# Lathe Threading Tools



## PeterT (Dec 24, 2018)

Specifically AliExpress sourced toolholders & inserts. I've had these sitting around since summer & finally tried them out. Note, I am not an experienced threading guy so had to learn this stuff by reading & web surfing. From what I can tell, these are pseudo clones of Carmex which are very spendy. Like 100$ toolholders & 20$ inserts. The Ali toolholders are about 10$ and pack of 10 inserts for 40$. I was a bit suspicious because I didn't see the anvils mentioned in the clones. I'm not sure what to tell you there yet. Possibly they just mill the pockets for the nominal rake angle, so you get what you get dictated by the insert & tweaking is just not possible. Or maybe anvils are available but by a different clone suppliers. Some sellers have rather brutal catalog descriptions. I tried to source from what looked to be more machining orientated as opposed to machine tools and Pokeman cards.

Anyways, onto the results. So far I think I would call it successful. This was just 6061 aluminum & 12L14 steel testers. I have to make my actual parts on stainless. They fit my (7/16x24 TPI) tapped holes very niceley which is a very gratifying feeling. I now have all kinds of threading projects I want to tackle when the time comes.

Those of you experienced threaders who measure pitch diameter with the 3 wire method have my respect. I could not get along with them. I've read recommended tricks like sticking them into position with grease, or rubber accessory do-dads to hold them on the (conventional) mic or hold 2 wires with the lower jaw & slide the top one in under the upper jaw.... ACK!  I must have dropped them in the chip pan 10 times & never trusted the measurement. I have an import thread measuring mic & it is so much easier. You just have to remember to pre-zero with each vee + point set though.


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## JohnW (Dec 24, 2018)

Great job on the threading!


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## RobinHood (Dec 25, 2018)

PeterT said:


> Those of you experienced threaders who measure pitch diameter with the 3 wire method have my respect. I could not get along with them.


I would not call myself “experienced” as far as the threading side goes, but i have gotten used to using the 3-wire method to measure PD over time. I had no choice on the last project since i have no thread micrometer and the mating parts are in Ontario....
The project was studs in 4140, 15/8” OD - 51/2 TPI on one end and 10 TPI on the other.








It is tricky work as the anvils of your mike are sitting on the tangents of the measuring wires which in turn sit on tangents in the threads. I found if the wires are wobbly and want to fall, i am not measuring on the tangents and need to re-adjust.

Another interesting part the customer wanted, was threads on a 304 SS sched 40 pipe: the first 3/4” on one end needed to be 3/4” NPT that transitioned into 3/4” National Straight Pipe Thread. The other end had just NSPT... here is what that looks like ( you can just make out the slight taper on the beginning of the  right hand end)


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## John Conroy (Dec 25, 2018)

Nice work Peter!


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## PeterT (Dec 25, 2018)

Nice threading RobinHood

These are crazy expensive. Do you think they would help or seem gimicky? Seems like a perfect application for 3DP. I'll do the CAD if someone wants to print them.
https://www.linear-tools.com/tools/thread-wire-holders.html

Dedicated? But I don't see how the wires could float. Again crazy $$.
https://www.cutwel.co.uk/measuring-...meters-with-635mm-spindles-insize-7382-series

I'm floored at how expensive thread measuring stuff is. Like $200-300 beat up Mitutoyo mikes with missing anvils. New they are like $500. Lots of brand name metric ones on Ebay more reasonably priced, fewer imperial. Why is that? Some offshore offerings. I don't get a warm & fuzzy with the Accusize based on comments.
https://www.shars.com/0-1-screw-thread-micrometer
https://www.accusizetools.com/screw-thread-micrometers/

Not clear to me if the Ali digital switches between metric & imp? The anvils sets infer that it should work this way
https://www.aliexpress.com/item/Scr...lgo_pvid=2c88d9bb-c57d-451c-9cc5-91bb3cf302c9

https://www.aliexpress.com/item/Inc...lgo_pvid=2c88d9bb-c57d-451c-9cc5-91bb3cf302c9


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## PeterT (Dec 25, 2018)

Question - when threading with a gearbox lathe, I assume once you pick a speed, you should not switch to a different speed selection, because you are altering the gear tooth selection slightly & messing up prior alignment with threading lead screw engagement? Same thing for switching to neutral & rotating the chuck?


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## Janger (Dec 25, 2018)

RobinHood said:


> I ...
> 
> Another interesting part the customer wanted, was threads on a 304 SS sched 40 pipe: the first 3/4” on one end needed to be 3/4” NPT that transitioned into 3/4” National Straight Pipe Thread. The other end had just NSPT... here is what that looks like ( you can just make out the slight taper on the beginning of the  right hand end)
> View attachment 3892



Robin - did you make the nuts too? Interesting finish which I like - how did you do that? bead blast?


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## Janger (Dec 25, 2018)

PeterT said:


> Question - when threading with a gearbox lathe, I assume once you pick a speed, you should not switch to a different speed selection, because you are altering the gear tooth selection slightly & messing up prior alignment with threading lead screw engagement? Same thing for switching to neutral & rotating the chuck?



I don't think switching speeds matters as the gears for that are between the motor and the spindle. The spindle is connected by different gears to the lead screw and I don't think changing speed would change that relationship? I do agree changing to neutral would be a problem.


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## DPittman (Dec 25, 2018)

RobinHood said:


> I would not call myself “experienced” as far as the threading side goes


I dunno know...an inexperienced person could not do what you described and did!  Nice work.


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## PeterT (Dec 25, 2018)

Hmmm.. the Christmas fat has enveloped my brain, I cant think straight! LOL I think power goes motor > spindle gears > feed gears. So if I alter speed gears, wouldn't that potentially mismatch gears a bit out of position. I recall seeing this discussion but not the answer. Maybe it varies by lathe.


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## RobinHood (Dec 25, 2018)

PeterT said:


> Question - when threading with a gearbox lathe, I assume once you pick a speed, you should not switch to a different speed selection, because you are altering the gear tooth selection slightly & messing up prior alignment with threading lead screw engagement? Same thing for switching to neutral & rotating the chuck?


As Janger mentioned, changing speeds does not affect the threading op, including going into and out of neutral. That is because the threading gear train is directly connected to the spindle via the feed box and selectors. As long as that feed train stays in mesh, spindle speeds and direction of rotation can be changed without losing the indexing.


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## RobinHood (Dec 25, 2018)

PeterT said:


> I think power goes motor > spindle gears > feed gears. So if I alter speed gears, wouldn't that potentially mismatch gears a bit out of position. I recall seeing this discussion but not the answer. Maybe it varies by lathe.


That could well be. But as long as the spindle drives the feed box (either via change gears or directly), once the feed relationship (thread pitch) is established, it remains constant regardless of spindle speed.

As an example, in this case i turned the spindle by hand to re-thread the acorn nut. I set everything up for 10 TPI. I fed in by feel so as to just cut out all the stud's threads which was rusted and unusable. The lathe was off. Only to feed the carriage out of the bore did i turn on the machine.

A SS acorn nut stuck to a stud; the stud was cut off and  bored out and you can just see the thread peaks showing





and after the thread clean-up the nut was saved...


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## RobinHood (Dec 25, 2018)

Janger said:


> Robin - did you make the nuts too? Interesting finish which I like - how did you do that? bead blast?


Yes, i did make them.
They are 304 SS flat bar stock rough cut to hex and then milled the flats in the indexer, followed by threading on the lathe.
The finish is achieved with a SS wire wheel. I have no bead blaster.


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## DPittman (Dec 25, 2018)

Is anyone else's significant other shocked that they are reading machining forums today? LOL Merry Christmas.


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## RobinHood (Dec 25, 2018)

PeterT said:


> These are crazy expensive. Do you think they would help or seem gimicky? Seems like a perfect application for 3DP


I could see them help. I looked at something similar, but just learned how to use the wires instead. The dedicated ones are nice, but again, I could see me not having the correct size and being SOL. So I just have a good set of wires which I measure and put into a thread calculator like this to get the dimension that I need over the wires:

http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

I adjust and recompute with my wire size. Worked great so far.


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## RobinHood (Dec 25, 2018)

PeterT said:


> Lots of brand name metric ones on Ebay more reasonably priced, fewer imperial. Why is that?


I believe that is because in Europe most people use thread mikes and not wires. Just like in Europe most folks use Inside mikes vs the snap gauges that are popular in North America....


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## RobinHood (Dec 25, 2018)

DPittman said:


> I dunno know...an inexperienced person could not do what you described and did! Nice work.


Thank you sir.


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## PeterT (Dec 25, 2018)

Wires is the least expensive way to go for sure. No micrometer upgrade required. Note to self. Shars has progressive digital thread mics that come with set of IMP anvils. But you can buy metric anvils & then hit the MM button & measure metric threads. Shars is expensive shipping though.
https://www.shars.com/products/measuring/micrometers/0-1-electronic-screw-thread-micrometer
https://www.shars.com/products/measuring/micrometers/metric-thread-micrometer-anvils-1-6-pairs-set

I've seen some lookalikes on Ali but not that much differently priced thus far looking they either don't come with anvils or default to metric anvils included.


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## Dabbler (Dec 25, 2018)

I've ordered from Shars before, and if you follow up with a phone call to their 'technical guy' who will change your shipping to USPS and recalculate your cost.  If you are ordering heavy stuff, they will ship via truck, but you again have to call to alter your order.  saves $$$ on shipping though.


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## Everett (Dec 25, 2018)

I've found using wires isn't that bad as long as the math has been done correctly for the pitch diameter to the measurement expected over wires.  For that, under full disclosure, I use the Theoretical Machinist online calculator page and as long as I put the right numbers in (which I didn't one time . . .) then it works out well for me:
http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx
The down side is that it only does Unified thread pitch calculations, never tried doing it with an SI Metric thread as most of what I do is in the Imperial system.  

I agree with PeterT that the thread measuring equipment is outrageously priced for what it is compared to regular micrometers.  Way too expensive for a hobby shop, for sure.  Micrometers are $$$, and it would cost a fortune to have an assortment of GO-NOGO gauges even if you sourced out of former Soviet states.  As mentioned though, thankfully I've found that a wire set is still much cheaper and after dropping them into the chip pan a lot one can get the hang of them after a while.  I generally do the two on the bottom and one on the top.


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