Homemade tram tool

If the bar were 30 degrees off, and you zerod it , it would still be accurate. Because they were both reading zero at the same spot. Spin it around to face you and they should still be reading zero if in tram.

Maybe I need another set of eyes on this, because I thought the purpose of the bar with two indicators was there is no need to spin. The process is to have both indicators read the same when the head is trammed in. i.e. both indicators read the same, whether it be 0, 10, 12.5 etc. To make sure the indicators and bar are accurate you would need to tram the tram bar setup prior to tramming the head. If we go with the bar being accurate then all is well, but if the bar is off a half degree, the head will be off as well. People who design things make it seem difficult so they can sell their product.
 
Ok I think I see the confusion here. You put the unit in the spindle, then you put a 123 block or such under one of the indicators and zero the indicator, with out moving the 123 block you need to rotate the spindle 180 degrees and zero the second indicator and remove the 123 block, you can now turn the spindle back so that both indicators are lined up on the axis in question and tram till both indicators read the same reading. By setting zero at the same point for both indicators any out of square on the unit is compensated for. I in my newby state of mind I had a heck of a time grasping the whole thing but think the theory is sound. Hope this all made sense.
 
Maybe I need another set of eyes on this, because I thought the purpose of the bar with two indicators was there is no need to spin. The process is to have both indicators read the same when the head is trammed in. i.e. both indicators read the same, whether it be 0, 10, 12.5 etc. To make sure the indicators and bar are accurate you would need to tram the tram bar setup prior to tramming the head. If we go with the bar being accurate then all is well, but if the bar is off a half degree, the head will be off as well. People who design things make it seem difficult so they can sell their product.
You spin the tool because you set the zero on the same spot. It doesn't matter where you pick the spot. It just has to be stable. I actually pick a spot at the front of the table because it's easier to read without rubbernecking
edit: tweinke, you beat me by a minute. Nice explanation.
 
Before I made my dual indicator tram tool I had the same questions and could not find exactly how to set the unit. I will try to go one step at a time.
With the tram tool in the arbor and the gauges facing you place a spacer of good quality under one of the indicators stem. The spacer does not need to be any particular height but should have parallel sides. I use a piece of 1" bar that has been faced in the lathe about 1/2" long.
Move the spindle down until the stem contacts the spacer and then down a little more (maybe 0.050) to there is some wiggle room for out of tram. Lock the spindle at this position and then turn the dial case to indicate 0.000.
With the spindle still locked turn the spindle 180 degrees so that that the other indicator's stem is resting on the spacer in the same location. ( The face is now read from the back side of the gauge) Now set the dial on this indicator to 0.000.

You have just calibrated the tool and am free to unlock the spindle and remove the spacer.
To use turn the spindle around so you see the dials and lower the spindle until you see both dials move and continue down until one of the dials reads 0.000. Lock the spindle and now read the other dial which indicates how far out of tram your head is. Now you can adjust your head so both indicators read the same amount and it may not show 0.000 but just the same on both dials.
If you now hold the indicator stems up you can just turn the spindle 90 degree and immediately read the nod of the head. Calibrating the tool in this way takes all the variables out of the setup and the tools shaft can even be bent.

Hope this helps

Ray
 
Ok I think I see the confusion here. You put the unit in the spindle, then you put a 123 block or such under one of the indicators and zero the indicator, with out moving the 123 block you need to rotate the spindle 180 degrees and zero the second indicator and remove the 123 block, you can now turn the spindle back so that both indicators are lined up on the axis in question and tram till both indicators read the same reading. By setting zero at the same point for both indicators any out of square on the unit is compensated for. I in my newby state of mind I had a heck of a time grasping the whole thing but think the theory is sound. Hope this all made sense.

Now I finally get it!
Zeroing the two indicators to the same spot calibrates the tool and cancels out any "out of square" imperfections in the t-shaped holder. Thank You!

-brino
 
You spin the tool because you set the zero on the same spot. It doesn't matter where you pick the spot. It just has to be stable. I actually pick a spot at the front of the table because it's easier to read without rubbernecking
edit: tweinke, you beat me by a minute. Nice explanation.

With the two indicators on the tramming bar what's the purpose of zeroing the indicators? If the bar is accurate then I begin with both indicators zeroed. I can bring the indicators down and touch the table and adjust the head until both indicators read the same. What they read isn't important as long as they are the same and we accept the bar as accurate and true. If the bar isn't accurate then we may as well use the tried and true one indicator setup.

To check the bar I would place a parallel on the table and bring the indicator down to touch the parallel and lock the spindle. Spin the bar and the second indicator should read the same on the same spot.

If I make my own bar then I need a surface plate with all the pertinent measuring devices to insure the bar is square to the round that's perpindicular. If the hole is drilled crooked through the bar I have defeated my purpose. You can't IMO, zero out two separate indicators on a bar that's inaccurate.
 
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With the two indicators on the tramming bar what's the purpose of zeroing the indicators? If the bar is accurate then I begin with both indicators zeroed. I can bring the indicators down and touch the table and adjust the head until both indicators read the same. What they read isn't important as long as they are the same and we accept the bar as accurate and true. If the bar isn't accurate then we may as well use the tried and true one indicator setup.

To check the bar I would place a parallel on the table and bring the indicator down to touch the parallel and lock the spindle. Spin the bar and the second indicator should read the same on the same spot.

If I make my own bar then I need a surface plate with all the pertinent measuring devices to insure the bar is square to the round that's perpindicular.
They don't have to be zeroed, its just convenient. They just have to read the same when resting on the same reference point. It is not necessary that the bar be dead nuts perpendicular to the shaft mounted in the spindle or that the spindle not have any angular runout because the zeroing process accounts for that. The way I made mine, I can move the indicators up or down and clamp them at any vertical position.

If there is excessive non-perpendicularity, the indicator that is down will be slightly closer to the spindle than the other and they won't track on the same circle. However, if the reference surface is reasonably flat as in a 1-2-3 block, the error will be so small the it won't matter. You are looking for variations on the order of a thou over six inches. If you are off by 1/4 inch on the position of the reference calibration, the error in the calibration would be a fraction of a tenth of a thousandth.
 
So zero one, flip it around 180, then set the other to zero at the same spot.
Now they are both good to read.

You don't spin it again, you position in front of you and your good to read.
When you move your indicator back and forth (single indicator) you are trusting the rig to hold right?
Now you have zerod both on the same point when you have 2.


I was referring to using the rig multiple usages. If it's really not that hard to set up... and I find myself in possession of a few spare indicators...
 
The way I made mine, I can move the indicators up or down and clamp them at any vertical position.
This video makes absolutely no sense to me. The device is zeroed on a surface that you have no way of knowing it's flat or accurate. The magnetic calibrating gimmic follows in the same order.

This is the tool that makes sense (it's the same as the Starrett 649) because I want my spindle to be perpindicular to the vice/table, not to a measuring device that's inaccurate. The spindle square is zeroed on the surface plate then inserted in the spindle. Tramming could then begin any time after both indicators move, but he took one to zero, split the difference by adjusting the head and zeroed them both.

Maybe I like a challenge but I don't see tramming with one indicator as being difficult or difficult to follow. OR,,,,maybe I'm just not as addicted. :D
 
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Maybe I need another set of eyes on this, because I thought the purpose of the bar with two indicators was there is no need to spin. The process is to have both indicators read the same when the head is trammed in. i.e. both indicators read the same, whether it be 0, 10, 12.5 etc. To make sure the indicators and bar are accurate you would need to tram the tram bar setup prior to tramming the head. If we go with the bar being accurate then all is well, but if the bar is off a half degree, the head will be off as well. People who design things make it seem difficult so they can sell their product.
To set it up you must spin it so both read zero on the same spot.
After that you have them face you and work them both to the same reading.
 
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