Tramming mills

The mill has an up-and-down Z movement, and a spindle, which should both be parallel to each other and at right angles to the table.

How do you do this? I guess you separate the two adjustments somehow, but what then?

Thanks,

-- Peter Fairbrother

Reply to
Peter Fairbrother
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There's nothing you can do to adjust the knee on any mill I'm familiar with. As for the quill just mount a dial gauge in a chuck or collet and adjust the headstock (assuming this is actually an adjustable headstock like a Bridgeport) until there's no runout against the table in both planes.

Reply to
Dave Baker

I'm assuming that you are referring to a 'knee mill' of some sort but please confirm.

If this is so, then the ways that the knee rides in would need scraping into alignment if they are out. As for the spindle, the construction of the mill will affect this considerably. Ie if a Bridgeport or clone, then the head can tilt for and aft, and side to side, and it is these adjustments that are usually referred to as tramming. If it is a column mill, then often the column will need its foot either scraping true or shimming true. But more details are needed for a proper answer.

AWEM

Reply to
Andrew Mawson

No, it's actually a converted BCA jig borer; it has a plate on the Z axis on which the spindle is mounted.

The Z axis rotates and that needs adjusting against the table: and the mounting of the spindle needs to be adjusted too so that it is in line with the z axis travel.

What I'm wondering is how to adjust both at once, so to speak.

Lester, you there? How do you do it?

-- Peter

Reply to
Peter Fairbrother

Well that's a whole new kettle of fish! Aren't BCA still in business somewhere around Redhill ? In which case ask them!

AWEM

Reply to
Andrew Mawson

Or even a whole new box of kippers?

Bob

Reply to
Bob Minchin

....ooooo....... yes please !!!!!

AWEM

Reply to
Andrew Mawson

Since you've got the (new?) spindle mounted on the existing ways, you need to do it in two steps.

If possible, use a good square against the dovetail of the BCA head casting to get that as square to the table as possible.

Mount a piece of straight bar in a collet in the spindle and adjust the spindle to sliding-bit-of-the-head until it's at right angles in both the X and Y directions (Z being spindle axis). You could mount a dti in a holder on the spindle and sweep it around the table of this as well. It's probably a better way than trying to eye-up a square against a bit of bar..

You've now got the spindle vertical, but the dovetails may not be completely vertical.

Use a dial gauge against the bar and note the movement as you raise the head up and down. There should be no movement in the Y direction, since the head isn't adjustable in that direction :-). The movement in the X direction is the amount that the rotating head/dovetail/casting is out of square. Adjust it to counteract the error:- If the error was 1 thou/inch then adjust it so the gauge moves 6 thou at 6 inches from the pivot bolt etc.

A couple of iterations and it should be ok, just like a 4 jaw chuck etc.

Did any of that make sense? It might be a bit rambling!

Reply to
Mark Rand

Yep, thanks: I think I understood it, though I'll have to do some thinking and convert imperial to metric and so on.

Yes, it's another new spindle, Chinese 800W water-cooled high speed. I'll post a photo link here in a week or two, it's nearly finished and I think it may turn out kinda tasty.

Thanks again,

-- Peter

Reply to
Peter Fairbrother

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