Newb concerns - noises and gouges in machine

[sru_tx]

I thought I would start a new thread from my purchase advise thread as I now have a PM1228. In that thread I discussed a problem with the power feed, found a broken part and documented how I repaired it. In the process of repairing I saw something that seemed odd. It took a few days to register but now I'm asking myself... was that right?

Issue 1
While repairing my power feed issue, I pulled the saddle and the apron off of the machine. While cleaning and reassembling I found that the V-section on the underside of the saddle that mates with the V section of the ways was gouged. By gouged, I mean it looked like someone took an angle grinder and dabbed their way along the surface that presumably slides on the way closest to the operator leaving perhaps only 1/2" at either end "fairly" untouched. Deep dabs/gouges and no attempt to smooth them and make a continuous surface. At first I thought it was something done at the factory for whatever reason but a few day later I found similar gouge marks on a bit of tooling that I know was not factory. I believe the original owner did this but don't know why. The V portion of the ways look pristine, not scratched or dinged up so this gouging isn't affecting it.

Any ideas as to what's up with that? Should I be concerned? Is there a way to repair it?


Second issue: Gear noise while running in reverse spindle (not left handed threading)

I don't have it mounted to a bench yet but I was able to power it up and run the various gears etc. to test the power feed and threading that I worked on. I found that the external gear train was distinctly noisier when running with a reverse spindle direction. The sound was periodic, repetitive, and sounded like a meshing issue. If I take it out of gear the noise stops.
Is this normal? Or should I go through that geartrain, clean, lube, and check all of the meshing?

thanks.
steve

[Fasttrack]

Any ideas as to what's up with that? Should I be concerned? Is there a way to repair it?

steve

Machine tool bearing surfaces were often "flaked" or "frosted" after being scraped. This is both decorative and functional. The slight "gouges" reduce the tendency for "stick-slip" conditions and provide a surface for oil to cling to. If you have an ultra flat, smooth ground surface and you put another ultra flat, smooth surface on top of it, it's going to stick. In fact, this is an advantage when working with gauge blocks. You can "wring" them together and build up larger blocks.

It sounds like someone tried to "frost" your ways but didn't really know what they were doing! It's probably still okay. You don't need 100% surface contact between the two parts (again, this is what causes stick-slip) and the surface may be hardened and ground, which meant a normal hand scraper wouldn't be able to flake... that might be why someone reached for an angle grinder If you had access to a cast iron straightedge, you could use it to spot the surface and make sure it's still flat and there are no raised burs around the divots.

Edit to add video link: https://youtu.be/LQhsDtS--wU?t=11 That's an example of a very common frosting pattern.

[754]

Is it crescent shaped gouges, like from an angle grinder with a sanding disc.?
Any evidence that the machine may have been rusty and needed cleanup at one time..

I am going to offer up this on the gear noise. It is possible the gear ran in for the most used forward direction, then when you reverse it, it may be slightly different profile making it noisy.. just a guess.
I if you could turn the gear around, it would prove/disprove this.

[sru_tx]

thanks

Fasttrack, I had not heard of frosting but I think you nailed it. I think they were trying to relieve the middle area with the hope of having four points of contact, one at each corner. The machine was in very good condition and only 1.5 yrs old so I'm pretty certain it wasn't a cleaning process.

754, the marks looked like a 4" angle grinder with a grinding wheel, not a sanding disc. no evidence of rust.
I suspect you are right regarding the gears running mostly in one direction and settling. I'll probably go ahead and remove all the gears, clean and relube and check, flipping if necesary.

thanks

[JCByrd24]

My new PM-30MV mill had some very rough scraping/frosting done by a complete hack with a power tool on the z-axis slide only, sounds the same and I suspect yours was a factory job like mine. I did put mine on the surface plate and the remaining contact was very good and flat so I didn't pursue anything. I did send Matt pics and he confirmed it's for oil retention and reduction of sticking, just not properly done, but I doubt effects function or even life.

[BCRider]

I've got the same markings on the ways of my machines. And yes, it's a cheap and rapid way of achieving the classic frosting function. I hadn't thought about the sticktion issue but that makes sense too. To me it was always about the idea of creating small points of clearance where oil could build up and be held.