# Advantage of collets?



## 2manyhobbies (May 25, 2013)

Hi,

  Just wondering what specific purpose collets are used for on a lathe as opposed to a chuck.
I can see why one would choose to use a 3 jaw vs 4 jaw for different situations but what situation would make you choose collet?

-Steve


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## kd4gij (May 25, 2013)

collets are used for accuracy and repeatability of small parts. in a lathe.


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## DMS (May 25, 2013)

To add on to what kd4 said, collets are also less likely to mare a part because they provide even pressure. They are a more expensive option, and you need lots of them to cover the full range. They also won't hold oddly shaped parts, round, square, and hex are the only ones I have seen. They are usually used in industry as part of a system with a bar feeder and a mechanical collet closer. The collet closer can be opened quickly, the bar fed in, and the collet closer re-tightened between each part.

In general, you don't _need_ collets. If you are only making a few parts, or you want the highest accuracy possible, use a 3 jaw or a 4 jaw. 3 Jaws are usually faster, but less accurate; 4 jaws are slower, but as accurate as your method of centering.


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## Codered741 (May 25, 2013)

Collets also don't take up as much room as the chucks do, and can allow you to use the Entire bed of the lathe, without the hassle of centers, faceplate, lathe dogs, etc. 

Collets are generally more repeatable, which is important when making multiples of the same part. 

Don't forget that the right set of collets can make lots of machining tasks easier.  A good 5C collet set, with some fixturing jigs, Can make transferring a part from mill to lathe, or vice versa, a dream. REALLY handy for small parts with multiple operations being done. 

-Cody


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## Jimsehr (May 25, 2013)

Lot of time collets repeat better and faster then chucks. See thread about a week ago called Advantages of collet chucks over regular chucks. Pic shows a rod end that was bore was machined in a soft collet. I ran thousands of them that way.
jimsehr


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## tigtorch (May 25, 2013)

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.


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## mrbreezeet1 (May 25, 2013)

tigtorch said:


> I
> 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.



So it don't matter, you can use them for standard and metric?
ls that better than getting the standard size set?
Where did you get them?
Does he have standard too?


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## itsme_Bernie (May 25, 2013)

Hey Steve

Each collet has enough range that the set covers every size.

What machine are you running?  Can you run collets directly in your spindle?  


Bernie


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## British Steel (May 26, 2013)

My lathe came with a full collet set, 1/16" steps from 1/16 - 3/4" with drawtube (so work can pass through the spindle), spindle taper bushing etc, they're much quicker than dialling in a 4-jaw and much more accurate than a 3-jaw, plus since hotrodding to get 2500 rpm (using the VFD at 80-some Hz) I really don't like the idea of a big 4-jaw spinning that fast! Disadvantage is that they only hold round workpieces close to nominal sizes, so I've added an ER collet Chuck on a backplate for intermediate sizes and a 5C chuck for square / hex - slowly building a stock of 5C collets as I need 'em! 
For small work / high speeds, there's no substitute, particularly if you can fit a length stop either in the drawtube or the spindle - setting up repeat parts can be done in seconds, not minutes!

EDIT - forgot to mention, they hold milling cutters properly, so with a vertical slide-equivalent I can do some light milling in the lathe, handy as I don't have a mill...


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## mrbreezeet1 (May 26, 2013)

I got the ER 40 chuck and a back plate from tools 4 cheap. 
What is the best way to fit a chuck to a backplate. 
Is there a best write up on the subject. I have never done one. 
I have heard of making a shoulder oversize and freezing .
Making a shoulder undersize and bolt holes oversize and tapping into true.


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## SE18 (May 28, 2013)

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


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## Codered741 (May 28, 2013)

SE18 said:


> 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


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## Ray C (May 28, 2013)

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





tigtorch said:


> 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.


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## fastback (May 28, 2013)

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.


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## itsme_Bernie (May 28, 2013)

Ray C said:


> 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


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## SE18 (May 29, 2013)

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


FOUND


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## SE18 (May 29, 2013)

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


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## Ray C (May 29, 2013)

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




itsme_Bernie said:


> 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.
> 
> ...


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