Yet another parting tool question…

[MuzzerParticipant @muzzer]

Posted by Neil Wyatt on 27/08/2018 16:37:56:

Choice between Cutwel prices (min £15 delivery) and APT a minimum order quantity of 10 so over £50 with VAT and shipping.

Might pop in next time I'm near a Cutwel as none of the hobby suppliers seem to do uncoated, not even JB.

Neil

Possibly one of those things to keep an eye open for. Each month, they do special offers that often include "buy 10 inserts, get free body etc". Or sometimes it's just a tasty price reduction. Pretty sure they did one on the KGT or MGT series not so long ago, which may explain why I have a few of them. This month's offers are here.

If you are in the Cleckhuddersfax area, it's possibly worth calling in, although the postal service is generally pretty quick and reliable. For small orders, they use Royal Mail at £3-4 or so. Free P&P for over £100, IIRC.

Murray

[Anonymous]

Posted by Muzzer on 28/08/2018 19:57:24

Possibly one of those things to keep an eye open for. Each month, they do special offers that often include "buy 10 inserts, get free body etc". Or sometimes it's just a tasty price reduction.

They time it just right to be a PITA. I ordered a range of cutters on Friday, got them in the post on Saturday. Today their special offer booklet arrived.

Andrew

[duncan webster 1Participant @duncanwebster1]

If I buy one of Ketan's SLTBN parting tool holders and bolt it down rigidly through the tongue onto a block at the back of the headstock with the blade in upside down does this sound like a recipe for disaster? Would I be better with the holder upside down as well, even if it does make getting at the securing screws a lot harder?

**LINK**

[Mark RandParticipant @markrand96270]

Having the holder upside down wouldn't make any difference except making it harder to get to the screws. It wouldn't make any difference to the tool or the alignment.

[JonParticipant @jon]

You can still access the screws to move the tool in and out to desired length, they should be universal top and bottom wth two angles each meeting in the centre.
In othe words mount tool post, block normal with screws at top and turn blade upside down.

Just had a look have broke or bent two tools over the years and both are the clamp type. None of the wedge types have bent or broken parting to turning.
Favourite tool used daily for turning, facing and parting Iscar Do Grip DGTR 1616-2 with DGN 2202J IC354 tips ok to 35mm dia. You wont know your born having just about all types of parting over the years.

Duncan the tool and block will be ok for parting only. Will see it deflect with a menial traversing cut.
Do use the 32mm x 3 thk blades though but have done a few 6 1/4" dia round in 6082 aluminium with same type of tips, just be quick and listen to the tone (chip clearance no matter what you do wedges in hence breakage). Steels and just about everything else will be far easier.

[David Standing 1Participant @davidstanding1]

Posted by Robin Graham on 27/08/2018 00:55:32:

After a spot of parting off unpleasantness:

I've got an Arc one that looks like that now!

[duncan webster 1Participant @duncanwebster1]

Thanks Jon, I'm saving up now, and will be troubling Ketan ere long

[JasonBModerator @jasonb]

The ARC one only has screws on the top so not sure where Jon's "top & bottom" comes from.

I would have thought it best to have the cutting force pushing the blade agaist the solid part of the block rather than against the screw on cap, so depending on which way you intend to run the lathe with the tool at the back set it with the solid part taking the load.

[Ketan SwaliParticipant @ketanswali79440]

These products are a little bit like Marmite. There are many factors involved. I for one, prefer to use this HSS-Co8 arrangement. As Andrew would ask: Are you a man or a mouse. In this particular case, I am a mouse.

Here are a few points:

1. The carbide products were/are originally made for use on CNC machines, which are:

• more rigid in all aspects than most of the manual machines we use
• run much faster than the manual machines we use… which is ideal for carbide tooling

2. There is far more vibration on manual machines, combined with 'lower' max speeds. This results in more 'rubbing' of the carbide inserts, and chipping of finer radius cutting tip.

3. The holder for these inserts:

• The high end holders (or shank in which the insert is held) for these inserts are made from carbide or similar exotic material. The general purpose holders for parting applications are made from various types/grades of steel….still, for CNC applications. See this Sumitomo link. They make both – carbide holders (SumiGrip) and steel holders (SumiGrip Jr.).
• The steel used in the Sumitomo holder is of a particular 'great' specification which they do not disclose, but it is very expensive. So, Sumitomo cut-off tools are not in ARCs range, as most of our customers would prefer to buy cheaper solutions for their purpose of use.
• The ones which are brown in colour which ARC supply for this purpose, are made from a good grade of alloy spring steel. This is not to be confused with certain other competitors which may have the same colour, which may or may not be the same material.
• The third type of holder for such purpose – black is yet another grade – which may or may not be more brittle.

Keeping the above points in mind, the results of use will be variable, based on:

A. Rigidity of the machine

B. Ability of user – new users – better to direct them to HSS, as chances of breakages increase.

C. Willingness, confidence 'to be strong' with positive engagement at the higher end of the machines speed spectrum, PROVIDED you have a manual machine which can handle it with low vibration, based on the material being parted off (soft/hard). Anyone can be willing and confident when carrying out this process on a correctly adjusted mini-lathe, on non-ferrous material such as aluminium or brass. As the material to be parted off becomes harder or dirty, things start getting interesting. The late John S, and our esteemed editor Neil and their likes were/are happy using carbide based parting off tools on a variety of materials on their lathes. Me, on the other hand, am happier with the HSS Co8 arrangement linked to above.

In conclusion, each user has their own experience, based on the above. Crank up the feed and speed?

Ketan at ARC.

[Anonymous]

Posted by Ketan Swali on 29/08/2018 11:18:06:

I for one, prefer to use this HSS-Co8 arrangement. As Andrew would ask: Are you a man or a mouse. In this particular case, I am a mouse.

One can still be a man with HSS tooling.

My repetition lathe uses 1/8" by 5/16" HSS blades for parting off. I've been parting off a lot of steel 11mm AF hex recently while making batches of nuts and bolts. Interestingly the overhang of the toolbit is 3/4" at the start of the cut, which will no doubt cause a group of experts to fall off their chairs tut-tutting and saying it'll never work. The resultant swarf measures 10 thou thick, so a reasonable feedrate, albeit by hand so it probably varies a bit.

Andrew

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Robin Graham on 27/08/2018 00:55:32:

After a spot of parting off un-pleasantness:

I did the same, felt ashamed ,changed trousers,and got rather angry.

It is not OK to sell narco to schoolchildren either.

I develloped a rather expensive system and never looked back.

It has parted 125 mm seawater resistant alu once and 100 mm scraptanium steel many times on my former Boxford .

It is based on Iscar TAG N4J and N2J inserts in a TGFH 32-4 blade spark modified at one end.

 

Link **LINK**

I want to repeat the succes with a TGFH 26-3 blade with TAG N3J and N1.4J inserts but cannot as seat geometries ARE not equal.

It can be of great benefit to mankind and trade as well if we unite and demand that Iscar or Glance or whatever make such a system.

I do not think it possible to do it myself.Grinding tolerances must be in my(0,001mm) range.

 

 

Edited By Niels Abildgaard on 29/08/2018 13:20:48

[Niels AbildgaardParticipant @nielsabildgaard33719]

We are close to the final part off solution.

A firm is selling a pirate blade+ 10 iscar 3 mm inserts and the block.

**LINK**

If manufacturer of blade can be persuaded to make one end suitable for TAG N1.4J inserts we are in safe heaven.

[EmgeeParticipant @emgee]

Can't imagine your link will get many orders for the tool, not just because of the 20×20 dimension but the cost is IMO way over what a model engineer will pay.

Emgee

[MuzzerParticipant @muzzer]

Posted by Niels Abildgaard on 29/08/2018 17:57:22:

We are close to the final part off solution.

A firm is selling a pirate blade+ 10 iscar 3 mm inserts and the block.

**LINK**

If manufacturer of blade can be persuaded to make one end suitable for TAG N1.4J inserts we are in safe heaven.

You can get a genuine Iscar version for less, including 10 inserts. Funny what the Germans will pay out for – at that price, they are "removing yellow fluid". The toolholder for the blade is an industry standard jobbie and they are available for under £50.

I'm very tempted. However, I'd also have to get the non-ferrous tips too, for cutting loominum.

Is Zoro another instance of Cromwell (Grainger)? The websites look remarkably similar, hold similar lines (they also stock Iscar tooling) and some of the page addresses contain the word "cromwell". Not sure how they are related but they don't admit to any connection.

Murray

[pgk pgkParticipant @pgkpgk17461]

One advantage of HSS parting blades is the ability to grind a slight angle on the tip to bias whether any pip ends up on the parted off part or the stock.

pgk

[Mark RandParticipant @markrand96270]

It should be noted that the carbide insert parting tools are, to some extent, a consumable item. Ever wondered why they normally have a holder at each end?

I like them, even on the ML7 because they are shaped to make the chips thinner than the slot, without having to do the GHT top-grinding modification on an HSS blade. If you want the pip to be on one side or the other, you can get inserts that are biased to the left or the right.

A power crossfeed is a really nice thing to have when parting, especially for anything that likes to work harden!

If you try one and find that you are chipping inserts at the end of the cut, try raising the tool a few thou above centre. The inserts will chip if the work gets a chance to climb up over the top of the cutting edge.

[JonParticipant @jon]

Jason the blade can go in either way up its universal and sits in a V, same with the top except the 4 clamps pull it in to the block and down.

See what you mean Murray £139 for 10, whereas from Israel (good seller) 1 off £6.98 delivered. Depends what you want to do just part off or part off, turn and face saving setup time!
These are the type of inserts i use every day for turning, parting sub 35mm dia and facing – Sure IC354 is for aluminium dont bother with left or right hand get the neutral they all leave a pip or thin protruding band.
https://www.ebay.co.uk/itm/1-X-ISCAR-DGN-2202J-IC20-Cut-Off-Carbide-Inserts-Cnc-Lathe-2-2mm-DGFH-DGN/141556923686?epid=1758642295&hash=item20f5733d26:g:aUoAAOSwm8VUyQai

Looking at the breakage again above looks like chip evacuation not working or wedging in down the side of tip. Only one way the tool can go before seizing, bending or breaking and the tip is forced to the other side.

[Robin GrahamParticipant @robingraham42208]

Thanks for replies. It looks like the answer to my original question about the functional differences between the two specific designs of tool I was asking about is that the blade type (first pic) has the obvious advantage of being able to cut deeper, but the clamp type (same insert, as JasonB pointed out) has perhaps more sideways rigidity. And less overhang from the cross slide centre line.

The Glanze toolholder has lasted me about eight years – I bought it for my first lathe (a 40kg Proxxon PD400) because I was getting chatter using HSS, and it worked. I was just happy and didn't think too much about it. The destruction happened when when I got a bigger lathe (600kg), which is obviously much more rigid. I think what went wrong was that I got a bit over enthusiastic – I made the jump from a situation where the machine's rigidity was the limiting factor to one where the toolpost/toolholder etc is perhaps more important. I need to think about that!

Anyhow, thanks to all for the discussion, much food for thought!

Robin

Edited By Robin Graham on 01/09/2018 00:17:55

Edited By Robin Graham on 01/09/2018 00:19:00

[MuzzerParticipant @muzzer]

Stung into action by several months of forced separation from my workshop, I suffered another serious accident involving a mouse. On this occasion it resulted in the delivery of a 3mm version of the Iscar TGFH parting tool kit from Zoro (see post above) and 5 of the uncoated inserts for loominum cutting.

Found myself back home and in the workshop this afternoon due to impending leave, so it would have seemed rude not to have done some initial tests.

Found a piece of 2" dia mystery steel and mounted the tool up in the holder. Being an industry standard parting blade size, I was able to swap out my existing Korloy "Saw Man" blade for this one quite simply.

The parameters for the (steel cutting) IC808 inserts are 4-10 thou per rev and 80-180 m/min (sorry for mixing units but my Bantam has an imperial feed gearbox). That translates to about 700rpm min surface speed.

Started out using girly settings ie 250rpm or so with tentative hand feed and the whole machine almost shook itself apart. Quite alarming and surely not good for anything.

Then upped the speed to 700rpm and took a more serious cut. Job done – no juddering and a nice curly ribbon of swarf. Juddering only started when the tool approached the centre, at which point the surface speed was obviously quite a bit lower. Engaged the feed (about 3 thou per rev) at 7000rpm and it cut like a good 'un.

No photos but a took a quick video for Seasick Neil.

Hope Elgar didn't object to being crowded out.

 

Seems to confirm what has been said here before – the cure for juddering during parting with these indexable tools is to use the proper surface speed and feed per rev and use power feed. Trying to girl out simply makes it judder unmanageably.

 

I should probably find some mystery loominum and repeat the exercise now with the (uncoated) IC20 inserts.

 

Murray

Edited By Muzzer on 06/09/2018 18:01:05

[Neil WyattModerator @neilwyatt]

Posted by Muzzer on 06/09/2018 17:59:34:

Seems to confirm what has been said here before – the cure for juddering during parting with these indexable tools is to use the proper surface speed and feed per rev and use power feed. Trying to girl out simply makes it judder unmanageably.

Great finish. Just another 2,796 to go and you acn make your own mirror ball…

Neil

[Andrew TinsleyParticipant @andrewtinsley63637]

Hello Murray,

Zoro is Cromwell's version of themselves for us poor model engineers. Prices are supposed to be cheaper, but still make me wince.

Andrew.

[David Standing 1Participant @davidstanding1]

Posted by Muzzer on 06/09/2018 17:59:34:

Engaged the feed (about 3 thou per rev) at 7000rpm and it cut like a good 'un.

Murray

Blimey, I bet it did!

[MuzzerParticipant @muzzer]

Posted by Andrew Tinsley on 06/09/2018 19:23:48:

Hello Murray,

Zoro is Cromwell's version of themselves for us poor model engineers. Prices are supposed to be cheaper, but still make me wince.

Andrew.

Aha, thought so but the different registered addresses etc puzzled me. Yes, the prices were very slightly cheaper. That parting kit at £98 (blade and 10 inserts) was a significant reduction over the individual prices for blade and inserts – blades are usually about £80 and inserts around a tenner each. Simpy wouldn't be prepared to cough up for that.

Murray

[Pete RimmerParticipant @peterimmer30576]

Posted by Robin Graham on 01/09/2018 00:16:09:

Thanks for replies. It looks like the answer to my original question about the functional differences between the two specific designs of tool I was asking about is that the blade type (first pic) has the obvious advantage of being able to cut deeper, but the clamp type (same insert, as JasonB pointed out) has perhaps more sideways rigidity. And less overhang from the cross slide centre line.

Robin

Edited By Robin Graham on 01/09/2018 00:17:55

Edited By Robin Graham on 01/09/2018 00:19:00

The grooving holder has a positive stop behind the insert to give consistently very accurate depths to the grooves you would cut. The parting holder has no stop, so the seating depth of the insert can be affected by the cutting forces. You might start cutting a groove at the required depth but high cutting forces would cause it to sink back in the seat and then your grooves would be shallow.

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