Clausing 5914 chatter -- solved at last

O.K. That will get you started anyway. :-) My preference (starting new) would be to get the BXA-16N (negative rake) with positive/negative inserts for it, and then get the straight pointed ones (and perhaps other tools) for the same inserts. You'll need something different for threading inserts anyway. For those, I prefer the laydown tools to the stand-up ones -- easier to adjust for pitch angle with anvils.

Enjoy, DoN.

The main holdup is pure confusion. I've been looking at catalogs, and it isn't a good idea. Too many choices.

You suggested BXA-16N with MSC stock number 07080062, which is TNMG-322 C6 TIN, for $3.84 apiece. How well does the insert fit the holder? TNMG has a central hole, and perhaps a complex shape, while the BXA-16N was designed for a simple flat triangle with perpendicular sides.

Another question is if spending more money gets better performance, or perhaps resistance to failure under stress and shock. Carbide inserts seem to vary from $4 to almost $30 apiece, with time off for good behavior.

Joe Gwinn

It was none, but it appears that a few degrees helps a lot. Teenut also discussed this at length. I'll try it.

I have not been successful at that speed. I don't think that the back gear reaches that high.

Joe Gwinn

Good to know. I've been using black sulfur oil from Home depot, under various brands. This is sold in the plumbing dept, for thread cutting.

Thanks. This was more from curiosity than need. I don't want to run all oil, because of the mess it will make. So, I'm running the Rustlick WS-5050 oil emulsion, the baby blue stuff. It seems to work well, and doesn't seem to rust the machines, even where some emulsion got under something.

Mobilmet S-122 is sold by MSC, and is also an oil-water emulsion. Wonder how it compares to WS-5050. Probably no dramatic differences.

Joe Gwinn

:-)

It fits it perfectly.

The BXA-16N has a flat screw which holds the anvil in place, and a clamp/chipbreaker which holds the insert in place. There is an alternate screw which has a cylindrical projection above the head if you really want to use the center hole -- but I haven't bothered using anything other than what came with the BXA-16N.

Some of that is a function of how many of them they make. The TNMG is a very common style, and the BXA-16N uses a very common size, so there are lots of them made. And -- it is the same size that my straight holders have. The straight holders have the pin on the head, and have less of a hold-down. It is a finger which swings over the area around the pin and clamps down. But both tools use the same inserts. which is a benefit when you are buying ten or twenty at a time.

There are special shapes, such as the 55 degree diamond which does a better job of reaching into a narrow space, and can be set to both turn and face with the same setting -- just different faces of the insert. Some of these days I'll get a diamond holder to use with the PCD diamond holders which I already have (on non-ferrous metals only, of course).

There are also differing coatings -- from none on the bare carbide to TiN to -- what is it? A purpleish coating over the TiN. Each of these does better when cutting harder material faster. Then there are the Ceramics and the CBN (Cubic Boron Nitride) which do better on much harder materials -- but which might be more subject to shock from interrupted cuts. You don't go to these unless you need them for production. I don't have them. (I would like to play with them, but ... :-)

Other coatings are better to avoid gumming up with soft aluminum alloys. Stick with something like 6061T6 and you should not need them. Lubricate the 6061T6 with kerosene or WD-40 (whichever is more convenient to apply. ;-)

The BXA-16N and the inserts which I suggested are a good general purpose selection. Go with that -- and worry about others when you discover that you need them -- such as when turning a lot of already hardened 4140 for example. :-)

Enjoy, DoN.

Because it seems to be required to avoid chatter on this lathe.

The highest marked backgear speed is 280 rpm on the 5914.

One difference seems to be that the usual roughing cuts are cutting on one side or the other, so the main force pushing tool into work is parallel to the spindle axis, while in parting or grooving the main force is perpendicular to the spindle axis.

The down force (from work spinning into the top of the tool bit) is the same in both cases.

Having chatter while parting off but not while roughing would thus point to the spindle bearings, as has been discussed.

Joe Gwinn

OK.

That raises a question: How do the triange inserts differ from the 80 degree inserts? I notice that Aloris offers holders for both, being the

16 and 16N for triangles, and 12 and 12N for the 80-degree inserts. I would guess that the 80 degree inserts are stronger.

On the mill and drill press, Rustlick WS-5050 works very well.

OK. Although I may also get the alternate screw with pin.

Joe Gwinn

[ ... ]

I would expect so. A bit more difficulty working in deep corners, but stronger for harder materials. Not likely to be something which you need for hobby metalworking.

Here is an example of a shank which would accept those inserts, but which is too big for our machines:

ebay 380015167655

but the photos will show you what the clamp is like on those -- which use the pin-head screws.

Beware that many have 1x1" square shanks and thus are poor choices for our machines. Look for 5/8" square shanks instead for our machines.

This one is closer, with a 3/4" shank -- which can be milled down to 5/8" on a horizontal mill. Not as sure about a vertical mill, however. Of course, none of these are the straight-ahead ones which I got with 100 inserts each some years ago. The photo shows the clamp clearly, the head of the pin-head screw, and the anvil under the insert. These were found with a search for:

TNMG inserts carbide

without bothering to specify the size.

[ ... ]

Good to know.

O.K. But you really don't need it with the chipbreaker style clamp that the BXA-16N uses. Try the holder and inserts first and only if you have troubles bother to order the pin-head screws (whatever the actual vendors call them. :-)

Enjoy, DoN.

OK. Much as I suspected. If triangles were too weak, they wouldn't dominate the catalogs.

Yes. I see that the pin sticks up above the top of the insert in this example, and would interfere if used in a holder intended for a simple flat triangle insert.

Or get the BXA-1S or BXA-2S holders, which accept 3/4" shanks.

I just did that search. Lots of inserts for sale, too. The sad thing is that the insert codes are beginning to make sense to me.

Brothers Machinery, which is almost near me, also has boxes of inserts for sale. As well as holders without end.

OK.

Joe Gwinn

One reason that they dominate is that they offer three (or six for the negative rake) possible working corners, while the others offer two or at the most four -- so they cost less per corner.

Well ... as long as the hold-down has a recess to accept the pin, you would be fine. Or -- if you use the thickest inserts.

O.K. I discovered those long after I had modified the shanks on my 3/4" ones from eBay auctions.

[ ... ]

:-)

You may have a good source then -- especially if they will deal with walk-in customers. :-)

[ ... ]

Enjoy, DoN.

Yes. Although the positive rake triangles have only three useful corners per insert.

Yes, but clearly you have not had problems with the inserts pulling out.

MSC doesn't offer them, but Aloris will sell you some.

Well, it's a bit too far to walk, but they haven't thrown me out just yet. They were happy to take my money too.

Joe Gwinn

Of course. Note that I said "three (or six for the negative rake)". But the positive rake four-sided inserts have only two so the triangular ones still win.

[ ... ]

Right -- and I've cut hard enough to slow down the 1-1/2 HP motor through step belts (which are more efficient than the vari-speed, so it is probably equivalent to a 2HP motor on yours).

That probably explains why I had not discovered them.

Good.

Enjoy, DoN.