# Made Some "Big" Threads



## Kevin T (Dec 4, 2021)

Just finished up some big, to me, threads to use as a go/no-go on my next project. 2 3/8-6 to match the spindle thread on my lathe. I plan on making a new spindle collar for use with collets. 

Until I am better, could be never, at using the machinists handbook to understand all the ways to measure threads I feel much better having a test thread in hand to check for fit. 

 I didn't respect the extra forces involved in cutting this large of a thread and ended up breaking the Aloris insert! Nice 52 dollar mistake. Sort of lucky that I am on a belt driven lathe too! Got a little slip in the second and a half reaction to shutting her down! 

Turned out real nice though!




Next to the beat up spindle collar




Test Fit


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## Flyinfool (Dec 4, 2021)

Looks good.
Yes big threads can generate a lot of force. Have to use a lot of shallow passes to get there.

I like those steel toe flip flops....


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## Kevin T (Dec 4, 2021)

Flyinfool said:


> Looks good.
> Yes big threads can generate a lot of force. Have to use a lot of shallow passes to get there.
> 
> I like those steel toe flip flops....


Slippahs my man! 

True about the shallow passes! My ten thou, as read on compound, usual passes were making big hot chips that burned my feet! ;-)


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## Flyinfool (Dec 4, 2021)

.010 on the compound usually means .020 on the Dia. That is a heavy pass for a forming tool.
.010 on the cross slide usually means .010 on the dia or .005 per side.


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## rock_breaker (Dec 4, 2021)

Nice Job, hope the spindle collar turns out as well.   

If you were making that in this area you may have brought on some much needed rain.  

Have a good day
Ray


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## jwmay (Dec 4, 2021)

Flyinfool said:


> .010 on the compound usually means .020 on the Dia. That is a heavy pass for a forming tool.
> .010 on the cross slide usually means .010 on the dia or .005 per side.


I think if he had the compound set over at 30 degrees (typical for threading), .010" on the compound is .005" off the diameter. Actually I already think I'm wrong about that.


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## Kevin T (Dec 4, 2021)

jwmay said:


> I think if he had the compound set over at 30 degrees (typical for threading), .010" on the compound is .005" off the diameter. Actually I already think I'm wrong about that.


Yes, compound set to thread at 29 1/2 deg so it's less than the direct read measurement. I forget the math so I rely on that test thread! lol


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## benmychree (Dec 4, 2021)

I make gages for fitting chuck backplates, and measure the spindle thread with wires or a thread mike and make the gage right on size, I form a knurled handle on them, it reduces weight and provides grip. I see your picture of the tool, same as what I use, when they get ground down from repeated sharpening, I taper them back at an angle as far as the angled mounting surface, this gives much better visibility of the tool point.
I have always set the compound at 30 degrees, and all the journeymen I worked with did likewise.


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## jwmay (Dec 4, 2021)

Oh and also I forgot to mention, Good Job! Looks great!


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## Flyinfool (Dec 4, 2021)

The math is that with the compound at 30°, .010 on the compound will move the tool in .00866 or .0173 on the dia.
29.5° in not much different at .00870 tool movement, or .0174 on the dia. Either way still a lot more than the cross slide.


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## Ultradog MN (Dec 6, 2021)

Though I love carbide, when it comes to cutting threads I'm still a fan of HSS bits.
Carbide likes more speed and pressure to give a good finish which increases your need for being totally on the ball. HSS  allows you to work at a more leisurely pace and lets you take smaller cuts. 
And with HSS a whoops means an inexpensive trip to the grinder to dress your tool instead of a $52 mistake.
Edit:
I meant to add, Nice job you did there.


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## Janderso (Dec 6, 2021)

benmychree said:


> I make gages for fitting chuck backplates, and measure the spindle thread with wires or a thread mike and make the gage right on size, I form a knurled handle on them, it reduces weight and provides grip. I see your picture of the tool, same as what I use, when they get ground down from repeated sharpening, I taper them back at an angle as far as the angled mounting surface, this gives much better visibility of the tool point.
> I have always set the compound at 30 degrees, and all the journeymen I worked with did likewise.


John,
Do you thread, feed in, with the compound or crosslide?


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## Just for fun (Dec 6, 2021)

Looks good Kevin T!


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## Kevin T (Dec 6, 2021)

rock_breaker said:


> Nice Job, hope the spindle collar turns out as well.
> 
> If you were making that in this area you may have brought on some much needed rain.
> 
> ...


Thanks! Me too! I've been going at the collar for a couple days now getting ready to single point the big internal threads! 





I definitely didn't account for how long it was going to take me to open up this I.D. 




My WWII boring bar might need an upgrade to something with less flex! 

Part is sized and ready for the next steps. That is a 3.5" O.D.  Next to the part I am remaking. You can make out the blown out hole for teh spanner wrench in the shadow and the reason for the remake!


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## Kevin T (Dec 6, 2021)

Ultradog MN said:


> instead of a $52 mistake.


The Aloris threading insert I am using is HSS! It's a fancy L shaped affair with mounting holes in it.

I had planned on never needing to replace it, even though I make a lot of threads! My error to let the tool go around an extra quarter turn and cutting on the big dia was too much and the tool caught and twisted and about 1/3 of the 60 degree point cracked off. It is still usable because I ground it a lot to be able to finish but I have to run the tool high to be on center so I re-ordered. BTW Amazon sells Aloris cutters and they are cheaper than the company sells them for and free shipping if you are a prime member.


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## rock_breaker (Dec 7, 2021)

You are doing great. My SIL brought home a shop made boring bar as a result of a shop clean up. It is 1.25" od with a groove in the end fir 0.25" x 0.25" HSS cutting bit and is approximately 10" long; manufacture of materials is unknown. I mention this in light of your rigidity problem. Would you be interested in using it? Hopefully the shipping charges wouldn't exceed the cost of materials to make one in Hawaii. 
I have not attempted to make any mounting brackets for either of my lathes.  
Good luck with your project
Ray


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## Kevin T (Dec 7, 2021)

rock_breaker said:


> You are doing great. My SIL brought home a shop made boring bar as a result of a shop clean up. It is 1.25" od with a groove in the end fir 0.25" x 0.25" HSS cutting bit and is approximately 10" long; manufacture of materials is unknown. I mention this in light of your rigidity problem. Would you be interested in using it? Hopefully the shipping charges wouldn't exceed the cost of materials to make one in Hawaii.
> I have not attempted to make any mounting brackets for either of my lathes.
> Good luck with your project
> Ray


Really nice offer thank you!  I'm not sure I could hold it. I should check my assortment of boring bar holders. Shipping? LOL Shipping is the pain we have to endure out here.

What kind of mounting brackets are you referencing?


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## jwmay (Dec 7, 2021)

Flyinfool said:


> Either way still a lot more than the cross slide.


I'm really having trouble understanding this.








						heres how to get 0.0001" precision on your ancient hobby lathe
					

Criticism of what I describe here is WELCOME!!! Please, lets dissect this, tear it apart, and make it better.   The good news is: I think I am getting control of diameters, +/- 0.0001" (tenths), on my ancient, worn out Atlas 10F lathe.  I also learned something very important about manual lathes...




					www.hobby-machinist.com
				




This thread seems to disagree with your math. But it could be that I'm misusing a word that changes the whole meaning of my statements. Curious.


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## rock_breaker (Dec 7, 2021)

Hello Keven T. The mounting brackets I would (will sometime) make would be for a 4way tool holder to fit my Enco 13x40 lathe. It would have three pieces, the base to be clamped in the  4way , two 1/2" thick arms perpendicular to the lathe ways and having 1.250" holes bored. The 1.250" holes would be made to clamp the 1.250" boring bar. Different size holes would require different size arms or possibly split bushings. Clear as mud, right". Will try to  make a sketch.

From your picture I think my clausing is near the same size, really a bit small for a 1.250" boring bar unless it was made to replace the compound rest. Probably not a good way to cut threads.   
Have a good day
Ray


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## Kevin T (Dec 7, 2021)

rock_breaker said:


> Hello Keven T. The mounting brackets I would (will sometime) make would be for a 4way tool holder to fit my Enco 13x40 lathe. It would have three pieces, the base to be clamped in the  4way , two 1/2" thick arms perpendicular to the lathe ways and having 1.250" holes bored. The 1.250" holes would be made to clamp the 1.250" boring bar. Different size holes would require different size arms or possibly split bushings. Clear as mud, right". Will try to  make a sketch.
> 
> From your picture I think my clausing is near the same size, really a bit small for a 1.250" boring bar unless it was made to replace the compound rest. Probably not a good way to cut threads.
> Have a good day
> Ray


I do have a CXA-41D that can hold it but I found a special cutter in my pile that I think will work. Your offer to help is really appreciated though. I use that holder with a double sided adapter to run 1/2 and 3/4 dia tooling or stock so I didn't recall the major ID. My lathe is a 16" x 6' FYI.


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## Kevin T (Dec 8, 2021)

rock_breaker said:


> Hello Keven T. The mounting brackets I would (will sometime) make would be for a 4way tool holder to fit my Enco 13x40 lathe. It would have three pieces, the base to be clamped in the  4way , two 1/2" thick arms perpendicular to the lathe ways and having 1.250" holes bored. The 1.250" holes would be made to clamp the 1.250" boring bar. Different size holes would require different size arms or possibly split bushings. Clear as mud, right". Will try to  make a sketch.
> 
> From your picture I think my clausing is near the same size, really a bit small for a 1.250" boring bar unless it was made to replace the compound rest. Probably not a good way to cut threads.
> Have a good day
> Ray



Do you mean like this vintage Willaims unit?


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## Kevin T (Dec 9, 2021)

Got past the hump of the collar project! It was a precarious setup without a good boring bar but I found an old lantern tool that did the job. i had to shim it in the tool holder because the shank wasn't square!








I'll probably drill the spanner holes next and then shape the OD of the part. Not sure about a knurl like the one I am replacing. I like to work close when using collets and a fresh knurl might be a hazard!


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## rock_breaker (Dec 10, 2021)

Again outstanding work Kevin T! The plan I am thinking of is constructed 0f all rectangular parts and is held in place by 3 5/16" set screws. Your lantern tool is better as it puts the cutting forces more directly into the lathe frame.
Not much experience with knurling tools but understand the need for strength and ease of use. 
Have a good day
Ray


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## Weldingrod1 (Dec 10, 2021)

Dont be afraid to skim the od of a knurl to make it less fang-y!

Sent from my SM-G892A using Tapatalk


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## Kevin T (Dec 16, 2021)

I realized I didn't post the finished product!  Turned out really nice. I added three spanner holes 120 degrees apart from each other which IMO is how the original should have been.







I'm calling my male thread my spindle thread master and treating it as such. I finally found a use for the printed thread protector I bought when I refurbished my machine. The only thing left to do is to steel stamp the thread size on the bottom.


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## rock_breaker (Dec 17, 2021)

Outstanding work!
Have a good day
Ray


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