PM-1030v cross slide surface

[ganzey]

Ive had my pm-1030v for about 2 months now, maybe 5 hours of run time on it, oiled regularly and kept clean, but recently i noticed the cross slide had a little bit of slop in it that was getting progressively worse over the last week, chattering no matter what. Since day 1 i could not accurately or repeatably set the cut depth, but I figured it was probably just from my lack of experience. Now after the cross slide started developing play in it i thought maybe the 2 problems are related, and took it off to clean/inspect it and found a broken lead screw nut. OK, no big deal thats and easy fix. But then i flipped over the cross slide and saw this (see pics). It looks like it was finished with an angle grinder and abrasive disc....the surface is very rough, with a straight edge on it i can slip a .025" feeler gauge under it in a couple spots, and it is only making contact on 2 corners.



My questions:



Is this normal?? I thought these were (ideally) scraped, or at the very least ground fairly flat. The opposing surface is very flat. My only other experience with a lathe is a cheap mini lathe, which looks a lot better than this.



Is this repairable? Im afraid if i scrape it, i would need to remove so much material that it would be making contact with the top of the dovetail before i get it flat. Which leads to the next question.



Am i correct that the top of the dovetail base and bottom of the saddle should not make contact? I thought the bearing surfaces are - the angles of the dovetail, and the 2 lower flats, given the shallow cut in them for oil, but ive been wrong before.



Im mostly just curious what some people that are more familiar with these has to say.



Thanks in advance.

 

[verbotenwhisky]

Ive had my pm-1030v for about 2 months now, maybe 5 hours of run time on it, oiled regularly and kept clean, but recently i noticed the cross slide had a little bit of slop in it that was getting progressively worse over the last week, chattering no matter what. Since day 1 i could not accurately or repeatably set the cut depth, but I figured it was probably just from my lack of experience. Now after the cross slide started developing play in it i thought maybe the 2 problems are related, and took it off to clean/inspect it and found a broken lead screw nut. OK, no big deal thats and easy fix. But then i flipped over the cross slide and saw this (see pics). It looks like it was finished with an angle grinder and abrasive disc....the surface is very rough, with a straight edge on it i can slip a .025" feeler gauge under it in a couple spots, and it is only making contact on 2 corners.



My questions:



Is this normal?? I thought these were (ideally) scraped, or at the very least ground fairly flat. The opposing surface is very flat. My only other experience with a lathe is a cheap mini lathe, which looks a lot better than this.



Is this repairable? Im afraid if i scrape it, i would need to remove so much material that it would be making contact with the top of the dovetail before i get it flat. Which leads to the next question.



Am i correct that the top of the dovetail base and bottom of the saddle should not make contact? I thought the bearing surfaces are - the angles of the dovetail, and the 2 lower flats, given the shallow cut in them for oil, but ive been wrong before.



Im mostly just curious what some people that are more familiar with these has to say.



Thanks in advance.

Do you have a DRO scale mounted on the back of the cross slide?

 

[durableoreo]

So rough it seems impossible that it would work---but it does, sort of. At least you've got some oil grooves. I had the same on a 9x20 cross slide. Everyone else will weight in in a minute but it's par for the course, I think. Unfortunately, it's a fairly big project to undertake if you're new to scraping.

I think you're right about the sliding surfaces. Do you have a way to measure the highs and lows?

In the most extreme case, you could mill the dovetail flats down and glue in Turcite (acetal with PTFE mixed in) so that the final height is about right. It can also be done with other bearing materials:

 

[Red96]

FWIW, my 1030-V carriage looked exactly the same. Cuts true. I guess it's to hold oil. I can see how a fully machined surface wouldn't be ideal either. We're not going to get hand scraping at the price point of these machines. Nor does it seem necessary - for what I do, at least. A friend of mine who does a lot of scraping encouraged me to go that route, but I just deburred and cleaned it really well, oiled it up and went about my business. There are other parts of the machine that warrant attention more than the carriage sliding surface, IMO. Solid tool post, reworking the compound slide, disassembling and cleaning EVERYTHING, including the insides of the gearbox and apron, along with deburring all sliding surfaces for example. These machines beg for a collet chuck setup, as well. I was amazed at the amount of sand and grit lying in the bottom of my apron gearbox. Good thing it leaked like a sieve, instigating a disassembly and inspection or that casting sand would still be in there.

 

[starr256]

With my PM1030V, I found that the bolt that holds the cross slide lead screw nut to the top of the cross slide was always coming loose. I drilled and tapped the nut for a larger bolt, drilled and reamed the top of the cross slide for the new bolt and cranked it down. No more play there!

 

[Harry Knutz]

Ive had my pm-1030v for about 2 months now, maybe 5 hours of run time on it, oiled regularly and kept clean, but recently i noticed the cross slide had a little bit of slop in it that was getting progressively worse over the last week, chattering no matter what. Since day 1 i could not accurately or repeatably set the cut depth, but I figured it was probably just from my lack of experience. Now after the cross slide started developing play in it i thought maybe the 2 problems are related, and took it off to clean/inspect it and found a broken lead screw nut. OK, no big deal thats and easy fix. But then i flipped over the cross slide and saw this (see pics). It looks like it was finished with an angle grinder and abrasive disc....the surface is very rough, with a straight edge on it i can slip a .025" feeler gauge under it in a couple spots, and it is only making contact on 2 corners.



My questions:



Is this normal?? I thought these were (ideally) scraped, or at the very least ground fairly flat. The opposing surface is very flat. My only other experience with a lathe is a cheap mini lathe, which looks a lot better than this.



Is this repairable? Im afraid if i scrape it, i would need to remove so much material that it would be making contact with the top of the dovetail before i get it flat. Which leads to the next question.



Am i correct that the top of the dovetail base and bottom of the saddle should not make contact? I thought the bearing surfaces are - the angles of the dovetail, and the 2 lower flats, given the shallow cut in them for oil, but ive been wrong before.



Im mostly just curious what some people that are more familiar with these has to say.



Thanks in advance.

That IS NOT NORMAL, And it would be on it's way back if it was mine. That surface should be precision ground and be hand scraped on a quality machine.

I would expect more for the price of this machine, It looks like a Vevor which can be had for $800 to $900. For 3 times the money, I would expect better than that.

 

[ganzey]

Thanks for the responses guys. Just to be clear, im not trying to bash PM or anything, these are import machines, and i would not expect them to disassemble them and inspect piece by piece, and can understand how sometimes stuff slips through the cracks. I have contacted them and sent some pictures, they responded with a parts diagram and asked me to confirm the part #'s to make sure we were on the same page.

Do you have a DRO scale mounted on the back of the cross slide?

No DRO on the lathe.

So rough it seems impossible that it would work---but it does, sort of. At least you've got some oil grooves. I had the same on a 9x20 cross slide. Everyone else will weight in in a minute but it's par for the course, I think. Unfortunately, it's a fairly big project to undertake if you're new to scraping.
I think you're right about the sliding surfaces. Do you have a way to measure the highs and lows?

In the most extreme case, you could mill the dovetail flats down and glue in Turcite (acetal with PTFE mixed in) so that the final height is about right. It can also be done with other bearing materials:

So i bought a minilathe last year that was in pretty rough shape, and a friend of mine that use to rebuild machines for a living helped me out a ton and showed me the basics of scraping and we scraped the ways, he aligned the head stock to the ways, then i scraped the cross slide and gib and it works surprisingly well, for what it is. I needed something bigger and after that i didnt really want to deal with a used machine that may need hours and hours of work to get up to par. This is my only experience with dovetail mating surfaces, and im now seeing that they all work on the same principle, lower flats and dovetails are bearing surfaces, top of dovetails can be milled down if needed. The gap on the mini lathe between top of dovetail and the cross slide was quite large compared to this lathe, and i thought maybe it was used as a mating surface, but i now see it is not.

I have a small surface plate and test indicator, i suppose would suffice? I dont think thats the most accurate method but it should give me a rough idea right? . I did smooth it a bit with a stone and checked it to the mating surface and it definitely helped a bit, but will still need a pretty good amount of scraping.

FWIW, my 1030-V carriage looked exactly the same. Cuts true. I guess it's to hold oil. I can see how a fully machined surface wouldn't be ideal either. We're not going to get hand scraping at the price point of these machines.

Yea i wasnt expecting perfection or a hand scraped machine, but i guess i thought it would at least had a stone run across it after grinding it to make it fit. I did that and checked it with some blueing, and its a little better. Not great, or even good, but it does slide a little better, im just hoping the new leads screw nut and this solve the problem. I thought i was crazy not being able to get even close to accurate cuts, i pretty much ignored the dial and went by feel , checking with a caliper/mic every couple passes. I mean i could very carefully zero it, set it to .010, turn material, then measure anywhere between .-07 to -.026 material removed.

Solid toolpost is definitely on my to-do list, as I will rarely, if ever, use the compound. I just finished up making my first backing plate to fit an 8" chuck. (which took me wayy to long)

 

[ganzey]

With my PM1030V, I found that the bolt that holds the cross slide lead screw nut to the top of the cross slide was always coming loose. I drilled and tapped the nut for a larger bolt, drilled and reamed the top of the cross slide for the new bolt and cranked it down. No more play there!

I wish that was all it was, but mine was tight. Perhaps, a little over tight

 

[Harry Knutz]

I'm sure Matt will make it right.

 

[starr256]

I wish that was all it was, but mine was tight. Perhaps, a little over tight

That looks like over tightening the backlash screws. The nut is not the most durable of materials.