Tramming my PM-950V mill....

[davidpbest]

Maybe you need a bigger diameter dial indicator? LOL Stop chasing your tail and focus on a diameter of tram equivalent to the width (y-axis) of your XY table. If you can dial in your spindle to 0.0005" of variance around an 8-inch diameter circle, you are at the limits of the tolerances of the this kind of mill.

 

[Firstgear]

Maybe you need a bigger diameter dial indicator? LOL Stop chasing your tail and focus on a diameter of tram equivalent to the width (y-axis) of your XY table. If you can dial in your spindle to 0.0005" of variance around an 8-inch diameter circle, you are at the limits of the tolerances of the this kind of mill.

Perfect....I didn’t have that reference, but that makes sense. You know, that tail just kept running away from me! I’ll get it next time for sure. I will say this, it was not fun chasing my tail! I’ll be on the lookout for a much larger dial indicator as I can see that would make a difference looking at it almost across the room! Ha! Good one!

 

[kb58]

Based upon many very positive recommendations on this forum, I bought a dual-gauge tram setup. Now I understand why it's so popular; because it reads the difference between the two positions, not the absolute readings, it's very easy to set it so the readings match. Of course, it doesn't get around the fact than everything shifts again when the head is bolted down!

 

[Firstgear]

Based upon many very positive recommendations on this forum, I bought a dual-gauge tram setup. Now I understand why it's so popular; because it reads the difference between the two positions, not the absolute readings, it's very easy to set it so the readings match. Of course, it doesn't get around the fact than everything shifts again when the head is bolted down!

The manual says to snug the bolts so that tightening doesn’t shift things. Also, there is a prescribed order by which to tighten them. My torque settings I used after getting where I wanted was 25 ft lbs, 40 ft lbs and final setting of 50 ft lbs. Lower left bolt is number 1, upper right is number 2, lower right is number 3 and upper left is number 4. That is the order that the manual suggests for clockwise and counter clockwise head rotation.

 

[Bob Korves]

We quickly get into an area of diminishing returns when we think that larger tramming aids and larger indicator faces will improve our results. It is the classic case of "measure it with a micrometer, mark it with a crayon, and then cut if off with an axe." After you get it "perfect", move all the axes a couple turns of the wheels, check it again, and see what you get. There is no such thing as perfect, only tolerances to aim for. Using micrometers to measure parts for making a welding table will not get you a better end result, only a more lengthy project...

Learning to use our tools for the very best possible results is most certainly worthwhile for improving our skills. The smart machinist's task then becomes determining when, where, and how much those skills need to be applied to specific operations and projects.

 

[Firstgear]

We quickly get into an area of diminishing returns when we think that larger tramming aids and larger indicator faces will improve our results. It is the classic case of "measure it with a micrometer, mark it with a crayon, and then cut if off with an axe." After you get it "perfect", move all the axes a couple turns of the wheels, check it again, and see what you get. There is no such thing as perfect, only tolerances to aim for. Using micrometers to measure parts for making a welding table will not get you a better end result, only a more lengthy project...

Learning to use our tools for the very best possible results is most certainly worthwhile for improving our skills. The smart machinist's task then becomes determining when, where, and how much those skills need to be applied to specific operations and projects.

Details....details.....

 

[darbikrash]

I use an "Indicol" attachment to tram my mill head in, this extends to 9"-10" radius from spindle center. I like these for both tramming and indicating in the table vise, as they can be used with a cutter (or anything else) in the spindle without removal. The Y axis table direction is the limiting factor to any tramming device, but I do tend to use the entire radius for the X.

I agree that .001" is fine for a tolerance.

The main advantage to a tight tram spec is flycutting, although boring is also important. Large diameter flycutters will cut a slight dish in the workpiece if the spindle is out of tram.