Author Topic: 3 -48 threading brass rod  (Read 2410 times)

Offline Davis2x1

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3 -48 threading brass rod
« on: January 19, 2016, 02:48:21 AM »
Building my second steam engine and am having trouble threading a brass rod. Its a 3/32 diameter rod with 3-48 RH thread. I am using a die holder on my Sherline lathe mounted in the tail stock. I cannot seem to get the lead right. I keep striping out the thread. The ID on the die is facing rod. I cannot determine if this is the entry side?? Turning the head stock by hand.

Should I try threading by preventing the die rotation while loosely mounted in the tail stock?

Thanks for any help.

Dave

Dave
Sherline Mill and Lathe

Online crueby

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Re: 3 -48 threading brass rod
« Reply #1 on: January 19, 2016, 03:16:54 AM »
The writing on the die face does face the rod, that is correct. The tail stock needs to be loose on the bed so it can feed in as it threads. I usually put a slight taper on the very end of the rod with a file while the rod is spinning to help it grab the die. When starting the thread push the die into the rod as well, and spin it backwards 1/2 turn every forward turn to break the chip. If all that still does not work, is the die dull? Thread clogged with a chip? The finer thread dies can be a little fussy on getting started.

Online b.lindsey

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Re: 3 -48 threading brass rod
« Reply #2 on: January 19, 2016, 04:14:14 AM »
Is the die adjustable? If so try opening it up some and see if it starts better then.

Bill

Offline jerry kieffer

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Re: 3 -48 threading brass rod
« Reply #3 on: January 19, 2016, 05:34:37 AM »
Building my second steam engine and am having trouble threading a brass rod. Its a 3/32 diameter rod with 3-48 RH thread. I am using a die holder on my Sherline lathe mounted in the tail stock. I cannot seem to get the lead right. I keep striping out the thread. The ID on the die is facing rod. I cannot determine if this is the entry side?? Turning the head stock by hand.

Should I try threading by preventing the die rotation while loosely mounted in the tail stock?

Thanks for any help.

Dave

Dave
      Assuming you have tried the things others have suggested, and are using brass rod of material that can be threaded (Not brazing rod or some others) this will be quite common when using dies from China and India.  If so, purchase higher quality USA or European.        Also, I never really understood the tailstock Die holder thing not that it has anything to do with this issue.    I simply place the Die in the chuck on the headstock.

Jerry Kieffer

Offline Davis2x1

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Re: 3 -48 threading brass rod
« Reply #4 on: January 20, 2016, 12:24:33 AM »
Thanks for the tips. The brass rod is from the kit from PM Research. The die is indeed from China, I will try to find another supplier. I bought these from Grainger. The dies I received from PM Research look different but do not have a country of origin on them. Tried tapering the end of the rod to no avail. The die still chews up the rod.

I an going to set up the threading attachment on the lath and see if I can get the thread started that way. I recall it was a previous suggestion. Cut a shallow thread then finish off with the die.

No problem with the small taps in steel, brass or aluminum, but I can"t seem to thread a rod!!!

Later, Dave

Dave
Sherline Mill and Lathe

Offline sshire

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Re: 3 -48 threading brass rod
« Reply #5 on: January 20, 2016, 03:16:10 AM »
I'm betting on a bad die
You've got the die facing in the correct direction, opened up, tapered start.
I do remember fighting with a Chinese die for about a week. Got a new die from McMaster (it seems that most of what I get from them is USA made.). Cut like butter.
I do have Chinese dies that are fine. That one missed it's visit to QC.
Best,
Stan

Online crueby

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Re: 3 -48 threading brass rod
« Reply #6 on: January 20, 2016, 03:23:43 AM »
I'm betting on a bad die
You've got the die facing in the correct direction, opened up, tapered start.
I do remember fighting with a Chinese die for about a week. Got a new die from McMaster (it seems that most of what I get from them is USA made.). Cut like butter.
I do have Chinese dies that are fine. That one missed it's visit to QC.
I recently got a 2-56 tap that must have slipped past QC too, it was way undersized with barely any thread on it. Others in same batch were fine. Swarf happens.

Offline Ken K

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Re: 3 -48 threading brass rod
« Reply #7 on: January 20, 2016, 05:36:37 AM »
 If you have a 3-48 screw, you could use it to check out the die. It should be a little tight, in the die.

Offline Davis2x1

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Re: 3 -48 threading brass rod
« Reply #8 on: January 20, 2016, 04:43:28 PM »
EUREKA!!!

I set up the threading attachment on my lathe. It cut a suitable thread which allowed me to get the die on and finish the length I needed. Once the die was started it cut "OK". I think its lead in is the problem. I did try to screw in a 3-48 screw but I could not get it started because of the three flutes in the die.

I am going to try to sharpen my bit so I can cut the full thread. This little Sherline lathe is amazing. Once I get a proper bit no more Dies for me.

Thanks for all the comments. This forum is great.

Dave
Dave
Sherline Mill and Lathe

Offline Allen Smithee

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Re: 3 -48 threading brass rod
« Reply #9 on: January 20, 2016, 06:01:36 PM »
Dave,

I hope you're not looking to put too much load on that thread - 3/32" (0.09375") is officially just below bottom limit (0.0938") for a 3-48 thread.

Also I wouldn't be too hasty in throwing away your dies. I'm no great expert, but I've always screwcut the basic thread and then finished the profile off with a die, and I was under the impression that's what most people did.

Jerry - "Also, I never really understood the tailstock Die holder thing not that it has anything to do with this issue.    I simply place the Die in the chuck on the headstock."

For me the tailstock dieholder (or pushing a standard dieholder with a blank arbor in the tailstock) does two things for me:

1. I can hold much bigger stuff much more securely in the chuck than in the tailstock.

2. I often want to turn a diameter and then thread it before doing other stuff. If I can do the whole thing without removing the job from the chuck it's far more likely to remain concentric! This is especially true where I screwcut a shallow thread before finishing with a die.

AS
Quidquid latine dictum sit altum sonatur

Offline V 45

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Re: 3 -48 threading brass rod
« Reply #10 on: February 10, 2016, 02:34:18 AM »
 "Assuming you have tried the things others have suggested, and are using brass rod of material that can be threaded (Not brazing rod or some others)"

  Why couldn't you thread these? I ask because I have some unknown brass rods (a lot of them) ranging from .125 to .190". It cuts hard and the die didn't like it either. The chips aren't like brass dust flying all over but rather spring like. It has a reddish color compared to 360 brass.
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Offline Stuart

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Re: 3 -48 threading brass rod
« Reply #11 on: February 10, 2016, 07:46:15 AM »
You have PB102 bronze. Horrid horrid stuff

Stuart
My aim is for a accurate part with a good finish

Offline V 45

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Re: 3 -48 threading brass rod
« Reply #12 on: February 10, 2016, 01:58:32 PM »
Horrid is a understatement. ...I have a piece broke in a 2-56  die :(
Haven't been able to get it out  !!
Never assume the implied task has been completed !!