Help confirm my tram

[wildo]

Would anyone mind helping me with my tram? What is interesting to me is that when the indicator has a little side load, it seems to move a little in a way that I don't think is representative of the surface it's riding against. This is seen in the second part of the video when tramming the vise. When I move left, the indicator rides at around +.001 on the dial, and when I move right it rides around .000" on the dial. I don't know what this means.

When taking a dynamic measurement like this, do you "start" your observed reading after the part is moving, or am I actually seeing a change in measurement of the surface here? Also- given my measurements, would you consider this a decent enough tram?

Thanks!

 

[mikey]

For general work, a thou over a 5" run should be okay but zero is better. I'm not sure how others do it but I normally run the table in the same way you're doing it and if I pick up a deviation, I move the vise away from the indicator, tap the vise into what I think is better alignment, then bring the indicator back and re-zero it. Then I make another pass to see if alignment is better. Rinse, repeat until vise is aligned as well as my machine will allow.

 

[wildo]

Would it make more sense to hold some 1 2 3 blocks in the vise and then indicate off of them? This way I'm validating that the work itself as held square to the spindle. Also, the blocks would give me a smoother surface for the indicator to ride against which might help me get a more accurate reading. Is my thinking correct on this?

 

[mikey]

Would it make more sense to hold some 1 2 3 blocks in the vise and then indicate off of them? This way I'm validating that the work itself as held square to the spindle. Also, the blocks would give me a smoother surface for the indicator to ride against which might help me get a more accurate reading. Is my thinking correct on this?

If you have blocks or a parallel you trust, sure. I usually indicate against the jaw but on my Sherline vise, I use a B&S parallel. Works for me, anyway.

 

[JimDawson]

What is interesting to me is that when the indicator has a little side load, it seems to move a little in a way that I don't think is representative of the surface it's riding against.

It looks like the stylus is a bit loose in the pivot. Maybe tighten it a bit, very carefully.

When taking a dynamic measurement like this, do you "start" your observed reading after the part is moving, or am I actually seeing a change in measurement of the surface here?

Usually the dynamic reading is slightly different than the static reading. But see above. You could also could be seeing some anomaly in the surface.

Also- given my measurements, would you consider this a decent enough tram?

0.001 in 5 inches is not bad. Plenty good for most work.

 

[intjonmiller]

I don't have nearly as much experience as these other guys, but when I'm unsure about the reading I will gently manually retract the indicator tip and gently let it return to the reference surface a couple times. That seems to take out any side load that may have been introduced, and the reading I then get has been quite repeatable.

 

[tweinke]

Just a thought from an expert by no means, gibs aren't loose are they?

 

[wildo]

Thanks for all the thoughts, folks! Looks like I have a couple options to investigate here.

 

[Bob Korves]

I prefer to measure things directly. Putting a second part or tool in the stack tends to add whatever errors it has to the equation. In my mind, if you want to measure or indicate something, do it on the part you are interested in, not on a surrogate, if that is possible. If direct measuring is awkward or wonky, sometimes you have to add something else to get a good reading.

 

[Wreck™Wreck]

If there is any play in the ways it will sometimes show up when changing directions, apply a small amount of pressure to the table locks and see what happens.