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Supermax YCM-16VS oiler check valves


Apr 3, 2020
Hi all,

TL,DR: Does anyone know what the proper oil check valve flow range (e.g. 0, 3, etc) is for a YCM-16VS Supermax CNC machine?

As the title says, I've got a YCM-16VS supermax in the shop. I decided to do some maintenance on it and went to check the oiler check valves (has an automatic Chiba oiler system). Sure enough, a couple of the knee elevating check valves are plugged. I know the pump pushes oil from both the automatic pump and the "forward assist" and if I crack one of the other knee elevator tubes, I get oil coming out, so I'm sure the valves are plugged and it isn't a pump issue.

I am the second owner of this machine: it came out of a university machine shop I used to spend ages in. I'm good friends with the guys in the shop, but obviously being 1989 vintage, the shop supervisor has now changed (twice) since the machine was purchased new. It received very light duty usage before it became mine, but I have no way to know what the maintenance history is on it, and I sort of doubt they would have changed the oil check valves (they're certainly caked in glazed oil gunk). Also, it turns out the original shop supervisor insisted that the only way oil acceptable was ATF. Okay, so I swapped that for Vactra 2 as part of my maintenance, and also popped off the check valves to look for flow control numbers. The ones on the machine now are 0's. I checked the original manual that came with the machine, and they spec PSS-3, not 0. As I understand it, 0 is more flow than 3. I think ATF is lighter than regular way oil, so if the shop guys retrofitted the oil valves I would have expected less oil flow, not more. The manual doesn't inspire confidence, either, as the schematic shows no flow valves going to the saddle, table, and leadscrew lube points, but I can stick my head under there and every single one has a check valve on it. So, as in the TL,DR summary above, what is my next move? Do I swap the 0's out for fresh 0's since it ran fine before and the downside is (just?) wasting more oil, or do I RTFM and revert to PSS-3's with plain unions (assuming I can find them) where the manual indicates? I would think this would result in very uneven oiling, but maybe that's the point?

Thanks in advance!
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