Tips/Techniques Mill Tramming Question

[whydontu]

So I've trammed my new RF30 mill, and I have a question on the validity of my results.

I installed a three-axis DRO, and confirmed the axis calibration by chucking a 2" throw dial indicator in a drill chuck. Zeroed the dial indicator at end of travel against the table, zeroed the DRO, and extended the quill 2.000" as read on the dial indicator. Confirmed DRO read 2.000" travel.

So today I chucked the same 2" throw dial indicator in a holder, zeroed it with about 0.200" of quilll extension, with the tip placed as far to the right as I could, zeroed the DRO. Moved the quill up and down to the zero point, DRO reads 0.0003", so I know the DRO is active and that's within the 5 micro resolution. Lifted the quill so the dial indicator wasn't touching the table, and spun the quill 180* without touching the dial indicator or chuck (spun it using the spindle pulley). Extended the quill to the same zero point at 0.200" extensions, and compared the DRO reading. DRO read the same 0.0003".

Is this a valid way to check tram? If I try to spin the quill with the dial indicator touching the table it twists and goes out of true.

 

[garageguy]

Sounds legit to me. the only other thing you could do to be more precise is remove the vise and eliminate the need to raise the quill between measurements. When rotating between RH and LH I just lift the indicator tip a wee bit to clear the T slots.

 

[Mcgyver]

Sounds fine, Technically I guess it would be better to not move the Z, but at that distance of sweep any amount out would be microcscopic at the diameter of a normal sized cutter

Just for convenience, try putting a parallel or 123 block under the indicator point. Read and remove the block. Then when rotating the spindle the indicator isn't touching anything, and also can't foul in the T slots.