PM932M PDF

richz

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When I first got this I trammed it. After using it for awhile and getting crooked parts I decided to tram again. I now have a better understanding the tramming process better. I have the z axis properly aligned to the column. I am having a very hard time aligning the column to the table. I shim left to right and then forward to back gets out of alignment. I am pulling my hair out trying to get this correct by shimming. Would it be possible to use studs with jam nuts for attaching the column to the base? This seems like it would make it a lot easier to align. I know I will be raising the column up some. Would this be a less rigid setup?
 
Yea, it will be a lot less rigid.

Shimming is a pull your hair out kind of task, but it's the price we all pay for not having a Bridgeport style mill. Thankfully it's the type of thing you only have to do once.
 
Stefan Gotteswinter has a video showing using pieces of annealed copper to become the shims as he tightens down the column and using epoxy for rigidity. Special epoxy.

You still need to go through the hassle of the tramming, but at least only once.

Tramming mill with epoxy video
 
Thanks for the link Dave. Is a precision square really that precise to use for tramming?
 
I think it depends on the square. Some will be more accurate than others. It may be a case of Stefan using what he had available.
 
I probably would not use a square, I use some precision ground 90 degree angle blocks/fixture plate. I have some 4" and 6" ones that are ground to 0.001" or better and will sit flat and stable on the table. Great also for clamping tall parts to the table. In theory the column once aligned should not need to be retrammed, but the head will nod if not clamped, and the gibs will wear asymmetrically over time because the weight on the lower part of the gib. Some people use a chain or cable system attached to the top of the head with a counter weight. In addition, with Z axis power feeds one sometimes forgets to release the locks when raising/lowering the head which accelerates the wear. Keep the ways well oiled, maybe consider a pump oiler over the long hall.

You may also be seeing compression, flowing of the shimstock once clamped, I would use steel shim stock, possibly the epoxy method but I do not know the long term durability of the systems. I eventually went to a knee mill, which was a significant improvement.
 
Stefan Gotteswinter has a video showing using pieces of annealed copper to become the shims as he tightens down the column and using epoxy for rigidity. Special epoxy.

You still need to go through the hassle of the tramming, but at least only once.

Tramming mill with epoxy video

Do you know of anywhere in the states to pick up this same sort of epoxy? I've watched this video multiple times in anticipation of picking up a mill in the future and was just curious where we might could pick this stuff up on this side of the pond.
 
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