Mini Mill head not aligned, but it is tramed ?

Endmiller

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Jul 14, 2019
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Hi to All
I have been at the trade since 1974. I have a Mini mill here at the house now that I am retired. Here's the thing, The table is trammed to the head. It's dead on. I used .007 shim under the riser to bring the table in to tram. It's good. Zero in the front and zero in the back of the table. I get a nice cross hatch with my fly-cutter. I just noticed that I am having an issue with the Z travel. I placed a new steel square on the table and ran my indicator up and down for roughly 4 inches. It's out .006. I can't seem to figure how to get it aligned. I switched to a 1,2,3, block. I got similar indicator travel. If I were to change the shim. I loose the table tram. I'm trying to overhaul my farm tractor engine. The machine has to be straight to fix the connecting rods.
Thanks in advance for any advice.
Steve
 

Navy Chief

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Based on the info provided it sounds like the column was close to perpendicular to begin with. The error you were seeing may be due to the relationship between the head itself and the mating surface on pivot mechanism. If you shim between the head and the z carriage and remove the shims under the column it should get you into tram, or at least get you on the right track.

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Endmiller

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Thank you for your reply. I would have replied sooner. Message went to Junk Mail. I have seen that done in other posts. I understand what you are saying. Z travel may be going opposite from how I originally shimmed. I will give it a try tomorrow and let you know the results.
Very grateful for the help. I am right in the middle of this overhaul. At the point where I need the mill.
Steve
 

davidpbest

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Based on the info provided it sounds like the column was close to perpendicular to begin with. The error you were seeing may be due to the relationship between the head itself and the mating surface on pivot mechanism. If you shim between the head and the z carriage and remove the shims under the column it should get you into tram, or at least get you on the right track.
It could also be that the quill travel and column are not in alignment. Watch this video:

 

Endmiller

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I just came up from the cellar. From what I can tell, it looks like It may be the "Z" dovetail. I turned the square around so I could get more stroke out of the "Z" travel. Towards the table where I was working the indicator is moving. As I get further away from the table the indicator stays steady. I can pull the gib and clean it and try again.
 

Endmiller

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I cannot thank you enough for your advice. I was at the end of my rope yesterday when I reached out to the forum. Navy Chief nailed it. The column must have been close to perpendicular and when I added shim to it when I first got it. I added shim to where it did not need it. I needed to shim between the head and the z carriage. Now I understand what I need to do. This morning, I compensated for the error by shimming .002 under the the rotary table. See picture. Thanks for setting me straight.
Thanks
Steve
VP -92 ADJ-6
U. S. Navy reserve 1978 through 1984
N.A.S. South Weymouth MA

20211229_105801.jpg
 
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