..actually its evil twin brother the GDR-built Ruhla 58.
Does anyone have an operations manual for a Ruhla 58, Thiel 58 or Sentinel 58 - I suppose they should all be pretty much the same ?
Anyone have tips on inspecting this type of mill ? All my (limited) experience is with BP-type mills. I've read everything I can find on this type of mill on this site and elsewhere - and there isn't much.
-Mark
A Thiel 58 would be a very old mill, certainly pre WW2. The Ruhla 58 would be post war, but I think there were multiple versions built in E Germany, starting with one that was similar to the pre-war Thiel 58. Later versions of Ruhla got much more sophisticated and were apparently built without compromise and regardless of cost. Although they were superficially the same general layout as the W German versions their internal designs appear to have diverged very considerably. They were sold at a loss to Western customers, presumably not many (none?) in USA.
The Thiel 158 and 159 were some of the best toolroom manual mills ever made, and a Ruhla 58 might be as good. I have a Thiel 159 and consider it to be a superb mill even though mine is old and was very well used before I bought it.
I don't know of any Ruhla 58 manuals, and there would be interest from others if you found one.
I can't help with specific Ruhla inspection tips, but if I extrapolate from Thiels I would look at the following:
Ensure all the ratios in both spindle and feed gearboxes engage properly and run without excessive noise. I understand that later Ruhlas had pre-selector gearboxes. It would be worth checking that this changes gear properly.
Check that the rapids engage and disengage properly The Thiel 159 has an electric clutch for this and replacements are very expensive. I'm not sure how the Ruhlas manage rapids, but possibly similar. The clutches might be a weak point if the table is really overloaded and vertical rapids used a lot (or if locks are not disengaged).
Look for wear on the bottom of the Z ways. This is particularly the case if the mill table was regularly overloaded (very heavy die plates etc) and the ways were not properly cleaned and lubricated.
Check for noise and any roughness in the bevel drive for the vertical head.
There should be tapered gibs on all ways (lots of them), Check that these are adjusted reasonably correctly before you check for movement and backlash. The ways on my mill are still very good even after a hard life. It will probably have high precision leadscrews and nuts, so check that these are not worn out. I doubt that you would ever find any replacements without a lot of surgery.
There should be bellows covering the delicate bits. If these are worn out or missing, check for wear/dirt in that area. You will probably need to make your own replacements unless you have a lot of money to spend on getting them made (really a lot).
You may never find another Ruhla mill,and similarly you will probably never be able to find any accessories, so make sure that you get all you can in the deal. For example an over arm support is important if you are going to get the best use out of the horizontal spindle. Additional tables etc would be a very big plus. This is not like a Deckel where you could probably get whatever you need if you can afford it.
As far as comparisons to Bridgeport, I think you will find that you will need a bit of personal adjustment before you will become used to a very different type of mill. The ability to use both spindles freely is a big difference, as is the flexibility of a tilting table ( assuming your example has one). Rigidity should be much greater than a BP type mill and you will notice this in the ability to take heavier cuts without chatter or difficulty. My mill is capable of climb cuts in most conditions and this makes a big difference.
In summary, if the mill looks good on demonstration and is not too expensive you could get a bargain.
