Full profile threading insert

D

dennisinaz

New member
For those of you using insert tooling for threading, have you ever used a full profile insert (pitch specific) for chambering a barrel, if so, do you use American UN 60* V-form or some other configuration?
 
I do too. Same Iscar inserts. You have to keep up on measureing with the wires though. For instance if a nice fit was .041 on the compound set at 29 degrees with standard 60 degree tool, now you will notice that .039, or .041 will give a good fit. With the full profile the last cut takes some off the top of the threads, and you can have a looser than desired fit with the barrel. If you are not carefull.

Paul
 
I wondered about taking the top of the threads off. I might have to get a full profile and try it. I use Sandvik but they all make them.
 
pbike, you need to leave the OD larger with a profile insert. Taking the tops off of a thread has nothing to do with fit, it's the pitch dia that matters.
The profile insert, tops the threads when the pitch is at it's proper depth. Thus the rough od is not as important.
The od of the part being threaded is more critical with a partial profile, or plain threading tool, with a profile, as long as its bigger than required it's a go.
 
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I have found when using the full profile cutters, exactly what you state. You worded it better than I could and I thank you. For Instance when installing Gene Beggs tuners, Gene states that you cut to .875 and thread for 28tpi. What I have found is that you can cut to .890 and begin cutting for 28 tpi, when the tuner fits snug you are there. It seems to be about .022 on the compound. And the last few cuts are taking top and bottom off the threads on the cut.

Paul in Michigan (Pbike)
 
Full-profile inserts might require fewer passes than a partial profile insert. A partial profile has a small nose radius (which effectively makes it longer) to properly cut the root of higher TPI threads. I don't think this matters much when it comes to threading a barrel. Eliminating a few passes on a manual machine doesn't save much time.

A full-profile insert cuts the flanks and crest of the thread simultaneously. The entire thread profile is ground into the insert. They will leave a very nice and finished looking thread with few if any burrs on the crest. They'll also make sure the crest is cut properly and will help to insure that the crest is not interfering with the root of the internal thread you are fitting.

A downside is the cost of all the extra inserts you will buy to cover the threads you want to cut.
 
One other tidbit is usually you need all the shims that are placed under the various inserts, it's not a very efficient system for casual use. The insert has a radius instead of a sharp edge, that's where they shine, is in CNC equipment where the SFM rates are high. A cnc will easily destroy v thread tooling.
 
I just got off the phone yesterday with my tooling supplier. Carbide threading inserts are indeed available in sharp grinds, but you have to know what to order. And "v thread tooling" does not know when it is on a CNC machine. It's all in the programming.

I am getting some new threading inserts, and will report back when I test them on 416SS.
 
Can someone post a picture of what these inserts and the tool look like. I've heard about them but never seen an example.
 
TRA said:
One other tidbit is usually you need all the shims that are placed under the various inserts, it's not a very efficient system for casual use.
Click to expand...

For threading barrel tenons the standard 1.5° helix angle anvil shipped with the tool-holder is most likely the only angle you will need.

Pictures and most if not all you need to know about inserted threading is right here http://www.vardexusa.com/vardex-pdf/thread_turning_products.pdf
 
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RoyB said:
Can someone post a picture of what these inserts and the tool look like. I've heard about them but never seen an example.
Click to expand...

Most of these inserts were purchased on ebay for less than $5 each.
P4090016_70_.jpg


A close up of a left handed threading insert can be seen here.
http://cgi.ebay.com/Sandvik-R166-OL...936?pt=LH_DefaultDomain_0&hash=item29edf2d288 The item for sale cuts 14 tpi, indicated by the 140 at the end of the name. The first R means "right hand" an L would mean left handed. The second L in the name means left handed. An G would mean right handed.
 
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THANK YOU!

Excellent source...........page C12 spells it out in terms even I can understand. I just might have to purchase some inserts and a holder and try it out.

This is a "must save" for most of us!
 
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An excellent source for inserted tooling is http://www.latheinserts.com/main.sc Curtis (aka Exkenna on the machining forums) is a good guy to deal with. I'd check with him and see what he could do for you, I'll bet he could save you some money. The Toolmex TMX inserts and tool holders are pretty good. I use the Iscar threading tool-holders and inserts because I bought them before I knew of Curtis. He can get far more than what his website shows.
 
You do not have to start larger with full profile insert unless you want to use od micrometer to determine where you are--much better idea to use thread wires as paul stated or use a good thread micrometer and control to pitch diameter. Threads for most most custom actions should not be cut to full ID--good way to have possible crest interference. For instance a 1 1/16 stub should be turned to 1.055 to 1.058--but not by using the full profile insert to get to that OD or the PD will be too small.
 
Nice to know this Jim.

Also, the helix angle on a 16 TPI thread is only about 1 deg- just slightly over. You won't need any special anvils for barrel threads. I'm not the expert here, but if you do the math, the angles stay less than 1.5 degrees until somewhere around 10 TPI. If you are making big threads like 6 TPI, you will probably need the anvils. Most of the smaller inserts (.25 and .375) aren't even available with anvils.
 
Jim
You do not have to start larger with full profile insert unless you want to use od micrometer to determine where you are--much better idea to use thread wires as paul stated or use a good thread micrometer and control to pitch diameter. Threads for most most custom actions should not be cut to full ID--good way to have possible crest interference. For instance a 1 1/16 stub should be turned to 1.055 to 1.058--but not by using the full profile insert to get to that OD or the PD will be too small.
Click to expand...

I don't see your logic in your post, if theirs some crest interference, you get out the file or turn the crest down. The pitch diameter is controlled the same no matter which type of cutter is used., As long as the pitch dia is correct there will be no issues with the crest and if there were you would never cut the pitch smaller to compensate for it. Now if profile tooling were used to thread the receiver and as a result the root was shallow, then a person thread a barrel with sharp V tooling then there is the possibility of excessive crest height could cause an interference........but you would relieve the crest, w/ file, never lover the pitch dia to compensate for it. This is very possible with home made tooling

From what I've heard on these posts that, some may in fact be cutting the pitch too deep thinking that that is the problem.
 
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