Getting started with carbide insert tooling

[John DeeParticipant @johndee53335]

Hello All,

I’ve got an old 11” lathe which will take 1/2(12mm) shank tooling or squeeze in 5/8(16mm) shank with the QCTP lowered to the maximum.

I want to get started using carbide insert tooling, but I’m new to this and trying to get my head around the options available.

I’ve read through a lot of topics and have come to the conclusion that positive rake, specifically the CCMT style tooling seems like a good starting point for general turning for my machine, especially as I can use the same insert for boring and turning.

However, I’m not clear on what size or combination of tooling would be most useful.

If I go with 09 inserts, I could get 16mm toolholders which seems likely to give more rigidity and a more robust insert, but I would be limited on the minimum size of boring bar I could use.

If I went 06 inserts and 12mm toolholders I could use smaller boring bars but presumably I’d be sacrificing quite a bit of rigidity and the inserts would be more fragile?

It seems I would need a combination of the two sizes to cover all boring operations, but is there any advantage to be had in also duplicating the SCLCR and SCLCL holders to cover both 06/09 sizes?

I’ve also seen the SCBCR and SCBCL holders for the normally unused corners – These seem like a good idea but I was wondering how useful are they in practice and if I would need both or if one is typically used more.

I suspect I could spend a fortune on holders and inserts in all the shapes and sizes, and while I’m sure they all have their own advantages – I don’t want to get too carried away and I’m trying to narrow it down to the most useful and economical combination.

Any suggestions would be gladly welcomed!

[John DeeParticipant @johndee53335]

CCMT06 vs CCMT09?

[JasonBModerator @jasonb]

My WM280 is often sold as an 11×28 lathe and I tend to use 8mm and 10mm shank holders and they seem fine with normal amounts of stickout.

That lets me use CCMT and CCGT 06 inserts for turning and boring except for my largest boring bar which needs an 09 insert.

SCLCR gets used most of the time and with the shank set across the lathe axis it can turn dia and also face without having to be touched, The left hand SCLCL does not get used much only on the odd occasion.

I also have both the holders that use the other two corners which are often used for roughing and working on castings as the obtuse 100deg corner is a bit more robust.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Many years ago I made some CCMT 09 holders that worked very well.Today I would make them 06.

ShipShapeHolder

[Howard LewisParticipant @howardlewis46836]

If your machine is old, it may not be fast or rigid enough to make the best use of carbide tooling. But that is not to say that it can't be used successfully on an older machine.

Carbide was developed for industry to maximise the rate of metal removal, and sometimes does not work too well at low speeds, feeds and shallow cuts.

My experiences.

However low speeds and feeds with lubrication have produced some fine finishes for me.

CCMT0604 tips are the ones most often used on my 6" centre height lathe.

(Carbide for Roughing, Boring, some screwcutting, and Radiusing . SUPERB on hardened materials. Red hot swarf off case hardened materials! Does NOT like intermittent cuts,tends to chip )

But work well on milling cutters.

A "Diamond" (HSS ) tool for finishing and fine cuts (Can do 0.0005" or less cuts when freshly sharpened. ) Carbide tips are not sharp if you examine them closely, unless the ground type, so better suited to deeper cuts…

Intermittent lubrication on a heavily loaded carbide tip can cause cracking, so is mostly used dry in the hobby sphere. Carbide tips do wear, though.

I use HSS and carbide, depending on what is being done. HSS withstands my accidentally banging the tool, where carbide does not, so is cheaper for the clumsy. like me.

Also, I can regrind HSS at the week end when the stores are closed, or when a non standard form is needed.

So horses for courses!

Howard

[SillyOldDufferModerator @sillyoldduffer]

Industry use a bewildering variety of inserts for reasons rarely explained in the catalogues. It's very confusing.

You might find it easier to start with inserts from the range sold by ArcEuro, as these are generally suitable for most hobby purposes. (Other suppliers available)

Tip: Slower / less powerful machines designed for HSS may cut steel better with the sharp inserts made for non-ferrous metals.

Opinion is split on insert holder sets. Some will tell you sets waste money because they include rarely used holders. I think sets are good for learners because finding out how different cutters behave is educational. If you know what you're doing, no need for sets, but they're helpful starting out. One problem is sets don't always identify the holder type or insert code, which makes buying spares exciting. Ask on the forum if you get caught by that – someone will know.

Dave

[John HaineParticipant @johnhaine32865]

Or contact JB Cutting Tools who sell good products and could probably advise.

[VicParticipant @vic]

I use carbide tips on my 8 1/2” x 14” Mini lathe lathe and they work well for some jobs. The best value if you can use them are the double sided triangular inserts. My lathe ideally takes 14mm tool bars so I either bond 2mm steel strip to the underside of 12mm bars or mill 2mm off the 16mm ones. This means they’re permanently on height without a QCTP which wouldn’t do the rigidly of my machine any good.

[John DeeParticipant @johndee53335]

Thank you all for your replies.

Just to pick up on some of the points raised – my lathe tops out at 1500rpm and while she is a reasonably rigid old girl, I'm under no illusion that it can push carbide inserts anywhere near their optimum performance! I'm mainly looking at using them for convenience and for the odd time turning harder materials. I do still intend to keep plenty of HSS around too.

I've spent quite a bit of time comparing the range available from ARC, APT and spoke to JB (it was Jenny that originally suggested going with the 09 size in 16mm holders because they were more robust). I've also seen it mentioned that some of the cheap banggood boring bars are quite reasonable for the price. It is just taking me a lot more time than I expected to try and get my head around all the options.

It is interesting to see that most of you are using 06 – do they offer an advantage over the 09 for external turning?

[JasonBModerator @jasonb]

Spindle speed is only half of the equation, you also need to figure in the diameter of the work. Even a 25mm dia bar at 1500rpm will give a surface speed of 117m/min which is in the ball park for Carbide. It's only on the very small diameters where you may not be at the optimum speed but they will still cut.

06 are cheaper than 09 as you are not paying for long cutting edges on a larger bit of carbide that you may never use.

[old martParticipant @oldmart]

I recommend that you start off with the smaller size, and later you may consider to add the larger to your collection. You can get a range of boring bar sizes which all use the 06 size, and your lathe can probably even hold 20mm ones as the tool height is actually nearer 10mm, about half of the holder size. Check out the APT website, although they are mostly catering for industrial users, they helpfully will sell carbide inserts singly from a range which home users find useful. The inserts are more expensive singly, but if you are not sure what works best for you and want to try a range of different grades then it makes sense to avoid buying a box of ten of the same. WNMG06 is a trigonic insert with 6 cutting edges which is available in steel, stainless, and aluminium grades and can be used in toolholders down to 16mm which might be a future thought.

[Dave SParticipant @daves59043]

You don’t say what lathe you have but I used carbide successfully on my L5 before I got my CVA.

I use CNMG inserts for general turning and ccmt06 for boring. There is a good chance you can use negative rake inserts just fine – 11” lathes are not generally wimpy bits of CI. Negative rakes inserts of course have more corners per insert so can work out cheaper.

I machined down my general holders – bought the cheapest size so my rh tool is a 25 and the left is a 20, but both have been machined down

I still use HSS for turning, usually for form tools like threading.

Dave

[Dave HalfordParticipant @davehalford22513]

I use CCGT09T304, which are meant to be used for ally on steel, using HSS speeds and feeds.

Push the feed and the tip will go.

Stall it in the job and the tip will go.

So they will all chip equally well if you are clumsy with them

They are no more nor less robust than any other size turning tool unless you include milling cutters which are much tougher. The 04 is the tip radius and means semi finishing, as in gives a decent finish but not as strong as an 08 rougher

[Chris MateParticipant @chrismate31303]

Have a question:
After starting wth HSS, I changed over to a QCTP & carbide toolhiolders, so now I use them the most.
Below is roughtly what I got, and then the question below….

I bought a set of small 10mm carbide toolholders with inserts, I also bought a set of 12mm toolholders with inserts

1-The 10mm set is neautral looking straight and if I place the holders on a flat surcface, all the tips up to thread & part off cutting insert tips measure precicely same height, so I made a toolpost for these only, just insert and the height is always correct. These give a beautifull finish.

2-The 12mm set not all the tips add up to the same height, so I use them on QCTP. They give mixed results.

4-I bought 6mm, 8mm, 10mm, 12mm Iscar boring bars, fitted each in a square machined block to fit QCTP.
-I really like these. I found the 6mm boring bar very handy sometimes.

5- I also have 12mm Kenametal boring bars Left and right type.

6- Bought a separate Part off toolholder with Iscar blade, inserts both sides. These iserts are extremely tough.
and need some pressure to cut. So I grind them sharp with a dremel diamond blade, quick actually, I actually like this, so I grind them now with this tool mounted horizontal on a dremel drill press stand you buy seperately.
-Sharp it part off like a dream. I can also take light cuts left to right without insert coming out.

Heres my question I am not sure about:
From somewhere I understood that although certain toolholders may look negative downward facing, the insert inserted may fit in such a way it actually positively cutting ………Is this correct-?
 

Edited By Chris Mate on 01/12/2021 20:25:54

Edited By Chris Mate on 01/12/2021 20:27:56

[old martParticipant @oldmart]

Positive inserts commonly are fitted in the toolholder horizontally and most have a 7 degree angle at the tip to give clearance and usually a chipbreaker to enhance the sharpness. Negative inserts are usually double sided, so the face of the insert must be square to the top and bottom. To work, the whole insert is tipped down at an angle of 7 degrees in line with the centre and the tip. Because there are usually some sort of chipberakers moulded in to the surface, the negative inserts are not that different from positive inserts when in use, and the grades for aluminium are pretty much equal to positive inserts.

 There are various charts which show the different types.

 

https://www.mitsubishicarbide.com/en/technical_information/tec_turning_tools/tec_turning_insert/tec_turning_guide/tec_turning_identification

Edited By old mart on 01/12/2021 20:44:55

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