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Should lathe bed be accurately fitted to a heavy cast cabinet?

avivz

Cast Iron
Joined
Jan 28, 2009
Location
Israel
Schaublin 135 is 28.5’’ between centers lathe. It has quite heavy cast iron cabinet and a healthy bed. The bad is fitted to the with x4 M12 bolts at each end. There are machine flat surfaces on the cabinet top which match corresponding bosses on the bed. My question- during the rebuilding process, should I blue it up and check for a good fit (and scrape if required)? Any chance the parts were distorted somewhat over the years in a way that the bed can be twisted when bolted to the cabinet?
If so, what would be the right procedure to do so?

Aviv
 

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Did the factory that built it, scrape it? You can scrape it. The tapped holes may have pulled out the iron around the holes so check that. It's a precision lathe as is a Monarch EE and Rivett lathes. Their base sits on the floor on built into the base casting 3 points to eliminate the twist. Im not sure on a Shabilin. Many precision grinders with a rectangular base like a Heald has 5 leveling Screws, 4 on the corners and 1 in the middle of one end. You level the machine on the 3 points and align or remove any twist with the 2 outside stabilizer Screws. In some lathes without the center 3rd point I used a leveler slide jack to start the leveling process.
 
Aviva. Please know many Americans like me support Israel. Dont believe what the media reports. Your in my prayers everyday. Take care my friend. Rich
Thank you Richard. You are amazing and I thank you guys every day. Those of us who clearly remember 9/11 know very well to distinguish good from evil. Those progressive brainwashed morons will not confuse us. 🙏
 
Thanks Rich. The rectangle cabinet has machines surfaces to meet the bed, definitely not scraped. Either milled or planned I guess. Could not say for sure due to surface rust. I will check it out as per your advice. The cabinet has four levelling screws and I think I saw one additional threaded hole in the right end in the middle, but there is no jacking screw there. I’ll check later in the manual what they recommend regarding levelling/twist elimination. As the moment, I just want to make sure that when I fasten the bed to the cabinet as part of the rebuilding process I do not introduce any issues that will later will require massive disassembly.
 
I think if there are 2 massive cast iron parts that are bolted tight together, it would be a good idea to blue and scrape them. Probably does not need to be a precision scraping job, just make sure there is contact near each bolt hole. Another possibility might be some kind of setting compound. I used JB weld between a lathe base and steel cabinet to make sure the lathe did not get twisted when bolting down.
 
Moglice.com has product called DWH that you can mix up that looks like cake frosting that you put in between parts like that. You clean and Ruffing one side to stick to and other side you spay on a wax mold release.. I know the OP is not in the USA but they might have a distributor there or ship it from Germany. It's made by the Diament company.
 
Many precision grinders with a rectangular base like a Heald has 5 leveling Screws, 4 on the corners and 1 in the middle of one end. You level the machine on the 3 points and align or remove any twist with the 2 outside stabilizer Screws.
Hi Rich,
I remember when you told me off for leaving my Studer RHU-450 universal cylindrical grinder sitting on a pallet. You were right of course - I studied the manual then took it off the pallet.

The grinder has threaded holes in the four corners of the base, and then a "pad" near the middle of the back. The owners manual say to put a steel plate 70 x 100 x 15mm (3 x 4 x 5/8") under the pad in the middle of the back, and then round plates 80 x 10mm (3 x 3/8") under the front two screws. Then level it to about 0.02mm/meter = 0.0002"/foot. So the final support is just on three points, without any attempt to remove twist. This lets the casting "relax" to the factory state.

On my machine, the remaining two screws in the back corners are for "tipping safety". I have steel plates under them, but have slacked off those screws so that there is no weight on them.

I would expect a Schaublin lathe to have a similar 3-point support. Aviv, what does the manual say about this?

Screenshot 2024-04-22 at 17.45.03.png
Cheers,
Bruce
 
Schaublin 135 is 28.5’’ between centers lathe. It has quite heavy cast iron cabinet and a healthy bed. The bad is fitted to the with x4 M12 bolts at each end. There are machine flat surfaces on the cabinet top which match corresponding bosses on the bed. My question- during the rebuilding process, should I blue it up and check for a good fit (and scrape if required)? Any chance the parts were distorted somewhat over the years in a way that the bed can be twisted when bolted to the cabinet?
If so, what would be the right procedure to do so?

Aviv
If the bedways are ground these corresponding bosses were on the magnet So if these bosses were not in the same plane or not shimmed before grinding the bed is twisted
Ideal is that these bosses are scraped/ground flat before grinding the ways and the flat surfaces of the cabinet as well Best to place the cabinet level doing the scraping So there is no twist in the cabinet
Peter
 
Well regarding levelling, Schaublin manual says it has to be leveled on all four screws. Check the manual below. I will check the flatness of the four surfaces separately, then check the fit between them and see where I stand.

IMG_8061.jpeg
 
It is a common misconception that all lathes are levelled using the cabinet legs. That of course is not so. Lathe beds that bolt to separate cabinets need to use shims between the cabinet and bed to remove any bed twist. I have in the past drilled and tapped the feet of the bed and used jacking screws to achieve a level straight bed. In that way, it is easy to determine the correct shim pack size with feeler gauges. Remember a level lathe is not important. A straight bed is.
 
I have used the 3 point method even when it's not there. In my humble opinion Hardinge and Monarch are better machines then a Scbhublin. I saw several in Europe.
Hello Rich. Hardinge and Monarch are super machines. Unfortunately I never saw them in Israel (SBL and Myford are quite common here). Probably transportation was an issue, so European (nowadays Asian) machines are dominant here.The Hardinge and Monarch I know from YouTubers like Keith Rucker.
In that case, how would you “convert” it to x3 point mount?
I guess in reality, any rigid enough structure always sits on three points. It’s up to the user to decide which three point and how much to push the fourth one. For example, when I move the lathe with four skates, always one is loose.
 
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