Dividing head tailstock alignment.

[loose nut]

Is there a preferred or "correct" way to align the height of a tailstock center so that it matches up exactly with the center of a dividing head/rotary table (horizontal) when used on a milling machine. Leveling the tailstock, parallel with the table, would be easy enough with an indicator but setting the height ???????

I have read about a couple of ways people have done it but they don't seem to accurate.

[Mr Fixit]

Not having a dividing head but thinking about it, can you put 2 dead centers, one in each end and align it like you would a lathe tailstock?
Just an idea.

Mr fixit for the family
Chris

[dalee100]

Hi,

I've always just used a thin ruler and do it just like setting a lathe tool on center. When the ruler appears vertical to the eye, it's centered. This has always been "good enough" for me. Do you need extra accuracy?

Dalee

[gundog]

If it were me I would use the mill spindle with a pointer chucked in a collet. What really matters is the orientation to the mill spindle more so than the mill bed. Of course if the machine is perfect this would be the same but if it has any wear this might change. You should be able to run the table back and forth using this method to get it centered for height Z and also aligned in X & Y.

Mike

[Blogwitch]

A dividing head and it's associated tailstock should both have angle adjustment, as that is a feature of a dividing head, totally different to a rotary table which is either square or parallel to the table, unless mounted onto a tilting table.
You should also notice that a dividing head tailstock centre is not ground central, but off centre.
When setting up a dividing head at an angle, in reality, it is done by eye and feel to get both ends of the piece part in unison with the centre.

John

[boslab]

I've never used one, I do have one but not got round to having a go, in school the instructor showed us how he did it, the head was fitted with a ball centre, and the tail with a point, a steel rule was trapped as you have all said and sighted vertical, there was another tail that had a morse socket, that was also fitted with a ball and the same done, but just to check he put a clock on the head ball, the zeroed, moved it to the tail but it was off a few thou, not a big problem but it does show it can be wrong, I don't suppose it would make a lot of difference.
Mark

[philbur]

If you have a tailstock that tilts and if the tailstock axis is not parallel with the table you can have the headstock and tailstock center points at the same level but the tailstock center cone will not necessarily be symmetrical with the tail stock axis. The result being that when the center is engaged with the work-piece it forces the work-piece high or low compared to the headstock.

Where ever possible I think it is good practice to indicate the work-piece and not the tool.

Phil

[dian]

i think the solution is a test bar (that you can make) and indicating it.

i have this, so i dont have to bother:



the long term solution would be to mount both permanently on a plate.

[Paul Alciatore]

I would think the best way, most accurate way would be to mount an arbor between centers and use a DI in the spindle while you traverse that arbor below it. Be sure to take any taper in the arbor into account.

This method is results oriented as you want the work to traverse properly in relationship to the tool mounted in the spindle. It would automatically take several additional factors into account, including any local hill or valley in the mill's table.

[LARRYR]

i use a test bar. if you are going between centers you will need a bar close to the length of your final setup. if you can use a chuck its easier. i mount the test bar to the dividing head and the tailstock which is aligned by eye. install a 1/2 inch edge finder in the quill and useing your dials or preferably your dro check the test bar at both ends and move the tail stock into alignment to the x axis. you can then use an indicator on top of the bar to test for vertical alignment. you may need to go back and forth a couple of times to get it right. if you are useing a chuck you can mount the test bar in the chuck indicate it as above but moving the dividing to get it into alignment and then you can move your tail stock up to the test bar and adjust the tailstock to meet the test bar. i usually put a little magnetic digital level on my tailstock to keep it level as i raise it up or down.once you have your tailstock set on vertical center you should only have to check for parallel alignment in the future unless you need to set up for angle. be smart and make a height gage once you get your vertical center.