4-jaw chuck dilema

W

Wino1442

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Hi all..... I will be making a backplate for a 4" chuck which will be used on a rotary table. I am having a little trouble deciding which way to hold the stock in the 4 jaw chuck. If I hold the workpiece with the jaws in the "normal" position the jaws stick out quite a bit. If I reverse the jaws the jaws do not stick out BUT because of how deep the workpiece sits into the jaws I am unable to put a dial indicator on it to center it.
So....I was wondering if I could get your opinions as to which way might be the best. I have attached photos to help show what I am talking about. Thanks for your help.tempImagerRtFcv.jpgtempImagerRtFcv.jpgtempImagegWIyJF.jpgtempImagegWIyJF.jpg
 
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Can you put a dimple in the centre of the front face and indicate that in?
 
Thanks for the responses....I put a couple of parallels behind the workpiece, which was pretty simple really. That pushed it enough to allow me to use a dial indicator. JW...I did try a DTI, but thought there must be a better way....
Thanks again.
 
I prefer a 1" travel dial indicator when centering work in a 4 jaw. If I can't use the dial I am stuck with the DTI. It is necessary to get the work centered within about .015" before using the DTI otherwise the range of the DTI is exceeded.

I was taught to read the dial at two opposite jaws (like 1&3 or 2&4). Note the readings at each jaw. Adjust the chuck to a reading half way between the high and low. Repeat on the second pair of jaws. That gets you very close to center. Repeat the operation one or more times to refine the centering.
 
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Yes, it will work quite well. I used to use one before I bought my first DTI. It will give a greater range of travel than available on most DTIs.
 
I like a part like that backed up, so with the jaws sticking up is my preference. What about using a DI on the carriage, move the carriage back to index the chuck?
 
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