difference between tru length and standard 5c collet chucks

MMC Design

Aluminum

Joined

Jan 2, 2007

Location

VA

• Apr 28, 2021

• #1

Good day,

I am looking at buying a spindle mounted 5C collet chuck. I found three types listed:
"Set Thru", "Tru length", and Standard.

I understand the Set Thru. Can anyone clarify what the difference is between Tru Length and Standard is?

I looked for information on both the Bison and Toolmex sites and here and nothing turned up. There is a good bit of price difference. Try Length being the most expensive generally, more expensive than the Set Thru. The drawings showed that he main difference between Standard and Tru length is the length, Tru Length being shorter and it is about as long as the 5C collet, whereas the other two are about an inch longer. Why would that make it more expensive. None of the pages indicate that there is an accuracy difference.

Thanks.

 

B

Booze Daily

Titanium

Joined

Sep 18, 2015

Location

Ohio

• Apr 28, 2021

• #2

Set tru is adjustable run out. Tru length is fixed collet position. Does not pull back when tightened. I've also heard them called dead length.
Standard collets pull back when you tighten them.

 

C

CORONA VIRUS

Banned

Joined

Feb 25, 2020

• Apr 28, 2021

• #3

I would advise one of the following instead of a typical collet chuck:
Nub Tools Master Jaw System, 6" Chuck Size for 5C Collets - 4720646-5C - Penn Tool Co., Inc

With a standard 5C collet spindle, if the OD varies a small amount, your length will vary a large amount. The chuck jaw style eliminates that. PLUS, the chuck jaw style is a whole lot cheaper.

 

MMC Design

Aluminum

Joined

Jan 2, 2007

Location

VA

• Apr 28, 2021

• #4

I see what you mean now after getting your explanation and relooking at the drawings. I guess you screw the collet into the chuck on the Tru length, and it doesn't have an alignment pin. When you turn the key, you will be pushing a collar out against the collet's taper, which can't move in any direction at all.
The obvious advantage of this being no loss of time resetting the Z 0 if you are using a stop.

I assume then, on the standard type, that you have to turn the key to draw the collet into the chuck? I have only used a rear headstock drawbar collet closer, which allows you to change collets fairly quickly.

Standard

Tru Length

Looks like it might be worth the extra money.

Thanks!

 

N

Nmbmxer

Stainless

Joined

Jun 22, 2008

Location

VA

• Apr 28, 2021

• #5

CORONA VIRUS said:

I would advise one of the following instead of a typical collet chuck:
Nub Tools Master Jaw System, 6" Chuck Size for 5C Collets - 4720646-5C - Penn Tool Co., Inc

With a standard 5C collet spindle, if the OD varies a small amount, your length will vary a large amount. The chuck jaw style eliminates that. PLUS, the chuck jaw style is a whole lot cheaper.

Click to expand...

i made something like that, I just bored tall soft jaws for taper of the collet head and made an expanding plug to fit in the chuck body that had ID threads for the end of the collet. Pretty easy.

 

Doozer

Titanium

Joined

Jul 23, 2001

Location

Buffalo NY

• Apr 28, 2021

• #6

It is not to do with the collet, it is to do with the closer.
If the collet moves relative to the spindle, it is not dead length.
If the collet is stationary relative to the spindle, and some sleeve
slides and closes the taper, then it is dead length.

-Doozer

 

B

Booze Daily

Titanium

Joined

Sep 18, 2015

Location

Ohio

• Apr 28, 2021

• #7

If your stock OD varies in size, a standard collet will move farther on small parts and less on bigger parts. Your length will vary accordingly.

 

F

FredC

Diamond

Joined

Oct 29, 2010

Location

Dewees Texas

• Apr 28, 2021

• #8

Hardinge sells dead length collets, they are really a collet inside a collet. The inside collet has a flange that locates on the spindle face that prevents the inside collet from pulling back.
Another way to control pull back is control your part OD. The pull back ratio for a 5C collet is 3 to 1. If you control your chucking diameter to plus or minus .0001 you will only have .0006 variation on your second operation length. Not really that hard to do with today's CNCs or centerless ground bars.

 

jims

Hot Rolled

Joined

Sep 12, 2004

Location

Sonora , Calif

• Apr 28, 2021

• #9

If you make parts where the length has to be dead on then you need dead length collet. But if you can live with plus and minus a few thousands length a regular collet works just fine. If the stock dia is the same you don’t have to worry about length changing. We used to centerless grind bar stock to avoid length changes. Hardinge also makes collets for controlling dead length. And I think if you use other types of collets that don’t pull back I don’t think length changes. But one other thing to think about is how true the stock runs. With a set true set up you can adjust it true like truing a 4 jaw chuck.

 

MMC Design

Aluminum

Joined

Jan 2, 2007

Location

VA

• Apr 28, 2021

• #10

The design of this chuck seems to hold the collet so that it won't move in the Z direction relative to the spindle face regardless of the OD of the part.

 

C

CORONA VIRUS

Banned

Joined

Feb 25, 2020

• Apr 28, 2021

• #11

Nmbmxer said:

i made something like that, I just bored tall soft jaws for taper of the collet head and made an expanding plug to fit in the chuck body that had ID threads for the end of the collet. Pretty easy.

Click to expand...

Yeah, I make my own, also. They are a lot easier to install than having to take off the chuck. I see they want $800+ for these now. Just 3 jaws with a back step and a threaded flange with set screw pin.

 

F

FredC

Diamond

Joined

Oct 29, 2010

Location

Dewees Texas

• Apr 28, 2021

• #12

OK, you are looking for a spindle mounted 5C adapter. 5c chuck to me probably means the collet itself. Not enough detail in your drawing but it looks like that design is giving up on the lever operated draw bar to close the collet and using a key on the adapter to tighten the thread? If so you have the headaches of a key operated chuck and also the necessity of buying collets. After chucking millions of parts with a lever or air operated closer you could not give me one of those adapters where I have to pick up and put down a key every part and make sure the key is out before starting the spindle. I am getting to old and forgetful for that.
Hardinge did sell some machines that used a B&S 21 collet and some kind of push tube to tighten the collet. Maybe Larry has seen or used one.