Got a new toy from Banggood today (finally). It's an Andonstar AD407 USB powered microscope with a 7 inch display on top. So of course, I had to find things to put under it (once I managed to pry SWMBO off the thing!). Results were kind of interesting. Apologies for the 'noisy' photos, and don't take that as a reflection of the picture quality on screen, as on the unit the picture is absolutely clear as day. The camera function just seems to struggle a little.

First up, a batch of 3 "Mitsubishi" CCMT inserts. All out of the same box, and I had a feeling they were probably knockoffs - but you decide...

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Interesting that one of them appears to have been deburred? Loving the nose "radius"....

This next one is really interesting to me - on the right, a "Tungaloy" CCMT. Not sure whether they're knockoffs, I don't even remember where they came from. I either bought them to try cause they were cheap, or they came with a toolholder out of China. But the one on the left is branded "Hu Li Gen", and definitely just came with a toolholder (almost free, if I remember correctly.)

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Considering they're complete no-name Chinese inserts, they actually look pretty good really. The "Tungaloy" don't look too bad either, keeping in mind they are 'M' inserts, which I believe are generally just 'as molded'...

Next up, on the left, a Mitsubishi CCMT (09T302 NX2525 grade, bought from CTC many years ago, hopefully genuine for the price!), vs a used... something. don't remember what. But I can only just see that this tip might not be right by eye, if I'm on the right angle, and I have pretty decent eyesight. The Mitsubishi looks nice enough along the edge, but the 'edge radius' standard to your normal insert is pretty visible.

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A Korloy parting insert and a Tungaloy threading insert - probably genuine by the looks of them:

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But the prizewinner for me is this one - I bought a batch of these twin tip Sumitomo CBN inserts in CCMT a while ago at $5 each. Excellent things to have around, I'm still on my first one, which although the tips are destroyed, still rip through hardened material nicely for getting under the skin. Under the microscope though, they're pretty impressive!

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And the prize for the biggest disappointment? These "Korloy" SEHT aluminium inserts for my facemill. I would be hoping they're knockoffs!

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I like the way they're actually ground, but not right up to the actuall cutting edge No wonder they weren't very impressive in use. Time to get on with finishing up that low speed 'Glendo" clone and make a jig for grinding SExx inserts, the "Mitsubishi" knockoffs I have for steel also don't have enough clearance angle for the amount of rake in the facemill, which means they rub about 1.5mm behind the cutting edge rather than actually cutting anything. Not sure whether genuine would still have that problem or not....

And finally, I bought a batch of carbide endmills from Aliexpress recently, mostly from a seller called "Xuhan cutting tools." They looked pretty high quality by eye when they first turned up, and every edge feels razor sharp - the microscope tends to agree. This is just one cutting edge, but the whole thing is very nicely ground. I bought a bunch of 12mm, and also a couple of assortments in higher hardness grades, all of them present as very high quality upon inspections, and quite reasonably priced.

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So what have I learned? About what I already knew. Carbide doesn't have a sharp edge as molded (obvious!) Many of my inserts are likely knockoffs, but they do still work fine (in lathe tooling anyway) despite that. But if struggling for finish on a light cut, swap to my 'probably genuine' ones, as the nose radius area on some of them is pretty horrendous. And my 'ground' inserts aren't exactly that sharp on the edge. They do tend to shave the fingernail, but I have to suspect real ones would have a cleaner edge. What surprised me though was how decent the complete no-name branded ones were, in fact better than many of the knockoffs!

And I was also surprised how good my freehand grinding on the insert for my scraper looked... Pretty clean and even, I expected a bit of a horror show.
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