Quick/Easy Way to Center Rotary Table?

[Tim#1]

Hi,

I bought a Grizzly G1005 mill/drill a couple years back, along with a rotary table. I haven't used the table much, but it's handy to have. I'm looking for a quick and easy way to center the table under the milling head. At one point, I used an R-8 with #2 MT, lowered the quill and engaged the tables' center hole. This seemed to work, but only for small jobs since I don't want to raise the milling head and lose the alignment. Any advice on the subject is very much appreciated. Thanks!

TIM

[Ron LaDow]

Tim,
I made two pretty accurate 60* centers, one goes in the drill chuck in the mill and the other in the center hole of the table. 'Twixt those and a hand lens, I can get +/-.002"
If it has to be closer, I stick an indicator in the chuck and indicate the center hole.

[Ben Shank]

I turned a piece of round stock that fit the hole, in this case your rotary table, and then turned the other end to fit my largest collet of my mill. Then mount my piece in the collet, put the table under the quill and move up and down until it slides in the hole easily, then bolt the r-table down, check it again, if it still slide in the hole easily you are centered. This will work for work that doesn't require high precision, other wise you will need to indicate it in..

[charlie coghill]

Hi Tim.

A way that you can find the cent of the RT,is use a edge finder in the spindle.

Go the left hand edge of table on the X axes and find the edge and move right the radis of the table minus the dia of the edge finder. Then on the Y axes move the table towards you and pick up the edge of the table and move the radis minus the dia of the edge finder. Repeat step one and then repeat step two. Repeat the steps a couple of times each. You will be surprised at how close to cent. you will be. Don't forget to subtract the dia of the edge finder or you will never get to cent. Been there and done that.

Hope this helps. By the way this is not orginal with me.

Charlie.
P.S sure wish this form had a spell check.

[halfnut]

Use an indicator, sweep in hole or plug for fixturing. Hold the indicator with an Indicol or equivelent, I've made a couple, never had a real Indicol myself.

No digital, remember to take out backlash watching indicator.

DRO on my favorite mill at work has a burnt up power supply, parts are on order. Working without DRO, like learning over again, almost, derned things will spoil you.

[Tim#1]

Hi All,

Thanks very much for your timely replies. You've given me enough info to try the suggested methods. I guess I wasn't too far off base. I like the idea of the adapter and then using a dial indicator for greater accuracy; using a little math to determine when the rotary table is centered is also appeals to me. Thanks to you all again very much!

TIM

[toff]

Hi,
Agree with the above! When needing a real accurate final result:
1 center as above
2 super glue a piece of 1/2" or thicker plastic over the hole in the rotary.
3 machine a round stud from the plastic by using the rotary motion of the table.
4 use a good indicator on a bent angle of rod ( or indicol) in the collet to center the spindle above the stud.
5 remove slack in the feed wheels and you are there.
Have fun
toff

[BrianH]

I use the indicator/indicol method, but if you want to get it a little closer still, do this;

-sweep the center
-put your indicator in a mag base, mag it on the rotary table, and locate the tip on the ID of the quill
-rotate the table, so the table is sweeping the quill

I've never done this on a small machine, just a Bridgeport-size. I don't know if you would have enough room......

[Tim#1]

Hi toff & BrianH,

Thanks for the additional methods. I'll give these methods a try too. I believe there's enough room for the placing the magnetic base on the rotary table. I also like the idea of using a plastic plug in the rotary table's center hole and indicated off that, once it's machined as you (toff)mentioned. Thanks again!

TIM

[timmer]

Tim I've used Ben's idea for many many years
and have found it works really well. This is a real quick and easy solution to finding the centre of the rotary table and the spindle.

timmer