Double ended stud holding in a 5c collet production run

S

saadracing

Plastic

Joined

Feb 22, 2016

• Feb 23, 2016

• #1

We are manufacturing a double ended stud where the center of the body is smaller than the major diameter of the threads on both ends. Threading one side is not a problem but flipping it over posses the problem. I want to use the 5c collet to help maintain concentricity but cannot grab the threads in the collet, only the body. I am use a thread roller and has a tremendous amount of torque so I am clamping the body with as much force as possible. The only solution was to remove the collet, insert the stud from the rear of the collet and then re-insert the collet back into the lathe and set my clamping force again. Fine for a few studs, but not for what we are trying to achieve as this is a repeat job of 100+pcs. Here are the details of what we have

Doall heavy duty manual lathe model LS17
Manual 5c collet closer
Thread rolling H11 annealed to 8rc
7/16-20 on one end and 11mm x 1.5 on the other
Body is cut to 7/16 pre-rolled diameter with no wrench hex (i.e machine a collet with the threads and thread the stud into it as it will tighten in the collet when roller with no "easy" removal)

Any thoughts would be great. Thanks

 

Finegrain

Diamond

Joined

Sep 6, 2007

Location

Seattle, Washington

• Feb 23, 2016

• #2

I don't think you can get there with a 5C.

3-jaw with steel soft jaws, recessed behind to allow clamping the center section. This should give plenty of concentricity as long as your 3-jaw isn't knackered.

Some other collet type, with wider collapse range, might work fine too depending on how much less the center is than the thread major.

Regards.

Mike

 

S

saadracing

Plastic

Joined

Feb 22, 2016

• Feb 23, 2016

• #3

Body diameter is 0.4085" and rolled major is 0.4350" for a class 3b fit. Just enough difference combined with the extra grip needed.

I am not finding any information on the wider collapse range collet. Do you any more information?

Would like to stay with the collet closer as it is much faster on change over than a 3 jaw, but my 3 jaw is in great shape if absolutely necessary.

 

M

mdshunk

Hot Rolled

Joined

Nov 14, 2015

• Feb 23, 2016

• #4

You can cut threads in a sacrificial 5c collet and clamp on the threads on your 2nd op.

 

O

onecut

Hot Rolled

Joined

Jun 27, 2013

Location

england-newcastle upon tyne

• Feb 23, 2016

• #5

Use a larger collet and a split bush

 

WizardOfBoz

Diamond

Joined

Sep 30, 2006

Location

SE PA, Philly

• Feb 23, 2016

• #6

Do you turn off some of the diameter between the threads? Could you thread the thing first, clamping on the unturned diameter, then turn it down after threading? This would give you more diameter to grip.

 

S

saadracing

Plastic

Joined

Feb 22, 2016

• Feb 23, 2016

• #7

With the required clamp load needed to hold the stud in place and the rotational torque load of the rolling head, i am concerned about damaging the threads. Thoughts?

 

M

mdshunk

Hot Rolled

Joined

Nov 14, 2015

• Feb 23, 2016

• #8

saadracing said:

With the required clamp load needed to hold the stud in place and the rotational torque load of the rolling head, i am concerned about damaging the threads. Thoughts?

Click to expand...

Try one. Spin a gauge on the clamped threads when you're done and see.

 

L

Limy Sami

Diamond

Joined

Jan 7, 2007

Location

Norfolk, UK

• Feb 23, 2016

• #9

Tap a set of soft jaws, .....you can load and unload quicker than it's taken me to type this.

 

Gordon Heaton

Titanium

Joined

Feb 19, 2007

Location

St. George, Utah

• Feb 23, 2016

• #10

Use a combination of what was said in posts 4 & 5: cut threads in a steel split bush, (split it completely, into 2 parts so you can simply clap it on your stud), then insert that into an appropriately sized regular collet. A little care in making the split bush and you're good to go.

 

jims

Hot Rolled

Joined

Sep 12, 2004

Location

Sonora , Calif

• Feb 23, 2016

• #11

Thread rolling

You might think about sending parts out to thread rolling shop. Where the parts are dropped thru the thread rollers and that way you don't have to grip them at all. It used to cost me about the same to cut or roll threads this way. And I used to get 316 stainless parts knurled this way and always ended up with good knurls.
I used Downey Grinding in Downey Ca. jimsehr

 

S

saadracing

Plastic

Joined

Feb 22, 2016

• Feb 23, 2016

• #12

bosleyjr said:

Do you turn off some of the diameter between the threads? Could you thread the thing first, clamping on the unturned diameter, then turn it down after threading? This would give you more diameter to grip.

Click to expand...

We are having them centerless ground to the specified diameters and then we do the finishing opts so unfortunately not an option. Thanks though

 

N

NodecoMachine

Cast Iron

Joined

Sep 7, 2011

Location

NJ, USA, Lebanon

• Feb 23, 2016

• #13

We have collets that are straight (no taper) with 9/16" OD, kinda like the bush idea above but with 3 slots like a 5c, and also a flange to butt up against ur 5c collet. You would unclamp 5c collet > remove 9/16" OD collet with part in it > remove part from 9/16" OD collet > insert new part in to small collet > butt flange of small collet against face of 5c collet > push part against stop > clamp. It's very repeatable (concentricity and length) and and u can still maintain high clamping pressure. I'll check in the morning if there are collet style markings and take some pictures for u if Ud like.

 

S

saadracing

Plastic

Joined

Feb 22, 2016

• Feb 23, 2016

• #14

NodecoMachine said:

We have collets that are straight (no taper) with 9/16" OD, kinda like the bush idea above but with 3 slots like a 5c, and also a flange to butt up against ur 5c collet. You would unclamp 5c collet > remove 9/16" OD collet with part in it > remove part from 9/16" OD collet > insert new part in to small collet > butt flange of small collet against face of 5c collet > push part against stop > clamp. It's very repeatable (concentricity and length) and and u can still maintain high clamping pressure. I'll check in the morning if there are collet style markings and take some pictures for u if Ud like.

Click to expand...

Yes please!

 

N

NodecoMachine

Cast Iron

Joined

Sep 7, 2011

Location

NJ, USA, Lebanon

• Feb 24, 2016

• #15

No markings other than the size. Here's a couple pictures







If u have a choice I'd recommend something larger. These are limited to 1/2" and under and you obviously can't fit anything larger than 9/16" thru ur 5c collet. If I could choose I would go with collets that fit into like a 1" 5c collet.