Looking for an insert

[Susquatch]

In a “ hobby” setting, it might be worth giving SS type inserts a try.

I was quite impressed by the work you characters did. It greatly informed my own processes and thinking on the matter. @Dabbler has talked about it with me several times in our conversations too.

But this SS insert advice is new to me. Somehow I missed that. More stuff to learn about!

In the meantime I have a related question. Most of the stainless inserts I've seen are coated. Doesn't the sharp edge cause the coating to wear off prematurely? I'd fully expect sharp to wear faster regardless, so I'm asking specifically about the coating. Or is that work yet to be explored?

 

[Dabbler]

Doesn't the sharp edge cause the coating to wear off prematurely?

These high end inserts (and a little pricey too) seem to have a predictable life, probably related to the coating wear. I'm sure @Alexander is the right person to chime in here. My experience with Kinnemetal is that it takes a long time for the coating to wear off. Once that happens, the chips get hotter and the inserts need careful attention to cutting forces (reduced material removal) or the insert will be damaged. It is about 50/50 for me if the tip breaks off or the insert splits in half, in Triangular inserts. I don't have enough data on trigon style inserts to compare it to.

 

[Susquatch]

It is about 50/50 for me if the tip breaks off or the insert splits in half, in Triangular inserts. I don't have enough data on trigon style inserts to compare it to.

I think you would like trigon inserts. I have never broken one in half. When they fail, it's almost always the top corner which leaves the bottom intact for another use (6 working edges total).

I'm gunna take a break from Honey Do's and see what my stainless edges look like.

 

[Susquatch]

Apparently, I don't have any dedicated stainless inserts. Any inserts that I have that are rated for stainless, are also rated for steel. None of them are what I would call sharp. Certainly not nearly as sharp as the same inserts from the same manufacturer for Aluminium.

So, I just ordered some for Stainless with both 04 and 08 tips. An observation will have to wait till they arrive.

 

[Alexander]

I am going to add in this screenshot, which helps in finding inserts. The size and shape follow ISO standards. The chip breaker and the coating are manufacture specific.

 

[Susquatch]

Apparently, I don't have any dedicated stainless inserts. Any inserts that I have that are rated for stainless, are also rated for steel. None of them are what I would call sharp. Certainly not nearly as sharp as the same inserts from the same manufacturer for Aluminium.

So, I just ordered some for Stainless with both 04 and 08 tips. An observation will have to wait till they arrive.

They just arrived this morning. Yup, they are definitely sharp. So that clearly supports what has been said.

Unfortunately, they didn't come with feed and speed recommendations so I'll have to see what I can find we elsewhere and them mark that on the insert package.

These are WNMG 080404 and 08 with a PC9030 coating for SSteel. If anyone has speed and feed info for inserts like this, I'd appreciate it.

I'll also ask the seller but I'm not exactly optimistic that they will know.

Scratch that - the info isn't on the insert box, but it is posted on the sellers page.

Ap = 0.1 (0.004 - 0.197)"
Fn = 0.008 (0.001 - 0.160)"/r
Vc = 492 (328-556) sfm

The above is the same for both tip sizes which seems a bit odd to me, especially the feed rate but then again it is from China.

The recommended speeds N feeds support what you guys said earlier.

Going to have fun trying these out on some fine cuts!

Constantly learning. Lovin it!

Edit - offline I was asked for a link. My bad.

Here it is:

WNMG Carbide Insert for Stainless Steel(WNMG080404 HA PC9030) https://a.co/d/hTp2mSq

 

[Darren]

This is a good resource:

Insert Designation Chart - provides ANSI and ISO designation code definitions for carbide insert shapes, relief angles, tolerances, chipbreaker codes, hole types, size values, thickness values, radius values, wiper lead angle, wiper clearance angle, cutti

 

[Susquatch]

This is a good resource:

I agree they get a lot of info onto that sequence of charts. I especially like that it includes both metric and imperial on the same charts instead of separate charts. But it doesn't include feeds N speeds as far as I know. I think it would need to be a lot more complex to do that too.

 

[Susquatch]

Ok, my wife will kill me if she finds out, but I did sneak out into the shop and took some cuts on different steels with the WNMG for Stainless.

@RobinHood, @Dabbler, & @johnnielsen - you guys deserve medals for innovative machining approaches! The 08 and 04 inserts for Stainless both did a great job on a variety of steels leaving behind a mirror finish at the median recommended rates for cutting Stainless. VERY IMPRESSIVE!

Only limitation is that I had to run the maximum speed of my lathe on a 3/4" bar. On the flip side, chip breaking performance was amazing - looked more like mill chips than lathe curls.

Of course, I have no idea yet how long they will last but so far so good! Gotta be better than inserts for Aluminium though and I was happy with that!

THANK YOU!

 

[Susquatch]

Just a small update.

I cut a long piece of an old bolt with the insert for stainless and took a photo cuz I think members might like it. The part clearly shows why long parts (over the magic 3:1 ratio) should not be cut without a tailstock. However, the resulting harmonic chatter was mesmerizing! If you zoom in, you can clearly see where the length stopped being an issue and you can see the resonance in the angle of the chatter marks. Almost beautiful!

 

[LenVW]

If you are still looking send your part numbers to . . .

Carbide Inserts

accusizetools.com

Accusize Tools may have an equal insert.
Look at their website or contact their local distributor.

 

[kstrauss]

All of this talk about WNMG inserts has piqued my interest. Where can I find holders (3/8 or 10mm shank?) suitable for my little Myford S7? Accusize seems to have only huge (3/4" and 1" shank ones).

 

[Upnorth]

All of this talk about WNMG inserts has piqued my interest. Where can I find holders (3/8 or 10mm shank?) suitable for my little Myford S7? Accusize seems to have only huge (3/4" and 1" shank ones).

Although holders are available usually it's best to avoid negative rake tooling on small lathes. I'm sure others will disagree with me on that.

 

[PeterT]

Almost beautiful!

..until the carbide edge goes 'tick' & never really cuts the same LOL

 

[Susquatch]

All of this talk about WNMG inserts has piqued my interest. Where can I find holders (3/8 or 10mm shank?) suitable for my little Myford S7? Accusize seems to have only huge (3/4" and 1" shank ones).

I have a 1/2" one. But it doesn't have anvils, has no negative rake, and uses 1-sided 1/4" radius inserts. So you only get 3 cutting points. On the other hand WNMG is quite a bit stronger than all the other alternatives except round. Quite frankly, it was the only carbide insert tool I ever used for 15 years or so. It was what made me question the superiority of HSS.

I can't find one in anything other than those stupid kits.

What is the maximum size you can handle? 3/8, 7/16, or 1/2?

 

[Susquatch]

..until the carbide edge goes 'tick' & never really cuts the same LOL

My comment was about a cute little live center. I don't know what that has to do with a carbide edge.

If you quoted the wrong thing by accident like I do sometimes, I agree that the problem with sharp carbide is a fragile edge. I don't personally hope they will last like a regular carbide insert, but when you need to take skim cuts they at least will work. Regular carbide edges won't take 0.001 cuts. So it's not about lasting, it's about using them when you need them.

 

[kstrauss]

I have a 1/2" one. But it doesn't have anvils, has no negative rake, and uses 1-sided 1/4" radius inserts. So you only get 3 cutting points. On the other hand WNMG is quite a bit stronger than all the other alternatives except round. Quite frankly, it was the only carbide insert tool I ever used for 15 years or so. It was what made me question the superiority of HSS.

I can't find one in anything other than those stupid kits.

What is the maximum size you can handle? 3/8, 7/16, or 1/2?

10mm is the max with my QCTP (0xA size) and the available distance between the top of the top slide and lathe centre.

 

[Dabbler]

Although holders are available usually it's best to avoid negative rake tooling on small lathes. I'm sure others will disagree with me on that.

I agree. But WNMG doesn't have to be a negative rake insert. The N refers to the negative angle the insert sits at. That way the clearance in the front of the insert isn't ground in. Usually results in a stronger insert.

I use WNMG 432 inserts on a 12X37 with a 3/4 HP motor.

Inserts for stainless and aluminum have between 3 and 5 degrees of positive rake. I'm sure that you can buy outside this range, but they aren't interesting to me....

 

[PeterT]

My comment was about a cute little live center. I don't know what that has to do with a carbide edge.

My comment was related to your comment in post #30, which I understood to be about chatter induced by > 3:1 un-supported stock. Anyways, disregard. It was a weak attempt at humor. I seem to have different experience with carbide than you do for whatever collection of reasons. Carbide is less... make that UN-forgiving of chatter which can lead to edge degradation (which was root intent of aforementioned humor). But I'm not here to convince you of anything. Machine with whatever works best for you.

 

[Susquatch]

My comment was related to your comment in post #30, which I understood to be about chatter induced by > 3:1 un-supported stock. Anyways, disregard. It was a weak attempt at humor. I seem to have different experience with carbide than you do for whatever collection of reasons. Carbide is less... make that UN-forgiving of chatter which can lead to edge degradation (which was root intent of aforementioned humor). But I'm not here to convince you of anything. Machine with whatever works best for you.

If I had clicked on the up link on your post, I would have seen that. So I missed it. Sorry about the misunderstanding.

Yes, you are right about the chatter nicking an edge. I normally wouldn't do a long stick out like that. I'd use a center in the tailstock. But I was taking such light cuts I didn't think it would hurt. The chatter clearly says otherwise. It really is beautiful though. I wish I could produce a finish like that on purpose!

Also, please note that I really only posted that to show others what can happen with too much stick out.

I think we are in the same page Peter. I wouldn't normally do that either. As you say, carbide is normally very unforgiving of such things and that is my experience too. I really think the only reason that I got away with it is because I was using a very sharp edge and taking cuts only a few thou deep.

You should try some inserts for Stainless yourself. I'd love to hear and see your experiences too.