Cutting threads

Coyote Shadow Tracker

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You can achieve excellent finish at low speeds with carbide. You just have to use the right tool. Trial and error. But HSS is much more cost effective for the hobby guy. And less of a learning curve. Most want to jump into carbide thinking its easier but its not.
Carbide chips at slow speeds when you say "excellent Finish" at low speeds - what are the speeds?
HSS slow, 50RPM to 75Rpm fast. there is no need to speed everything up, even production Match chambers are done SLOW
 

Alex Wheeler

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Different grades of carbide have different edge preps. Some are dull for heavy cuts and have to be run hard and fast to get a good finish. Others are razor sharp like tools meant for aluminum and you can leave a great finish with light cuts and almost any speeds. I typically thread with carbide at 180-275 rpm, but can go slower and still get the same finish, it just takes longer. I chamber at 275 with hss reamers. I have a few carbide reamers too, I run them at the same speeds. Edge prep is everything in carbide and theres people that make a living knowing what tools to use for what jobs. Since most tools are not made for what we are using them for, its trial and error to find the ones that work. I do think hss makes the most sense for the hobbyist unless you want the learning curve involved with carbide.
 

shortgrass

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You've got negative rake, positive rake and neutral inserts and tool holders. Dozens of different inserts available for each. Many, many different styles, which means different tool holder for each style. Some triangle, some square, some parallelagram, some round (for turning/facing) and others, too (like WNMG). Thousands of $$$ can be tied-up in tool holders and inserts.
 

bamban

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Just a hobbyist, no business commitments, time is no issue, but I still use carbide inserts. Have multiple holders for DCGT, VCGT, CCGT, WNMG, TNMG, and laydown threading bits. All uncoated intended for Aluminum. I like WNMG with 6 sides to wear out for roughing. All these uncoated real sharp bits are extremely fragile, lost a few due to carelessness.

Tool holders, I use the Warner for the VCGT bits. Use VCGT 221 or 220.5 for crowning.

For square, acme, and grooving I use ThinBit carbide inserts. Have their threading and grooving holders. I did order special bit from them for threading 60 degrees close to shoulder.

Screenshot_20210728-132133_Adobe Acrobat.jpg


I did spend quite a bit trying to figure out what works for me with my limited skills, and what does not. I did not start learning how to run machines till after I was retired for a few years, never tried to learn how to grind bits. Maybe now I can learn.
 

shortgrass

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Carbide chips at slow speeds when you say "excellent Finish" at low speeds - what are the speeds?
HSS slow, 50RPM to 75Rpm fast. there is no need to speed everything up, even production Match chambers are done SLOW
OK, say you are turning 1 1/16" diameter. 75SFM is fairly conservative for barrel steel with HS tooling, considering the weight and rigidity of what many use for a "gunsmithing lathe". 75SFM at an 1 1/16"dia. translates to 270RPM! 50-75RPM is just loping along! Even if you are threading @50SFM, that's about 180RPM. (these are numbers for high speed steel tooling). "Match" chambers are really not done "SLOW". A 'match chamber' usually only has different dimensions than SAAMI (a longer or shorter throat or maybe at a different angle, a tighter neck diameter). "SLOW" just means the tool rubs more than it cuts. I can pretty much say, that when a chamber is cut the "old fashioned way", by cutting a short ways, withdrawing the reamer and cleaning it and the 'hole', re-lube and then cut again, the reamer gets 'rubbed' to death over time, the edges don't dull from cutting but from rubbing. I have been running a low pressure muzzle flush system since before it became popular and have reamers which have cut 15+ chambers and are still cutting strong! After 15-17 chambers I send 'um to Dave for a re-sharpening if they need it or not!
 
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066wally

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You can achieve excellent finish at low speeds with carbide. You just have to use the right tool. Trial and error. But HSS is much more cost effective for the hobby guy. And less of a learning curve. Most want to jump into carbide thinking its easier but its not.
I'm learning this is true.
 

Boe

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I haven't seen this mentioned unless I have overlooked it, Is your threading tool on center?

I thread with a nitride coated carbide insert at 60rpm. The finish rivals any HSS tool. And you don't have the BUE like HSS.

Richard Hilts
Hilts Accuracy Custom Rifles
www.hiltscustomrifles.com
 
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milestown

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Nov 13, 2014
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I haven't seen this mentioned unless I have overlooked it, Is your threading tool on center?

I thread with a nitride coated carbide insert at 60rpm. The finish rivals any HSS tool. And you don't have the BUE like HSS.

Richard Hilts
Hilts Accuracy Custom Rifles
www.hiltscustomrifles.com
Richard
Thanks for the info on cutting inserts. How much do they cost?

Hal
 
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