Leblond 1340G lead screw not turning?

[Livewire]

I hope this is an appropriate forum to ask these questions. If not what would a good forum be?

My high school’s shop classroom has a brand new Leblond 1340 G which is virtually never used by the students. They recently started up their adult night class and I was helping the shop teacher make sure it was in working order before using it. In doing so, we observed that the lead screw wasn’t turning. After fiddling with all the controls we finally hit on that moving the VWXYZ lever from W to V, Y or Z, and sometimes X (?), the lead screw would turn normally. This seemed to us to be incorrect behavior but with our limited knowledge of the machine we couldn’t be sure.

So a couple questions:

Shouldn’t the lead screw be turning whenever the spindle is turning? It doesn’t seem right one position on that lever doesn’t work.

What could cause that position to not turn the lead screw when W is selected? The feed rod has no issues.

The VWXYZ lever is sometimes impossible to move. Jogging or rotating the spindle seem to help. Then suddenly it may release easily and switch. It’s also very clunky. Is this normal? Is there a linkage or something that can be adjusted?

Thanks for any help.

Steve

 

[Beckerkumm]

Doesn't that lathe have a separate feed rod so the leadscrew only turns when threading? Most lathes are designed that way with a feed/threads lever to engage either rod or screw. Dave

 

[mksj]

Shouldn’t the lead screw be turning whenever the spindle is turning? It doesn’t seem right one position on that lever doesn’t work.
NO, only when the levers are engaged for threading

What could cause that position to not turn the lead screw when W is selected? The feed rod has no issues.
Same issue, you cannot just flip the levers randomly and expect the lead screw to turn all the time, the other settings may not correlate to a threading position. There are also interlocks.

The VWXYZ lever is sometimes impossible to move. Jogging or rotating the spindle seem to help. Then suddenly it may release easily and switch. It’s also very clunky. Is this normal? Is there a linkage or something that can be adjusted?
First off you cannot change the gears statically. You always hand turn the spindle chuck and you must have the feed lever engaged (usually to the L-Low position) so that the transmission gears are engaged. A lever will shift but not be fully engaged, you rock the chuck slightly while applying light pressure on the gear lever until you feel it snap into gear. I always will just bump the lathe jog to make sure everything is engaged properly. Newer lathes, can be quite stiff when changing gears, in particular in the transmission.

Example below should be similar to your lathe. The L -Low lever should be flipped up and the spindle/chuck rocked when shifting the levers, do them in sequence while rocking the chuck.

 

[tailstock4]

Regarding whether the lead screw should be turning – Not necessarily. Most machines that have separate leadscrews and feed rods, the leadscrew only turns when you are in turning mode. This is usually done because the leadscrew is typically mounted with a set of precision bearings that are preloaded, and this prevents wear on these bearings and gears.

Feedboxes can be difficult to shift because of misalignment of gears or dog clutches. Yes, you can turn the chuck when the headstock is in neutral, or some machines simply have a jog. One universal way that works on all machines is to reach down and turn the leadscrew or feed rod by hand, whichever mode you are trying to shift into. A quarter or half turn of these shafts will quickly and safely get you into gear. And, of course, I mean when the machine is stopped.

One other thing to be aware of is there are some machines where it is possible to get too many things in a neutral position, either in the headstock or feedbox. This can cause you to virtually lock yourself out from shifting. In this case there are some shafts or gear assemblies in the headstock or feedbox that are simply not turning because of being in a neutral position and thereby making alignment or shifting almost impossible.

 

[markba633csi]

That model looks more like a newer South Bend- what year was it made? It's not listed in the current LeBlond catalog