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SCLCR Boring Tool Geometry and TCT & HSS inserts

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Peter G. Shaw02/01/2016 15:13:27
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Hi folks,

Looking for confirmation here that I might have made a mistake.

Many moons ago, there was a thread about the possibility of HSS inserts and following a little bit of discussion, it appeared that the Arthur Warner HSS inserts CCMW2-1.5-0.5 (ANSI designation) might be equivalent to the CCMT 060202 metric designation and that probably they would be suitable for use in the SCLCR type holders.

In the past I have tried various carbide tipped tools and found them rather poor, but I have used one of Greenwoods Tools milling cutters using their NJ17 material and found it surprisingly good.

On this basis, and especially as the Arthur Warner holders are expensive, and that there would/might be VAT and/or import duty to pay plus a charge from Royal Mail, I recently bought one each of:

SCBCR 1010 F06-APT, and SCLCR 1010 H06-APT turning tools, along with a S08K SCLCR 06-APT boring tool, and five Type 1 (CCMT 0602) carbide inserts from Greenwoods, the idea being that I might later buy some of Warner's HSS tips.

Now, one of the turning tools looks as if the top of the insert is horizontal, the other turning tool looks as if it might be slightly tilted down which suggests, I think, a positive cut (sorry if the terminology is wrong) whilst the boring tool, whilst nominally circular, has two flats which I assume are used for clamping purposes in which case the insert most definitely is angled down, hence even more positive. This concerns me, because my understanding is that HSS, and presumably inserts as well, requires the cut to be negative, ie with the cutting edge upwards, which would mean that the Warner HSS inserts might not work correctly.

Therefore, I have two questions:

Am I right in thinking that the boring bar does indeed mean that the insert is set up for positive cutting, and that the flats on the bar are for clamping purposes?

Secondly, does this mean that I will not be able to use HSS inserts in these holders?

Thanks in anticipation.

Peter G. Shaw

Raymond Anderson02/01/2016 15:58:16
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Peter, as far as I know all the SC** R/L are for positive rake inserts usually 7 deg but also 11 deg All my ones have the insert seat horizontal not tilted down Even internal boring bars are horizontal. Toolholders where the insert seat tilts down are for negative rake inserts. The flats on your boring bar are indeed for clamping although I prefer to use split sleeves as it gives total contact with the bar not just at 2 or 3 points. I would think that the AR Warner inserts would be fine with the S C ** Toolholders as long as the seats are horizontal, but would be best to cross check the ANSI / ISO sizes first.

Emgee02/01/2016 16:03:34
1763 forum posts
237 photos

Hi Peter

You are right to believe the flats are for clamping which dose give positive angle to the cutting edge/tip.

You can of course drill and ream or bore a hole through square section of material, slit end to end and fit the tool in the toolpost, set the insert at your angle of choice and tighten the clamp, finally adjust to centre height before clamping the toolholder.

Emgee

Raymond beat me to it !!!!!!

Edited By Emgee on 02/01/2016 16:04:42

JasonB02/01/2016 16:14:27
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You have your terminology wrong, if the tool points down towards the tip then it is negative, if up towards the tip then positive.

Yes the boring bar inserts point the tip downwards to allow more clearance on smaller diameters, I posted this the otherday in another thread

dsc00501.jpg

This would mean all your HSS inserts would be negative if used in the boring bar or have less clearance if the shank were rotated to give a positive cutting edge.

Before getting teh HSS inserts have a try with some CCGT ones that will fit your holder and are good for fine cuts in difficult steels, Stainless and non ferrous

Peter G. Shaw02/01/2016 18:06:49
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Jason,

I did say I wasn't sure of the terminology! Trouble is, I had a mental picture of a drawing (by T.D. Walshaw as it turns out) but didn't know which of 50+ books it was in (Milling Operations in the Lathe as it happens) so couldn't easily search. Also, given the sheer quantity of posts on this forum, I simply find it impossible to keep track of who said what, and when. Anyway, thanks for putting me right and explaining things.

Raymond & Emgee,

Your idea was what I intended to do until I received said items week before Xmas. But then finding the two flats I thought "Ah, no need for it!" And promptly mounted the work, turned it, and am now trying bore a concentric hole. And not doing very well.

Right then, the tool doesn't seem to work that well. Or maybe it's me tickling rather than cutting. Regardless, it's back to a home-made 20+ year-old slim-jim HSS boring tool, and if that doesn't work, then I'll give in and ream it.

Thanks everyone.

Peter G. Shaw

Raymond Anderson03/01/2016 07:12:41
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Jason, Have just been checking me SCLC boring bars, and here is what ive found,

Walter 40 dia, seat horizontal, fully round steel shank, no flats,

Arno Werkezuge 32 dia, seat horizontal, fully round steel shank, no flats,

Walter 32 dia, Carbide shank [ tilted slightly down ] Flats

Arno Werkezuge 20 dia steel shank [ tilted slightly down ] Flats

Walter 16 dia, Carbide shank [ tilted slightly down ] Flats.

All me others with flats are tilted slightly down . So it would appear that fully round shanks are horizontal so that the clearance can be set to suit , whilst ones with flats have the clearance set.

Peter, If you try as Jason suggested and use CCGT inserts you should have no problems and they leave a super finish.. Just make sure all is clamped rigid and no more than about 3 x the bar dia sticking out [ i'm presuming its a steel shank and not Carbide ] There is a case for boring bars to be set a LITTLE above center height to allow for the deflection during cutting. Only use the CCGT for light cuts [ finishing ] best stick to CCMT for the rough boring.

ega03/01/2016 10:27:13
1850 forum posts
157 photos

JasonB:

With diffidence, as I am not a QCTP user, those boring bars in your picture look awfully uncomfortable. Don't they make a dedicated holder for boring bars?

Vic03/01/2016 10:38:44
2642 forum posts
20 photos

Yes, they make one with a V in the bottom for clamping boring bars.

KWIL03/01/2016 10:48:41
3317 forum posts
63 photos

Yes but a "V" would not suit all diameter bars with a flat !!

Vic03/01/2016 12:25:17
2642 forum posts
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Posted by KWIL on 03/01/2016 10:48:41:

Yes but a "V" would not suit all diameter bars with a flat !!

I'm not suggesting it's a good design just that they are available! wink

JasonB03/01/2016 13:29:08
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They work fine so I'm comfortable with them.

No reason you could not put then into a toolholder with a round hole. As I have a holder for each a "one size fits all" is not an issue. Thats unless the bar is too big for the toolpost then a couple of comfy clamps also do a perfectly good job when combined with the seldom used 4-way toolpost.

Muzzer03/01/2016 14:38:58
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The "boring bar" tool holders are for the boring bars without the flats. The problem with those bars is that most of us would fit them at the wrong angle. If you have a more modern bar with the flats, you'd want to use a standard tool holder.

AFAIK, "SCLCR" doesn't just mean the generic boring bar with CC** insert, it also defines the angle of the insert, so arguably if it hasn't got a flat, perhaps it isn't really an SCLCR.

Raymond Anderson03/01/2016 14:52:39
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Peter, I have uploaded a couple of pics to my albums of, Arno Werkzeuge ISO Hss inserts. The CCFT would be the type you require. They are ISO sizes to fit ISO boring bars. just make sure that you are sitting down when you find out the price !! The box in the pic was £168 but I get a good discount through the brothers employers [ 20% ] So wasnt quite as painful.

I have always used split sleeves ever since I broke a 10dia carbide shank bar It broke off right where the middle screw was. although steel shank bars would be ok. The advantage of split sleeves can really be seen in the surface finish, even though a fine surface finish can be achieved using only the flats the difference when using sleeves is noticeable. So folks are comfy with using the flats, and if it works then great , but i'm most certainly a sleeve guy.

chris stephens03/01/2016 17:21:56
1047 forum posts
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Just to add confusion, surely the chip breaker design defines whether an insert is positive or negative. You can have an insert seat pointing downwards (nominally negative) but with a high rake insert, it is actually positive. Or is there a flaw (again) in my logic?

Raymond Anderson03/01/2016 18:20:34
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Muzzer, All me boring bars that take CC** inserts are SCLC, both R and L and as mentioned in an earlier post

some are round shank ,some have flats ,some are carbide, and some are steel. Me PCLN ones are a different breed ,although the CN** inserts are the same shape as CC** the geometry of the insert seat on PCLN bars turns the negative insert into a positive. The vast amount of toolholder styles boring bar styles and inserts are a massive subject all on its own.smiley.

Chris, as far as I know the chipbreaker style is of no relation to either negative or positive. I have inserts with the same chipbreaker style in both neg and pos. Negative inserts are 0 deg but when in the correct holder they become positive because the insert seat angles down to provide the side clearance. I think CC** inserts are 7 deg positive so on an external toolholder the insert seat is horizontal because the side clearance is taken care of with the 7 deg insert. I think that because boring bars with flats are tilted then the angle must be about 11deg but as mentioned earlier, me round shank ones are horizontal. and can be adjusted to suit.

Its certainly a subject that im always interested in [as you can probably tell ] I know its sad really smile p

Bill Pudney03/01/2016 20:33:19
469 forum posts
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Time to add a little more detail. I have been an enthusiastic user of AR Warner stuff for some years. I use both the triangular inserts, and the trapezoidal (CCMT) type, for normal turning. I also have an ARW boring bar, which uses a CCMT insert with greater front clearance, I think it's 11 degrees instead of 7 degrees for the "normal" insert. This insert is mounted "negatively", pointing down at the tip, and the boring bar has at least one flat for clamping.

The inserts all have a flat top, which means that they can be very effectively sharpened with a diamond plate, in a matter of seconds.

No connection with ARW other than as a very satisfied customer

cheers

Bill

Muzzer03/01/2016 21:07:22
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Inserts and tools / boring bars follow ISO / ANSI standard (ISO-1832 etc), so the numbering system is common to all manufacturers.

Here's a guide to inserts and one for boring bars. And one that summarises grades and chipbreakers. Similar publications are available from all of the big manufacturers.

Peter G. Shaw03/01/2016 21:22:53
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Whew, what a can of worms I've overturned.

I've been looking at the Warner, Greenwood & Glanze websites. The first point is that Warner specifies different inserts for their boring bars and turning tools, whereas Greenwood specifies the same insert for both. The difference appears to be that Warner quotes 20 degree relief for the boring bar inserts as against 7 degrees for those for the turning tools. Glanze show a very nice diagram of the SCLCR boring bar showing that the insert is definitely slanted w.r.t. the flats. It seems to me that I've made a mistake, probably due to being misled by Greenwood's information. Not that Greenwood's info is wrong, it's just me that misunderstood.

Given that my whole idea was to buy, ok perhaps with a load of taxes added in as well, a set of 10 CCMT equivalent inserts from Warner and use them on both boring bar and turning tools which were to be sourced in the UK, then I'm obviously going to have to think again, maybe even abandon the idea especially as a rough total estimate was going to be around £100 or so for the inserts plus taxes etc.

Now, just to clarify matters, I don't want TCT inserts. I've tried TCT tipped tools with a conspicuous lack of success - chipping, won't cut, and in one instance, the brazing gave way. That's on 2 sets of tools, 5/16in & 3/8in. So I'm not exactly enamoured with TCT. It may well be that my technique is wrong. Plus I suspect that my lathe slides are not up to it. I'm trying the Greenwood inserts because their Omega milling cutter using their NJ17 material worked surprisingly well on my milling machine so I thought as I'd bought some holders ready for Warner's HSS inserts, then I'd try Greenwood's inserts. I think with the boring bar I'll create a holder as has been suggested above and try that, otherwise I'll just use them for rough turning to get down to somewhere near the required size.

FWIW, although for me HSS works better than TCT, I've recently been experimenting with high carbon tool steel, and found to my surprise, that these tools actually seem to work even better for me: they seem to be sharper than HSS, remain sharper longer, and are easier to re-sharpen. Indeed, all they seem to need is a quick rub with a diamond hone. The downside is that I have to keep speeds down to avoid overheating and hence softening the tool, but for me, speed hardly matters. In a way, this is confirming what T.D.Walshaw/Tubal Cain says, ie that properly made high carbon tools are actually harder than HSS. Another minor problem is that I am getting material build-up on the cutting tip, but this is easily removed with a stroke or two of a diamond hone.

Incidently, the hole I was boring which set off my original query is now almost the required size with, as far as I can tell, a smooth bore. At least I've got rid of the marks left by the TCT insert. The tool I used was a 1/8in HSS boring bar about 35mm long. I used (many) repeated light cuts to get to the size and state I wanted.

Many thanks to all, I've learned something, mainly what a minefield this is.

Peter G. Shaw

Edit: Grammatical change!

Edited By Peter G. Shaw on 03/01/2016 21:25:19

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