Carbide selection help

[loose nut]

Been looking at Bang good carbides, the "good" name brand ones are out of my price range. Is there a good all around carbide style, maybe a high relief angle positive one that would be good on a smaller lathe, or have carbides now been heavily designed for specific materials and use. Looking for a good finish on various materials, high cutting rate is less important and I can't afford to stock a bunch of different types for different jobs. I have used TMNG style with mixed results on everything up to now but generally rely on HSS bits which I have a lifetime supply. Just trying to get into the 20th century, the 21st isn't looking so good.

[danlb]

I've some tool holders for CCMT inserts. The CCMT works well as a general purpose cutter. It's a sharper angle than the 60 degree triangles.

One of the nice things about the CCMT insert is that in the right orientation you can turn down the OD by moving right to left and then face the end by moving it straight in with the cross-slide without changing the orientation of the tool.

The designation SCLCR is the "right hand" tool for cutting toward the headstock. SCLCL is the left hand tool for cutting towards the tailstock.

Bankgood has several sets that use this insert for prices under $30. They include left, right and boring bars and the sets are available in several shank sizes.

I still use the Triangle inserts for most of my turning. The right speed, holder and radius lets you do a lot.

Dan

[Yondering]

I've some tool holders for CCMT inserts. The CCMT works well as a general purpose cutter. It's a sharper angle than the 60 degree triangles.

I think you mean it's a blunter angle than the triangles, CCMT is an 80 degree (IIRC) diamond, almost a square, or are you thinking of DCMT which are a sharper angle? I use them as well, from Banggood and am happy with them. For finishing on steels and aluminum, I like the sharp CCGT inserts; they have a ground sharp edge and high positive rake for clean cuts, although they'll chip more easily and aren't good for roughing. I use the 32.51 size for outside turning, and the 21.51 size for inside turning on boring bars. If you're looking for inserts on Banggood, the xCMT inserts are either brown, grey, or gold colored and have molded edges and chip breakers, while the xCGT are a bright polished finish with highly raked points and dead sharp tips. Both fit the same holders for a given size and shape.

I use either CCMT inserts or the TT style triangle inserts for 99% of my lathe turning these days, with a few exceptions for hard to reach areas where something like a DCMT or VCMT insert works better. And of course the laydown threading inserts, can't be without those.

[MattiJ]

These are reasonable nice if you happen to get the exact model shown:
https://www.banggood.com/10pcs-DCMT0...rmmds=category

It appears that banggood and two dozen of ebay sellers have the same supplier. If one of them sends you slightly different but inferior insert then you are going to get them from all of the sellers.
I have more than 20 boxes of wrong dcmt and ccmt inserts when I have tried to get the "good" ones. After a complaint I have got refund from all of those, 200 free inserts but not the model I want..

[loose nut]

So which would give the better finish CCMT or DCMT?

CCMT would seem to be stronger but DCMT can get into tight spots. Is there any other difference?

I can use my TMNG for roughing, just need something for a good finish on most materials.

[MattiJ]

So which would give the better finish CCMT or DCMT?

CCMT would seem to be stronger but DCMT can get into tight spots. Is there any other difference?

I can use my TMNG for roughing, just need something for a good finish on most materials.

Not any different surface finish vise. Depends lot more on the exact model, chip breaker and coating than CCMT vs. DCMT.

For very light cuts and good finish the dcGt and ccGt are usually super-sharp inserts for finishing and turning aluminium/non-ferrous material.
( xxG versus xxM is actually tolerance code, but in practice the G-inserts in lathe are almost always sharp finishing inserts)
http://www.carbidedepot.com/formulas-insert-d.htm

And DCMT/DCGT gets to to tighter spots but CCMT/CCGT is more usable to small boring bars.

TNGG would be the sharp version of TNMG.

If I were to choose only one finishing insert from banggood it would be this or one of these :
https://www.banggood.com/10pcs-CCGT0...l?rmmds=search
https://www.banggood.com/10pcs-CCGT0...l?rmmds=search
https://www.banggood.com/10pcs-CCGT0...l?rmmds=search
(is there some other difference than box color and price??)

[photomankc]

I use CCMT inserts for most of my turning in steel and aluminum. It generally does a good job on either material at 750 to 1200RPM. I use CCGT inserts for finishing on either material too. The CCGT is supposed to be just aluminum but I find it works nicely on low depth of cut on steel as well and is sharp and raked enough to take shallow cuts without just rubbing. My CCXX holders are 1/2" for best rigidity letting me take 0.1 to 0.150 of diameter per pass. If space is more constrained I tend to switch to the TCMT/TCGT holders and inserts at 3/8". The behavior and finish they produce is on-par with the CCXX inserts of the same tolerance and material/coatings.

I have invested in a couple of DCMT/DCGT holders and inserts for when space and clearance are tight.

My 10x22 handles carbide tools just fine and I prefer to spend a few dollars on inserts than spend afternoons grinding and sharpening HSS toolbits.

[mattthemuppet]

ditto on the CCGT inserts - I use them for everything other than knocking off rust or mill scale. I have a small lathe and they give a beautiful finish on pretty much anything, even crappy gummy mystery steel.

[loose nut]

Is the TNGG basically the same as a CCGT but except for the shape. Will TNGG they won't fit into the holder for a TMNG if they are the same size.

[lakeside53]

yes the third letter "N or G" is just the tolerance.

[danlb]

Is the TNGG basically the same as a CCGT but except for the shape. Will TNGG they won't fit into the holder for a TMNG if they are the same size.

The first letter is the shape.

Second letter is the clearance. N = None and C = 7 degrees. That clearance means all 3 sides slope from top to bottom by the specified degrees.

Third letter is the "tolerance", which I think of as possible variation when swapping inserts. M = tip can be .002-.005" off. G = tip can be .001" off. I think of it as Molded and Ground, since the G typically has been ground to get it within specs.

Fourth letter is the hole for mounting and the chipbreaker. G= chip breaker on both sides, so it has to have zero clearance. Theoretically you can't have a TCCG insert. It also has a cylindrical hole in the middle. T= single sided with chipbreaker, hole in the middle that is countersunk.


Now to use that.... The tool holder specifically for TCGT inserts should be cut back enough to provide clearance while still supporting the full outline of the insert. A tool for TNGT should take into account that the insert has straight sides and so the tool needs a bigger base to support the tool fully. KIn hobby use the same tool holder is used for any TxxT insert.

Dan

[MattiJ]

There is no such a thing as TNGT, the double sided xNxx does not use tapered haed screw.

[danlb]

There is no such a thing as TNGT, the double sided xNxx does not use tapered haed screw.

The TxxT is not double sided. And it is available from amazon. The chart at Carbide Depot is a nice quick reference.

But you are right that double sided are not supposed to have countersunk mounting holes.


Dan

[loose nut]

This is a metric insert on Bang Good CCMT09t304-pm. Ok I get what most of it means but what does the -PM on the end mean. I looked it up on Carbide Depot and it doesn't have any explanation. Bang Good has several similar inserts but with these different letter on the end???

Can they be ignored???

P.S. for those guys that shop on Bang Good do the prices for inserts mean for 10 inserts for the quoted price or for individual insert but in packages of 10 which is how other places tend to sell them.

[dalee100]

Hi,

I ignore the -pm myself. Perhaps it has something to do with coating? All 7 boxes I have ordered of various types were priced per box of 10. Dirt cheap and good enough for HSM. I've been impressed with the DCMT and ER11 threading inserts.

Sad when carbide inserts are cheaper than grinding HSS.

Dalee