So where am I going wrong

[Oompa LumpaParticipant @oompalumpa34302]

I am trying to replicate a small – 22mm long 3mm diameter – adjusting screw.
Left Hand Thread. Split Die bought from RDG – Not UK Made

I have made it twice now, both times they made it to the scrap bin!

I am turning it from a piece of EN3B, down to 2.9mm the first time 3.1mm the second time. and both times I ended up with something that vaguely resembled a thread, about 2.5-2.6 mm in diameter and it fell through the threaded hole both times.

Any pointers gratefully received. I was thinking maybe the steel was too soft?

graham.

[Oompa LumpaParticipant @oompalumpa34302]

[JasonBModerator @jasonb]

Posted by Oompa Lumpa on 09/12/2013 19:17:37:

I was thinking maybe the steel was too soft?

graham.

Is that the steel teh die is made of or the EN3B

I did have similar problems with a 5/8×40 die from RDG a couple of months back and ended up screwcutting it on the lathe

J

[blowlampParticipant @blowlamp]

A problem I've experienced is that either one or more of the securing-screw holes in the die-holder, or the 'dimples' around the die are not aligned, so when they're tightened down they tend to distort the die and make it cut a horrible thread. It might be worth your while to check it out.

Martin.

[Oompa LumpaParticipant @oompalumpa34302]

Posted by JasonB on 09/12/2013 19:32:51:

Posted by Oompa Lumpa on 09/12/2013 19:17:37:

I was thinking maybe the steel was too soft?

graham.

Is that the steel teh die is made of or the EN3B

I did have similar problems with a 5/8×40 die from RDG a couple of months back and ended up screwcutting it on the lathe

J

I did think it just might be the Die Jason

Snag is that it is 3mm AND left hand thread.

Bugger.

graham.

[Oompa LumpaParticipant @oompalumpa34302]

Posted by blowlamp on 09/12/2013 19:45:15:

A problem I've experienced is that either one or more of the securing-screw holes in the die-holder, or the 'dimples' around the die are not aligned, so when they're tightened down they tend to distort the die and make it cut a horrible thread. It might be worth your while to check it out.

Martin.

This is why I love this place. Great thinking Martin and certainly a possibility.

I was just thinking myself there – always a danger – could it be that the die is also faced? What I mean is, there is no lead in on one side?

graham.

[Ady1Participant @ady1]

I got my best results by roughing most of it out on the lathe, then finishing with a die

If I wanted a nice tight thread, I never used a die, the ones I have always overcut a bit too much

No doubt they cut "within acceptable tolerances", but still too much for the more precise scenarios

Edited By Ady1 on 09/12/2013 19:55:47

[old AlParticipant @oldal]

EN3B will tear a bit, but you should get better than you have done.

Are you using any tapping fluids.

Are you using a tailstock dieholder, if not are you using something behind the die to keep it square.

EN3B allows you to have a second stab at it, so you can open up the die, take a cut and then close down the die for a second cut. Don't try this in stainless.

Is the die, carbon steel or HSS

[Oompa LumpaParticipant @oompalumpa34302]

It's not cutting within any tolerance Ady, it's turning the screw down from 3.1mm to 2.5 mm and unable to function as a screw..

Al, yes I use cutting fluid and a Die stock holder. Rather, I hold the Die in a Die stock and then against the tailstock, it works well and I have always done it this way with 100% success. I suspect the die is carbon steel. Also tried the light cut/heavier cut scenario you describe.

Doyou think it's worth buying another die? Left hand – 3mm?

graham.

[jason udallParticipant @jasonudall57142]

Split die. Are you spreading the die.?

Left hand tread. Just possible you forgot and turned wrong way ?

Also does your chuck unscrew..

Edited By jason udall on 09/12/2013 20:50:29

[Tony Pratt 1Participant @tonypratt1]

From my own experience these budget dies do have 'issues', they do a job but not always very well. If you turned the job the wrong way as suggested the left hand die wouldn't go on. Try turning to 2.9 mm and have a nice 45 deg. chamfer on the end, open up the die for the first pass, hold it in a tail stock die holder if possible, use cutting oil and not too fast on the spindle speed.

Tony

[VersabossParticipant @versaboss]

Posted by Oompa Lumpa on 09/12/2013 20:37:50:

It's not cutting within any tolerance Ady, it's turning the screw down from 3.1mm to 2.5 mm and unable to function as a screw..

Al, yes I use cutting fluid and a Die stock holder. Rather, I hold the Die in a Die stock and then against the tailstock,

Hmm, Graham, did you forget to let the lathe running backwards for the left hand thread???

Hansrudolf

[old AlParticipant @oldal]

I had something from Tracy Tools do something odd once. They exchanged it straight away. Good customer service. See what RDG say before shelling out on another.

[Gordon WParticipant @gordonw]

With a small dia. thread there is a lot of metal to bend when opening the split. It may be that cutting grooves, with a thin cutting disc, will allow the die to open a bit more. I've done this with some success, but not if the die is going to be returned!

[Oompa LumpaParticipant @oompalumpa34302]

This:

"turning to 2.9 mm and have a nice 45 deg. chamfer on the end, open up the die for the first pass"

and This:

"and shouldn't be overtightened. In fact, I only ever use one screw, not all three"

worked for me.

Opening the die – quite a bit actually – has stopped it 'overcutting' the small rod i turned. I now have a workable thread. Bit of a result really as I really didn't want to be shelling out for a new HSS die and hoped the steel one would work. It can now go into the drawer for the next millenia to come along when I might need it again.

This is the problem when you are spoiled with first class kit and you buy something "on the cheap" just to get you away on a job. I really should know better. Not to worry, something else I have learned. Bit of a result really.

graham.

[Anonymous]

Posted by Oompa Lumpa on 10/12/2013 15:30:27:

It can now go into the drawer for the next millenia to come along when I might need it again.

graham.

If it was mine it'd be going straight into the bin.

Andrew

[Rik ShawParticipant @rikshaw]

In a perfect world do this:

Put a "good" split die in the holder and use the centre screw to slightly spread the die. Cut the thread. Use a die nut to remove the last little bit down to size. Works for me every time (Where I have a die nut the correct size that is).

Rik

[Author]

Posts