Internal threading tools and cutters

[pmath]

The couple of recent threads discussing external threads have helped me a great deal. After several years of frustrating results I've had a really good run with it this weekend.

After a very careful adjust and clean up of my mnini lathe even my internal threads are working better, but I am frustrated that I can't get as clean a cut (in aluminium) using my HSS tool as I can with my carbide inserts.

OK, I thought. I'll buy both internal and external tools and a new parting tool while the aussie dollar is running nicely high. Trouble is from the recent links you've all provided I can't figure what to buy for internal threading.

Is it the same holder with a different insert?

Or a dedicated holder and insert?

Sorry for what seems like such a dumb assed question, but I can't figure it out.

Peter

 

[Codiak]

I ended up with this http://littlemachineshop.com/products/product_view.php?ProductID=3695&category= and am very pleased. Maybe Curtis has another idea.

http://littlemachineshop.com/products/product_view.php?ProductID=3695&category=

 

[precisionworks]

I can't get as clean a cut (in aluminium) using my HSS tool as I can with my carbide inserts.

In sticky & gummy materials (like 6061) coated carbides almost always perform better than HSS.

I run a HSS thread tool for just a few jobs (very large pitch & very small pitch threads). Coated carbide does 98% of the threading. Unless there's a compelling reason to use HSS, set it aside for those few special situations where it works better.

The tool shown below is an Armstrong #50 ... invented before WWII, so the technology (if there is any) is not cutting edge ... pun intended :nana:

The nicest feature of the A50 is that it is a form tool, meaning that a worn out edge is not a big problem. Touch the top of the thread form on a fine grinding wheel, turn in the adjusting screw, recenter the tool, and go back to threading. The drawback, as with all HSS tools, is the very low speed at which it can be run, which sometimes produces threads that are less than smooth.

I wouldn't rush over to eBay & buy an A50, as it really is a specialty tool for those few situations where a coated carbide threading insert has problems.

 

[wquiles]

For 3-4 years now I have exclusively been using a SECO Snap-Tap Internal Threading Toolholder, which uses custom threading inserts from SECO.

The toolholder part # is: SNR000625-60-16 (5/8" shank)

The Insert parts# is: 16NR AG55 CP500 (TPI range 48-8)

The SECO inserts also come in full profile and partial profile. I got a few pictures that show the full profile insert vs. the universal 60 deg insert (partial profile). The insert in the tool is the full profile 20 TPI insert. The insert on the tool is the partial profile insert:

And the resulting threads are very nice (using the partial profile inserts here):

Will

 

[pmath]

That's very neat. Thanks. I now know what I'm looking for.

Peter

 

[pmath]

Thanks Will. I've three good suggestions and some great photos. Now reaching for the credit card. Aussie is $1.06 aganist the greenback this morning!!

Peter

 

[pmath]

Thanks Will. I've three good suggestions and some great photos. Now reaching for the credit card. Aussie is $1.06 aganist the greenback this morning!!

Peter