Is it time for ME friendly inserts resource?

[Clive FosterParticipant @clivefoster55965]

I'm really impressed that Mark C is able to routinely get into the blue blizzard regime with his Boxford. My old Heavy 10 could barely manage that under optimum conditions but, as might be expected, the Smart & Brown 1024 manages it with pretty contemptuous ease unless the insert book specifications are approaching insane for manual machines. Even with a reasonably effective chip guard the swarf is still a complete pain in the, well, pretty much everywhere and is why I've pretty much given up on inserts for routine work. When contemplating the benefits of full motorcycling gear; leathers, helmet an all; over the standard shop coat or overalls starts looking almost serious rather than distinctly facetious something has to give. So I've gone back to tool grinding, mostly.

Although blue blizzard AKA proper book regime pretty much guarantees good surface finish its not really appropriate to Model Engineer or Home Shop folk with machines at the bench and smaller end of the spectrum. Quite apart from the chip issue everything happens very fast, especially for neophytes, and full bore lifetime of ill chosen inserts can be distressingly short. With cutting edge cost starting at something of the order of £1 even the most awesome finish is a poor bargain for a couple of hours or less life in cut. Doesn't help that ME or HS guy frequently needs to scrape the odd few tenths or thou or so off which really isn't the sort of thing inserts are designed for. Well chosen ones can do it but its not part of the designers brief.

Given that it probably costs something between £50 and £150 from a standing start to have reasonable lathe tool and end of end mill touch up capabilities going insert only from day one looks quite viable from a financial perspective. In the end HSS Sharpening Man will probably spend less but if Insert Guy (or Gal) can be provided with suitable inserts having lifetimes of hours, hopefully 10 or more, in cut giving a good finish at comfortable speeds and cutting depths, right down to sub thou if need be, insert only seems perfectly viable way to work. As well as avoiding swarf embarrassment the chosen inserts need to be tolerant of interrupted cut and damage from inadvertent too fast / too heavy engagement with the workpiece. Buying a box of 10 insets with, say, 4 edges each and an anticipated life in cut approaching 10 hours for £20 off E-Bay is a good bargain until less than perfect skills chip a cutting edge after only a few minutes use. A theoretical 400 cutting hours or more for £20 to £30 is nice but thats only 400 edge destroying mistakes per box and I seriously doubt if anyone gets to a reasonable skill level without committing 100, or more, sins capable of destroying the edge of an ill chosen insert long before the end of its lifetime. With HSS edge damaging errors just mean a short walk to the grinder but every chipped edge on an insert is a chip out of the play budget. Which is always way too small to start with.

The various shape type suggestions mean little to a beginner. Shape really only defines what spaces the insert can get into. Although less edges per piece I'm inclined to consider the diamond style as being most appropriate as the one and only second turning insert purchase as being better able to get into the smaller spaces typical of much ME work. The first insert purchase should, of course, be a parting off type whose all round superiority to HSS is unquestioned. What the neophyte, and HSS switchers need, is decent advice on speeds, feeds, insert material and insert edge design style that will work well on their particular type of machine. I'd be unsurprised to find that there are hundreds of different, for example, CCMT inserts in sizes useable on ME machines. Probably a quarter to a half of which can be coaxed into good, or some semblance thereof, results by skilled folk. Maybe 5 to 10 percent being a pretty decent choice for a beginner in being reasonably robust and giving decent results over a fiscally acceptable lifetime using experienced ME advised speed, feed and depth of cut information. Maybe 1 or 2 percent will be real ME stars giving awesome finish over a long life in a variety of materials whist standing up well to the odd Boo-Boo.

Finding the stars will take a community effort.

Clive.

[Mark CParticipant @markc]

Clive,

It never occurred to me when I typed the description regarding my Boxford, but I should have said it was a VSL with 1.5 horse rather than the 3/4 horse in most other models.

I am a little way short on enough power to get really into the work but I have uploaded some pictures of the tool and a bit of swarf that came off it. They fly around like bullets and you don't want them in your hair or down your neck (or any other contact with you). I have once or twice managed to get enough power in the job to get flakes flying but this only happens when the swarf doubles back on the chip breaker and hits itself. Those curly projectiles in my picture are about an inch long and result from the swarf curling back and hitting the work just ahead of the cut so not true "blizzard" conditions you get on industrial kit but not bad for some home turning!

I also added a picture of a worn out (I do have another name for this condition) tip and you might be able to see the damage – it was still cutting but not producing "proper" chips and it was taking some feeding and a lot more power from the motor.

Mark

PS. I should point out that that bit of evil swarf was not fresh, there are bits of it all around the workshop if you go looking for it, there is an annoying pile behind the VSL that is very hard to reach so no shortage of samples to show!

Edited By Mark C on 09/10/2015 19:37:50

[MuzzerParticipant @muzzer]

Posted by Roger Head on 07/10/2015 13:30:37:

…..extols the virtue of the TNGG160404R-S PR1125 (see the post from carbidenz about halfway down the page). They aren't cheap, but with six edges it isn't so bad. They are listed at the very end of this page

See page 64 of the Kyocera catalogue here. Rather annoying viewer but the up and down arrows zoom in and out. Right and left arrows page right and left.

The PR1125 is the coating. The 160404 is the size and TNGG defines the shape and chip breaker which seems to be a sharp edged ground insert. Sounds like an interesting alternative to the ##GT ground inserts, although at least the latter are established and widely available.

No idea if you can buy Kyocera inserts in the UK (ideally of this sort) – the website seems determined not to make it easy to answer that question. Perhaps you can only buy from them if you are industrial users.

Anyone know of an accessible (to us) Kyocera stockist in the UK?

[Roger HeadParticipant @rogerhead16992]

Yes, even the catalogue itself is a bit painful to sort through. I have a paper copy from several years ago, but it's so heavy it is hardly bedside reading!

Instead of stuffing around with their web view, you can d/l a pdf copy – see the button just to the left of the page-number box at the top of the screen. Be aware though, it's ~300MB so you need a reasonable link. Their server seems pretty fast, fortunately.

I haven't bought any of these, I'd have to get a new toolholder as well. But I would really like to hear comments from anyone who has…

Roger

 

Edited By Roger Head on 10/10/2015 02:57:41

[MuzzerParticipant @muzzer]

ideally from my POV they'd do a CCGG version (ie the 80 degree rhombic shape) with the same sharp edges. But I was losing the will to live by the time I'd found he TNGGs….

[Roger HeadParticipant @rogerhead16992]

Posted by Muzzer on 10/10/2015 09:20:30:

…But I was losing the will to live by the time I'd found he TNGGs….

Which is the great thing about a pdf copy instead of the web viewer. They don't have a CCGG (i.e. 7deg clearance), but there's a heap of variations of CNGG (0deg clearance, which of course is a requirement if you are going to be able to flip it over. Among all the variations, there is the same sharp chipbreaker style, but I don't know that it truly is double sided. We'd need to talk to a distributor to get the definitive answer to that.

Anyway, I just placed an order for a MTJNR/L1616H16 toolholder, and I'm deciding whether to buy a single TNGG insert from carbidenz, or bite the bullet and get a pack of ten from Aliexpress for ~US$86, with free postage.

Roger

[MuzzerParticipant @muzzer]

I was really referring to the time it took to chase down the Kyocera turning insert catalogue, PDF or otherwise, from the depths of their labyrinthine website, ideally with some prospect of seeing prices and UK distributors. They don't make it easy. I gave up on the latter but at least managed to find some trace of the TNGGs before the will was finally lost.

Where did you order the toolholder and what was the AliXpress part you spotted?

[Roger HeadParticipant @rogerhead16992]

The toolholder is also from Aliexpress

http://www.aliexpress.com/item/Free-Shipping-MTJNR-1616-H16-Indexable-External-turning-tool-holder-93-Degree-Lathe-CNC-Carbide-Turning/32345693044.html?spm=2114.01020208.3.12.LVMkaM&ws_ab_test=201556_8,201527_3_71_72_73_74_75,201560_4

There are quite a few sellers, some cheaper, some more expensive. I chose that one simply because they didn't seem to be a bottom-of-the-heap seller.

The set of ten inserts is at

http://www.aliexpress.com/item/Genuine-Kyocera-Kyocera-CNC-blade-TNGG160404R-S-PR1125/32409210601.html?ws_ab_test=201556_8%2C201527_3_71_72_73_74_75%2C201560_4&spm=2114.01020208.3.1.rUTLaE

They don't seem to have much rep on Aliexpress (only 7 feedback ratings, although they've only been operating for a few months), I guess there's only one way to find out!

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