Full profile threading insert

[dpb]

I've done barrel threading with a Mesa partial profile tool, and a hand ground HSS tool, both with good results.
I'm interested in full profile insert tooling. Which specific inserts have given you the best thread finish at conventional lathe speeds, say 200 rpm / 60 sfm, or less?

 

[Ray C]

I've done barrel threading with a Mesa partial profile tool, and a hand ground HSS tool, both with good results.
I'm interested in full profile insert tooling. Which specific inserts have given you the best thread finish at conventional lathe speeds, say 200 rpm / 60 sfm, or less?

Carmex.... hands-down winner for slow speed hard material. Use the selector on the left side of their page then check eBay etc once you have the part number. I started using these a long time ago and and purchased multiple packs in the most common sizes; it looks like prices have increased considerably. They're worth it...

http://www.carmexusa.com/products/TT00/TT00 LD00/TT00 LD00 I000/TT00 LD00 I000 UN00.aspx


Ray C.

 

[dpb]

Thank you, Ray.
Is there a particular grade you prefer? This is where I get hung up, so many grades, and not much information (that I've found so far) on how to choose for a particular application.

 

[Ray C]

Thank you, Ray.
Is there a particular grade you prefer? This is where I get hung up, so many grades, and not much information (that I've found so far) on how to choose for a particular application.

From their resources page [ http://www.carmexusa.com/content.aspx?file=customerpages/inch_catalog2018.htm ], I've included the technical threading guide. The grades are shown in the first couple pages and are based on the type and hardness of material you're working with. All mine are BXC but they work just fine on all materials. For manual, one-off threading jobs, any of them will do fine. The differences/benefits in grades are seen in high-production environments when you're cutting thousands of inches of thread per day.

Ray

 

[wrmiller]

I too have been using the a hand ground cutter for threads, and have been looking at the threading bars that Matt at PM sells. The inserts they use look similar to those in your link, Ray, but I will have to Google 'full profile' as I am not familiar with the term or it's meaning.

 

[Ray C]

I too have been using the a hand ground cutter for threads, and have been looking at the threading bars that Matt at PM sells. The inserts they use look similar to those in your link, Ray, but I will have to Google 'full profile' as I am not familiar with the term or it's meaning.

You've probably figured it out by now Bill but, full profile cuts the crest once the root reaches the depth defined for that pitch. Full profile inserts are specific to a particular thread pitch. If you have an insert for 20 TPI, it will make a thread where the root and crest are exact to specification provided you started with stock with adequate diameter to achieve the pitch diameter for the desired class of fit. Once the insert gets to a depth that it's cutting the full profile of the crown, you're done. Usually, you'll start with a very slightly larger diameter and sneak-up on the final size by letting the insert cut the crown off until the desired class is satisfied.


Ray

 

[wrmiller]

You've probably figured it out by now Bill but, full profile cuts the crest once the root reaches the depth defined for that pitch. Full profile inserts are specific to a particular thread pitch. If you have an insert for 20 TPI, it will make a thread where the root and crest are exact to specification provided you started with stock with adequate diameter to achieve the pitch diameter for the desired class of fit. Once the insert gets to a depth that it's cutting the full profile of the crown, you're done. Usually, you'll start with a very slightly larger diameter and sneak-up on the final size by letting the insert cut the crown off until the desired class is satisfied.
Ray

Just ordered the OD/ID threading tools from PM. They come with partial threading inserts, but I want to experiment with a couple of full profile inserts also. May be better for barrel threading.

 

[dpb]

I have ordered the Carmex BXC, in 16 & 20 tpi. I'll report on my results.
Thanks for the help, Ray!

 

[Ray C]

In my view, there is no right or wrong when it comes to full vs partial profile inserts. Either can be used in any circumstances but, full profile is helpful (but not essential) when you need to meet a particular class of thread on a standard size diameter or bore. For general work, partial profile is just fine. Dig the thread, skim the crest with a sharp cutter, make sure it fits and call it a day.

Only on a few occasions did I have jobs with specs on the threads. On those occasions, full profile inserts saved me some time. For my own stuff??? -meh!

Ray

 

[Ray C]

I have ordered the Carmex BXC, in 16 & 20 tpi. I'll report on my results.
Thanks for the help, Ray!

Cool... Everything has a learning curve so take a close look at that insert, understand what it does and develop your own technique on how you can utilize it. One thing I will say, for carbide, they are remarkably sharp and have a very positive face angle. All standard cautions apply (translated, don't go below centerline with it).

Ray C.