Need Help!- Best way to center rotary table

[Micro Milling]

I need an easy way to precision center my rotary table? I've tried to search on the topic but not sure what method to use.

I have a 6" vertex rotary table. I was wondering what I need to buy in order to center it. Do I need a xoaxial centering indiacotor? Is there some kind of device to put into my end mill holder that will fit into that round hole in the middle of the rotary table?

What are my options and what do I need to make this an easy task to get me centered exactly?

[M250cnc]

Micromilling

I take it you are working manually

You need a DTI "Dial Test Indicator", some fit on attachments which you can make IE "L shaped bar" 1/4" dia

Either that or it goes straight in the collet or chuck and you rotate the spindle by hand to centre on the hole.

Searching for these terms will give lots of answers

Phil

[Geof]

All three methods to center it have been covered so far.

Using a mandrel in the spindle is the least accurate but the easiest. You simply lower the mandrel down into the hole in the center of the rotary table with the clamping bolts loose and then tighten them; now it is centered to an accuracy determined by the fit and accuracy of the mandrel. If the mandrel is not perfectly on center in the spindle the table will be off a bit but plus or minus 0.002" is possible this way.

The Co-axial indicator in the machine spindle with the probe in the hole in the rotary table is the next best. Using a Co-ax you bolt the rotary table down first and then adjust the X and Y position of the machine table to get the smallest needle deflection. Plus or Minus 0.0005" is possible with a Co-ax indicator, maybe better.

The most precise is the DTI held in the machine spindle and rotated around the hole in the rotary table. You can get to within plus or minus 0.0002" by this method which is probably better than the accuracy of your machine.

[Fegenbush]

My solution is much more low tech. Maybe not as accurate, but it doesn't involve a dial indicator at all.

Wiggler / Edge Finder

1. Place Wiggler / Edge Finder in tool holder
2. Position tool in center hole of chuck
3. Start spindle at ~1000 RPM
4. Go to left side of hole (it doesn't matter if it's the extreme left of the hole or not) until you find the edge.
5. Set this point as X=0 on your DRO or Dials (be sure to account for backlash if using dials)
6. Go to the right side of the hole without touching the Y screw at all.
7. Find right edge of hole.
8. Take the distance travelled, divide by 2, and go left that amount, you are at X=0
9. Repeat steps 4-8 for the Y axis.

Example calculation, hole diameter is 1.25", using 0.25" diameter wiggler tool. Left side is equal to zero, right side is equal to 1, go back 0.5", you're at zero.

[Iron-Man]

Watch this video:

YouTube- Tramming a mill with a coaxial indicator

YouTube- Tramming a mill with a coaxial indicator

http://compare.ebay.com/like/3303537...PriceItemTypes


Hope this helps.

Iron-Man

[Micro Milling]

Thanks for the comments, I have on order a dial test indicator, but I will use some of the methods here until I get that.

What I did that seemed to work OK was like the mandrel method someone explained. I put in my drill chuck and made the jaws come all the way out. This acted like a cone that I assumed would be close to center and I lowered those jaws into the center of the rotary table. It wroked out because the jaws closed were wider than the hole so it helped center the table.

It seemed pretty close to center.

I will have to try the other methods listed here.

[kvnlrndt]

Originally Posted by Micro Milling Thanks for the comments, I have on order a dial test indicator, but I will use some of the methods here until I get that. What I did that seemed to work OK was like the mandrel method someone explained. I put in my drill chuck and made the jaws come all the way out. This acted like a cone that I assumed would be close to center and I lowered those jaws into the center of the rotary table. It wroked out because the jaws closed were wider than the hole so it helped center the table. It seemed pretty close to center. I will have to try the other methods listed here.

i just eyeball the chuck in the hole
to get within .01 then tram it
kinda easy