Is There An Easier Way For Initial Set-up of 4 Jaw Chuck?

I have a group of different diameter jobs which keep coming up repeatedly. Lightly center punch the face of the chuck at each jaw where there is a sharp edge (on the side easily viewed while adjusting) after the job is accurately indicated, and in the future you can be very close right off the bat.
 
nice! I'll make one! And, that will get me using the 4-jaw one of these days.
Tim
 
Not adding anything, but doing it over and over definitely speeds things up. The two chuck key method is a big help. I primarily use a 3-jaw set-tru chuck and have two hex keys on opposite sides when truing up the work.

I'd recommend numbering your jaws 1, 2, 3, 4 if they're not already numbered. Lightly hold the work and do jaws 1 and 3. Zero the indicator on jaw 1, then rotate to jaw 3. Adjust the jaws until the number is half-way between the initial reading and zero. Reset zero on jaw 3, swing back to jaw 1 and repeat. Then repeat the process on jaws 2 and 4. Two keys work great for this exercise as you can put a little pressure on the jaw that's being tightened and very slowly loosen the opposite jaw for good control. When you get within 0.001", don't loosen a jaw, only tighten the appropriate jaw.

Bruce
 
For me it was about practice. When I first tried it took ages. Now I can get to a thou in under 2 minutes.
What I had to learn (and I’m embarrassed to say this) was how to read the indicator and what direction to move the work


Sent from my iPhone using Tapatalk
 
All very good advice.

As most have said, when I first started messing with the 4 jaw, it took FOREVER to get close.
After I admitted to myself that I had to get it figured, I left the 4 jaw mounted and used it whether I needed it or not. The 3 jaw stayed on the bench for over a year.

I no longer worry about it. If I need the 4 jaw, I hang it and run it, and it is no big deal. I simply needed to gather the patience to learn how to use it.
To be honest, it may go back on, just cuz the Chinese POS 3 jaw I have is NOT as accurate as I am on a 4 jaw:big grin:
 
It is hard to convince someone to use a 4 jaw over a 3 jaw scroll chuck that has fought one. But the best advice I and others here have given is to bite the bullet and just use it. Before long you will come to appreciate it and how accurate your work will become as a result of it. Plus, when you really need to use it, especially for those odd shaped parts, you will be way ahead of the curve and appreciate your efforts.
I haven't used a 3 jaw scroll chuck in years, there isn't a 3 jaw scroll chuck out there that can match the accuracy of a 4 jaw used properly. I haven't used the lathe I have in storage yet, but plan to remove the 3 jaw for the 4 jaw before I put it into service. The 3 jaw will no doubt become one of those artifacts that sits there on the bench, that I just don't get rid of because.
 
Yep! Using a 4 jaw comes down to practice. The 1/3 then 2/4 method WORKS, but you get better results if you choose the pair that is furthest out.

My process is getting close with the rings on the chuck. THEN I put a tool in the tool holder and get it close by eye there. By then I'm within the ~50/100 thou that makes the dial indicator method easy. I spin it until I find the 'high' spot, then rotate the chuck 180 degrees. I split then difference, so I get it 1/2 way between both measurements. Then, I do the same on the other 2 jaws.

THEN, repeat the process (find the high pair fix that, then fix the other). I've never had it take more than ~4 cycles of that.

That said, when it comes to indicating in square things in the 4 jaw, I am awful! I always forget to pull the plunger back on 1 and screw up my setup.
 
You must log in or register to reply here.
Back
Top