High Alloys and turning threads PART3

We discussed the case of high alloy (13% Cr, 9HRC) which harden itself
during threading and higher Vc is beneficial. Really hard having
leading screw without a special clutch.
Now question to the experienced guys:
1) I'm trying to translate "compound". Now having access to ftp look
formatting link
's a angle scale or the name of an action?
2) What's your experience, benefits with top of the line inserts. For
example - renowned Sandvik, Iscar insert cost 10$ and more or less the
same on the market about 0.5$. Picture:
formatting link

I looking for experience in everyday work and what means "more or less
the same" here. Everything except that top of the line insert is able
to work on very high Vc, mass productions etc. and with rare
materials. So the question would be: are Iscar or Sandvik or ... worth
of buying for typical materials and Vc200 RPM?
For D. Nichols - I've sent two mails - one came back and another from
another server wasn't bounced. This is my very first part that was
turned as a subject of this article - just in case:
formatting link

With kind Regards,
Jack Zagaja,
Reply to
Jacek Zagaja
Loading thread data ...
"Compound" is a lathe term that means "the slide that can feed the cutting tool at an adjust able angle to the lathe axes."
In your photograph the angle has been adjusted to be parallel with the long bed axis of the lathe.
In this photo it is at approximately 30 degree angle:
At the bottom of the photo there is a large handwheel (partly obscured) which moves the carriage along the bed.
Above that there is a smaller dial which moves the cutting tool across the bed, the "crossfeed dial."
Above that is an even smaller dial which is the "compound dial" which moves the tool in an angular motion. In the photo it is sort of under my elbow.
Threading often uses the compound to infeed the tool because it permits the 60 degree tool to cut on only *one* edge, which simplifies the chip feed and also makes the final thread form insensitive to the exact tool shape.
Reply to
jim rozen
I see that you have already received an answer to this, and acknowledged it to indicate that you understood.
I can't access that web server at the moment, So I don't know what you are showing -- unless it is the brazed one which you showed once before.
For me, they are. The inserts have three points, so you can consider them as costing $3.33 per point. When one wears out, you just loosen the clamp screw, and rotate 120 degrees to present the next point, and don't even need to reset the dials (assuming a good quick-change toolpost which positions the next point precisely where the previous one was. However, there are choices to be made.
1) You have to get them pre-made to the proper angle for the threads which you are cutting. Mine are all 60 degree, except for some shaped to cut specific acme threads..
2) You then have to choose the material and coating to match the workpiece material. One grade of carbide works better on metals like aluminum, which may be abrasive thanks to its oxide coating, or even anodization if present. Another grade works better for steels, including rather hardened ones. Coatings, such as TiN (Titanium Nitride -- a rather gold appearing coating) can reduce the problem of BUE (Built-Up Edge), where the material you are cutting sticks to the cutting tool, thus changing its shape. But the same coating results in an edge which is not quite as sharp, thus impacting finish. (Of course, the BUE can also degrade the finish.)
The threading inserts which I have for my larger machine are TiN coated, but those for the smaller machine -- the Compact-5/CNC (which came with the machine) are uncoated. I have not yet needed to purchase more for this, though it will happen someday.
3) The choice of sharp-V form, or full thread form.
The former can be used to cut a wide range of thread pitches (at the cost of having a sharp V bottom to the threads, thus weakening the material a bit. Since what I have cut with this does not need that much strength, nor do your optical threads, so this is fine for the application.
The latter (full form threads) require a separate insert for each thread pitch, but cut the thread to the official shape, with a rounded root, and the crest of the threads is cleaned up as the insert reaches its full cutting depth.
I have not received either.
I don't see any signs of them in the spam folders. Any which are larger than 30K will be automatically rejected, as most virii start at just a little bit over 30K in size. I've got no way to make exceptions for a single user or for a single system. So, I guess that we will have to continue to use the newsgroup for this discussion.
Did you receive the drawing (in .pdf form)?
Hmm ... all I see is a gray square, with the following below it:
====================================================================== [] Bookmark Us [] Set Us Homepage [] Contact Us
© 2004 HTTP.COM. All rights reserved. This website is undergoing further web development. This website is unaffiliated with any other website, company, or organization. Services provided by the SearchMachine.com Network. ======================================================================
As I did not wish to do any of those, but rather to see whatever image you had, I clicked on none of them (Bear in mind that I am *not* using a Windows web browser, but rather Mozilla on a Sun workstation.)
Good luck, DoN.
Reply to
DoN. Nichols
Check the files again. They should work.
Yes an insert has basically even 6 sides :)
In good tools you have the tolerances tight but resetting dials or not is important is mass production. Any lathes with wear compensation so far :) ? So no benefits of using renowned inserts ? You know the fortune spent by Sandvik, ISCAR for research etc.
Yes - thanks a lot. I think I got enough advices for threads. What left is a trapezium thread but everything in due time :)
Regards, ______________________________________________________________________
Jack Zagaja - photographer, designer, programmer free photoshop plugins, photographic assistance opinions and much more ... snipped-for-privacy@poczta.onet.pl
Reply to
Jacek Zagaja
They do, now.
Depends on whether it is positive rake or negative rake.
The larger of the ones in your photo appears to be a negative rake design, with the addition of a special chipbreaker groove to turn it into a positive rake at the cutting edge. That one, in the proper holder, should be excellent. The proper holder mounts it at an angle, so the bottom edge is somewhat away from the workpiece, leaving the top edge to do the work. It can be turned upside down when all three corners are worn, to provide another three -- assuming that the wear or damage does not extend to the other side of the insert.
The two smaller ones are positive rake inserts -- see the taper on the edges (one right-side up, the other upside down). That provides the relief, so the insert can be mounted either totally flat (zero rake), or with the edge angled up a bit, to produce a positive rake. Those can only be used one side up, so they are only three sides. But the angle makes the insert somewhat more fragile when doing heavy cutting. And the fact that they are smaller overall adds to that weakness. Those need an overhanging clamp to secure them.
The larger one can use either a screw, or a guide post and a clamp, depending on the holder's design. Overall, a much stronger system.
Note, of course, that *none* of these are threading inserts. (The larger one even seems to have greater than 60 degrees between sides, so it would not work anyway.)
A threading insert has a different appearance. I'll attempt to draw on side, and a part of the other two to show you what they look like:
/\ ________________ \ > \ / \ ( ) /
The sharp spurs on the corners are what actually does the threading. The rest is support only.
I find the inserts speed my work, even when not doing production work. But I do grind my own HSS tools at need. The most recent example was a set of inside and outside threading tools for Acme threads of a size a bit too large for the largest insert tool which my lathe and toolpost can handle.
Looking at the drawing in the other URL, I would include what you have labeled the "angle scale" as a part of the compound. Your arrow for "compound" points only to the dial and crank for the compound feed. That, the ways, the T-slot in the top, and the angle scale are all part of what is known as "the compound".
Looking again, I don't see a T-slot in the top of the compound to accept the toolpost. Instead, there appears to be a single-sided tool holder secured by a single bolt threaded directly into the top of the slide of the compound.
Good Luck, DoN.
Reply to
DoN. Nichols

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