New guy with a die

[ProSingulisArts]

Hello all! I am just getting started with taps and dies for pen making. I thought I'd start simple and make a mandrel for making a finial. I'm practicing on .5" aluminum rod. I am using an M9x0.75 single start die. I cut the tenon to 9mm OD. Threaded on the lathe with a die holder. Ran it down markings facing the work, flipped the die and ran it down again. The major diameter on my thread came out at a final 8.25mm which seems undersized by about .6mm. Is there something I'm not doing correctly? I'm also wondering about the die. It appears the threads are relieved on both sides of the die, so, I'm not sure how I would run threads clear to the shoulder with that being the case. Please help me figure this out or direct me to some info on proper technique. Thanks!

Taking a closer look, I'm wondering if I got the die started correctly when I flipped it. The threads almost have an "every other thread" look close up.

 

[tomtedesco]

Welcome from Colorado.

 

[rherrell]

When using dies the tenon needs to be slightly under nominal.

I use the pitch x 10% method.

.75 x .10 = .075

9mm- .075mm= 8.925mm

I always convert to imperial... .354"- .003" = .351"

Cut your tenon .003" under nominal (9mm or .354")

 

[farmer]

Lube the die when cutting metals ,, I lube wood if I am using a die.
If you have metal lathe you can use a live cutter and cut the threads in that way too.

 

[darrin1200]

Welcome aboard Frank.

With your major diameter ending up at 8.25, tells me that something is not right.

First note. You do not have to flip the die, unless you need the full thread all the way to end. In your case, with the relief cut, you don't need to flip it.

Is your die adjustable? If it is to tight, it will cut the tenon, as well as the thread.
There should be a screw on the side of your die. Screw it in to force the die to open more. Try threading again. If the threads are to shallow, loosen the adjusting screw (maybe 1/8 of a turn). Then run the die again. It should cut a little deeper. Continue adjusting this until your get a thread at the depth you want.
Its a bit of a process, but it's what you will need to work on to get nice smooth functioning threads.

 

[ProSingulisArts]

Welcome aboard Frank.

With your major diameter ending up at 8.25, tells me that something is not right.

First note. You do not have to flip the die, unless you need the full thread all the way to end. In your case, with the relief cut, you don't need to flip it.

Is your die adjustable? If it is to tight, it will cut the tenon, as well as the thread.
There should be a screw on the side of your die. Screw it in to force the die to open more. Try threading again. If the threads are to shallow, loosen the adjusting screw (maybe 1/8 of a turn). Then run the die again. It should cut a little deeper. Continue adjusting this until your get a thread at the depth you want.
Its a bit of a process, but it's what you will need to work on to get nice smooth functioning threads.

The die I'm working with is non-adjustable. I think I'll flip the bar and try again without reversing it to see how it goes.
After that, I may look into finding an adjustable die if the result isn't there.

 

[ProSingulisArts]

Lube the die when cutting metals ,, I lube wood if I am using a die.
If you have metal lathe you can use a live cutter and cut the threads in that way too.

I'll look into the thread cutting attachment. I am working on a Sherline and they do have one.
Currently using 3n1 oil, will try Tap Magic next go around.

 

[duncsuss]

The die I'm working with is non-adjustable. I think I'll flip the bar and try again without reversing it to see how it goes.
After that, I may look into finding an adjustable die if the result isn't there.

Did you chamfer the end of the tenon before starting to cut the threads? Typically I chamfer at 45 degrees 2 or 3 mm so the die can slip on and get started without having to cut full depth threads from the get-go.

Quick question: is your die hexagonal or round?

Reason for asking is that hexagonal dies are for chasing - that is, clearing out crud and/or rethreading existing threads. You didn't mention which you have, and I fell into the trap of getting hex dies when I started out.

 

[farmer]

I'll look into the thread cutting attachment. I am working on a Sherline and they do have one.
Currently using 3n1 oil, will try Tap Magic next go around.

What do you have? a Dremel , Ridgid veneer trimmer , porta cable veneer trimmer .?
Look at the mounts I have . first two are
Made by mid American cue lathes
Ridgid trimmer mount.
Third is a Dremel
Fifth photo is a cue man billiards Ridgid mount with the mid American mount in the back ground .

 

[farmer]

Router mounts - Pool Cue Lathes by Mid-America

www.midamericapool.com

 

[ProSingulisArts]

Did you chamfer the end of the tenon before starting to cut the threads? Typically I chamfer at 45 degrees 2 or 3 mm so the die can slip on and get started without having to cut full depth threads from the get-go.

Quick question: is your die hexagonal or round?

Reason for asking is that hexagonal dies are for chasing - that is, clearing out crud and/or rethreading existing threads. You didn't mention which you have, and I fell into the trap of getting hex dies when I started out.

I did, but, not as much as that. I will chamfer more on the next attempt.

I am using round threading dies, not hex.

 

[ProSingulisArts]

Much happier with the second attempt. Thank you for all the tips and suggestions!

 

[Aurelius]

With your major diameter ending up at 8.25, tells me that something is not right.

I know I'm a little late to the party, but could you explain this? As I understand things, an m9x.75 should leave a major diameter of exactly 8.25 after threading, no?

 

[leehljp]

View attachment 335476
Much happier with the second attempt. Thank you for all the tips and suggestions!

You certainly made a huge leap from the first to the second one! Congratulations! Great people on this forum with lots of experience and wisdom! That second attempt is excellent! Now you can teach others!

I haven't started theading yet, but it is great to know the difference between round vs hex dies.

 

[duncsuss]

I know I'm a little late to the party, but could you explain this? As I understand things, an m9x.75 should leave a major diameter of exactly 8.25 after threading, no?

No, you have major and minor confused.

M9x0.75 definition is "major diameter = 9mm; minor diameter = 8.25"

 

[Aurelius]

No, you have major and minor confused.

M9x0.75 definition is "major diameter = 9mm; minor diameter = 8.25"

Yes, you are absolutley correct. I had it right in my head but it came out all backwards then I typed the backwards part.