Seeking 4 jaw advice

[pontiac428]

As much as I'd love to tell you all about my method for dialing zeros in two minutes flat, I'll spare you the wall of text because it's not a Rubik's cube. It's not even as complicated as untangling and extension cord. All you need is some practice, and you'll have it mastered in no time.

 

[ltlvt]

Terry,

When you get close to true, lets say .005 or so, snug up all four jaws the same amount to medium tightness, then rotate
the chuck to the low jaw. Then rotate the chuck 180 degrees and tighten the opposite the low jaw one half of the deviation
as observed on the indicator. Any indicator will do and a .001 is just fine. Hopefully my explanation is good enough to
be of some value to you.

Burt

Thanks Burt. I realized today that as the stock was bring rotated it was wiping against the indicator spindle therefore knocking the indicator off its origional position. I was using a button on the end of the stem so I changed to a smaller one. here is apicture of where I left it when I came in tonight. The thought struck me that when I first started using a dial indicator in 1974 as a Millwright doing coupling alignment we would draw a circle and write down the numbers. So 51 years later I decided it might be a good idea to write the numbers down. The bottom right of the picture is where I stopped. Jaw #1 at 0 Jaw #4 at -3 Jaw #2 at -45 and Jaw 3 at +43, So helop me interpret what I am seeing. Tell me if I am wrong Jaw #4 needs to move +.0015 making 1 and 4 both 0 Jaw # 2 and #3 are what is confusing me. does the -45 and +43 cancel each other out and I am actually out by .002 and need to move Jaw #2 +.001 making them both in theory 0 ? this is where I am getting confused.

 

[ltlvt]

As much as I'd love to tell you all about my method for dialing zeros in two minutes flat, I'll spare you the wall of text because it's not a Rubik's cube. It's not even as complicated as untangling and extension cord. All you need is some practice, and you'll have it mastered in no time.

thanks John. I did do some praticing today and also practiced my confusion. LOL

 

[Larry$]

I'm a member of the two key method. Reasonably fast and when I'm pretty close, final tightening while checking.

 

[mickri]

I read through all of the posts and noted that you are making two spindles. Do you have to remove each spindle from the lathe to do something and then get it back to concentricity to finish each spindle? I ask this because if you do not have to remove the spindle from the lathe, it doesn't matter if the work is dialed in when you start. No mater how far out it is when you start it will be absolutely concentric when you are finish turning the spindle. Am I missing something?

 

[ltlvt]

I read through all of the posts and noted that you are making two spindles. Do you have to remove each spindle from the lathe to do something and then get it back to concentricity to finish each spindle? I ask this because if you do not have to remove the spindle from the lathe, it doesn't matter if the work is dialed in when you start. No mater how far out it is when you start it will be absolutely concentric when you are finish turning the spindle. Am I missing something?

I do understand that if I am using a 3 jaw and not removing it from the chuck each end will be concentric how ever my 3 jaw is bellmouthed and I will be making the tool post grinder to correct this problem. My vision is to make the spindle in 3 peices. 2 bearing caps attached to the center with bolts similar to the end bells of an electric motor.

 

[snoopdog]

I'm in the practice, practice, practice camp, and jaws only snug until you get to the destination. Not much help , I know. And , everyone has a day where they chase their tail, just walk away for a bit.

 

[cathead]

Thanks Burt. I realized today that as the stock was bring rotated it was wiping against the indicator spindle therefore knocking the indicator off its origional position. I was using a button on the end of the stem so I changed to a smaller one. here is apicture of where I left it when I came in tonight. The thought struck me that when I first started using a dial indicator in 1974 as a Millwright doing coupling alignView attachment 527358ment we would draw a circle and write down the numbers. So 51 years later I decided it might be a good idea to write the numbers down. The bottom right of the picture is where I stopped. Jaw #1 at 0 Jaw #4 at -3 Jaw #2 at -45 and Jaw 3 at +43, So helop me interpret what I am seeing. Tell me if I am wrong Jaw #4 needs to move +.0015 making 1 and 4 both 0 Jaw # 2 and #3 are what is confusing me. does the -45 and +43 cancel each other out and I am actually out by .002 and need to move Jaw #2 +.001 making them both in theory 0 ? this is where I am getting confused.

Terry,

The tip on the indicator isn't extremely important so just something simple and standard will work fine. One and four
are pretty close for the moment so I would leave them alone for the moment and work on 2&3. You don't need to use any math to
center the part, one just needs to look at hi or lo and how much. Just locate the low (2) and rotate to the hi (3). Move
the hi down 1/2 of the total distance of the dial movement. You would be pretty close now. At that point I would change
my strategy and go to the high jaw and give it a push. Then rotate the chuck and find the hi and tighten again. You can
actually move the part around several thou (to a point) just by using the key. If it won't move enough, just loosen the opposing chuck a hair and go back to the hi jaw. Have you ever tried centering a part without using an indicator? You can get pretty close just using anything in close proximity to the part, maybe a cutting tool or a stiff wire like one sees on those you tube videos from India. Of course an indicator is better but a little experimentation sometimes helps one grasp the concept. Just keep practicing and you will improve your skills like
Pontiac John & (snoopdog too) said likely is the best advise out there.

 

[WobblyHand]

Not much to add, but sometimes I like to use a bearing attached to a metal shank in a tool holder, to get the initial alignment. It works as @cathead described in his post. You can tell that you are close when the bearing rolls smoothly as you rotate the chuck. Then I use an indicator for final dial in. I made the roller out of a cheap bearing and screwed it to a piece of key stock. Button head screws for less stick out.

 

[ltlvt]

I followed up with Wobbly's roller advice. Mine works great on a QCTP but without the adjust ment on center height I need to go back to the drawing board and make one for the Turret Style tool post. Making a 2 step shank so the roller will be on center without a lot of hassle. I've included pictures of the one I made form bearings out of an old hard drive i scrapped. Also a picture of the final results. Ant the final result is a combination of many of the suggestions including Practice . Now all I need to do is Rinse and Repeat many more times. Thanks a million for all the suggestions. I know 4 Jaw is not Rocket Science but when one hits the limit on Frustration it's time to settle back and ask for advice. Thanks a lot guys for being so kind and helpful. BTW it is amazing what one can "discover when practicing". One of the things I did was change chuck keys. The shorter one was part of my frustration causing me to bump the indicator. So I put the short Chuck key away and used the long one and eliminated the problem.