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View Full Version : Itís time for carbide inserts (seeking opinions)



dan s
05-03-2007, 11:44 PM
I know hss vs. inserts is a hotly debated topic, so let me explain. Last night I gave my self a nice cut while picking up a razor shape piece of 316 swaf. While icing my finger, and debating if I needed stitches, I decided I need to try some indexable tooling. My primary goal is to start making chips, because no matter what I try I canít grind a chip breaker into hss to safe my life.


With that in mind, can anyone recommend a good brand of holders? I have heard good things about glaze, and Dorian. I plan on using CCGT & CCMT, what type of chip breakers are people using on small lathes (12x36 and smaller)?

Swarf&Sparks
05-04-2007, 03:49 AM
I've never had any luck with chip-breakers (carbide or HSS) on 316.
That's why I've got kevlar gloves for clean-up.

torker
05-04-2007, 08:26 AM
Another thing to think about..a small lathe sometimes can't turn the r's or handle the DOC you need to make the chipbreaker work. I used to use inserts on my SB9 and had to put up with the rivers of long swarf ribbons. The finish on harder steels was amazing but the swarf was ugly to deal with. My 14X40 makes the proper chips with the same inserts at a much higher speed or a deeper doc, depending where the sweet spot is for the insert.
That being said, even with chip breaker inserts you can't always used the sweetspot rule and end up dealing with the swarf.
This is my experience only but I think nearly everyone has experienced this.
Russ

BobWarfield
05-04-2007, 12:46 PM
Glanze are nice. Micro 100 sells essentially the same holders, and Penn has those on sale from time to time, so keep an eye out. Grizzly also sells Glanze if you can't find them elsewhere. Here are my original Glanze holders:

http://www.thewarfields.com/cnccookbook/img/LatheStuff/PA192597.JPG

I have 2 sets of the Glanze style CCMT holders. One is 1/2" shank and the other is 5/16" shanks. I started with the 5/16" and bought the 1/2" after I saw them on sale at Penn and I had lost one of the 5/16" tools. A noticed an immediate difference--the 1/2" were very noticeably more rigid. OTOH, it was a very near thing whether I could get them on center with my AXA Phase II QCTP.

I will tell you that I found the boring bars included in these sets to be nearly useless. Wait for a sale, and get yourself a couple nice circle indexable carbide boring bars. The difference is night and day.

Note that all CCMT inserts are not created equal, either. Your average inserts look like this:

http://www.thewarfields.com/cnccookbook/img/LatheStuff/CCMT.jpg

They perform okay, but not the best. Look for these inserts:

http://www.thewarfields.com/cnccookbook/img/LatheStuff/ccgt.jpg

Note the little "crown" shape. They have gobs of positive rake. The catalogs will tell you they're intended for non-ferrous materials, but they produce a fine finish on steel too. They're a bit more delicate due to the fine edge. Used to be they were listed as CCGT, but now I see them often as CCMT too.

I have a page on my web site about lathe tooling that may help:

http://www.thewarfields.com/cnccookbook/CCLatheSurfaceFinish.html

Enjoy!

BW

dan s
05-04-2007, 06:56 PM
Bob,

How do the ďCrownĒ inserts do at making chips on your 9x30 (my lathe is similar 8x14)? Iím assuming your using the smaller ľĒ inscribed circle inserts?

BobWarfield
05-04-2007, 11:05 PM
Crowns cut real sweet--great service finish and takes very little pressure.

Even the standard CCMT's cut okay, it's just that I think the crowns are needed to get the kind of surface finish you can get with a well ground HSS tool.

These are the 21.51 inserts, so yeah, something like 1/4" inscribed circle.

I love 'em, and only use HSS for special purposes. You can, after all, grind HSS to do whatever you want, while the inserts are pretty much limited to how they come out of the box.

Best,

BW

wierdscience
05-04-2007, 11:13 PM
My advice for turning stainless is buy the inserts that are optimised for cutting it.MSC has a good general information page in there catalog for that purpose.Reading up on what you need before you buy will save you some aggrevation and a lot of money.

dan s
05-04-2007, 11:34 PM
Crowns cut real sweet--great service finish and takes very little pressure.

OK i can tell I was in the middle of a bad day when i wrote my last post. :D

what i meant to ask, is are you getting chips (6's & 9's), or the nasty razor wire?

BobWarfield
05-05-2007, 11:37 AM
I can get 6's and 9's with either insert type. You need to be aware I did install a variable speed DC motor on the lathe which makes it a heck of a lot easier to dial in the speed to get nice chips.

BTW, never touch those chips! I use chip brushes only.

Sometimes I like to dial in longer chips as they will leave a nicer surface finish than 6's and 9's on some materials. I think Torker alluded to that. Mostly, I dial 'em out though. And yes, carbide does love speed, and it hates really shallow depth of cut. I want somewhere from 0.010 to no less than 0.005 for my final finish cut, and will arrange the rough cuts to make sure that happens.

Best,

BW

LarryinLV
05-05-2007, 12:47 PM
DAn,
I like, and use Dorian insert holders. They're made well and hold up; I prefer the clamp type.

When I was using a 4-way tool post I bought the 3/4" size and milled the bottom for ~80% of length to put the insert on center and give a little shoulder at the front for consistency of placement.

This has come in handy with the QCTP since the QC holders only take a 5/8" tool and the milled Dorians fit nicely.

I don't buy chip breakers, but once you have the holder get some inserts of each type, chip groove and non - see what you like.

I usually use a pair of pliers if I dig into the swarf pile since I like my fingers right where they are.

dp
05-05-2007, 03:27 PM
Two sources of chips I use: the local supplier, Aronson-Campbell http://www.aronson-campbell.com/, has counter sales of broken sets and mystery chips, and Boeing surplus. I make my own holders. This allows me to experiment with lots of different chips and holder configurations and when I find something that is exceptional I buy them retail. Boeing surplus (Seattle, at least) has zillions of chips, some new, some used, for pennies on the dollar. Same with end and shell mills, reamers, drills...

This proved to be an excellent way to get to know chips. My trash is full of swarf that was generated just experimenting with different chips and setups.

toolsrul
05-05-2007, 09:32 PM
Whoever you choose be sure it can take a standard insert, eg: CCMT21.51, that'll insert shape & size will fit in anybodies holder that takes that insert. After those letters & numbers there is a chip breaker designation then a grade. For an example a Kennametal would be CCMT 21.51 FF KC730. A CCGT 21.51 would only mean that it is ground to a tighter tolerance but would still fit the same holder. Be careful about nomenclature you cannot identify, otherwise you might not have any other choices to get inserts. That could get expensive if the inserts don't work. Most of your reputable carbide companies have the nomenclature explained in the front of the insert section. Good luck, if you have a problem e-mail me & I'll get you help.

dan s
05-06-2007, 12:39 AM
Thanks everyone, I think I'm going to pick up a 1/2" shank set. not sure what brand yet most likely either Glanze or Micro 100 since they both come with a SCSCR holder.