Regrinding carbide inserts

One suggestion, carbide comes in "grades", from harder to tougher. Harder inserts will keep an edge longer, but tend to chip/crack easier, whereas tougher inserts will dull more quickly but are less prone to chipping. For starting out with inserts, chipping is a frequent problem. You can reduce this to some extent by getting the "tougher" inserts.
 
From the photos provided by the OP, the cutting edge of the insert is grounded instead of molded so it should be on the sharp side. The rake angle looks quite large and there seems be no coating. If I am right the insert is designed for cutting aluminium. Using it on other materials such as brass or steel will end up it what's shown. Chinese-made inserts of this kind are very cheap and the quality is more than good enough for hobby machinists. Those I am using last quite well.

P2110531.JPG
 
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Thanks for the replies, lots of great info in here. I do intend to learn to work with HSS, but carbide allows me to start cutting immediately without the trials and failures of HSS grinding.

compact8 said:
From the photos provided by the OP, the cutting edge of the insert is grounded instead of molded so it should be on the sharp side. The rake angle looks quite large and there seems be no coating. If I am right the insert is designed for cutting aluminium. Using it on other materials such as brass or steel will end up it what's shown. Chinese-made inserts of this kind are very cheap and the quality is more than good enough for hobby machinists. Those I am using last quite well.
Click to expand...

This is the insert I was using, states it is suitable for steel and stainless. And not a cheap chinese insert.
carbidenz.co.nz

CCGT09T302MP-CK

Kyocera CCGT09T302MP-CK inserts
carbidenz.co.nz carbidenz.co.nz
 
Okay, I think there is some confusion regarding CCGT inserts. Lots of hobby guys think any insert with the designation "CCGT" is a high positive ground insert primarily intended for use with aluminum but "can" be used with steel and SS. The insert the OP linked to above is a CCGT intended for use with steel. The difference between this CCGT insert and the high positive rake CCGT inserts intended for use with aluminum is the CHIPBREAKER. The very high positive rake chip breaker on a CCGT insert intended for use with aluminum is usually designated as an AK or H01 chip breaker; on the insert the OP used, the chipbreaker is a CK and it is a finishing insert for steel.

I totally get using carbide inserts so you can learn to use your lathe. Many, if not most, hobby guys start out this way but you are going to find that HSS holds so many advantages that it is well worth taking the time to learn to grind a tool. I took a look back in your postings and you are using a tiny mini-lathe that is totally unsuitable for use with carbide tooling. It doesn't have the speed, power or rigidity required for use with carbide tooling so you are really setting yourself up for a hard time. Do yourself a big favor and start using HSS. Tool grinding isn't hard to learn and if you need some tools to get started while you are learning to grind your own, I know a few guys who can grind them for you for a reasonable price. With care, a HSS tool will last for a decade or more so you'll have time to learn to do it on your own.
 
Thanks, FWIW Mikey my lathe is a small import bench machine, but not a "tiny mini lathe". It's got a little 1hp motor but it's a 280kg machine. But I take your point and will invest in some HSS blanks and a good grinding wheel.
 
Wheat.Millington said:
Thanks, FWIW Mikey my lathe is a small import bench machine, but not a "tiny mini lathe". It's got a little 1hp motor but it's a 280kg machine. But I take your point and will invest in some HSS blanks and a good grinding wheel.
Click to expand...

I meant no disrespect to you or your lathe. Pictures can be deceiving.
 
I wonder if you would indulge me by telling me what kind of cuts your lathe can take. How deep can you rough and how fine a cut is your lathe capable of making with your current tooling?

I'll give you a ferinstance. My Sherline lathe (35# soaking wet with a 0.08HP motor), using HSS tools, can take a 0.050-0.060" deep roughing cut in mild steel (0.100-0.120" off the diameter) and a 0.100" deep cut in aluminum (0.200" off the diameter). In both kinds of material, it will directly cut 0.0001 - 0.0002" in a finishing cut.
 
Wheat.Millington said:
This is the insert I was using, states it is suitable for steel and stainless. And not a cheap chinese insert.
carbidenz.co.nz

CCGT09T302MP-CK

Kyocera CCGT09T302MP-CK inserts
carbidenz.co.nz carbidenz.co.nz
Click to expand...
Ok , I have got some sharp inserts like that for cutting steel but they are all coated. If the cutting edge of the insert is sharp, its meant to be used for finishing or light cutting load only. It is the sharpness that gives the feel that it cuts steel like butter but the cost is insert chipping occuring more easily. You may need to use different inserts for roughing and finishing.
Another thing is that carbide inserts do not like rapid change in cutting load so if the lathe is not able to maintain a steady spindle speed or the feed is unsteady, chipping will occur more easily also. My solution is using cheap inserts. The convenience of replacing inserts and continue cutting within a minute is just too hard to give up.
 
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Stefan Gotteswinter
4 years ago
With a normal insert you simply don't do a shallow finishing pass ;) Finishing takes place with a reasonable deep cut - With a stout machine you will have no problem hitting close tolerance/good finish, when taking a 0.5 or 1mm finishing pass. But my toy machine is another game.. ;)
 
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