PM-935 Tramming and other questions.

Just for fun

Just for fun

Tim Young
H-M Lifetime Diamond Member
Joined
Oct 7, 2020
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How often should I need to tram my mill? I trammed it when I first placed it in place a couple weeks ago. I have moved the Ram back and forth a couple times, maybe that was enough to mess up the tram. It was out of tram this morning by a couple thousands. Maybe I didn't have it right the first time.

I also noticed this morning that the center slot of the table is not as wide as the two outside slots. My vice came with a couple of locating pins or little blocks, they will not fit in the center slot. I was thinking that I was going to have to mill the sides down a bit, and I might still have to do that. I decided to try one in the outside slots, they fit. The center slot measures .624 and both outside slots measure .630 is that normal?

Tim
 
I check my tram about once per month or if I feel the need to really check the accuracy. H have this badboy which makes tramming a joy
1649884277086.png


On mine:
Center is: 0.616
Outers are: 0.620
 
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I have the one from Boring Research my Edge dial indicator fell apart, and another DI I had didn't fit it.
 
Tim,

The slot widths on my PM-935 vary as well. I've attached a drawing with exact dimensions of my XY table FYI. I would suggest you thin down the mounting hardware to fit the most-narrow slot on your table rather than machining the slots on the XY table.

As for the tram, I check mine after every job that involves aggressive milling (particularly slot cutting in steel and stainless), and when I move the Ram in or out. The knuckle and related bolts that secure the nod are the weakest part of the 935 rigidity. It is possible to throw off the tram with aggressive cutting (something like 3/4" corn-cob end mill, slotting at a DOC of 0.250" in 4041 or 304. Also, you might remove the gib on the where the Ram mounts to the turret, check it for flatness, and deburr it. The gibs on my 935 were all pretty sloppily made and contributed to considerable table and Ram movement under load. I spent half a day fitting all four gibs properly and it made a huge improvement. You might have a look at the videos I've posted here. And while you're checking things, might as well examine the rigidity of the quill as shown here. I rarely move the Ram on my 935 as a result, and you can see how I have it nominally positioned in the second drawing that's attached.

Hope this helps.

David
 

Attachments

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How do you feel the Boring Research compares to the Edge? Looks like it's pretty well made on their website and in that pic
 
It's simple, and it will take the stem of the dial indicators, the Edge is not universal.
 
I had to provide my own indicators, but I like it, and it's adjustable.
 
Thanks for all the pro tips guys. I ordered one of the Edge Technology tramming devices before I posted this morning. I like the idea of the Boring unit using standard dial indicators, oh well.

The good news is it sounds like everyone's mill is the same as mine or at least similar.

David, I'll check out the video later and thanks for the links and drawings.

Tim
 
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