PM25-MV saddle squareness

BladesIIB said:
Also, maybe captain obvious here but tightening the gib is not tightening the lock screws on the side until it is snug. Tightening the gib is adjusting it from the end and wedging it against the dovetail. You mention the tapered dovetail earlier so sounds like you have it. But also mention you have not run it in 3 years so just figured it was worth a mention.
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The table only moves about 0.002" up and down and side to side without the axes side locks. With the axes locked the the deflection is better about 0.001" each time it returning to zero. I have done the same test as in the video with other 123 and 246 blocks with the same result and locking the axes.

As for not using the mill in 3 years. I've been using the Bridgeport at work for most of the parts I need. I only bought the PM25 for when the machine at work is not available. I also knew the PM25 would not compare to the Bridgeport and there would be some tolerance differences for an import mill.
 
I think that video is telling. Your saddle is not ground square with the x axis. If the gibs are OK this is a manufacturing defect. Let us know what PM will do for you.
Robert

I just checked my PM 728 using the same technique as in your video. With my X axis aligned to the short side of the block, my Y axis is off about 1/2 thou over the 3" side of the block.
Robert
 
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I have found the exact same issue with my PM25. The mill is just under a year old and noticed that all my parts coming off the mill are no where near square. I spent the first 6-8 months converting my mill to CNC and so my out of squareness issue has just reared its head.

I measured .008" out of square over 3 inches on a 123 block. I checked my 123 block using a square comparator; it's out of square .0002". I've been through the whole gib adjustment phase multiple times and have never found a difference. Like you, if I grab the ends of the table and try to twist with an indicator on the side of my vise or a 123 block I can only see .002" of deflection in either direction.

I've been in contact with Matt over the last week or so, he has been very accommodating so far.
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Sounds like you both have exhausted all the tests and it is defect in the manufacturing. Glad Matt from PM is working with both of you. I am sure they will come up with a solution.
 
Any update on this? What has PM recommended be one here?
 
davidpbest said:
Any update on this? What has PM recommended be one here?
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Matt suggested I pull the saddle off my mill to take some pictures of the dovetail surfaces before jumping to conclusions. He wants to verify that there are no burrs/knicks/blatant surface imperfections that may be causing the issue. Due to my mill being CNC, I haven't had the time this week to fully commit to disassembling everything - hopefully this weekend I will.

I hope to take some measurements of the X-Y dovetail squareness on the surface plate while the saddle is off the mill. I don't have the necessary tools to get a truly accurate reading on how out of square the dovetails are (I am by no means a professional at restoring machines/scraping), but I should easily be able to get an understanding if the dovetails were machined incorrectly - which is what I have hypothesized. I will definitely report back once I learn more.
 
Amazing. I've had my PM25 at least 5 years, maybe 6, never thought to check. I put my Starret solid square in the vise, jiggered the vise around until X read 0 in four inches, moved the indicator to the blade and cranked the Y four inches. it's out perhaps .0002. Could be my Square's out, I've had it 30 years and it was used when I got it, never had it certified. BUT, what are the odds that my square is out within .0002 of the table.... The table clamps were snug enough that I couldn't see any wobble as I cranked the handles.
 
If all else fails, I have a friend who lives in Berkeley CA who is a decent machine repairman who could come and repair it. If PM want to hire him, have them email me and I'll forward it to him. Richard@Handscrping.com
 
tkalxx said:
I have found the exact same issue with my PM25. The mill is just under a year old and noticed that all my parts coming off the mill are no where near square. I spent the first 6-8 months converting my mill to CNC and so my out of squareness issue has just reared its head.

I measured .008" out of square over 3 inches on a 123 block. I checked my 123 block using a square comparator; it's out of square .0002". I've been through the whole gib adjustment phase multiple times and have never found a difference. Like you, if I grab the ends of the table and try to twist with an indicator on the side of my vise or a 123 block I can only see .002" of deflection in either direction.

I've been in contact with Matt over the last week or so, he has been very accommodating so far.View attachment 363770View attachment 363771
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I was able to get my PM25 down to .003" over 4 inches today. Here is what I found. First the X axis gib had a radius on the face where the adjuster screw was making contact (gib photo). The radius was forcing the gib up into the table surface. I milled that face flat at work and the run out improved by .004" now only .006" out over 4 inches. Once that was corrected I noticed the saddle was sitting flat on the lower dovetail surface. The saddle had one corner higher by 0.002" (saddle photo). While I had every thing apart again I checked the base for level and found out it had a 0.02' twist to it. I loosened the bolts holing it to the stand and most of it went away. With everything back together I now have the mill within 0.003" over 4 inches in Y with the X indicated at 0.0005" over 6 inches. Matt at PM has been very helpful. He has offered to correct any issues with the mill, vary have with PM support.
 

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