Advantage of collets?

[SE18]

I've got a 9A South Bend and always wanted collets but the cost has kept me at bay. It's like $140 for just the closer for 3C set. And, some folks are saying the 3C isn't even the best for the 9A lathe as it only goes to like half an inch but the spindle bore is 3/4 and there are other collets that have greater size range.

Ideally, I'd like to make my own collet closer and then purchase the collets but unsure what size collets are best for the 9A lathe and also unsure exactly how to make the closers. I've seen that some have made them but I never really saw good detailed plans for beginner types like myself. I believe all the closer parts can themselves be made on a lathe.

Dave

 

[Codered741]

I've got a 9A South Bend and always wanted collets but the cost has kept me at bay. It's like $140 for just the closer for 3C set. And, some folks are saying the 3C isn't even the best for the 9A lathe as it only goes to like half an inch but the spindle bore is 3/4 and there are other collets that have greater size range.

Ideally, I'd like to make my own collet closer and then purchase the collets but unsure what size collets are best for the 9A lathe and also unsure exactly how to make the closers. I've seen that some have made them but I never really saw good detailed plans for beginner types like myself. I believe all the closer parts can themselves be made on a lathe.

Dave

Funny you say that about building a collet closer, I was just looking at closer and chucks myself, and was thinking that I could build one as well. I have a Heavy 10, which I'm in the middle of rebuilding so it might take a while, but if/when I get some designs roughed out, I will be sure to share. Obviously the design would have to be tweaked to work with your 9A, but it should be a good start.

-Cody

 

[Ray C]

In addition to the safety issue, there's never a balance problem with collets. Most chucks are not perfectly balanced (unless you're working with very expensive chucks or high speed CNC equipment) and the vibration can (and does) show-up in the work piece in many situations.

Ray

If you need to turn something of smallish diameter that requires a high speed, it is much more pleasant to be cheek to cheek with a simple collet chuck spinning at 1500 rpm instead of the lethal jaws of a big 3 or 4 jaw chuck flying by every revolution...

I recently finished an ER40 spindle mounted chuck for my Rockwell 10 and I really like it a lot. I found a deal ($139) on a precision (runout at or under 0.0002) set of 24 metric ER40 collets which span the entire clamping range so the fact that they are metric instead of inch based is meaningless. I use them for the lathe and also got an R8 chuck for my mill, fits drill bits under 1" and all of my endmills.

 

[fastback]

FYI, you can get 3C collets up to 5/8 of an inch. The problem with the 9 inch lathe it may have a 3/4 inch spindle hole but the draw bar has an inside diameter of around 5/8 of an inch. I made my own draw bar on my 9B its a 26 pitch. I got the closer with my lathe. Collets are definitely nice to have and use. I have 3C set for my 9B and a 5C set for my Heavy Ten. I also have a set of Van Norman, just can't remember the size of hand. Oh, almost forgot, I have a set of 3 AT's I'm not using them at the present.

I also use collets in the mill. I have a collet holder for hex and one for square. In addition I have a collet indexer for use on the mill.

 

[itsme_Bernie]

In addition to the safety issue, there's never a balance problem with collets. Most chucks are not perfectly balanced (unless you're working with very expensive chucks or high speed CNC equipment) and the vibration can (and does) show-up in the work piece in many situations.

Ray

Hey Ray-

So I guess I should balance my chucks? I have seen chucks with holes drills for balance, but have never done my own hah.

But I rarely spin mine very quickly.

Bernie

 

[SE18]

View attachment 3C_collet_adapter.pdfView attachment 3C_collet_tube.pdfView attachment 3C_collet_tube_sleeve.pdf

FOUND

 

[SE18]

I've never uploaded a pdf, hopefull you can see the 3 I put up

btw, i don't know why the 3c never took advantage of the full 3/4" bore of the 9A spindle. add that to my list of mysteries

 

[Ray C]

Well, maybe... If you're happy the way things are, leave well enough alone (and I'm not saying that in a sarcastic way; I really mean it).

I go by feel of the machine. If I can feel 1/2 ton of metal vibrating with notable difference from one speed to the next or, if one chuck behaves significantly different than another, then I fix it. -Or at least try to anyhow. After a good bit of fine-tuning the bench and chucks, all my chucks are doing fairly well. The 6" has a very slight vibration in the 800 RPM range but, it goes away at speeds slower or faster. That's due to a dynamic balance issue and I can live with it or chase it away with the VFD.


Here are a couple threads that discuss chuck balancing. Please pay attention to the safety concerns which are: Don't forget to tighten chuck bolts, don't leave jaws wide open, work speeds up from slow to fast and be prepared to hit the panic putton if the lathe starts dancing on the floor.

On thing I forgot to mention, is baseline your machine by running it at all speeds without a chuck installed. If you have serious problems there, don't bother working on your chucks yet. To test a chuck, I first run the machine w/o one installed then, install the chuck and make a call if you're happy or not. None of mine are perfect but but they're good enough -and I know from experience how much vibration shows-up in cuts and I can adjust my DoC accordingly. When things start shaking, a heavier DoC is often the cure.

http://www.hobby-machinist.com/showthread.php/13332-Fitting-new-chuck-to-backplate-for-beginners?highlight=balance+chuck<O></O>
http://www.hobby-machinist.com/showthread.php/10651-D1-4-Spindle-amp-Chuck-Measurement-and-Setup?highlight=balance+chuck<O></O>


PS/EDIT: Good balance is important. As long as the machine does not scare you when it's running and the cuts are clean... life is good. Don't go overboard... A perfectly balanced empty chuck runs crappy about 80% of the time you put a piece over 2" diameter. The stock you're working on is likely far from balanced -that's a sure bet. Sometimes, if I get a noisy piece, I just rotate it in jaws to see if it will quiet down. Most of the time, it helps a little.


Ray

Hey Ray-

So I guess I should balance my chucks? I have seen chucks with holes drills for balance, but have never done my own hah.

But I rarely spin mine very quickly.

Bernie