shaft, you will need to remove the Leadscrew, and switch shaft, including the bearing block at the  tailstock end of the bed. That will be difficult to remove as it locates to the bed with two rollpins.

Ensure that the keyway in the power shaft is at the top, before removing it.

DO NOT disturb the four setscrews retaining the worm housing on the back of the Apron. The capscrews are almost inaccessible!

HTH

Howard

 

[Howard Lewis]

On Howard Lewis Said:

 

Ensure that the keyway in the power shaft is at the top, before removing it

 

Nope, other way up or the key falls out of the worm and runs under the bench. Geoff also has a video on apron removal. Also instructions on the old forum thread I linked above, and finally the video has a link to an instruction document that is slow but does work.

[DiogenesParticipant @diogenes]

Bazyle, that’s a really worthwhile & useful set of links – interesting that these assemblies are all so generic – it’s similar enough to so many other models that it’d have been a real shame to have ‘lost’ them – Good work by Geoff & you!

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