Dorian Cutoff Tool on a manual lathe where am I going wrong?

I just purchased the following parting tool set with some toy money. Amazon.com: Cut-Off Sets without Tool Block SGIH32-3S, SGIH 32-3 Blade, 10 SGTN-3-DC656 Inserts and Storage Box: Industrial & Scientific.


I had used an Iscar cutoff tool off tool back when I was in college of the same design and at the time we were cutting some weird exotic nickle alloy that work hardened and wore out cutting tools real fast, and yet I recall the Iscar one would go dull and barely cut but I can't seem to recall it going catastrophic on the first cut and ruining its holder too! I am pretty sure back then we didn't have any coolant on the part either.

Well I purchased my set from Dorian as I got a good deal on the price. The whole set was $100. I made up my own holder as I have an AXA toolpost but built it as rigid as I could make it.

First cut on the machine, I set it up just a tiny bit below center, it was chattering for the first few moments, but once I adopted a steady feed it went about 1/2" then all of a sudden poof the cutter disintegrated and took the bottom of the holder with it!

Since I only have 2 sides I am very hesitant to try another shot. For coolant I am using brushed on cutting fluid which I know probably isn't ideal but I don't have flood coolant on the lathe. Do I really need flood coolant? I don't seem to recall having it back then. I am not too concerned with cutter life as if I get a few hundred cuts an insert I will be happy. But with that being said, I do need the insert and holder to last for more than 1/2 a cut!

If it is of any help here's a photo of my setup and the aftermath.



Here's a photo showing the slot, it is totally shot!


Other than that not much else I can say, it just happened so fast that I am hesitant to try again until I have a better idea where I went wrong. I should also say speeds and feeds were real conservative. On 2"dia I was turning at 250rpm.

What do you guys think caused the issue?

I snapped both ends of the one that came with my dorian BXA set.
There's a major fuck up somewhere with those, cause we're not the only ones who've broken them.

Overall I just don't like GTN inserts at all, and that's part of the why.

There was no bottom piece left attached when mine took off.

edit, oddly enough the one with my axa set survived better though I don't use it much, at least it never snapped. I used the one with the CA set a short while(maybe used 2-3 inserts) and replaced it with sandvik and a different insert style that is just way better.

What does the opposite side of the holder look like? I take it you indicated the tool in. Was the part solid or had some sort of I.D. bored into it. In my short time machining I think I have only burned up one edge of a parting tool but I see it common in our shop with our "metal lockers" who make bushings at times. And I am quite sure Ill burn up more in the years to come.

Can't say about the actual toool but your speed was way low.

2" at 250rpm gives you <> 130' / minute which IME is right in the BUE zone.

Swarf sticks to tip, grows and rubs in groove, seizes, blade snaps.

From your pics I see Overhang! - back to basics and retract that topslide

Same goes for blade extension, you've only got to go ''just past'' centre, any more sticking out ain't helping.

Intermittant coolant is often worse than none at all......... also causes carbides to crack, tip getts hot, then chilled and ping!.......... edge goes off tip and blade goes bang - and it alll happens quite quickly

In my case the thing just broke right off the bottom, insert still good oddly enough. Surely bad heat treat, no tempering, maybe geometry a bit off on how the pocket is cut to make it suddenly grab and wreck everything. Definitely was a surprising moment and unexpected.

I've parted up to 6" monel with regular sandvik 1" blades, sticking it out a bit more a few times until I was barely holding onto any of it(past what they even recommend), ain't broke one yet.

I don't know why people like these things. I tried a slightly different style, but the same idea. The insert would often shift slightly, then jam up and destroy the holder. Give me a good old fashioned T-style cutoff blade any day of the week, mounted at the right rake angle. Dab on some decent oil and go to town. IMO, any given size/rigidity lathe has a limit on material and diameter where parting off is a problem no matter what, but you shouldn't be there yet.

What does the opposite side of the holder look like? I take it you indicated the tool in. Was the part solid or had some sort of I.D. bored into it. In my short time machining I think I have only burned up one edge of a parting tool but I see it common in our shop with our "metal lockers" who make bushings at times. And I am quite sure Ill burn up more in the years to come.

Click to expand...

Here's the holder that I was using, I machined it up out of some steel I had here in the shop. It has a 60 deg dovetail in it that sucks the part in. I could see how perhaps it was a chattering issue but if anything that would more be in the AXA I would think than in this holder block. As far as setting it was concerned, I just sat my 6" scale to the side of the part and used the poke method where you see if the scale is vertical to know you hit dead center. I then went a hair undersize.

As to the part in the lathe that was just a piece of scrap steel that I had lying around. I couldn't wait to test out my new toy.

I snapped both ends of the one that came with my dorian BXA set.
There's a major fuck up somewhere with those, cause we're not the only ones who've broken them.

Overall I just don't like GTN inserts at all, and that's part of the why.

There was no bottom piece left attached when mine took off.

edit, oddly enough the one with my axa set survived better though I don't use it much, at least it never snapped. I used the one with the CA set a short while(maybe used 2-3 inserts) and replaced it with sandvik and a different insert style that is just way better.

Click to expand...

When that happened was it just the sudden out of nowhere yield? That is what happened here to me. In my case I have always hated cutting off material, and never been able to get any good at it. Unlike Conrad, I have shattered and blown up more of those T style parting tools than I care to think of. The only time that I ever had cutting off work well (other than on aluminum or delrin)for me was when I used an Iscar version of this tool and it was awesome! The professor I was working for was having me make these groved sample parts where we would take a 3" dia part put a groove down to 1" and do that every 1/8" of an inch so you had a part with 20 groves. The material was the toughest stuff I have ever seen, it was an aerospace Hasteloy type material, he would then study how the material cut and send the data off to Pratt and Whitney so they could optimize how they cut the material. At the time I just couldn't believe how easy the right cutter made doing cutoff. This was a material that if you cut it wrong it work hardened and you had a layer like 1/8" deep that you just couldn't get through. If the cutter was good enough for that I would have thought my piece of steel would be no match for it!

As far as speeds and feeds being too slow, do you really think that could be an issue? I am usually used to going much slower than what the modern carbides can do but than again I don't have a 30HP machine with flood coolant on it and everything. I really hesitate to crank the speeds up quite a bit now as I only have one side left to try on this before I am really screwed!

Since this is a hobby for me I am going to hear a lot of grief from my wife and wind up with a whole pile of shoes if I have to destroy a few of the blades before I figure out how to use them if you know what I mean.

As far as the blade being a Dorian, has anyone else other than SND had these issues with these tools? Was my real mistake not buying an Iscar?

It's possible the insert pushed back in the holder, and got to far below center. I got rid of that style blade an insert because of that problem, and switched to Manchester holders.
Set the tool on center and crank up the RPM's to 300 -600 SFM, and keep coolant on the cut.
Harry

Too many people listen to the home shop dopes and go with a small parting tool, that total bullshit. A big parting tool close to the collet or chuck will part off thousands of parts a day. like 3/16 to 1/4".

When high speed machines break a parting tool its not a bit funny.

I have pictures..



Normally the short part ,is reamed, internal snap ring groove, roll stamped with a part number, knurled, internal champher and parted in 2- 3 seconds.

when the parting tool breaks it makes one of those twisted F****d things every 2-3 seconds. Ever see a lathe mill with a reamer? Same part same machine.

Once the parting tool dies and the high dollar paid yoyo wakes up and puts his playboy magazine or cell phone down you get a nice pile of garbage and busted tools beat to hell.

Im not saying you cant use a thin parting tool but if you are making lots of parts and hire people who dont watch you can end up with parts baskets full of trash and busted tools.

adammil1 said:

As far as the blade being a Dorian, has anyone else other than SND had these issues with these tools? Was my real mistake not buying an Iscar?

Click to expand...

Sorry buddy, but in case you didn't know it....the Dorian tool (the blade and inserts, that is) is MADE BY ISCAR.

It's their GTN/GTR/GTL style pieces of crap. The inserts move in the pocket and implode the tool.

Get yourself a blade for Sandvik N151.2 or Valenite VSG style inserts or similar, never look back. If you need single-ended for deep cutoffs, look for insert systems where the insert has V-grooves on the insert or blade top and bottom, plus seats the insert against a solid stop. Tungaloy, Taguetec, Kennametal, they all have them. Even Iscar's own replacement for that system, the Tang Grip, is better than those things.


4mm wide insert:
Safe_fast_Cutoff - YouTube

3mm wide insert:
MVI_0516.MOV - YouTube

A lot of guys are having trouble parting. All my trouble was from HSS parting blades. I will never use one of those again, Ever. If you don't have a coolant pump, You need to get a squirt bottle and really douche it when you cut. You need to flood the groove or you will have problems. I always turn low rpm's when i part, so the coolant doesn't fly off the chuck that bad. it works for me. My Leblond gives me no issue at all when parting, But my enco always gave me problems till i figured it out. If I parted with the compound angled parellel with the work piece like you have in the picture, it would always grab, dip down and break. If i didn't have coolant flowing in the grove, the metal would melt and stick to the cutter and snap. Try the compound at 45 dgrees, or 60 (59 and 1/2 for you old schoolers) or even at 90 degrees, Let the coolant flor.. and try it.

I've blown out a slot grip too. Can't recall what size, I can see trashing the insert but trashing the slot was disappointing.

Key thing is your lathe needs to be tight about the cross slide, my assessment is small lathes and extra play in the leadscrew seem to suck up all the backlash in a millisecond, quadruple the depth of cut and kaboom weakest link is the bottom of the blade.

PixMan said:

Sorry buddy, but in case you didn't know it....the Dorian tool (the blade and inserts, that is) is MADE BY ISCAR.

It's their GTN/GTR/GTL style pieces of crap. The inserts move in the pocket and implode the tool.

Get yourself a blade for Sandvik N151.2 or Valenite VSG style inserts or similar, never look back. If you need single-ended for deep cutoffs, look for insert systems where the insert has V-grooves on the insert or blade top and bottom, plus seats the insert against a solid stop. Tungaloy, Taguetec, Kennametal, they all have them. Even Iscar's own replacement for that system, the Tang Grip, is better than those things.


4mm wide insert:
Safe_fast_Cutoff - YouTube

3mm wide insert:
MVI_0516.MOV - YouTube

Click to expand...

Nice videos with a manual machine, you have it right.

PixMan said:

Sorry buddy, but in case you didn't know it....the Dorian tool (the blade and inserts, that is) is MADE BY ISCAR.

It's their GTN/GTR/GTL style pieces of crap. The inserts move in the pocket and implode the tool.

Get yourself a blade for Sandvik N151.2 or Valenite VSG style inserts or similar, never look back. If you need single-ended for deep cutoffs, look for insert systems where the insert has V-grooves on the insert or blade top and bottom, plus seats the insert against a solid stop. Tungaloy, Taguetec, Kennametal, they all have them. Even Iscar's own replacement for that system, the Tang Grip, is better than those things.


4mm wide insert:
Safe_fast_Cutoff - YouTube

3mm wide insert:
MVI_0516.MOV - YouTube

Click to expand...

Pixman,

These all say made in USA where as last I knew all Iscar's stuff was made in Israel. I know in the past I never had issues with this type of tooling and thought it worked real well. With that being said those videos you posted are cool, and I would love to be able to see that level of performance out of my machine.

The only issue I see now is it is going to take a leap of faith for me to try going at such high speeds and feeds until I know 100% slow speed is why I toasted it. The holder died so quickly I would really hate to loose the other side if that wasn't what I was doing wrong. In an ideal world I would like to take it slowly and build up confidence before I try running like you did. Do you think the leap of faith is required? It isn't like these things are cheap to experiment with either.

How many others of you have holders like this? It wasn't even like I had a good run going I lost the thing on the first 1/2" DOC on a 3" dia piece of steel!

Well, another surprise for you would be that Iscar has a huge plant in Arlington TX where the Iscar Metals Group (a Berkshire-Hathaway-owned company) makes a LOT of tools sold here under the Iscar, Tauguetec and Ingersoll brand names.

There's a decent chance that they didn't make that blade, then all the more reason why it's a POS. Chances are still pretty good that they made the inserts though.

The patent for the DGN style holders ran out probably 20 years ago, anyone could have made it. The point isn't where it came from, rather the poor design and/or quality.

Overhang, and barely a grip, with a barely adequate 3 jaw chuck.

At least grip your work on a long enough area, that it does not act like U joint in the jaws...

Soft jaws that grip a larger area of part, and reduce overhang will help a lot...

Yout pic is not that clear, but never extend end of compound much past bottom of compound for parting.. You don't need the diving board effect, or possible breakage of compound...

I HAD trouble with those inserts/holders until figuring out the root problem. It took a month, mostly after trying everyones suggestions and finding them wrong.

After sitting back and really thinking about it.... now it works, cuts like butter, no coolant, no problem. I get 1,2,3,4 foot long curls..thats in 6061, I didnt catch what material you were using. I actually brought some home and screwed them onto the ends of the Christmas tree branches, cool decorations..Im using exactly the same tool holder and the cheapest blades and inserts money can buy from CHina, they cut like razor blades.

What breaks things is excessive stress (force). To really , suddenly, catastrophically break things takes IMPACT force. Something suddenly changes.

That cant happen with a tool that wont cut, because if its not cutting, nothings happening except friction and some heat (or a lot). No digging in to break.

Think about that, then notice youre trying to cut a THIN cut off the END.... That one bit me too.

I tried "the tool isnt on center" and that was baloney. I dont even bother now, and it cuts great. 040 below works as well as 010 above, except it leaves a tit. But I like big tits..

I tried cutting oil, coolant, changing speed, standing two inches to the left., cussing and throwing tools. nothing worked. Especially advice from those who said they solved the problem, didnt work.

What is "cutting?" Its a process of forcing a hard tool against a surface until heat from friction causes a bucking of the work that starts the tool to digging, after that, material shears off.

I knew from the HEAT it was making friction, so that must mean TOO MUCH heat. From a thin contact line on an insert? NO, from the SIDES of the tool.

It was crooked. It was 005 or 010 crooked.

on a face cut, who cares? Lots of angles between the tool and work will cut something (theres an ideal angle) but not with a cutoff tool like this, only ONE angle works and its ZERO. The big difference is that in a face cut, the insert isnt TRAPPED between two faces, its skating across one. The only friction and heat source is the cutting contact. In the cutoff tool, the SIDE of the blade and insert can rub.

What was happening is that, especially in Al, the excess heat was work-hardening the material, then that's the end of any cutting. Al is bad for that. And it gets ROCK hard real quick.

The thin end of the work is getting super hot and expanding into the tool. JAM! BANG!

Get a NEW blade and insert, and indicate it ABSOLUTELY straight with a dial indicator. Set blade depth, then travel the mic feed (cross feed, whatever) and read runout with a dial indicator (0-15) along the blade, and tweak the holder till its not measurable (<<0005). Make sure the excess slop is out of the gibs.

001 doesnt sound like much, unti you sit with a magnifying glass and study that insert profile. Its curved on the end, just a TINY misalignment, and the insert is free to rotate and jam, and bend the blade.

Screw the tool height, just get it close. Put it a tad below center. Ive gone as far as 040 below, it made no difference.

Get the right surface speed. I still get problems cutting through 3" Al stock when the diameter hits 2-1 inch, its too slow then.

Start with as little blade out as possible to make an initial cut. IF thats not enough, later, then move the tool out, but start with as little as possible to keep the CUT straight.

When I do this (on Al, again) it makes curls or strips as long as I want to make (3-4 feet long, it just spools it off like butter). UNTIL... until FRICTION starts building up, the work slows down, and most critical - the curls turn to fragments, then its all over, the fragments clog the clearance and there goes the heat. When its cutting right, down inside, it spools off coils of material like a coil spring. When those coils stop and it starts spitting out broken segments, its about to go South. What helps there is to put a couple drops of Al lube so the pieces can flow out, but Ive found lube makes it worse overall.

Ive done this on 3 inch Al rod with no coolant, it runs so cold I can lay fingers on the work and theres barely any heat. That is, with a significant amount of material overhanging. Theres no way that paper thin end will keep its shape, its about guaranteed to deflect into the tool. On one thin cut, I held a wet sponge against the end, sucked the heat right out without rusting the bed rails.

The other thing that really screws it up is the cross slide travelling just a bit to one side when cutting, that also jams the blade against the work and makes a lot of binding and heat.

PS look at your picture, short stout part, very thin end (no place for heat to transfer away) and a SMALLER diameter chucked into the jaws, no path for heat flow. The chuck jaws are the best path for a heat sink. As the chucked end approaches zero diameter, the part has no place to dissipate heat to.

Rigidity of the lathe definitely plays a role, but its still a crappy design vs other options, and other options will do better in a less rigid lathe. The insert is definitely not held very good in those set up, they do push back and are no good for side cutting either.

I want to try doing this again today, based off of what I have read here, my plan will be to start with a 2" dia or so piece of material. I looked up the recommended speed for my inserts which are CVD and they recommend 540-870fpm which on a 2"dia part would have me between 1740 and 1000 or so RPM and at 1" on the lowside would have me at 2160rpm. So with that being said I am thinking I will start the machine at 1500rpm which just seems really fast, set my feed at about .001" per rev and prey! Does this sound about right?

I will also go and indicate the tool so that it is perfectly 90, start with a piece that is fully chucked in the chuck, and go and turn the compound to 60deg and put it so the tool is directly over the base.

Am I missing anything? I really don't want to mess up this end too. Going as fast as it seems to say will really take some balls the first time but we shall see. Does anyone see any holes in my plan?

Indicate the side of the blade to go directly into the work using your indicator , try getting it dead nuts.
Make sure your tool is on center to the work on its height.

I have only tried to auto feed a tool in once. It didn't go so well ( don't believe my machine tool teacher will ever forget that). I would feed by hand to get a feel for how the tool is cutting .

Also if your trying to practice parting off why not pop a hole through the middle?
Say maybe a 1/2 or 3/4 hole. Would still give you plenty to part through.