Learning to dial in a 4-jaw

DavidR8

DavidR8

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I got the 4-jaw mounted up on the new backplate today and so tried my hand at chucking up some round stock.

It was a bit frustrating as I struggled to start from a place where the shock was even reasonably centered so my indicator was spinning round like a top.

I was using the rings scribed on the face of the chuck and eventually got it dialed in to about thou of runout but it took me probably 10 minutes of fussing.

Part of the problem is the my mag stand is a piece of rubbish so I was struggling to get the thing to stay put.

Any tips on the dialing in part?


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If the part is not perfectly concentric or has surface finish issues, 4 point it. Meaning instead of chasing the max highs & min lows on the indicator which could be false, adjust at each jaw comparing to the opposing jaw. Set zero on the indicator, whatever the difference is from the opposing jaw, adjust half the difference.

Also, when dialing in the OD, remember "tighten the highs, loosen the lows" (pinion). Vice versa for ID.
 
Watch Abom & Tom Lipton's videos.
Adam is a master at it.
I think that there is one video of a bar Z - where they had a contest to see who was quickest and they had a gag wrench for Adam to use.
Proper equipment is a requirement.
 
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I have a few.
  • Make a mount for your DI that fits on your QCTP. You can make something that fits into a standard tool holder so you can adjust the height to get the tip of the DI on center. This is really important.
  • Use two wrenches to adjust two opposing jaws at the same time; much faster and easier to work like this.
  • Look at centering as working with two pairs of jaws. Turn the chuck and look for the pair closest to the max deviation and adjust those first. Once you get that pair close to center, the other two will be easy to do.
  • Once you're as dead on as you want, go around and make sure each screw has about the same amount of torque on it. Believe it or not, if one is loose that part can move.
  • Be patient. Centering a part accurately takes skill, and skills take time to build. The more you do it, the faster you get.
When I was a baby hobby guy, I remember spending weeks learning to dial a part in. Now I can dial in a part to zero, and I mean zero, in less than half the time it took me way back then. Hang in there.
 
I'm thinking practice makes perfect. You will get faster/ better with practice. On my 3in1 machine chuck changes are a pain so I put the four jaw on and forced myself to use it for all work for awhile. Now when I put the four jaw on it doesnt seem so time consuming but still takes a bit to have it feel like I'm quick at it again, but at least I don't feel like I'm chasing my tail like the first time.
 
darkzero said:
If the part is not perfectly concentric or has surface finish issues, 4 point it. Meaning instead of chasing the max highs & min lows on the indicator which could be false, adjust at each jaw comparing to the opposing jaw. Set zero on the indicator, whatever the difference is from the opposing jaw, adjust half the difference.

Also, when dialing in the OD, remember "tighten the highs, loosen the lows" (pinion). Vice versa for ID.
Click to expand...
40 years mucking around with this stuff and I don't think I've ever heard that phrase.
 
The quick and dirty method is to align it by eye to start, then rotate the chuck by hand, then use a piece of chalk held against something solid. Once the chalk shows it centered, then use the dial indivator. I learned on a 4 jaw, it was slow going at first. Speed comes with time and experience. There is no easy way that I know of, you just have to keep doing it.
Some people use two chuck wrenches, on opposing jaws. I think they are pros that do it on a regular basis. For the occasional user, it takes me longer to set up that way. I stick to what I learned way, way back.
For roughing and most general work, I use a 3 jaw.(now) But for something that needs dead center and must start dead center, the 4 jaw is my fall back.
Sorry I can't be more specific, time and experience I cannot pass on through text.

.
 
WOW!
That help came quicker than calling an ambulance, you all are awesome!

Ok... 4-point it. That makes sense to me.
@mikey thank you for "look for the pair closest to the maximum deviation" This is super helpful as somehow I was expecting the runout to be conveniently located at a jaw, not in between :oops:
I'm going to figure out how to make a tool holder for my indicator. Without a mill Hmmm.
 
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