Learning to set up a mechanical "swiss" lathe

[JH-Q]

Just bought a small "swiss" style cam-operated automatic lathe from a retired gentleman machinist. He used to run a single brass electrical contact part on it, which he used in his own product line. So the machine has been run somewhat little, i'm guessing less than 50k parts since new. Couldn't pass the deal at €350 and a small trailer worth of birch firewood in exchange to the machine

It appears to be a pretty well-built sliding spindle 7mm Bechler/Tornos copy, made in USSR (Ukraine) in 1988.
Five tools, runs up to 12500rpm and 2680parts/hour. 3m (10ft) barfeeder included.

Somewhat unlikely i'll get the contract to make the parts the machine is set up for, so i'm doing a full cleanup and adjustments and look into jobshop work. Might make some good profit if i get contracts that fit this machine work envelope. But you never know what the customers might ask, so i'll have to learn to "program" the machine first.

This is somewhat different of the kind of work of conventional mills and lathes both manual and CNC i'm used to in the past, and it might take a while to wrap my head around the concept. There's about dozen simple cams that run the "program" on each slide, parts catcher, collet closer etc..

I'm looking for any information how to approach setting a part on this type of machines, preferably if you have some books to recommend. I read English well, but technical German is also okay, although i don't fully understand everything in that language.

I don't have any local machinist to ask for help, so i'm on my own figuring this out. I know there are a lot of skilled "swiss" style machinists over here, so please do share anything related to setting up these machines!

Currently i'm mostly thinking about how the cams are designed when setting up a new part. How steep can and should be the hills and valleys be, to not overly wear cam followers? How deep should they be in order to obtain the desired part profile? How to time the multiple tools to each other? Are these just cases of trial and error, measuring the desired position related to tool and cam radius? Should the cams be hardened or softer than the cam followers?

Also, how can threading be done on these? There is a shaft for arranging a flat belt drive to the attachment mount table so a coarsely synchronized spindle speed can be obtained. If i understand correctly, there should be a kind of tapholder or tapping head spinning at a slightly different speed than the main spindle. Let's say a part is run at 8000rpm, the tap or die spins at 8500rpm to thread into the part and then drops to 7500rpm to retract. Is this correct, and does a drum-type cam synchronize the feed well enough? Single pointing is obviously out of the question, but could some sort of threadmilling work?

 

[JH-Q]

Here are the parts for the support collet. It appears the collet has carbide contact pads brazed in it. If i desire to produce different size of a collet for smaller bar diameter, how does hardened steel perform in this use, or does it wear out too quickly? Making this small carbide collet pads is way out of my shop capabilities, and getting them done might be insanely expensive if anyone is even willing to do them. The upside is, any other support collet should be fairly easy to fit in the holder, any sources for this kind of special collets?

When i adjust the support collet, how much clearance there should be in order to run smoothly? Please specify if the units are imperial or metric, i run 100% metric work!

How about bar tolerance and smoothness, how much imperfections are allowed in the material? Cold rolled h9 is easily avaitable, but should precision ground rod be preferred when making precise parts?

 

[john.k]

There are plenty of old books on cam automatics ,cam design and production ,and other things of benefit to these machines ...............I personally think the seller got the better deal ,as these machines are generally scrapped ,being of little use to hobbyists.

 

[JH-Q]

There are plenty of old books on cam automatics ,cam design and production ,and other things of benefit to these machines ...............I personally think the seller got the better deal ,as these machines are generally scrapped ,being of little use to hobbyists.

I see the reason why very few are interested about mechanical automatic lathes today. Setup time and skill required to "program" a part.. I could just walk to a Tsugami or Citizen, touch off the tools and start writing a program on the Fanuc instead of learning complex mechanical cam and tool designs for making simple parts. Modern CNC swiss are much more user friendly and faster to set up. Yet i see a profit advantage running the same part on a €350 machine versus €80000 machine, and they might even be as fast and turn out the same quality part when properly set up.

Just fount the basic cam design principles on a book called "Automatic screw machines" by Douglas T. Hamilton and Franklin D. Jones. Although the book is mostly about B&S and Cleveland automatic machines which are very different from mine, same basics do seem to apply. Almost readable free book was fount at forgotten books website, apart having annoying ads and unreadable pages.

Seem like i have to put in a lot of elbow grease to get all the parts work smoothly. I don't know if the cutting oil used was a mixture of honey and superglue, but this has got to be the stickiest machine i've ever cleaned up. Chisel was the only way to remove caked brass from the bottom tray, while a rotating steel wire brush slowly removes all the chips and crud off each part. Luckily the most precise parts have been fed with proper lubrication oil, so they clean up with much gentler methods..

 

[tom in nh]

I like it.
Keep us posted on your progress.
Good luck!

 

[JH-Q]

Alright, seems this has turned out to be another project machine for my shop of machine projects! Since everything was stuck solid, i proceeded to dismantle the whole machine. Everything runs with only one motor mechanically, so i'm ditching the underdrive cabinet and modifying the machine to run from my main overhead lineshaft without electrics. (Fyi, soviet-era electrics are always crumbling apart and no spares are avaitable, so those are a headache for reliability)

First thing to catch my attention was the "tool octopus" with all kinds of weird linkages. There must be well over 200 parts in this subassembly, which i took apart and cleaned all the parts before adjusting and putting them back together. While spending evenings doing this, it was good time to get known of all the parts and their functions.

Each of the toolholders have a spring-loaded (to counter backlash while adjusting) micrometer adjusment in X and Z-axes, and a fine adjustment for center height. There's also adjustable scaling ratio for the three plunging toolslides as well as simple adjustments for cam followers and retract positions.
I'm quessing the rocking toolslide is used for profiling and precise diameters since it has 0.0025mm graduations (about a "tenth" in inches!), whereas the plunging toolslides are for grooving, internal tools and such operations. Btw, the cam followers seem to have carbide contact pads brazed in them, so that answered my question about cam material. Hardened steel should be the right material for production cams. The former owner used mild steel which has worn out to have a burr during production runs, thus resulting an error in cam (and part) profile.

Here's some pics again, i'm sharing them as the project progresses. Hoping it'll help others learning these machines. Please be patient, i have shop days only when the weather is too crappy to work on other projects, and i have to do some work gigs the next few months..
Sorry for the dark pics, i had poor light in the shop yesterday evening, and painting everything to matte black shop colour didn't help it!

 

[Limy Sami]

FYI this seems to be the ''Goto'' for automatics in the UK

Floyd Automatic Tooling | The Tooling Specialists for Precision Component Machining

Created by Fluid Studios for its clients

www.floydautomatic.co.uk

 

[DPM]

Hope you get that thing back together. Get a copy of this manual. I've also seen it on ebay. It has a pretty simple and thorough explanation on how to make a job layout and cam design. The theory applies to all swiss cam machines. I learned how to make swiss cams from this same manual. I'd think there are plenty of collet and bushing suppliers and tornos after market parts in europe such as Floyd automatic as someone already pointed out. Google is your friend on this one. Good luck and hope to see more.

 

[JH-Q]

Thanks a lot Sami and DPM!
There isn't a swiss tooling supplier in Finland that i know of. I know Sandvik works great and have used their XS tooling line in the past with good results in difficult parts.
Floyd seems to have everything necessary on their shelf, definately will drop them an email when i'm starting to tool up for the first production parts for customers (whatever they might be, not viable to buy all kinds of tooling just in case, but rather build up the inventory as needed) For small items, the Brexit hassle shouldn't be too bad, and in past i've fount the customer service in UK companies is excellent, and i we actually have a common language.
German suppliers might be cheaper, but there's the language barrier. Not to even compare when i had to order some 2CV classic car parts from France in french, which i don't know a single word!

Fount the Gorton handbook for automatic screw machines at vintagemachinery.org, such a great site!
That book answered all questions i had in mind, including cam design, tool station uses etc.
The maximum recommended cam rise mentioned is 0.018"(0.45mm) for 1°
Stock roundness allowance would be around 0.07mm max for guide bushing. Of course i'll use a ground bar if avaitable and required for tight tolerance parts.

 

[john.k]

revisit the previous owner and see if hes found anything more for the machine ...try to find every part ...dealers who sell tooling arent cheap ,as in one piece costs more than you paid for the machine.

 

[DPM]

You can reach out to these guys for collets and bushings. They are an Italian based company. This is their American website. They ship from italy to USA so Finland should be doable.
ttcnorthamerica.com

 

[Mechanola]

Yeah, from my experiences in long turning as it’s called here a ground bar is very important. Can also be drawn, most often the case with brass. Adjust guide bush to nice slip fit. Don’t cut too deeply because you would build up pressure on too many things machine and stock. Use a good cutting oil. If you make screws take care to mill the slot well centered. And don’t put swiss between quotation marks. Nothing is to be written with quotation marks except direct speech. They look like that in English: “ ”, not " ". Perkele.

Congratulations on this.

 

[???]

I worked at a swiss shop in Sydney and the owner had 2 CAM autos for a autmotive part, when set up properly on the right job they can makd you some serious money.