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Mill Traming

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richz

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Question on mill traming. Awhile ago I was reading about someone who used treaded rods to tram their mill. There was talk about a loss of rigidity and someone else also stated that if it was done this way it should be grouted. When I tramed my PM932 I have one side shimmed with 0.020 thousands. Technically the two surfaces would not be touching. Should this be grouted?
 

Winegrower

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I have a Bridgeport. And no grout. And no treaded rods.
There must be something about tramming this PM932 mill that’s way different?
 

COMachinist

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You don’t need grout or shims to tram the PM-932 mill side to side. You adjust the head tilt toget the side to side tram, and a long pieces of shim stock to adjust nod front to back tilt. I have my 932m PDF so close it cuts mirror facing cuts no ridges. It stays in tram too.
Good luck.
CH
 

warrjon

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I had an RF45 clone a while back and shims under the column did not effect rigidity. I had the column shimmed for tilt and nod.

I also replaced the 4.6 column bolts with 12.9 and added additional torque to the bolts.

You need to tram the column in both X and Y. If you only tram nod and the column is leaning (as mine was) it will effect X axis positional accuracy when you move the head up and down. You can check this by boring a hole with the head down as far as possible, raise the head as high as it will go and use a centre finder to check if it is still centred in the hole.
 

richz

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warrjon do you think replacing the column mounting bolts with threaded studs and using nuts under the column would affect rigidity?
 

warrjon

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Yes using threaded rod will effect rigidity, it has to. Although to what extent I do not know. A bolt (or rod) will stretch. When the bolt is torqued down correctly the stretch is reduced. This is why I used shims, I used 12.9 bolts and torqued them to spec. Shimming takes longer but IMO is the better way to go.
 

yendor

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The Threaded Rod option works pretty well for the Mini Mill type units.
But on those units we typically tke light cuts and the work effort isn't as demanding.
 
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