New PM1228 Lathe erratic dial test readings on spindle and any chuck

[mac1911]

I've been very busy but finally am getting back to addressing the machine. It took several weeks following my initial inquiry of PM about the subject of this thread, but a spec sheet from a Sieg machine was provided to me to check tolerances and excuse some of what I was seeing as being within allowable tolerances, along with all of the other suggestions offered.

I still could not accept that I did not have a simple within-tolerance runout, I have dancing runout that moves, which means no matter how much I tweak the adjustable 3-jaw & 4-jaw chucks I purchased specifically for the purpose of maximal possibility to achieve perfect centricity, I would never be able to achieve it.

I located some new old stock P5 bearings, both tapered roller to be exact because it is my intent to convert the lathe to a double tapered bearing spindle like the the Taiwan made 12x36. I removed the spindle once to take measurements of the bearing housings and seals (which are plastic/nylon, non sealing end caps held in place by paint) because I also intend to convert the spindle bearings to oil bathed. I noted that the belt pulley bore, had been severely galled when the machine was assembled at the factory, hence my self quote above.

I purchased a P4 NSK, 6010 bearing prior to deciding on angular, and installed it on reassembly of the machine. I had pre-marked the spindle at the runout trouble spot. On reassembly, the max point of runout moved about 5 degrees clockwise, but I left the initial mark in place.

The FAG P5 bearing for the chuck end of the spindle finally arrived (Ordered from France), to pair with the P5 URB bearing intended for the tail end. I removed the spindle a second time, and used a clamping style bearing remover to successfully remove the stock bearing without damage.
Both OE bearings are made in China, I can not attest to their quality. Below are pictures of what I found and this is where I am as of this post.

The bearing sleeve rides directly over this rough area of the spindle which extends from the stop point .300" inward, 360 deg. The pictures are at various points around the shaft with one or two duplicates at different angles/closeups.
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This is the roughest area of the shaft from my observation and coincidentally it lines up with the point of greatest deviation in spindle.
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This machine appears to have been assembled rough and in a hurry. The bearing bores in the housing are rough to. There was a piece of swarf about 2" long attached to the inner groove at the clear end of the tape in the first pic on tear down as well. I'll send this new found info to PM and find out what a new spindle costs, as I doubt a replacement would be shipped looking like this. I'm going to call this a "Covid" machine more so than a Monday model, or the "Let's squeeze one more machine out of these inserts". The liquid residue wiped from forward housing was magnetic to the point that a 1//4" dia magnet could be suspended easily from the paper towel it was on. I haven't posted the pic of it.

For $4000 it was definitely slapped together. As you tear into that machine you might see more of what $4000 does not buy….

 

[maticulus]

For $4000 it was definitely slapped together. As you tear into that machine you might see more of what $4000 does not buy….

So it seems, but straight holes and a decent finish are paramount to lathes and mills at any cost. There's nothing about my findings suggestive to me of a price/quality mismatch, but instead a decision by someone to turn a blind eye to the obvious, or not give a hoot regardless.

I've paid the going rate for expected quality on several occasions and still received less than a quality outcome, so another $1000 or more offers no consolation my findings here would have been any different if the person handling the matter and in a position to make a difference decided not to. This is not a Harbor Freight lathe, this is a Precision Matthews/Quality Machine Tools lathe with many proper examples serving their intended purpose well, suggesting a better outcome than this was included in the budget.

 

[mac1911]

Here are some of the other pictures taken. I have no idea of what the standard is for what the bore should look like in terms of finish, but there are shiny and dull contact points throughout, apparently born out by the bearing cup surface at both ends.

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A good bit of the grease is squeezed into the forward area of the housing away from the bearing. There's not as much as I was expecting to see.

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There was very little patience shown on installation of the pulley in my opinion.
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This was attached inside the groove.
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That magnet has a pretty strong attachment to the residue wiped from the spindle onto that paper towel.
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I have a old abused lathe.
It came to me with the gear box empty. What

So it seems, but straight holes and a decent finish are paramount to lathes and mills at any cost. There's nothing about my findings suggestive to me of a price/quality mismatch, but instead a decision by someone to turn a blind eye to the obvious, or not give a hoot regardless.

I've paid the going rate for expected quality on several occasions and still received less than a quality outcome, so another $1000 or more offers no consolation my findings here would have been any different if the person handling the matter and in a position to make a difference decided not to. This is not a Harbor Freight lathe, this is a Precision Matthews/Quality Machine Tools lathe with many proper examples serving their intended purpose well, suggesting a better outcome than this was included in the budget.

I could only imagine the factory and parts supply chain and the , get them lathes together screams by the Foreman, lol

 

[matthewsx]

If there’s an issue with a PM machine I’d suggest posting it in their sponsored forum. The owner seems to monitor it and address issues pretty regularly.

I know this is an old thread, and I made a suggestion about how to address your concerns a while back, but now that you’ve brought it back up I respectfully suggest a new thread in the PM forum.

John

 

[maticulus]

If there’s an issue with a PM machine I’d suggest posting it in their sponsored forum. The owner seems to monitor it and address issues pretty regularly.

I know this is an old thread, and I made a suggestion about how to address your concerns a while back, but now that you’ve brought it back up I respectfully suggest a new thread in the PM forum.

John

It's been nearly a year since I last posted in this thread, however, it had not been resolved here and continuing it toward conclusion seemed the better choice, to a second thread on the same topic, but fragmented in the absence of the beginning. I have a direct communication via email with PM which my new findings will be added onto for context and any further guidance they may have to offer when they open for business.

 

[mac1911]

It's been nearly a year since I last posted in this thread, however, it had not been resolved here and continuing it toward conclusion seemed the better choice, to a second thread on the same topic, but fragmented in the absence of the beginning. I have a direct communication via email with PM which my new findings will be added onto for context and any further guidance they may have to offer when they open for business.

The lathe has 3 year warranty correct?

 

[maticulus]

The lathe has 3 year warranty correct?

Yes and to my surprise a short while ago, someone at PM was sifting through messages during the holiday today, to see my update with pictures of what I found and informed me that a new spindle was being sent, before the keys on my computer had fully cooled from typing the initial message. I'm very pleased about that.

 

[maticulus]

Got everything put back together and am very happy with the results. I still have some run-in time to do but performing the same dial indicator checks at the spindle nose that I was previously concerned about, the runout is right at 1/10th of a thousandth and steady, turning by hand, or under power at the lowest rpm setting.

I did have a little difficulty getting the higher quality 6 inch 3 jaw and 8 inch 4 jaw chuck to seat fully, but with careful tightening of the lugs I was able to work out the ~.0015" gap I was seeing and measuring with the feeler gauge. It doesn't sound like a lot but I could see that runout at the rim edge of the 8" chuck. I polished the nose a little with an 800 grit strip for a little added help.


I substituted a tapered roller bearing #32010 in place of the stock 6010 roller at the tail end and had to make a shortened spacer to replace the original to adjust for the difference in thickness. Obviously I did some polishing on it before parting it off. the original has a rough appearance to the surface, about like the bar shown just ahead of the rust area.

The tapered roller at the tail end of the spindle was a little tricky. Since the spindle is not optimized for it, there will be a little more resistance to the preload adjustment. It wasn't until I put a dial on the face of the spindle mount and pushed and pulled on the belt pulley that I realized I had more work to do on the preload despite how it felt.




I also made a seal/cover for the front bearing to replace the loose fitting original, only to discover that the shaft steps up from 55mm for the bearing sleeve surface, to 65mm for the seal surface area, so my seal (not installed in the pic) inner diameter was too small, but the socket for the seal in the cover was just right, except for the small step stop. I ended up using a lip seal that I ordered while the machine was down. The stock covers are near loose fit in the bores, except for paint serving as glue, and make no contact with the spindle. I have seals at all four bearing end locations and scrapped the oil filled idea and just packed the bearings with grease.



Now that everything is nice and tight, I'll be gearing up to make my electric turbocharger using conventional parts adapted to and driven by a high rpm brushless RC hobby motor, along with my other projects.