# How to quickly tram a Bridgeport Mill



## HMF

http://www.neme-s.org/Shaper Books/...g Machine Parts Diagrams Series IJ and 2J.htm

"HOW TO QUICKLY TRAM A BRIDGEPORT MILL"

Extend the quill a little over 3" and lock it.
Place a 0-1" dial indicator so that it rests against the top of the quill.
Adjust the table to read a preload of 100 thousandths.
Crank the table down exactly 3" using the dial on the crank.
Multiply the reading times 3. (the indicator is now ~9" below the pivot point
of the head and you read 1/3 of that)
Adjust the head in the opposite direction the indicator moved by your figured
amount.
Check your work by doing it again, it should be dead on.
This works for both directions.


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## RandyM

The slow guy needs a little help on this. I can not begin to imagine how this is done. I can not visualize the quill, table, and indicator setup. HELP!


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## Maglin

Oh I wish I had thought of this.  This makes using a DTI and swinging around the table obsolete.  I often wonder about the flatness of my table or even the flatness of my ways since my Y ways are worn.  In the manual it says to use a machinist square on the 2 bosses on the front of the head to align it in the Y plane.  I'm going to give this a go later today to see how my dirty tram using my vise and a flycutter worked out.  That was in a pinch and did a pretty decent job of getting me square.


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## DMO

I haven't been able to make sense out of this either. Can someone please explain?
Dave


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## Tony Wells

When the quill (the shiny part that extends out when drilling) is dropped out of the main housing, it should represent a cylinder that is square (perpendicular) to the table, and parallel with the ways that support the knee. So, use a mag base on the table to hold the indicator, point it against the quill. It doesn't have to be a 1" travel indicator, but those are the most common in the shop. Also, it doesn't need to be engaged by the "100 thousandths". Just some zero point. With the indicator pointed against the lower end of the quill, crank the knee up. This runs the indicator up the side of the quill cylinder. If it is parallel with the knee ways, it should be square with the table. In reality, this isn't going to be as accurate as a real sweep, IMO. Also, this should be done on the right or left side of the quill, and the front or back. If either is out of square, it will affect the process on the other axis, which is why I see no real improvement over the standard sweep, or tram, for those who prefer that term.

I can probably take a picture or two later if needed.


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## Pacer

I agree with Tony -- While Ive never tried this method, thinking about it seems theres little end difference than a doing a sweep -- and, I dunno, I think I'd just feel more confident in a sweep.... 

But, as with so many things, there are different ways to get results ....


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## DMO

Okay, thanks Tony. That clears it up for me, I wasn't even seeing it before. It does seem like some cases might require a few repeats to get it right.
Dave


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