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Weiler LZ330 Repair/Restoration and Manual?

plainjane

Plastic
Joined
Jan 21, 2022
Location
New Zealand
Hi

I am in the process of repairing and restoring a Weiler LZ330 my Formula SAE team has had for the past 17 years. I joined the team last year, and the lathe had recently had 3 teeth shear off the driving pinion of the carriage. This is likely due to fatigue and friction due to rust in the gearbox (when dismantled, had no oil inside whatsoever, just congealed rust clumps, water came dripping out... yikes.)

I have dismantled the lathe and taken the gearbox out for repairs, taken out the shaft that is broken (the gear is machined onto the shaft, I found out). I will need to make new dowel pins for the locking collars as they could not be removed by other means, and will do so for any other parts I have needed to remove in order to get the broken piece out of the gearbox.

This is my first experience in a repair like this, and was looking for suggestions on how best to repair this damage to prolong the life of said lathe. :confused:

It is clear that with all the press-fit connectors it was not meant to be dismantled under normal, well maintained circumstances but I suspect that in the 17 years the team has had the lathe, it has been neglected. Disappointed but not surprised. :toetap:

I was considering TIG welding new material on and machining it down to shape as the repair.
Also looking for a manual for this specific lathe, PDF if possible.

Any tips regarding coercing university engineering boys to maintain and use the machinery properly are also welcome.

Cheers,

Michelle
(Third Year Engineering Student)
 

Tom A

Hot Rolled
Joined
Apr 26, 2009
Location
NW Florida
I was considering TIG welding new material on and machining it down to shape as the repair.
Also looking for a manual for this specific lathe, PDF if possible.

Whatever you weld it with, be sure that the deposit CAN be machined - Not too hard.
Maybe you could TIG braze it - Gear repairs are often done by brazing vs. welding.
Depending on the damage, and the configuration of the shaft, you might need a dividing head to re-cut the gear, if you have that capability there.

Here's where you can get a manual, but pricey : Weiler LZ330 Lathe

Also, if you could post a photo of the damaged shaft, you'd be more likely to get some suggestions here.

And, sorry, no suggestions on how to make people behave ......
Good Luck
 

Joe Michaels

Diamond
Joined
Apr 3, 2004
Location
Shandaken, NY, USA
My recommendation is to use oxyacetylene brazing for the gear repair. It is a very forgiving process, moreso than TIG brazing. Depending on the pitch of the gear teeth, it may be possible to tap into the rim of the gear at the roots of the broken teeth. The root(s) of the broken tooth/teeth are filed down to sound and clean metal. The broken gear will need to be cooked in a fire to burn out any remaining grease or old oil. The roots of the broken teeth are then built up with bronze brazing metal. I prefer oxyacetylene for this sort of work.

The beauty of a bronze brazed repair is it will 'take' to cast iron as well as steel. Using a hand hacksaw and files, the teeth are then profiled in the brazed areas. Using a loose mating gear and some Prussian Blue will let you 'roll in' the gear teeth and see where the contact is happening. The bronze braze metal is fairly ductile. Even if you get the teeth close to profile, once you start running the gearing, the harder mating teeth (iron or steel original gears) will cold-work the bronze brazed teeth into final profile. This will work-harden and burnish the surfaces of the brazed teeth.

ANother repair method uses steel studs. The root of the broken tooth is filed off to a flat surface squared to the face opf the rim of the gear and parallel to the centerline of its bore. Steel studs are made up with a threaded section and a plain unthreaded shank. The holes are tapped as close together in a line as possible. The studs are then driven into the tapped holes and turned in tight with something like a 'Vise Grip'. Once the studs are in place, the gear can be setup and turned in the lathe so that the tops of the studs meet the circumference of the gear. The studs themselves are then hand filed to form the tooth profile. It makes a durable repair for low speed gearing such as is in the lathe apron. If the gear teeth are of a pitch that allows it, the projecting studs are then filed to form the missing teeth. These studs can also be incorporated in a brazed repair, acting as reinforcing posts.

As for preventing further abuse of the lathe, wire in an enclosed disconnect switch for the power to the lathe. Padlock the disconnect switch and do not let the key fall into common usage nor put it in a hiding place. Hiding places eventually get discolosed and abuse of the lathe will recur after your repairs. At the powerplant I retired from, we had a fully equipped machine shop. The plant ran three shifts, 24/7. On second shift and graveyard shift, we had no mechanics working. However, people working those night shifts used to get into the machine shop and do 'government jobs' (an old term in the USA, at least, for making stuff for home or your neighbors rather than for the company). We'd find messes in the shop and sometimes damage regularly. We took to locking up the electrics on the machine tools, and that pretty much took care of the problem. Everyone figures they can run a drill press, so we used to find those turned-shank drills with bend and chewed-up shanks, having been run in too light a drill press at too high a speed. We'd find an extra hole or two in the table of the lighter drill press, grinding wheels clogged up with aluminum, and a mess on the little 10" Southbend lathe. Every second person claimed to have run a Southbend lathe in HS shop, or at least claimed to know how to run one. The mess and damage that little lathe suffered was a constant.

We solved it all handily. I got rid of the lighter drill press, which had only a 1/2" chuck. We replaced it with a heavier Clausing drill press with a number 3 MT spindle. Locked up the arbor with the chuck, locked up the drill bits. Got rid of the cute little Southbend 10" (heavy 10" cabinet base) lathe by donating it to a high school shop program. Replaced it with a 15" LeBlond Regal lathe and put a lock on the disconnect switch. Locked up the tooling in 'Lista' cabinets. Between a lack of familiarity with the Regal lathe and being unable to get it started, let alone get to the tooling, unauthorized use of the lathe stopped.

We had a 25" Southbend 'Nordic' engine lathe which also saw its share of 'government jobs'. People who had some vague ideas of how to use the bigger lathe did a lot of damage and left the usual messes. When the electric clutches in the headstock of the Nordic lathe gave out, we were trying to hunt down some replacements (European parts, changes of ownership of the firm making the lathe, etc). It was all the excuse I needed to get rid of the Nordic lathe. We replaced it with a much heavier duty wide bed NK series LeBlond lathe, 25" x 96". To mount the chucks, the overhead crane in the shop has to be used. A lock on the disconnects for both the crane and the engine lathe did the trick, along with more locked Lista cabinets.

If you were a member of the 'inner circle' in the Mechanical Department, you had a 'common key' which opened the locks in the machine shop. If not, you were out of luck. Of course, those of us who were in that inner circle used to get pestered to do government jobs by people who no longer could make free with the shop resources. It was easy enough to say 'no', and another defense mechanism was to leave a job setup in a machine tool with a sign to the effect that the job was setup and woe betide the SOB who disturbed that machine tool. I was 'management' and by union rules, really was not supposed to be 'picking up the tools'. However, as senior mechanical engineer and an oldtime machinist, I had a desk in my office filled with Starrett and Mitutoyo machinist tools and some odd cutting tools. I'd get a call to come to the machine shop for 'instructional purposes', and often those 'instructional purposes' resulted in our doing a 'government job' to teach a mechanic or two some more of the work. The main thing was we had a literal lock on our machine shop and we kept the 'midnight shift' out of the shop once and for all.
 

jwearing

Cast Iron
Joined
Aug 26, 2017
Location
Bay Area, California
I don’t see how rust in the gearbox will cause the pinion to break. I would inspect and make sure the interlock is functional. Is the rack damaged also? Have you checked the rest of the geartrain?
 

j-weiler

Plastic
Joined
Apr 30, 2021
Michelle

I should be able to assist with replacement parts and a parts manual. Please reach out to me thru email in my profile.
 

plainjane

Plastic
Joined
Jan 21, 2022
Location
New Zealand
Whatever you weld it with, be sure that the deposit CAN be machined - Not too hard.
Maybe you could TIG braze it - Gear repairs are often done by brazing vs. welding.
Depending on the damage, and the configuration of the shaft, you might need a dividing head to re-cut the gear, if you have that capability there.

Here's where you can get a manual, but pricey : Weiler LZ330 Lathe

Also, if you could post a photo of the damaged shaft, you'd be more likely to get some suggestions here.

And, sorry, no suggestions on how to make people behave ......
Good Luck
Hey Tom, thanks for the response, and apologies for getting back late. Busy times.

We ended up noticing further stress fractures on adjacent gear teeth to the ones that had broken off, and so rather than repair we were fortunate enough to have our university technical services make a replacement shaft and reassemble the gearbox and lathe for us as they have a much more advanced workshop with a wider range of equipment.

Thank you for the link, I will look into it, and I will keep your advice in mind if there happens to be any further issue.

Cheers!
 

plainjane

Plastic
Joined
Jan 21, 2022
Location
New Zealand
I don’t see how rust in the gearbox will cause the pinion to break. I would inspect and make sure the interlock is functional. Is the rack damaged also? Have you checked the rest of the geartrain?
Was just theorising on contributing factors that could have caused some wear and tear. Again, could just be age, but likely just lack of maintenance and care/misuse.
Rest of gear train appeared to be fine, just dirty with old coolant caked on. Have cleaned fairly thoroughly before handing off for another department to make a replacement shaft and conduct reassembly
Fortunately rack was not damaged.

Thanks for the reply!
 








 
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