# My first threads



## David_R8 (Apr 7, 2020)

I’ve been learning to thread over the last few days and tonight I had a major success. 
My first attempt in aluminum was a minor success. 






I had the compound at the wrong angle and I lost track of zeroing the cross slide so I had to re-zero once or twice. 

Second attempt tonight on some 10L went loads better. 
Faced and turned to no particular diameter. 






All blued up and gutter cut. 






Scratch pass for 16 TPI 






All done. 






Spurred on my success I turned a piece of CRS to the major diameter for 3/8” and went for it again. 






Success!







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## YYCHM (Apr 7, 2020)

Nicely done!  Mine never turn out that crisp.  It that a threading specific tool bit you're using?

Craig


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## David_R8 (Apr 7, 2020)

YYCHobbyMachinist said:


> Nicely done!  Mine never turn out that crisp.  It that a threading specific tool bit you're using?
> 
> Craig


Thanks Craig, I'm totally stoked as it feels like a major milestone in my learning.
It is an 16ER insert on a SER1212H16 holder. It came as part of a set of insert tool holders. I'm quite happy with the whole set actually. Do need to get some more CCMT inserts though.
https://www.banggood.com/Machifit-7...p-1102496.html?rmmds=myorder&cur_warehouse=CN


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## Everett (Apr 8, 2020)

Nice!  I find the threading operation fascinating, really.  Learn something new every time.  I admit to cheating on the math a lot by using this site for measurements over the wires:

http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

I like those style inserts too, but found that they give a better surface finish at threading speeds that increase the pucker factor . . . still use the HSS ground tool too.  Those threads look good, better than my first ones, for sure!


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## John Conroy (Apr 8, 2020)

Nicely done!


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## Hruul (Apr 8, 2020)

Very Nice!! I hope my first attempts go as well.


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## Tom Kitta (Apr 8, 2020)

Looks good. With gummy metal and low speed it sometimes helps to clean the thread up with a die afterwards.


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## David_R8 (Apr 8, 2020)

Thanks all!
Good idea @Tom Kitta, I will give that a try.
CRS is pretty awful as far as my experience goes.


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## Crosche (Apr 8, 2020)

Nicely done!


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## Johnwa (Apr 8, 2020)

You’re motivating me to take another stab at a backplate for my Southbend.  My blank is 4140.  I got impatient on my first attempt and tried to big of cut.  My boring bar mounting moved and then it was downhill from there.

I second @Tom Kitta comment on cleaning up with a die.


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## David_R8 (Apr 8, 2020)

Johnwa said:


> You’re motivating me to take another stab at a backplate for my Southbend.  My blank is 4140.  I got impatient on my first attempt and tried to big of cut.  My boring bar mounting moved and then it was downhill from there.
> 
> I second @Tom Kitta comment on cleaning up with a die.


Go for it! Internal threading is next on my learning curve.


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## Tom Kitta (Apr 8, 2020)

Internal boring, from a lot of experience I now have, to be done precisely, needs very fine cuts at a low feed in rate - i.e. you slowly are taking the final cut feeding say 0.002 per rev. This will get you accurate hole you are expecting. 

Rough boring can be done of course when you are far away from final dimension - just make sure you don't go so far that you break something.

Internal threading is not much different then external - even LH internal threading is not a big deal. Main issue is that you need a tool to do the internal thread - making one from HSS can be an "adventure" in grinding. As in grinding the sucker from a tool blank can take a while. IF you have a boring bar with some insert or even HSS insert its not a big deal.

Main issues with threading is fast threading that looks good close to the shoulder - here is when pp try all sort of strange things like tools that are placed upside down etc.


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## Brent H (Apr 8, 2020)

@David_R8 - for me, depending on accuracy required - I will use a tap and die up to 1/2” or 13mm - once accuracy and such enters the picture:

set up on the lathe and single point thread to a reasonable depth (say half thread) and then run over with a die.  You have already set up the thread path.   Typically you will not have a die over 1/2” so You will need to cut threads using the lathe all the way.  

Internal threads - no problem - run your threading bar at final depth several passes to clean up any deflection in the bar.  
For left hand it is great to run your lathe in reverse and cut in on the opposite face of the bore (you can see what you are doing and feed direction stays the same - going into the bore) other way is to run lathe in forward and start your thread at the back of the bore with reverse feed.  I have had success both ways.  

sharpening your threading tools is important.   It will take practice.  I have a 3/8 HSS with a beauty 60° from my early days (30 years ago) that works great with just the odd stoning for threads 3/8 and bigger.  

for the smaller lathes you can only use the carbide inserts to a certain thread size as they will bottom out before the thread depth is reached ( blew out one cutting a 1-8 TPI).  

chasing threads is also fun.  (For repairing threads or if you remove your piece for a test fit -Doh!-  or if you have great success screwing on a nut but it does not fit a higher tolerance 50 taper .... argh!).  

practice will get you going!!


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## Tom Kitta (Apr 8, 2020)

I actually have large dies - over 1" in size (I think I have NF / NC in all sizes up to 1" as well as some specials). Problem is situations where thread is strange. Like 1/2-12 --- not 13 but 12 (hello BP mill). Or when I was doing a collet chuck - it is M50 - 1.5 if I recall correctly. 

One problem with large NC thread is that it may be a bit hard to thread by hand - even with some large holders I have.


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## David_R8 (Apr 8, 2020)

I have set of NOS Patience & Nicholson taps and dies. 1/4 - 3/4 UNC and UNF


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## Brent H (Apr 8, 2020)

@Tom Kitta  - not saying them thar dies are not out there but pretty costly for most hobby guys.  I have taps Over 1” but dies I am maxed out at maybe 9/16 - good ones are $$.  at work- different story. I think we go up to 32 mm - but as you say, dang hard to thread onto anything- for clean up of threads though- perfect.  

@David_R8 - very nice set of taps and dies.  

Here is a handy die holder you can run on a lathe that helps keep things straight and holds dies for quicker threading.


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## DPittman (Apr 8, 2020)

David_R8 said:


> I have set of NOS Patience & Nicholson taps and dies. 1/4 - 3/4 UNC and UNF
> View attachment 8533


Ooo those look nice!


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## David_R8 (Apr 8, 2020)

DPittman said:


> Ooo those look nice!


Never been used!


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## trlvn (Apr 9, 2020)

David_R8 said:


> Never been used!


I hate to break it to you...but I don't think these have the collector value of, say, Beanie Babies!  

Craig in Oakville


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## shooter910 (Apr 9, 2020)

Great Job!!    it is always exciting moving into the next cool thing to try!!  but if i might add i use a tread file to finish mine, you can get them as single point 60 degree files or as multiple tooth file that exactly match the pitch you are cutting then just "sneak" up on the fit you are looking for,this pic is not mine just stole off internet to help show


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## Bofobo (Apr 10, 2020)

So who else has used muscle power to form threads on a lathe besides me? I used power feed for backing out after the cut some times but I turned the chuck by hand after engaging the feed and setting the start depth with .005” cuts, the material was brass and aluminum the thread was fine and the size about 3/4”. Best thread I think I’ve made yet. No chance of cat ass trophie


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## Johnwa (Apr 10, 2020)

[mention]Bofobo [/mention] yes I’ve done it that way. It works well especially when threading up to a shoulder. 


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## Johnwa (Apr 10, 2020)

I got up the nerve for another attempt at a back plate.  It turned out not to bad.  Those are chatter marks but they look worse than they are. I used a 16IR insert on 4140 and I doubt my lathe could do any better.  
Right now the collet chuck is frozen onto the backplate.  While I was sneaking up on the central boss I decided I should warm up the chuck first. As soon as it started to slip onto the cold backplate it shrunk on.


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## YYCHM (Apr 10, 2020)

Nice work John.  Was shrink fitting that collet chuck on intentional?


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## Johnwa (Apr 10, 2020)

I didn’t intend for a shrink fit but I did want it as close as I could get.  Warming up the chuck ensured that I wouldn’t cut the backplate too small.  Tomorrow I will see how hard it is to get off.


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## PeterT (Apr 10, 2020)

Looks great! In the future if you have an assembly like that where removing light interference parts is required, consider pre-drill some threaded holes in one of the plates. Then you can put some bolts or set screws in from behind & kind of jack screw the plates apart. Need even & equal pressure obviously. But it beats trying to wedge things in from the side which immediately causes mis-alignment & can make parting ways worse.


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## Johnwa (Apr 10, 2020)

Peter, the chuck has threaded holes so I should be good. There probably was less than 40 deg temp difference so it shouldn’t be too tight.


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## Johnwa (Apr 10, 2020)

According to some online calculators there might be as much as 0.002 interference. It might be tighter than I thought.


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## PeterT (Apr 10, 2020)

I have a whole new appreciation for thermal interference fits from my radial engine cylinders. Coincidentally also 0.002" diametric. Doesn't sound like much but that can make for a lot of gription between parts unless you have a means to heat one part rapidly before the other conducts the heat & just grows at the same rate (assuming steel + steel). And even if you have different thermal expansion materials like aluminum + steel, any surface imperfections like typical machining marks act like engaged threads so the thermal gap has to clear those engaged hills & valleys.

It kind of clicked with me when you see vids of those big hydraulic presses installing or removing bearings. When its the same temp & minor interference fit, the  amount of axial force can be considerable. And typical bearings & bushings are relatively small surface contact area.


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