PM25-MV saddle squareness

[Bluebutton]

Any update on this? What has PM recommended be one here?

PM has offered to repair the saddle on my machine and replace it if necessary. My saddle measured .004" out of square on the CMM at work and 0.0037" when checking it out on another mill at work. Even with the saddle out I believe the squareness was corrected with the tapered gibs. I found a few issues with a radius on a gig interfering with the adjustment screw face. The biggest issue seem to be that the base had a twist to it from the stand. I loosened the stand and it is a lot better, but not perfect. I will make a test part tomorrow to check the final squareness. Once again PM has been very supportive in trying to find the issue.

 

[Richard King 2]

Down to .003" in 4" ? That's pretty bad in my opinion. Years ago when I was still rebuilding machines I was a contractor for Jet and MSC and they would pay me to go out and repair problem machines. Has PM offered to fix it at their cost? The gib picture is hard to believe with that bevel bottom. I suspect the Y is still twisted. A easy test would be to set a precision level on the table and zero ut side to side and crank it in and out and watch it. You can buy imported levels on eBay for 100.00 . .0005/12" You could get a 12" or 6" level. You might be able to shom under the base and above the frame to twist it good. Rich
PS: keep track of your labor and charge them for it. $50.00 p/h would be a bargain for them.
Another thing, put a parallel under the 1 2 3 block to rise it above the jaws, then indicate both sides at the same set up.

 

[Bluebutton]

Down to .003" in 4" ? That's pretty bad in my opinion. Years ago when I was still rebuilding machines I was a contractor for Jet and MSC and they would pay me to go out and repair problem machines. Has PM offered to fix it at their cost? The gib picture is hard to believe with that bevel bottom. I suspect the Y is still twisted. A easy test would be to set a precision level on the table and zero ut side to side and crank it in and out and watch it. You can buy imported levels on eBay for 100.00 . .0005/12" You could get a 12" or 6" level. You might be able to shom under the base and above the frame to twist it good. Rich
PS: keep track of your labor and charge them for it. $50.00 p/h would be a bargain for them.
Another thing, put a parallel under the 1 2 3 block to rise it above the jaws, then indicate both sides at the same set up.

It was 0.010" across 3 inches. I not saying .003" over 4" is perfect, but it better than before. PM has offer to fix the issue once the issue has been determined. Not sure if they cover shipping costs, it has not been discussed yet. I have a Starrett 6 and 12 machinist level and will check the table tomorrow. I did have parallels under the 123 block in the video. I have removed the vice and replaced it with a 246 block clamped directly to the table to eliminate any vice tolerances.

 

[Bluebutton]

Latest update. I have the saddle back out of the machine and will have it surface ground to remove the 0.002" high spot. I found if I put a 0.002" feeler gauge between the saddle and the base and the base is not bolted to the stand I can get 0.001" run-out over 4" in the Y axis and few tenths over 6" in the X axis. Without the feeler gauge the best I can get is 0.0025" across the Y axis. Another reason for the grinding, I am seeing the X table move slightly when the table weight shifts from right to left when passing the mid point in the table travel.

I have been in contact with PM and there support has been great. I should everything back together this weekend.

 

[Richard King 2]

Not knowing exactly how it looks under there, but you might be able to drill and tap a hole say 3/8"- 24 near the hold down bolt and and use the 3/8 -24 cap Allen cap screw with a jam nut /lock to tweak it closer then a .001" .

 

[tkalxx]

As @Bluebutton and Matt at PM suggested, I completely loosened off the mounting bolts of the mill. While the mill was still secured to my stand, I took a feeler gauge under the saddle of the Y-axis and could fit a .009" shim under the back of the saddle. With all the mounting bolts loose I can fit a .002" shim under the rear of the saddle but only under the rearmost 3/4" of the saddle.

With all the mounting bolts loose and my vise trammed within .0003" in the x axis I'm seeing the y axis out by .003" over 3 inches now. It's not amazing, but it's better... The crazy thing is that the mounting bolts weren't even that tight.

 

[Bluebutton]

As @Bluebutton and Matt at PM suggested, I completely loosened off the mounting bolts of the mill. While the mill was still secured to my stand, I took a feeler gauge under the saddle of the Y-axis and could fit a .009" shim under the back of the saddle. With all the mounting bolts loose I can fit a .002" shim under the rear of the saddle but only under the rearmost 3/4" of the saddle.

With all the mounting bolts loose and my vise trammed within .0003" in the x axis I'm seeing the y axis out by .003" over 3 inches now. It's not amazing, but it's better... The crazy thing is that the mounting bolts weren't even that tight.

After I loosened my base I readjusted the gibs and it got better. Now I have the saddle off to a local shop to have it ground. It has a 0.002" twist to it. I should have it back Monday. Will keep you posted.

 

[Bluebutton]

Not knowing exactly how it looks under there, but you might be able to drill and tap a hole say 3/8"- 24 near the hold down bolt and and use the 3/8 -24 cap Allen cap screw with a jam nut /lock to tweak it closer then a .001" .

That the plan. We do the same for the automation equipment we build. The old push pull method for leveling and securing.

 

[tkalxx]

I spent the last 3-4 hours playing around with the mounting bolts, tightening/loosening them individually, and re-checking squareness in between. I made a mental image of how the base of my mill was twisted and ended up shimming between the base and my stand to reverse the twist. I added a .038" shim to the rear right corner and am now seeing less than .0005" out of square in Y. I'm at the point where I can't do any better without purchasing some higher precision tools due to the error stack up (vise trammed within .0003" and my 123 block being out of square approx. .0002"). Either way, I think I'm going to call it good for now - it's a major improvement over the .008" I was seeing originally. I machined a 2"x3" block and checked it with a square comparator on my surface plate. It showed approx. 4-5 tenths out of square over 3 inches.

I just want to iterate how accomodating Matt and the customer service at Precision Matthews has been. When I originally emailed Matt I explained that I knew the mill was well out of warranty due to the CNC conversion and if it came down to it, I was OK purchasing a new saddle from him. He assured me that if the saddle was truly machined out of square, he would replace it under warranty because he recognized that the conversion had nothing to do with it. Overall, Precision Matthews has been a great company to deal with.

Now I have the saddle off to a local shop to have it ground. It has a 0.002" twist to it. I should have it back Monday. Will keep you posted.

Let us know how the grinding turns out.

 

[jwmelvin]

Feeler gages showing saddle twist when the base bolts were right made me wonder about shims so I’m glad to see it appears to work at least in some instances. Nice work.