# Easy simple threading



## Suzuki4evr (Jan 18, 2020)

How's this for easy threading? Don't know if it was posted before but here it is.


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## Tozguy (Jan 18, 2020)

Great idea, especially if it means we can use a broken or dull tap that has been ground back to life.


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## Suzuki4evr (Jan 18, 2020)

Tozguy said:


> Great idea, especially if it means we can use a broken or dull tap that has been ground back to life.


My thoughts exactly


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## mmcmdl (Jan 18, 2020)

Wasn't there a thread where the guy did this with a broken die also ?


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## Ed ke6bnl (Jan 18, 2020)

and that was a pipe thread from what I see


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## Janderso (Jan 18, 2020)

That is a great idea.


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## Dhal22 (Jan 18, 2020)

Ed ke6bnl said:


> and that was a pipe thread from what I see



Yes, us plumbers recognize that taper from years of operating a threading machine.


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## ThinWoodsman (Jan 18, 2020)

So that's basically using a tap (or die) as a form tool, instead of a thread chaser as in Sparey's lathe boo)? Interesting idea, and much cheaper than buying chasers.


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## Downunder Bob (Jan 18, 2020)

I believe I might have done something similar in the distant past. Works well as long as your lathe has the correct pitch available. You can also use a piece of a broken die. 

Note that you don't need to have the tap of the correct dia, as long as the pitch and thread form is correct.


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## RJSakowski (Jan 18, 2020)

I was skeptical at first as you still need to use the lead screw and half nuts and I didn't see much advantage over single point threading.  However, it would definitely be useful to cut tapered threads if your lathe doesn't have a taper attachment. I would think that you would want to use a pipe thread tap for the cutter rather than angling the tap to the taper angle as by angling the tap, you are also rotating the thread form which would cut a leakage path. 

You will have to be very quick at backing out at the end of the cut as you cannot disengage the half nuts.  He is also cutting with the heel of the tap and I'm not sure what effect that will have on the thread form.  

I will be interested in seeing a report from someone from HM who has actually tried this.


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## Latinrascalrg1 (Jan 18, 2020)

Honestly, I don't think this is any different then single point threading!


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## Suzuki4evr (Jan 18, 2020)

mmcmdl said:


> Wasn't there a thread where the guy did this with a broken die also ?


Don't know if it is the same guy,but I saw that one


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## RJSakowski (Jan 18, 2020)

Latinrascalrg1 said:


> Honestly, I don't think this is any different then single point threading!


You can cut a tapered thread.


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## epanzella (Jan 18, 2020)

Cool idea but a little scary as you have to back out with the carriage still moving or the thread is instantly wiped out.  I think I would risk it on a tapered thread but single point the rest.


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## Latinrascalrg1 (Jan 18, 2020)

RJSakowski said:


> You can cut a tapered thread.


I havent had the need to yet but I guess I dont understand the question!  Wouldn't you still need to lock in the split-nuts with the lead set to the correct pitch to use this method  just like you would with a single point?  And if you set the needed taper into your lathe setup wouldnt that be the exact same thing with the exception of the tap having multiple follow up skim cuts?

Ahh!  Ok now i see it, the tap itself is tapered, which cuts the mirror image when used to cut this way, correct?


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## RJSakowski (Jan 18, 2020)

Latinrascalrg1 said:


> I havent had the need to yet but I guess I dont understand the question!  Wouldn't you still need to lock in the split-nuts with the lead set to the correct pitch to use this method  just like you would with a single point?  And if you set the needed taper into your lathe setup wouldnt that be the exact same thing with the exception of the tap having multiple follow up skim cuts?
> 
> Ahh!  Ok now i see it, the tap itself is tapered, which cuts the mirror image when used to cut this way, correct?


Yes


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## Suzuki4evr (Jan 18, 2020)

I basically posted this just to show that there is a lot of methods doing the same thing. I do wonder, is that a left hand thread tap? If you look at the cutting edge side he used.


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## RJSakowski (Jan 18, 2020)

Suzuki4evr said:


> I basically posted this just to show that there is a lot of methods doing the same thing. I do wonder, is that a left hand thread tap? If you look at the cutting edge side he used.


I wondered that as well but looking at the grind on the flutes, it appears not. (around 10:20 in).  Also, the tap threads look like r.h.


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## epanzella (Jan 18, 2020)

Suzuki4evr said:


> I basically posted this just to show that there is a lot of methods doing the same thing. I do wonder, is that a left hand thread tap? If you look at the cutting edge side he used.


Looks like a right hand thread to me. Lathe is going counter clockwise and the thread is climbing towards the headstock. I don't think there's any hocus pocus going on with the tap because it's not turning so it just a form tool in this application. I think a left hand tap would reverse the lead angle. That said, I freely admit I'm freaking OLD!


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## derf (Jan 18, 2020)

I've done this many a time for fine internal threads. I used a 3/8-24 tap to thread the inside of a 1-3/8" suppressor tube. It only took 3 passes.


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## pacifica (Jan 18, 2020)

I've done this with a single die head chaser in a tool bit holder, and use a retractable tool bit holder to retract the cutter at the end of the cut.

To me it is just as easy to single point thread.


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## brino (Jan 18, 2020)

hmmmmm......one thing I don't get.....

in the video before removing the long part for a trial fit, he bothers to mark the hex side between the two upper jaws, but I don't see that he marked the depth into the chuck jaws!

Without the depth being controlled, that would also wipe out the threads on the next cut.....right?
I suppose there could be a depth stop on the outboard side of the headstock?!?!?

okay a second thing I don't get.......
I turned on english translation subtitles and got references to "fallopian" and "uterine".
are those references to female or internal threads?
one might have been referring to the half-nuts......not sure.....

-brino


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## mmcmdl (Jan 18, 2020)

brino said:


> Without the depth being controlled, that would also wipe out the threads on the next cut.....right?
> I suppose there could be a depth stop on the outboard side of the headstock?!?!?



Sure would . Most likely he does have a stop in the spindle for depth and it wouldn't take much of a variation to wipe those threads out .


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## Shootymacshootface (Jan 19, 2020)

Latinrascalrg1 said:


> Honestly, I don't think this is any different then single point threading!


I agree.


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## Suzuki4evr (Jan 19, 2020)

brino said:


> hmmmmm......one thing I don't get.....
> 
> in the video before removing the long part for a trial fit, he bothers to mark the hex side between the two upper jaws, but I don't see that he marked the depth into the chuck jaws!


When he put the shaft back, it looked to me that he picked up the thread first before doing the next pass.


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## Downunder Bob (Jan 19, 2020)

I think you are right, he used the compound to pick up the thread.  Which makes me wonder why he bothered to mark it at all, unless he is aware of some runout in that chuck, and he wanted to put it back in the same place to eliminate the runout effect.


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## epanzella (Jan 19, 2020)

brino said:


> hmmmmm......one thing I don't get.....
> 
> in the video before removing the long part for a trial fit, he bothers to mark the hex side between the two upper jaws, but I don't see that he marked the depth into the chuck jaws!
> 
> ...


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## epanzella (Jan 19, 2020)

I think the marking of the part in relation to the chuck jaws was for runout. I do the same thing with my 3 jaw. It's good for .003 but I can usually get .001 if I put the part back in the same relative spot.  Even if he had a depth stop I can't see that thread lining up well enough using that fat mark without reaquiring it. Everyone probably know's this but there's a point I wanted to mention.  To get a tapered thread you need to use a tapered thread tap like a pipe tap.  On a regular tapered tap for a machine thread the taper is produced by grinding the crests off the threads so the thread form is wrong in the tapered area.


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## higgite (Jan 19, 2020)

If you freeze the video at the right instant (9:00) you can see he used a 3/8”-24 UNF tap, not an NPT thread. So, it really isn’t any different than single pointing except for maybe fewer passes to complete the thread and the taper that’s left near the end of the tap. That can be a pro or a con, depending on your application.

Edit: To correct time in the video. Thanks to RJ.

Tom


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## RJSakowski (Jan 19, 2020)

higgite said:


> If you freeze the video at the right instant (11:16) you can see he used a 3/8”-24 UNF tap, not an NPT thread. So, it really isn’t any different than single pointing except for maybe fewer passes to complete the thread and the taper that’s left near the end of the tap. That can be a pro or a con, depending on your application.
> 
> Tom


Ile time is actually 9:00.  11:16 the the length of the video.

Using a straight tap, the thread form will be wrong.  The flanks of the thread won't be equal with the longer flank towards the headstock.  The angle between the flanks will be 60º but they will be rotated by the taper angle, around 1.8º.  In searching. I couldn't find any tapered thread with 24 TPI.  It is possible that he cut the female thread in the same way and the threads would mate properly.  It is also possible that this is just a "made for t.v." video.


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## plunger (Jan 19, 2020)

Ive seen this done with rigid die thread chasers . The rectangular blocks with bsp tapered thread. You are basically single pointing with a multiple cutter that is tapered.


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## higgite (Jan 20, 2020)

RJSakowski said:


> Ile time is actually 9:00.  11:16 the the length of the video.



Thanks for catching that, RJ. I corrected my other post.



RJSakowski said:


> Using a straight tap, the thread form will be wrong.  The flanks of the thread won't be equal with the longer flank towards the headstock.  The angle between the flanks will be 60º but they will be rotated by the taper angle, around 1.8º.  In searching. I couldn't find any tapered thread with 24 TPI.  It is possible that he cut the female thread in the same way and the threads would mate properly.  It is also possible that this is just a "made for t.v." video.



Okay, you lost me there unless you're talking about tapered pipe threads, then it makes sense. But, the guy in the OP's video wasn't cutting a pipe thread. He was using a standard 3/8"-24 UNF tap. If you aren't talking about tapered threads, please expound. Thanks.

Tom


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## RJSakowski (Jan 20, 2020)

higgite said:


> Thanks for catching that, RJ. I corrected my other post.
> 
> 
> 
> ...


Yes, I was talking tapered threads.  I had assumed that the operator was cutting a tapered thread from some of the discussion above.  Unfortunately I couldn't understand the operator not read the subtitles. From the point starting at 7:17, it also appears to be a tapered thread as he is using a wrench to continue.  Either that or it's not a very good quality thread.

If he is cutting straight threads, I see no advantage over single point threading.


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## Suzuki4evr (Jan 20, 2020)

RJ I also took it as taper threading. The advantage I see is that if you have to MAKE a single point threading tool then you don't have to because it is already made for you. I must say the discussion around this is going longer than I expected.


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