wnmg tool holder

Well, there's a difference between an insert of the type used in your holder not being available at all, and it being a bad idea to use that insert in your specific holder or on your specific lathe.

The insert type for the trigon holder you posted seems to be pretty widely available. I don't know enough about the holder to say whether there will be problems using a positive rake insert in it. Inserts are cheap, though, and can be bought singly (e.g. from shars, travers), so you can just get one and give it a go, see how it cuts. Maybe it cuts bad, maybe you break the insert, maybe it works out great.

Don't forget, you can also use a diamond hone or a diamond burr (e.g. for a dremel) to modify the insert - sharpen the edge, increase the nose radius, add a chip breaker, maybe even change the rake (might be too much, they are just sintered powder after all). Same goes for those crappy brazed carbide tools.
 
I've researched a lot of the ideas given here. Either it's a 3/4" holder ( which I can't fix in my 10x22 lathe, or they are wc_ 21.5 inserts and I'm back to limited options.
kinda of leads to my lathe is too small to give me options. Either I go crazy laying down some TIG beads and reshaping the shank on the mwlnr to change the angle of the cutter, but that would change the temper if the steel, i could reharden, but I have to clearance for relief in the cutter. Either this works as is, or I move away from trigon. *we all know where negative rake in a small lathe goes* but no risk no reward, i would LOVE the options that would give me.
Thanks for all the suggestions.
 
As far as your current Accusize trigon holder it has a uncommon size insert. You cannot mill the insert pocket for a larger insert because the screw location. The higher end holders usually have replaceable carbide seats and the screw insert thread. The WNMG does not use a locking screw, it uses a guide pin and a locking arm.

Maybe it is unclear, but a SWLCR082 is a 1/2" neutral rake holder that takes a trigon type insert. The insert is a standard size which is a 1/4" inscribed circle so either something like a WCMT (molded edge) or WCGT (ground edge) in a 21.51 insert size. The W denotes a trigon shape, the C is neutral rake M is molded/ G is ground, T is the way that the insert is retained in the holder. Other size variants would be a 21.52 and a 21.05 where the last digit is the nose radius. The inserts come with various degrees of positive rake on the cutting edge, various coating and different chip breakers. The ones I reference above, the Kennametal would be general machining in steel, for softer materials you usually want a WCGT and uncoated. The downside is it is a very uncommon holder and insert, so expect to pay more for the inserts. The inserts have 3 cutting edges and they can last quite a long time, I probably use 2-3 inserts per year.
This is the 1/2" holder for these inserts http://www.carbidedepot.com/SWLCR082-P293233.aspx

The smallest WNMG would be a 5/8" holder and by nature of the insert, it can only be used in a negative rake holder. You cannot change the angle of the insert in the pocket or the holder, there is not enough clearance between the edge ant the material, it will not work (it will not cut). If you look at the chart below, a negative rake insert has a 0 degree rake on the leading edge, therefore it is the angle of the holder that gives the cutting clearance below the edge of the inset. Neutral or C has a 7 degree rake and P is 11 degrees, each insert must be used in its designated holder. There is the angle of the insert in the holder and then there is the angle of the insert edge relative to the cutting interface. See the cross section geometry below. There is a description as to the applications.

I use the WNMG with inserts that have a positive sharp ground edge and so cut very well in softer materials or for lighter cuts in steel. These take less cutting power, but are more fragile. You also need rigidity in your lathe for use of negative insert. The minimum size lathe is probably a heavier 1236. There is a trigon positive rake insert which would be the WPMT/WPGT, these are pretty much relegated to use in boring bars where the positive rake is more advantageous.

Insert Nomenclature.jpgRake.jpg
 
Thank for a wealth of info mksj. I have read that kind of info for months now, wish I could say I fully understand it, but that will honestly probably be a year from now. I have already given up that idea (or hope) to somehow to use WNMG inserts, but I have also given up trying to use that swgcr06-2j holder. There are no real options for SS or titanium. I decided to purchase the swlc holder & wcmt inserts.
Thanks for your patience & help.
 
These inserts are for stainless Mitsubishi WCMT040202 WCMT040204 US735 is the coating
You can also call Carbide Depot and they can give you recommendations. These inserts tend to last a long time, so one can try to buy 1-2 on eBay and if you like them buy a box from Carbide Depot.
These are 21.51

WCMT21.51 US735

www.carbidedepot.com www.carbidedepot.com

Mitsubishi Wcmt32.51 Nx55 Carbide Inserts 4 Pcs for sale online | eBay

Find many great new & used options and get the best deals for Mitsubishi Wcmt32.51 Nx55 Carbide Inserts 4 Pcs at the best online prices at eBay! Free shipping for many products!
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These are 21.50.5 (smaller nose)
www.ebay.com

Mitsubishi Carbide Inserts WCMT040202 US735 Qty 8 | eBay

Mitsubishi Carbide Inserts WCMT040202 US735 Qty 8. Shipped with USPS First Class Package.
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Mitsubishi Carbide Inserts Wcmt040202 US 8 for sale online | eBay

Find many great new & used options and get the best deals for Mitsubishi Carbide Inserts Wcmt040202 US 8 at the best online prices at eBay! Free shipping for many products!
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Yep, I’m definitely going with that holder I spoke of and then then options are at least better if not “endless”. I think it’s kinda crummy that Accusize made a holder that you really have to buy their os Oscribides and they just do one or maybe 2 kinds of inserts.
 
I have an Enco 12x36 lathe with a 1.5HP motor. I've tried a ton of different inserts and have found that positive rake inserts seem to perform the best. Negative rake can be used, but it doesn't cut as cleanly and the machine struggles more for the same cut compared to a positive rake insert.

I use the following inserts most often:
  • CCMT32.50 - General turning, OD finishing, Boring, Fine boring
  • CCGX32.50 - General turning in aluminum, fine finishing in all materials
  • 16ER, 16IR - Threading, internal and external, both towards and away from the chuck
  • 11ER, 11IR - Same as above, smaller tools
  • VCMT1103 - Fine finishing, turning in hard to access areas
  • TMCT, TCGX - inserts for my smaller boring bars
  • SCMT, SCGX - Square insert for a 45 degree chamfer tool
These are also less expensive than the larger negative rake inserts.

EDIT: I also use a Kaiser Thinbit Groove N' Turn tool for grooving, small parting operations, and turning in small OD grooves.
 
I don't think I fully appreciated that we were talking about the front rake (the "N" of the insert type), as opposed to the top rake.

I'm surprised front rake makes that much of a difference, even on a small lathe. The chip formation is usually up or out, not down along the tool face, so issue must be with the amount of tool that is in contact with the work - and that varies with DOC and, to a lesser extent, work diameter. Is it just that the DOC required to get a decent cut from the insert causes too much of the tool face to enter the work?

I've been using the same WNMG-332 insert on steel and aluminum recently, DOC from .002 to .040, diameters ranging from 1/4 to 2", and it cut well leaving a satisfactory finish (though I had to hone to a very sharp edge before the .002). This is on a 14x40 lathe, so I cannot speak for the small-lathe experience, but like I said I am surprised that it becomes unusable on a lathe with a 12" or a 10" swing so long as they have a BXA toolpost.
 
Thinwoodsman, I feel your points pulling me back to the evil wnmg....j/k, I know when I'm beat. From my very green view point, i agree with you, but I don't know what the hell I'm talking about. It is amazing that the angle of the cutter against the work piece has such dire consequences. I'm sure there will be some good input to follow, I'm interested to read...
 
macardoso said:
I have an Enco 12x36 lathe with a 1.5HP motor. I've tried a ton of different inserts and have found that positive rake inserts seem to perform the best. Negative rake can be used, but it doesn't cut as cleanly and the machine struggles more for the same cut compared to a positive rake insert.

I use the following inserts most often:
  • CCMT32.50 - General turning, OD finishing, Boring, Fine boring
  • CCGX32.50 - General turning in aluminum, fine finishing in all materials
  • 16ER, 16IR - Threading, internal and external, both towards and away from the chuck
  • 11ER, 11IR - Same as above, smaller tools
  • VCMT1103 - Fine finishing, turning in hard to access areas
  • TMCT, TCGX - inserts for my smaller boring bars
  • SCMT, SCGX - Square insert for a 45 degree chamfer tool
These are also less expensive than the larger negative rake inserts.

EDIT: I also use a Kaiser Thinbit Groove N' Turn tool for grooving, small parting operations, and turning in small OD grooves.
Click to expand...
I'm interested in your scmt/scgx inserts as I struggle with a tool that gives me access to a decent chamfer. I'll have to look into it. And just to be clear (to the conversation) I'm not opposed to smaller tooling, I just dislike the the trigon tool holder I got with my 6 piece kit. It is HORRIBLY limited to insert options. I DO very much want a trigon and I want a decent lineup of insert choices, but this thread has given me that now. Thank you for that.
 
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