School me on 5C vs. ER series, please...

[daved20319]

And while you're at it, I could use some schooling on ER collets in general :-). Why all the different ER numbers? Does it relate just to size range, and are they otherwise interchangeable?

To get back to my subject line, what are the pros and cons of the different collets? I seem to recall reading somewhere that the 5C tops out larger than the ER, but I'm not even sure of that. Some clarification here would be much appreciated. Later.

Dave

[Mcgyver]

they all have slight differences created advantages/disadvantages.

5C (or similar, ie 2J) are better because of ease of use (collet closer/chuck) vs those frustrating little end caps, come in square/hex etc, have things like emergency collets, pot collets, and are fine for hold very short parts . ER otoh gives the complete range of sizes (without having to buy 64 collets).

I've both my lathes set up with rubber flex (for range) and 5C or 2J for the above reasons....you truly need one of everything

in short, imo ER would work fine in a lathe as a lower cost solution but would be a bit of compromise insofar as ease of use and types of collets available.

[TGTool]

The number of the collet is the size in millimeters right at the mouth of the collet holder. Maximum OD is somewhat larger. I don't have all the numbers right to hand, but the ER-32 takes a maximum of about 3/4", ER-25 up to 5/8" and ER-20 up to 1/2". You can figure up and down from that.

[DICKEYBIRD]

Not long ago I bought a replacement 3/4" ER32 collet from Maritool and noticed they also had a 20mm and a 7/8" collet in ER32. I bought 1 of each and darned if I didn't need a 7/8" collet the next week after receiving it! Saved me the hassle of removing the collet chuck from the lathe and sticking on a 3 or 4 jaw to do the job.

[Forestgnome]

Typically 5C collets are used for workholding, ER collets are used for tool holding. Lathe vs. mill. Although there are some large ER collets in use on lathes.

[Black_Moons]

ER32 are double angle, Meaning they compress along the entire collet and will NOT hold short parts without something in the rear of the collet.

5C on the other hand only compress on the front, and won't hold items of the 'wrong size' very well, and only have 3 slits. I know very well first hand you can't put a 1/4" threaded rod into a 5C collet and expect it to hold worth a damn without tightening it up to the point where your threads are ruined.

I suspect an ER32 would hold it with only minor damage to the threads, since it would grip the entire length with multiple contact points due to all the slits.

ER32 more or less has to be closed by a nut on the front. 5C has to be closed by a nut (or draw tube) on the back.

5C has a nice internal thread to the collet that you can put a locking depth stop in.

[dian]

the depth stop in the 5c collets is great, will set you back 10 bucks.

what about precision? regular er32 collets are specified with a max. 0.015 mm runout, ultraprecision have 0.005 mm. (the average collet being much less than that.)

[justanengineer]

I know very well first hand you can't put a 1/4" threaded rod into a 5C collet and expect it to hold worth a damn without tightening it up to the point where your threads are ruined.

Not to nitpick, but that is an example of when you need a threaded collet, not a plain collet, which is the reason many love 5C collets. Theyre cheap, plentiful, and as someone else already mentioned, they come in every possible shape internally. Ive even got a few arbors with a 5C taper.

[Black_Moons]

Not to nitpick, but that is an example of when you need a threaded collet, not a plain collet, which is the reason many love 5C collets. Theyre cheap, plentiful, and as someone else already mentioned, they come in every possible shape internally. Ive even got a few arbors with a 5C taper.

Ok very good point, Did'nt know they made threaded collets. I juts end up making my own threaded collet by drilling and taping a small bar or square stock, and using a jam nut, or sliting the bar and compressing it in my 4 jaw

[Jim Caudill]

As was already pointed out, 5C collets have a very narrow clamping range and can be "sprung" and damaged by trying to close them down more than a few thousandths.

ER collets (I believe) stand for "Extended Range" and can clamp way below their designated size, due to their design with many slots. You can cover a greater range of size requirements with fewer collets.

[metalmagpie]

Ok very good point, Did'nt know they made threaded collets. I juts end up making my own threaded collet by drilling and taping a small bar or square stock, and using a jam nut, or sliting the bar and compressing it in my 4 jaw

Whenever I needed to turn threaded parts and hold them by the threads, I used to just sacrifice a nut and slit it, then thread it onto the part and grab it in the 3-jaw chuck, bandsaw vise, etc. Not high precision but then what about allthread or hardware store bolts is?

MM

[DR]

In very general terms.......

5C collets are work holding collets.

ER collets are tool holding.


5C collet holders come in hand wheel type closing, lever closing and power closing. The lever and power closing are suited to rapid part changing as in production work. 5C collets come in all sizes up to 6 inches (step collets). Round, square, hex and any other configuration you can think of, including soft to be machined to size.

When the machine is properly designed for 5C's the collet is back into the spindle so the work does not extend much out from the spindle nose. This adds to the rigidity and accuracy.


ER collets (to the best of my expedience) only are closed with a nut. Not suited to rapid work changing. The use of ER collets for work holding is a fairly recent thing, mostly in the hobby machinist area. ER collets come in rounds and tap holding with a square at the back to prevent the tap from rotating.

ER mounts extend the collet out from the spindle nose leading to less rigidity and possibility of runout.

[dian]

so (again), what about the acuracy of 5c collets?

[gbritnell]

There are many different manufacturers of 5C collets, likewise ER collets. You would think that by using a collet that your work would run true, not always the case. Some collets are not as accurate as they are listed to be and likewise the chucks that they mount into have varying degrees of accuracy.
Some fellows have purchased import collets and chucks and say that they are 'very good' while others, including myself, have had mixed success with the whole affair. About the only way you can guarantee accuracy is to buy a set true collet chuck. That will guarantee repeatability but not necessarily accuracy.
gbritnell

[Mcgyver]

There are many different manufacturers of 5C collets, likewise ER collets. You would think that by using a collet that your work would run true, not always the case. Some collets are not as accurate as they are listed to be and likewise the chucks that they mount into have varying degrees of accuracy.

good point, I buy quality brands used and check them...having much runout defeats the point of collets. The best set up I have had was a hardened collet spindle adapter and drawbar, eliminates the chuck and mounting error. With a hardinge collet a tenths indicator would barely flicker