Trammed the mil yesterday

Ignoramus10056 fired this volley in news:hMOdnTIKkcP4NmXQnZ2dnUVZ snipped-for-privacy@giganews.com:

Hardly done!

That means it's off more than two tenths just over the diameter of a 1" bit. That wouldn't give very pretty facing work.

But that's just my opinion.

I do have a question, though: Since yours is a fixed ram machine, how did you go about it? Did you follow the maintenance manuals, or come up with your own technique? That's a heavy head, and when you loosen the bolts, it wants to move all on its own.

LLoyd

I'm rather a fan of this:

Would you mind explaining that math? Not saying you are wrong, but it doesn't make sense to me. How can it be off true of .001 at 4 inches, and off true of .2 at 1 inch?

"tenths" refers to "ten thousandths" in a machining context.

I don't like that, because it relies on two separate indicators, and that introduces uncertainty as to their mutual adjustment an reading.

"T.Alan Kraus" fired this volley in news:4df8d9c2$0 $2133$ snipped-for-privacy@news.sonic.net:

Nope. Just turn it 180 degrees to check any reading.

LLoyd

You should let Iggy know getting it this close is ten times the work of getting within .001 over 4 inches.

I fiddled with my Large Super Max till it was --O--O--> (that's an arrow through two balls, or "dead nuts", an official engineering term) and then drilled and installed a taper pin to keep it there.

Karl

Have you actually used one?

The scheme I used is to use a CNC program to mill a shallow circular groove in a piece of scrap about as large as the machine can reach. On your machine, it might be about a 10" diameter circle. I position the spindle back to the center of the groove. Then, I mount a dial indicator on an arm and sweep the groove. Because my ways are worn, I get a bit of a saddle-shape, ie. a hump in one axis and a valley across the other. I try to straddle all these variations when tramming. This aligns the spindle to the XY plane of motion, not just to the surface of the table.

Tramming your head is probably harder than mine.

Jon

Nope. While its nice if they are the same its not necessary for them to be. You can make a home made one all wonky and have it work perfectly. Just set your manual zero indicator mark the same for both indicators at the same spot on the table. They can be within the range of the indicator off from each other and still work perfectly that way. It took me a while to get a reflexive feel for relative vs absolute measurement, but once I did life became a lot easier.

I have a piece of square aluminum bar stock with threaded holes all over it I use for all kinds of things now. I just bolt an indicator and a stud on wherever I need them. Work on my lathe, any of the mills whatever.

I like that idea. Is there any reason one could not install a big taper pin, with a ring on the outer end so you could pull it if you really needed to swivel the head? Then return it to tram by aligning the pin and tapping it snug.

The taper pin is drill and tapped so a bolt could be used to jack screw it out if needed.

Use pins that come with a hole tapped in them.

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

His doesn't do either -- it's a rigid ram machine. The only tramming available is to loosen the head mount bolts, and wiggle it. No "rotation" available.

LLoyd

Rex fired this volley in news:89e0363a-9604-4e99- snipped-for-privacy@m10g2000yqd.googlegroups.com:

If it were that easy to get it true to tenths over (say) a foot, then the mill makers would have already done that. It's about the same as trying to replace the gap block in a lathe. Yeah, there are taper pins, but they only get it close.

It would make it easier to get it _close_, but the final work will still be to tweak it that last two or three tenths -- by hand.

LLoyd

>

No, I was going on theory, and I realize I wasn't thinking.

How do you use your home mader? Do you set them to zero, then turn the device 180º and move the head until it's half of the difference from the original reading? Rinse & repeat until it's zero?

Are the SPI ones accurately enough made so that you don't have to turn the device 180º and try to read the back?

[ ... ]

He means 0.0002 ("tenths" is slang for ten-thosandths.)

Enjoy, DoN.

This is a good point. Well, I did it with one indicator, just because I did not have this fancy one. I used top of the Kurt vise as a reference surface.