Can a lathe chuck be too big?

[genec]

That is big, I'd guess you can always raise the head stock. :nuts:

 

[Pacer]

A 5" reversible 3 jaw chuck would just about be perfect for the 9" lathes. I got one from Shars and was pleasantly surprised at the fit/finish/accuracy on it - will give consistent .0015 to .002 read out and with a couple bumps will often come dead on.

 

[strantor]

Thus is invented the big bang theory of lathe destruction!! Yes,that heavy chuck is hard on the lathe's bearings,too.

HOW MUCH runout does that chuck have? Chuck up something accurately ground,like the shank of an end mill,and check the portion sticking out with a dial indicator. These China chucks are usually rated for .003" run out. If it's better,I might buy it. I gave away the original chuck on my 16" Grizzly lathe,and if I sell it,I don't want my 8" bison going with it. They now cost 2X as before. You can take off the back plate and keep it. Mine is a D-6 spindle. Wonder if shipping would kill the deal?

Remember,Enco is always giving free shipping nearly every month. That's when I buy heavy stuff from them,like bars of 1" brass.

I'll check the runout after I finish the backplate. All I have left is to do is locate and drill the mounting holes, after I make locator screws.

 

[Metalmann]

So Bigger isn't always better? Strantor be careful opening it up to big, might make a BIG Bang when you turn on the spindle. I was also thinking of those "poor spindle bearings" I know where you can sell or donate the chuck on the board (wink, wink).
Seriously, be careful opening the jaws to wide. Rich

Back in the day, we were taught to ALWAYS rotate a workpiece/chuck by hand...before turning on the spindle.

Especially, after mounting an expensive part; or an offset workpiece.

 

[AR1911]

I recently bought a 6" chuck for my 9" South Bend. Now that it's mounted, I wish I had bought a 5" instead. I may relegate this to rotab use and order a 5" BTW, the best i can get out of my Shars 6" is .008" runout.

 

[Ray C]

Make sure spindle bearings are tight ect. Power off the lathe.

Mount a straight, clean shaft in the jaws (about 1" diameter, at least 5-6" length) and have about 1.5" protrude from the jaws. Loosen the blackplate bolts to just a snug level. Put a dial indicator on the shaft about 1" from the jaws. Spin by hand and use a wood block and hammer to shift the position of the chuck on the backplate. Tighten bolts when it reads clean. If it won't read clean at all, the jaws need to be aligned first.

Assuming the above worked, mount the rod further out of the jaws only so that the piece is grabbed by the full face of the jaws. Take indicator readings down the length of the shaft. If it's way off, your lathe might need to be aligned or the jaws need alignment.

Ray

I recently bought a 6" chuck for my 9" South Bend. Now that it's mounted, I wish I had bought a 5" instead. I may relegate this to rotab use and order a 5" BTW, the best i can get out of my Shars 6" is .008" runout.