ER40 vs. 5C collets accuracy in a lathe?

[Stanshire]

A few additional points.
My Bison SetTru 5C chuck is on the lathe 90% of the time. It takes just a few minutes to clock it in to darn near zero runout. In truth, even though I check it occasionally, it rarely goes out.
I don't believe that anyone has mentioned the 5C hex or square collets. Very useful.
My collet collection is a combination of used ebay Hardinge collets (I may be lucky, but the Hardinge collets have all been perfectly true), some new Interstates (I've gotten a few that were out and returned them) and some new Lyndex-Nikkens (dead on).
I believe that the larger sizes (above .75") have an internal shoulder that prevents work from going into the spindle bore.
In those cases, I will switch to the 3 or 4-jaw.
The 5C 3-jaw chucks are not particularly accurate in the runout department.
Switching collets, with a chuck key, takes many, many turns. I use a screw gun with a shop-made adapter to fit the square holes in the chuck. With that, changing collets takes a few seconds.

 

[Dataporter]

I didn't see it mentioned above, but with 5C you can get collet stops. You need 5C collets with the internal threads in the back (although I think some stops don't need them). The stops are real handy when making several parts the same exact length. I haven't seen stops for ER-40. The stops are also very handy when you use the collet in a block on the mill for secondary operations like drilling holes in the side, milling flats, slotting, etc.

 

[Stanshire]

Correction and an addition.
All of my 5C collets except 1.0625 and 1.125, allow the part to pass through the spindle. Those two have a reduced area at the bottom of the gripping area to provide a sufficiently thick wall.
The reasonably priced Asian spindexers have 5C tapers. Just used it yesterday to make some 5/16" hex bar from roundstock.

 

[David VanNorman]

I use 5C collets as my Spacer used 5C so I made a chuck for my SB 9A. I would rather Have an ER40 chuck, but the number of times I need a collet is not that often so I am happy with the 5C.

Dave

 

[ranch23]

Thanks for all the feedback.

Here's some of what I have learned with your help:

1. 5C is for work holding

2. ER's are for tool holding

3. Many have applied ER’s in work holding as well

4. Get a good chuck for 5C

5. Lathe chucks for ER are hard to come by

6. Get decent holders for ERs – mill and lathe application

7. Nice to have ER holding capability for the tailstock of the lathe for tools

8. 5C is narrow in clamping range for an individual collet

9. Buy a complete set of 5C collets up front and get it over with

10. ER's come in multiple ranges

11. May need fewer ER collets due to their flexibility in clamping range

12. Buy decent quality collets

13. Get collet blocks for use in the mill

14. Both 5C and ER are accurate - depending if you apply them as intended and you buy good quality hardware

15. Figure out how to store all these freaking collets

I have once again confirmed what I knew already – “A little here and a little there and soon you have spent some real money.” One of my buddies here called it right via a pm, buy it all!

Thanks for all the help, this forum is a great community.

One more thing, turn a complete set of fractional drill bits to fit in collets, then you dont have to mess with a drill chuck in the mill.


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[65Cobra427SC]

If you get a 6-jaw Set-Tru, the only reason to get a collet setup is if you don't want to bust your knuckles doing hand work close to the chuck. My Bison 6-jaw"s accuracy is more than I can ask for. I rarely even use my ER4o chuck. I use the 6-jaw most of the time.

Before & I'm sure I've said somewhere else that if I could start over & if I wasn't using ER40 for my mill that I would go TG150. Well I take that back now, I'll stick with ER40. I did not realize TG150 also did not go smaller than 1/2". That would be a deal breaker for me not being able to go smaller than 1/2". But then again I could always just stick my ER16 straight collet chuck in a 1" TG150 collet, like this:

DarkZero, I was online and happen to notice MariTool has ER40 collet sets in sizes under 1/2" (9/32, 5/16, 11/32, 3/8, 13/32, 7/16, 15/32 ) although I don't know if they're sold separately. Just wanted to let you know.

Also, I want to purchase a set of collets for my PM1236 and wondered if you would still get the ER40 collets, or purchase another set instead.

Thanks

 

[ddickey]

I think you meant ER50. smallest I see is .1972" for $41.

 

[P. Waller]

Thanks for all the feedback.

Here's some of what I have learned with your help:

1. 5C is for work holding

2. ER's are for tool holding

You have it figured out.
5C may be closed from the back requiring no tools and are pass through. This is fast.
ER requires a tool to open and close. This is slow.

If your major concern is accuracy use an independent 4 Jaw chuck at all times. This is slowest.

 

[Jimsehr]

Nobody has said that with a 5c setup you can get square ,hex, emerancy collets and a collet to hold a washer shape part like 1/8 wide 3 inch dia part with ease. Or that you can hold a part on it’s bore with an Id collet. Also with most 5c setups you can move the 5c held parts to the mill or the drill press for the next operation. Also with a lever collet setup you can load parts in seconds while the spindle is running.

 

[magicniner]

I use ER40 for most lathe work because I regularly need 30mm through capacity and ER40 gives me 2mm to 32mm through capacity with excellent runout, when I chuck up a 1m length of 30mm bar with 30mm protrusion at the front there is negligible run-out on the end hanging out at the back.
Despite much faux-information to the contrary I have found that I have no problems holding regular polygonal material with ER collets, I'm sure really heavy cuts could cause slipping but I've had no issues up to now.