Threading with inserts

[PixMan]

I thought it would be good to share more about the threading I did yesterday. I needed to thread 5 different parts with 4 different threads of 2 different leads.

I used full form (cresting) lay-down style (ER) carbide threading inserts. There were two different leads, so I bought two Vardex 16ER1.5ISO grade VSX. I already own 5 of the Carmex 16ER1.25ISO grade MXC. I believe the Vardex grade is PVD TiAlN coating, and the Carmex is PVD TiN coating. The grades are high cobalt content for lower speed rates but high toughness against chipping.

Here's what the Vardex insert looks like after making (1) M25x1.5, (1) M20x1.5, and (2) M14x1.5 threads in 316 stainless steel.


Here's what the Carmex insert looks like after making just ONE M12x1.25 thread, also in 316 stainless steel.


Now here's a better photo of the M12x1.25 thread, which I posted elsewhere yesterday. You would be hard pressed to get a higher quality thread with anything other than thread grinding.


It is especially preferred to use full form threading inserts when making metric threads because they are specified to have a given radius @ both the root and the crest of the thread. With "UN" (Unified National) inch sized threads, the crests of an external thread are flat, the root only is a radius. Lay-down threading inserts for those DO also cut the flat on the crest of those threads. Using hand ground HSS tools you are always compromising, though that's often overlooked in the home shop.

[EdK]

Good to see you back in the shop Ken.

Beautiful threads!

Ed

[PixMan]

Thanks Ed!

I've made more chips in the shop (primarily lathe work) in the past month than I had in the past year!

My motorcycling friend Neil brought me the job for SS axles and a few other bits needed for his custom bike builds (two of them) and it's been fun to make chips again. Earlier this year Darren had come over to make parts for his steady rest project, that was fun too. I don't have any of my own projects planned so jobs like this have been my only endeavor in the shop after the big cleanup.

[dallen]

Ken how about a little more info on the use of inserts and threading, cause I know I could use some.

DA

[PixMan]

Dave,

I'm very well versed in this technology, so fire away with questions.

For starters, let me offer this. First identify the size of the holders your lathe uses. They must be QCTP or indexing four-sided blacks that hold square shank tools parallel to the ways, as the insert holders and inserts have the geometry built in. There are some 6 different I.C. sizes of the lay down inserts available, though probably up 90% of those sold are the "16" (3/8" I.C.) size shown in my photos above.

The nomenclature for the holders can vary, though inserts are fairly standardized. The two biggest makers are Vardex and Carmex, both based in Israel. Oddly enough, Vardex uses a non-conventional numbering system for the "first" characters. Specifically, where I've stated 16ER, Vardex actually uses "3ER".

That first part aside, the ER means "External", and "Right hand". The numbers that follow describe the thread they make if full profile, or generic angle if "partial profile". I should note that there are also partial profile inserts which fit the holders that can make either 8 to 48 threads per inch, 14 to 48 or 8-14 threads per inch. (Convert to metric if you must, I'm lazy.)

There are external left hand, external right hand, internal left hand and internal right hand inserts.

16EL (or 3EL) - external left hand
16ER (or 3ER) - exernal right hand
16IL (or 3IL) - internal left hand
16IR (or 3IR) - internal right hand

The insert designation following the 16xx is, for full profile inserts, what thread pitch they make. The same inserts are used for each pitch, regardless of diameter. For example, here's a few designations I have in stock:

16ER-14UN (14 tpi Unified National, right hand external thread)
16IR-24UN (24 tpi Unified National, right hand internal thread)
16EL-10ACME (10 tpi Acme, left hand external thread)

I have seen holders for the 16 size threading inserts down to 3/8" square shank, and they work fine.

One of the lesser known features though best benefits of the full profile inserts is that you don't need to use pitch micrometers or thread wires to measure the threads as you cut them. Leave the diameter at "nominal" and let the cresting insert cut the finished outside diameter of your thread as it nears finished size. For example, if I'm making a 1/2"-13UN thread, I turn the blank to .500 (or leave stock diameter.) As I'm cutting the thread I wait until I see the threading insert start cutting the O.D., and when that reaches .494" I know I have a finished 1/2-13UN class 2& class 3 compliant thread.

Ask any question at all. If I don't have the answer, I know where to find it. ;)

[dallen]

so with a full profile insert I would need to have one for each different thread pitch that I was going to cut,

I have several different holders, is a small 3/8 holder designed to use the 16ER series inserts, the one I use the most is a TLSR-163D Top Loc that I modified by cutting a dovetail in it so that it mounts directly onto the QCTP on my 12 inch lathe and the inserts I have are some that I got off of the Evil Bay for like cheap but I like it cause it does a decent job of threading, not sure on the insert number but I know that there are a couple different ones cause some are purple and some TIN coated.

I also have both a right and left vertical threading holders but don't care for them too much, something about them I can't put my finger on that I don't like.

[EdK]

(12-30-2013, 06:45 PM)dallen Wrote: so with a full profile insert I would need to have one for each different thread pitch that I was going to cut,

I have several different holders, is a small 3/8 holder designed to use the 16ER series inserts, the one I use the most is a TLSR-163D Top Loc that I modified by cutting a dovetail in it so that it mounts directly onto the QCTP on my 12 inch lathe and the inserts I have are some that I got off of the Evil Bay for like cheap but I like it cause it does a decent job of threading, not sure on the insert number but I know that there are a couple different ones cause some are purple and some TIN coated.

I also have both a right and left vertical threading holders but don't care for them too much, something about them I can't put my finger on that I don't like.

David,

Post some pictures of the tools you've got. That will help a lot.

Ed

[dallen]

have to dig the camera and take one, don't have one on the computer.

Ed ask me to post a photo so here is one of the two holders that I mentioned in the above post.

[PixMan]

OK, so the holder on the left is one that uses the more-common 16ER inserts. The large modified one on the right is similar to one I also have, though my 1" square shank holders fit into the CA/400 size tool blocks for my QCTP. The inserts that one uses can be single point threading, straight grooving of widths up to .189", and full radius inserts. Very useful tool, though the one on the left is technically capable of making nicer threads.

You can actually get cresting inserts for the one on the right, though they are limited in availability and as such are costly. I think only Kennametal makes them. HOWEVER, if your tool holder is a Sandvik Coromant Top-Lock, it uses Sandvik Coromant TLT threading and TLG grooving inserts that have a clamping notch long the top of one side of the insert. All other Top Notch/V-Lock inserts of the same genre use an angled radiused groove on the TOP of the insert. The good news is that you can access a whole new world of insert by changing the insert clamp of the tool holder. The clamps are interchangeable and can be had from Kennametal, Valenite and many others for under $10.

Your lay-down threading holder is one of the smaller ones. As such, it may not have the interchangeable anvils under the insert as the larger ones do. This is also common with smaller internal threading bars, as there's no space on the holder to add the interchangeable anvil. Here's what my larger holder looks like under the threading insert:



The vast majority of threads you may do would fall within the range of the "standard" tilt of the insert, about 2º to 3.25º helix angles. The interchangeable anvils of the larger tool holders allow you to make coarser small diameter or multi-start threads with increasingly higher angles for right hand threads, or by changing to "minus" angle anvils you can make nice left hand threads.

[wrustle]

Ok, I'll bite..........

What's up with the foam on the torx driver?