Lets Revisit this 'Tramming'

[bjmh46]

Whyemier,

No offense taken! I stick with what I've stated so far. If you use the spindle rotation to sweep the workpiece, (tram) it (the workpiece) can be made perfectly parallel to the plane of rotation, and for all practical purposes perpendicular to the spindle axis. Then if you proceed to drill a hole and bore it with the quill motion, plunge a cutter, tap the hole, then all is well. As soon as you use the xy motion of the table to do your machining, you've introduced an error, if the spindle is not trammed to the table (xy motion). The degree of the error may be insignificant for the work you are doing , if so, all's well! I shoot for .001 max total error in a 9 inch diameter sweep. Sometimes I do a little better, but I don't accept worse. At the .001" error level, you can still detect heel drag in one direction if using a fly cutter. It's all a matter of what you are willing to accept for the class of work you do. After 40+ years of doing this, I've decided the best course of action is to make my machines as close as I can, and check often.

BTW, Pete's advice about "Machine Tool Reconditioning" is good advice. I bought mine back in the early 80's, and it's served me well. It will teach you that there are many sources of errors in machine tools, many of which are not intuitively obvious.

Regards
Bob

 

[brucer]

author=Tony Wells link=topic=3624.msg26650#msg26650 date=1316567391

author=Magnum link=topic=3624.msg26648#msg26648 date=1316564680

author=DaveH link=topic=3624.msg26641#msg26641 date=1316563200
Found it http://hobby-machinist.com/index.php?topic=1723.msg10506#msg10506
Some good info here about tramming.
;0
DaveH

Thanks for going the extra mile... I'll try and read through it.

But you raised a good point. As I have moved my head across my vise at times to check to see if I had some chips under it (paranoid). But now I realize a "sweep" would have been more appropriate.

Moving the head (moving the table, really) will tell you if the part, vise, parallel, or whatever, is running true, or parallel with the ways of the axis you are moving. A chip under the vise, etc. will show up as though you were seeing a incline, either up or down.

Leaving the table stationary and sweeping the surface in question by rotating the DTI in the spindle will tell you if the spindle is perpendicular to that surface, whatever it is. A chip will show up on that test ONLY if the spindle is perpendicular to the table, and the chip has one side of the part elevated.

It's really two different tests.

this is why i actually call it squaring the spindle... i've actually never called it tramming until i came here, because thats the term people were using here..

Whyemier, are you a good wood worker? have you ever heard of the term "Plum" this is basically what your doing, your adjusting the spindle centerline "Plum" to the Work Table.... at that point your mill table and spindle are square and perpendicular with each other, then you put your vise on the table, your back jaw (hard jaw) on vise should also be square and perpendicular with the spindle.. then when you locate a block of material in the vise, if it is saw cut, it doesnt matter if its square or not, when you cut it, the cut surface will be parallel with the world, then when you flip the surface you just cut and place it against the hard jaw, clamp your vise, if the block is firmly seated against the hard jaw, when you cut it ,the side to the hard jaw and the side you just cut will be square to each other....


now if your spindle was out of square/tram to the mill table when you started, the block you just cut would not be square..

hope this helps some....

 

[Tony Wells]

Brucer, I'm with you. Tramming??? What is that? Taking the little tram ride from the parking lot at Six Flag to the gate? I never heard the word used in connection with machine shop work until reading some forums. I had to look it up, and sure enough, way down the list, it does have to do with machine alignment. We always just called it "sweeping" whether it was a vice, or the spindle on a Bridgeport or something along those lines.

 

[bjmh46]

Kind of like a regional thing. Tramming is common parlance in machine shops around here. Some expressions vary by company, such as "duck-board" vs. "chicken ladder". (The nailed up lattice of pine boards that ease the pain of standing in front of a machine all day)

Bob

 

[Chazz]

Kind of like a regional thing. Tramming is common parlance in machine shops around here. Some expressions vary by company, such as "duck-board" vs. "chicken ladder". (The nailed up lattice of pine boards that ease the pain of standing in front of a machine all day)

Bob

That's 'Old School' they're called 'anti-fatigue matting' now.

Our 9,000Lbs Miltronics Mill only gets trammed after the head has been moved off axis, the little 250Lb mill gets trammed about once a month.

Cheers,
Chazz

 

[Shopdawg]

We had the outer race of a 6" tapered roller bearing that we would lay on the table. It had a perfectly ground surface for the DTI. You could sweep a full 360 degrees and not worry about jumping T-slots.

Kevin B.
(Shopdawg)