I sent this once before, but it doesn't seem to have made it to the newsgroup.
--------------------- There are lots of threading inserts, and the several catalog pages I've looked at to try to understand them don't do a very good job. The turning inserts make a lot more sense than the threading ones.
So first, can anyone point me to a reasonable explanation of how the inserts are numbered (threading, not turning)? Are threading insert brands compatible with each other? For instance, can I expect to use company A's insert in company B's holder?
And in the too convenient to be true department, can I use a triangular threading insert to cut internal threads with my insert boring bars?
I could make threading insert holders, but don't know the angles and such, how much it varies from insert type to insert type, etc.
I saw it, Steve, but didn't respond, not being up to speed on current carbides. I left the shop behind about 22 years ago. My opinions follow:
Can't help there. Not familiar with them enough to have an opinion.
Unless they are identical in appearance, most likely not, and maybe not even then. I've seen them made in various ways, so one would obviously not fit another's holder. Could be there are standard sizes and configurations today, however, and they may just interchange. I'm surprised no one with knowledge has stepped forward. That could be a result of having only one brand of holder, and not being familiar with others.
You can generate the thread, but it isn't likely to have the correct configuration. You may also lack clearance for the holder as you get to depth with the thread. Boring bars aren't intended to be used for threading. For coarse threads, it may also lack side relief adequate for the tool to cut without dragging. If you're cutting to specifications, the flat (radius on the tip) would likely be proper for only a single pitch, maybe 2 of them. Further, any deviation from flat is likely to affect thread form regards included angle. May not be enough to be of concern, but something to consider. What thread pitch is in question, and what is the tip radius of your insert?
If you know how the insert is intended to be mounted, certainly making holders isn't beyond one's ability. Someone, somewhere, makes the holders for the companies that sell them. You have to understand if the insert should be mounted flat, or angled, negative or positive, side rake, etc. Without that, you may not achieve a functional holder. There's no single answer.
The on-edge threading inserts seem to compatible with each other. I have used several brands of TNMC-43NV/TPMC-43NV in several brands of holders.
I have used laydown thread inserts like Kennametal/Carboloy 16ER series and Vardex 3ER series in each others holders. Also the internal versions 16IR and 3IR series.
Threading inserts have thier own holder styles. I have never tried to use a threading insert in a turning holder. Also the laydown inserts usually have an anvil (like a shim) under the insert. Anvils are used to adjust the angle of the insert to the helix angle of the thread.
I believe the vertical angle for on-edge threading inserts is zero.
I have a NEW Valenite 1" internal threading/grooving bar, takes TNMC-32NV inserts, comes with 5 uncoated TNMC-32NV and 10 coated TNMC-32NV inserts. You can buy a Valenite external lathe threading tool which will also take these inserts. I bought this stuff (big $$) for my big lathe but never used them, now my lathe is gone. If anyone wants this stuff, you can have the whole shebang for $35 plus shipping (might fit in the big flat rate envelope) which is about what I paid for one batch of the inserts ..
I saw it, and I spent some time typing a followup. Perhaps you need to go to Google to pick up things which your news server drops -- either drops because of a sort expire time, or it just never got there.
Google does archive everything on usenet.
I don't really feel like re-typing all of what I posted.
Using a standard 60 degree cutting insert you run into the problem of relief for the helix angle. In other words, the bottom of the insert will drag on one side of the thread. You could grind relief in the insert and check it on a already threaded bolt. I would go with a standard threading insert. laydown inserts are nice because they form the full thread shape but you need a different insert for each pitch. Single point tools seem to work better for manual threading. You can buy an E type brazed tool for very cheap prices but make sure you check it with a fishtale gauge. I had some I bought once that were ground wrong. They were kennametal from MSC. I went to the store and all the ones in the box were screwed up. Single point inserts are nice because if you break the insert you just put in another and you are already in position. You got to watch that the point does not get broken off. The thread will look nice but the root will not be completely cleaned out and you will over cut the thread if you are using a thread gauge to check the fit. If your lathe has a thread stop it makes it a pleasure to cut threads. If not it becomes a little more of a challange. There are a lot of good sites on the web on threading... search "double depth threads."
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