MetalworkingFun Forum

The time came to replace some of my inserts and have lost the data about them. Need to order a few and looking for the right number/code to get the same. Attached are a few pictures for reference. Any info appreciated. Thanks.

Danny,

Can you give us the number on the tool that the inserts fit on? That would help, although I'm sure Ken can tell you without that information.

Ed

Pretty good demo of the inaccuracy of digital calipers though.

I can't quite be certain as it's hard for me to tell from the photos if that insert is a screw-down positive rake or a double-sided negative rake. I lean toward is being the former, which would have a countersunk hole. If it also has 11º clearance angles on the sides, then it's a TPGT or TPMT 321 or 320.5. That one does appear to be ground on all sides, and if so it's the TPGT.

Those are getting harder to find. The more common thickness is 3/32"- 2.5mm for a TPGT32.51 or TPGT32.50.5. The angle is hard to judge in photos. If it's 7º it's a TCGT 321, and if it's 5º then it's an oddball TBGH 321 from Circle and that's the only maker you'll get them from.

You might be able to use the slightly thinner TCGT32.5x size, depending upon what holder or boring bar those are used in.

Just checked and the caliper is calibrated, the insert is chipped on all sides...It is installed (was) on a 1/2" sq. tool holder as seen in the picture. All sides are equal with the same rake angle.

TPMM-321 TT

I have the same set of lathe tools


http://www.usacarbide.com/catalog/produc...s_id=15725

http://www.dbcindustrial.com/index.cfm?f...o=20355321

http://www.ebay.com/sch/i.html?_trksid=p...&_from=R40

Light duty use with those only. I hate 'em because they don't nest the insert and rely upon one surface and the screw for insert security and stability.

Triangular insert have really started to fade in popularity because they can really only work for single direction turning, while a W or C can be used for turning and facing without reorienting the holder. The tips are notoriously weak too, as you may have found.

/rant

Anyhow, you can also use TPGT, TPMT or TPMW in 321 (.015" corner rad), 322 (.031"), 320.5 (.008"), as long as the counter sink matches the head of the screw within reason.

EDIT: Aw crap, I have to correct myself. Those holders appear to use a much shallower side clearance angle that the 11º of a TPxx. Go with the ones Jack linked to, as they appear to be a 5º or less clearance angle. Plus, there doesn't appear to be many TPxx in a 32x thickness. Most are a 32.5x (.093-.098 thick.)

Ken,

I never said they were good, one of the first sets I ever bought, since then , thanks to you, I've found better choices.

Found the tool holder make/model and it mentiones for inserts:
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http://www.guardiancatalog.com/Made-in-U...641321.htm
Indexable Cutting Tools - 1/2 SHK AL 8 USA-INDEX TOOL HOLDER, Indexable Carbide Turning Tool System Shank Width: 1/2 Shank Height: 1/2 Insert Type: TCMM, TCMT, TPMT Cutting Direction: Left Hand
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What is the difference between all types of inserts. Googled all and now I know less than before. I use them for AL to SS all grades and sizes. Which is the best type for me? I have LH and RH tool holders that I use 90% of the time.

Found this link:
http://www.carbidedepot.com/formulas-ins...#clearance
Looks like I need TPMT 321 C6 insert TiN coated.