New Pm 727m Mill

I don't intend to keep the steel gib in use for very long. I just want to do it for the experience. I already have a nice piece sitting on the bench. I am going to stop by the local scrap yard and see if I can find a nice piece of brass. If I can, I will use that instead.
 
I found a guy to inspect the saddle. He was (or maybe still is) a machining instructor at the local community college. He has his own shop and has all the goodies (surface plate, etc) to inspect this properly. I am hoping to stop by there sometime tomorrow to have him take a look at it.
 
Well, the saddle is flat as can be. They put it on a surface plate and found no apparent issues. Seeing as how the saddle rocks when it sits on the base, I am now inclined to think perhaps the base is being twisted due to either the hold down bolts, the base being twisted, or even my wooden sub base. I'm going to go home and loosen all the base bolts and check it again.
 
On my PM25, it sits on four aluminum plates at the corners and a 3/4" piece of plywood on top of a 40" toolbox. My mill is only slightly snugged down to keep it from moving as I don't want to load/tweak the machine's base and only want to keep it from moving sideways during cutting. Not suggesting anything just describing how I did it. :)
 
Well, I think I finally found the main culprit. Since the saddle was perfect when checked on a surface plate today, this got me looking at the ways and base. I loosened up all the base mount bolts to see if this made a difference and nothing changed. So I looked at the factory metal stand and for some reason, I hadn't noticed that the stand was not square across the front. The front right corner tapers down. So, this was causing the base to flex, and then the saddle rocked. I shimmed under that front right corner of the base, and the rocking is gone. I then shimmed my y axis gib, and everything seems much better now. Looks like I am going to build a base sooner rather than later.
 
Just a quick follow up. After I shimmed the front corner to make up for the poorly built sheet metal stand, all seems to be doing very well with my mill. The rocking of the saddle is completely gone, the lifting of the saddle has been reduced to about .003" on each side when the table is fully extended left or right. The head tram is consistent all the way through the range of motion in relation to the table top. I check everything with a fly cutter and got a consistent cut across an 11" long piece of aluminum stock. I actually had to re-tram the column to the table by removing approx. .018" worth of shims that I had originally installed. I just wish I would have though about the basics when I was chasing my tail, and then started inspecting where the mill sits. I would have saved myself and you guys reading this a bunch on grief.

Here is a picture of the sheet metal stand. You can see how big the gap was in the front corner. I have shimmed it with some aluminum angle. Apparently the factory that makes the stands is separate from the factory that makes the machines (and that's a good thing!!).

20151011_125636.jpg
 
But...if you hadn't gone through this you wouldn't have gotten as familiar with your new machine as you are now. :)

Still looking forward to your impressions when you actually get to use the machine as intended.
 
Apparently a package arrived at my house today direct from China that has two nice new gibbs inside.
 
Man matt is really taking care of yah!!!


I bought my PM25 this summer.... wish i knew this was out. Nice looking machine..... (can U post some more pics of the whole machine Please!!!!)

I agree on the stands... they are flimsy at best. I made a 2x4 steel tube frame to raise mine up and give it more stability . i wanted to just bolt it to the frame, but i ended up welding it because of too much flex. Im now thinking bout making a new stand with shelving underneath. I am running out of tool storage and my workbench is pilling up.......
 
I just bought one of these. So far its a great machine for the size. Its a lot quieter than I thought a gear head machine would be. I almost bought the PM-25 but the travel on this machine sold it for me.
 
Back
Top