How do I tram/align the 4th axis to tailstock?

[biomed_eng]

I think I know how to tram in a 4th axis rotary table.

However, there is the whole yaw, pitch and roll thing, along with x,y,z positioning of the tailstock. How do you align the tailstock to the 4th axis?

Thanks!

[HuFlungDung]

Keys are usually used in the bottom of the 4th axis and in the bottom of the tailstock to quickly position the two devices along one T slot in the table. The manufacturer takes care of most of the alignment problem this way on your behalf.

The final check of course, is to place a shaft between centers, and check the alignment with a dial indicator along the top (to check uniform Z) and along the front or back to check parallelism to X.

If you have a chuck on the 4th axis, you should chuck up a straight piece of shafting and dial it in first, checking for runout by rotating the chuck. This should be done in two places, one near the chuck, and another spot, maybe 4 inches from the chuck. This will help you see if the part is truly held straight and parallel to the rotary axis by the chuck jaws. A small amount of detectable error would be common in this test. If the test shows a small amount of wobble to the part, you may be able to align it with light hammer blows. Do not overdo it. If the jaws or collet are not in perfect condition, you cannot really fix the misalignment with a hammer, you would have to perfect the jaws and/or collet. This is why crucial alignment is better done between centers, with a gauge mandrel that also has perfect centers in the exact center of the ends of a very straight piece of stock.

If you have a universal tailstock, it is possible to use it to support shafts that are not level. Doing this requires loosening off the clamp bolts and shifting the position of the barrel and screw assembly. Undoing this misalignment requires simultaneously leveling the barrel and screw assembly and checking its height. It is a bit of fiddling around. A height guage with a dial indicator comes in quite handy for this realignment. You need to know what the center height of the 4th really is, then can use the height gauge to set the tailstock to the same height.

[widgitmaster]

Originally Posted by biomed_eng I think I know how to tram in a 4th axis rotary table. However, there is the whole yaw, pitch and roll thing, along with x,y,z positioning of the tailstock. How do you align the tailstock to the 4th axis? Thanks!

Why not use a dial indicator!
Mount it to the 4th axis, so it rotates like a spindle, then indicate the hole or point of the tailstock! That will allow you to get it perfect!

Eric