An improvement to the improved mill tramming devices

[Winegrower]

You know the dual dial indicators on a bar that you use to tram a mill, compared to sweeping a single indicator? It got a little tedious with a single indicator, lots of move the head, check, no, wrong way, try again, rotate indicator, what was that last reading? Was it plus .002 or minus .002? So I built a dual indicator bar, where the stem of the indicators were held at the right height with a screw through the side of the bar. That was a good improvement, but it seemed like half the time the indicators faced the wrong way. A little annoying.

so I had a couple of 6202 bearings lying around. Not in this order of operations, but to explain, I pressed the bearings into the bar, pressed a brass insert turned to the ID of the bearing into each bearing, and tapped a 1/2-13 thread through it. I pressed another brass piece knurled like a thumbwheel onto the bushing. Then, I had some matching 1/2-13 all-thread, cut a short piece and bored through it to take a snug fit on the indicator stems, and super glued the all-thread to the stems. Then thread the indicators through the threaded brass inserts.

So you see the idea...it you just rotate the brass insert (and thumbwheel) the indicator rotates with the insert for better viewing but does not move at all vertically. However if you hold the brass insert and rotate the indicator relative to the insert, you can screw the indicator up or down precisely, much easier than with a screw through the side. This makes it very easy to zero the indicator. Set one side to zero with the quill or knee, swing the bar 180 and holding the indicator facing you, thumbwheel it to zero. You’re zeroed. Rotate the indicators as needed for visibility. Tram as normal, but always being able to see both indicators easily and simultaneously is very convenient.

Now, I actually like tramming the mill. Really.

Yes, you can see that the top of my vise is .001 out front to back. The table is level, the vise body and fixed jaw are just right, it’s a not important part of the vise that’s out .001 over 5”. Shoulda got a Kurt I suppose.

Winegrower

 

[davidpbest]

Very interesting. I don't know squat about bearings, but I would have assumed that they would have enough sloppiness that vertical registration of the indicator might change as the indicator is rotated in the bearing. Maybe a 6202 bearing is a type that has minimal slop, and I just don't know the specifics of bearing numbers and corresponding specs. To the extent you can illuminate my thinking/paranoia here, please comment and thanks for the posting.

 

[Winegrower]

DAVID, that was my original thought, so i tested that specifically. There is literally no slop in the bearing, at least none resolvable with a .001 indicator. There is zero needle movement when rotated.

There could easily be superior bearings. These are about $1.50 each.

 

[ttabbal]

Well dang, why didn't I think of that! Nice setup, I might have to make an upgraded tramming tool now.

 

[4ssss]

I like your idea, but I was taught how to tram a head with a B&S Best Test indicator sweeping the table and I could probably do it in my sleep, so a supposedly better way doesn't cut it for me. It's kind of like nowadays a kid can fire up a computer but can't add 2+2

 

[Winegrower]

Sure, 4ssss. I think probably everybody learned to tram by sweeping. This is just substantially faster for me, especially if the mill is out through intentional setting, or if you want to set a specific angle with a reference triangle or sine gauge. Sweeping is much harder then.

But time does not matter to some. I recall telling a software developer that his code, for a medical instrument, ran too slow. He said "what's time to a pig", implying that doctors and nurses would not be sensitive to speed here. I didn't agree. He departed soon thereafter.

 

[Larry$]

I've tilted the head on my mill several times in the last year. Always hesitate to do it because of getting back to 90. Using a mirror is a PIA & like you said, which way? If someone is worried about slop in the bearing it would be pretty easy to add some form of tension device.
I spent my working life in manufacturing. One thing that drives better outcomes is the fact that there is always a better, faster or cheaper way to get the job done. Some people are resistant to that and should never be put in charge of a project. In my business we would re-write the code to save 1% of the cycle time.
Now its likely to be argued that we are not in business, as retired people, so time doesn't matter. I submit that time is even more important since we have a lot less of it left.