HSS or carbide cutting tools for first lathe.

[Brian JohnParticipant @brianjohn93961]

Which are easier to use ?

[Brian JohnParticipant @brianjohn93961]

Would you recommend HSS or carbide cuttings tools for a beginner using his first lathe. The Optimum L685 machine will arrive this week and I realised that it does not come with any cutting tools. The size required is 8mm.

I was going to buy a carbide cutting tools set because they are so cheap but some people have said that the HSS tools are easier to use and give a better finish. I have found this nice set of HSS tools by Arceuro in a wooden box which is very cheap by Australian standards :

**LINK**

NOTE : I will NOT be grinding my own tools for a while yet. If I do that and things do not turn out well then I will not know if the problem is me, the lathe or the cutting tools ! By buying precut tools, then I can eliminate one variable ie. I cannot blame the cutting tools

Edited By Brian John on 18/08/2015 12:32:50

[VicParticipant @vic]

The linked set of 8mm HSS tools should be fine to start.

[Steve PaveyParticipant @stevepavey65865]

If you use HSS tools you will be grinding them far sooner than you're hoping for – fine to buy some ready ground to various profiles but you will still need to touch them up on a grinder. If you buy carbide tools with the replaceable tips, how will you know which tips to buy? There are literally thousands of combinations of shape, size and tip geometry available for many different types of material and machining process. The tips provided with cheap chinese tool sets are often nothing to write home about.

What I'm trying to say is that it is far better to go for HSS (at least initially) as there are fewer variables to worry about. It has never crossed my mind to be concerned about grinding a tool to shape, and there are loads of books to refer to if you're bothered about it.

[Nigel BennettParticipant @nigelbennett69913]

You'll learn a lot about cutting angles if you buy a cheap 6" double-ended grinder and some HSS and grind your own tools!

Tipped carbide tooling has to be worked hard, and it needs a rigid machine to get the best results. Yours isn't in that category.

Many of the cheap sets of carbide tipped tools I've seen are not really suitable for taking fine cuts; feel the edges and they're surprisingly blunt. In these sets, the grade of carbide and the geometry are usually "general purpose".

However, lurking out there are many grades of carbide and carbide geometry to choose from. I've had a lot of success on a Myford Super 7 using DCGT11 tips; they're designed for aluminium and they're really sharp. They work well on steel, stainless, and bronze as well as aluminium. Downside is they're really brittle, so chipping them is all too easy. They do not work too well on brass as they have the wrong top rake and will often dig in with disastrous results. For peeling thick, smoking lumps off, (it's all relative!) I will usually start with a DCMT11 "standard" grade, and then finish with the DCGT11.

For 8mm tooling, DCGT07 size would be the one. DCMT07 is the "standard" grade with the "blunt" cutting edges for use on steel.

JB Cutting tools in the UK sell them; I've no idea about suppliers in Oz.

[Gordon WParticipant @gordonw]

Buy a set of HSS tools, that way you will know what the different angles are. You will only need to touch up the cutting edge, with a bit of luck. This can be done on a sander or similar. This way is easier to learn than a lot of pictures in a book, later on the book will be useful, but by then you will know what you are trying to achieve.

[mechman48Participant @mechman48]

The linked set would be more than adequate for a beginner; I bought a set initially,even better, if you can afford, it go for the diamond tool cutter from Eccentric Engineering ( usual disclaimer ) as shown in the ads on the right of home page, it is Oz based so you should get it easily enough. I bought one & it does 95% of my machining, & you only need to sharpen the top face using the provided guide, simples, well worth it, all my other tools are rarely used now & have been relegated to storage with just a few specific tools on hand.

**LINK**#

George.

[Michael Cox 1Participant @michaelcox1]

Hi Brian,

For what it is worth this was my experience when I first bought my mini- lathe:

http://mikesworkshop.weebly.com/initial-experiences.html

I would recommend that you start with a set of HSS tools like the Arc set. You should think about buying a bench grinder because they will need regrinding sooner or later. A cheap 150 mm bench grinder is fine but you will probably need to make a new grinding rest in order to grind consistent angles. My version is shown here:

http://mikesworkshop.weebly.com/grinding-rest.html

Mike

 

Clickable links added

Edited By John Stevenson on 18/08/2015 15:33:28

[mark costello 1Participant @markcostello1]

Just remember, to cut a tool MUST have clearance. All the other angles make the tool cut more efficiently, but if it rubs anywhere it will give You problems. Use a Sharpie to color the cutting edge to make clearance problems show up better. ( Have a boss in the distant past screaming " Hallelujah He"s finally got it.&quot

[MetalmuncherParticipant @metalmuncher]

I hardly ever buy cutting tools, just braze a bit of carbide onto a square bar and grind to shape. When Witson's was in business I bought a lot from them and had a jar of used tips given me. I never bother grinding to a set angle, just make sure you get a good edge and set to centre height. Just my two penny worth and it works for me.

[EugeneParticipant @eugene]

Brian,

I was in just your position eighteen months ago; this is my experience…..

Freehand grinding HSS tools I found a difficult skill to acquire; I actually ruined more than I succeeded in sharpening, and wound up with a small box of useless dog end tools, so I couldn't do any turning work at all. Some of the HSS ready formed tools I bought off Ebay were rubbish; they chipped all the time and gave a very poor finish. So I abandoned HSS.

At the Harrogate show I spoke to JB Cutting Tools who recommended a grade of carbide insert suitable for use on small lathes. They also have a good range of insert holders, left hand, right, hand boring bars, all that sort of stuff. These I found very easy to use, and got an excellent finish. I had to be careful with them because any clumsiness on my part would result in a chipped tool that was then useless on that corner (they are a rhombus shape so have four cutting corners).

I had been told by many experienced turners that carbide was unsuitable for small lathes of low power and suspect rigidity, because they have a negative rake and great speed and power were essential. What they didn't say or more likely didn't know is that there are carbide tools that don't fall into that class.

The grade I use is CCGT 09T304, about £3.20 each. They don't like interrupted cuts but even at modest speeds cut very cleanly on all metals including Al and stainless.

In time I intend to go the HSS route, but freehand grinding is for the birds especially if you are forming a new tool from a blank. Right now I'm making a Harold Hall type grinding fixture as shown in his book on the subject, and I'll certainly give HSS tangent tools a try too.

My recommendation is to speak to Jenny at JB, tell her what your needs are and I'm sure she'll fix you up; she seems to be a knowledgeable lady and very helpful. When you've got a bit of turning experience under your belt, make a judgement as to which way you feel you want to go.

Eug

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Metalmuncher on 18/08/2015 20:40:08:

I hardly ever buy cutting tools, just braze a bit of carbide onto a square bar and grind to shape. When Witson's was in business I bought a lot from them and had a jar of used tips given me. I never bother grinding to a set angle, just make sure you get a good edge and set to centre height. Just my two penny worth and it works for me.

But perhaps not ideal for an Optimum L685: "Ideal for the model maker machining miniature parts"

I'd follow Eug's excellent advice. A couple of CCMT and CCGT tips will get you started. I'm sure there must be a supplier in Oz.

Rod

[Paul LousickParticipant @paullousick59116]

The Diamond tool holder sold by Eccentric Engineering (also advertised in MEW) is a great HSS tool. It comes with a grinding jig which makes it very easy to sharpen on a standard bench grinder. Well worth the expense of the purchase.

Paul.

[Nick ThorpeParticipant @nickthorpe64546]

Brian. I agree with Paul about the Diamond tool holder. Like you I am new to lathe work and while I was fitting out my workshop I spent a while trying to sharpen HSS tool bits. It was a slow process and I eventually bought the Diamond tool holder. Sharpening the tool is dead easy and only needs a very basic grindstone. I was cutting swarf as soon as my lathe was up and running. The great advantage was that I knew that any problems I was having were down to me and not the tool . Regards. Nick

[Douglas JohnstonParticipant @douglasjohnston98463]

There are some really dreadful carbide tips out there and this can persuade people to give up on them, but if you get the ones designed for cutting aluminium they really are very good. These tips are very sharp and are polished with a high positive rake and work a treat on small lathes.

Although designed for cutting aluminium they also work very well on all types of steel (including stainless ), and despite the positive rake they will also cut cast iron. I now use these tips for most of my machining and rarely use anything else.

Just one word of warning, treat these tips with care since they do chip quite easily and are not for the ham fisted.

Doug

[AjohnwParticipant @ajohnw51620]

If you do buy disposable tip tools do go for this style of tip as they are suitable for most turning tasks.

**LINK**

As the tips wear out they can be replaced with raked tip inserts which are even more suitable for small lathes. On a small low powered lathe I would be inclined to try the ones micro polished for aluminium. Then stainless steel types if needed.

HSS tools can be kept sharp with a slip stone. The trick is little and often. Tools will last for years that way with no need to visit a grinder unless using the stone the wrong way rounds off a cutting edge. Tools should be polished up with a stone after grinding anyway.

The usual problem with HSS is getting it too hot when grinding, If it shows any colour – blue pale straw etc it basically is unlikely to be any good there after. The only fix is to slowly grind it away without overheating it again,

The other problem may be too acute angles. Angles in the range of 10 to 15 degrees all round will generally be fine.

Different tool materials have different ranges of usable cutting speeds. In all cases the faster these are the quicker the tool will wear out.

John

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[VicParticipant @vic]

Posted by Paul Lousick on 18/08/2015 23:19:01:

The Diamond tool holder sold by Eccentric Engineering (also advertised in MEW) is a great HSS tool. It comes with a grinding jig which makes it very easy to sharpen on a standard bench grinder. Well worth the expense of the purchase.

Paul.

Agreed, very useful tool and easily sharpened by beginners.

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by John W1 on 20/08/2015 10:14:57:

The usual problem with HSS is getting it too hot when grinding, If it shows any colour – blue pale straw etc it basically is unlikely to be any good there after.

I'm afraid I must disagree with you there John. The whole point about High Speed Steel is that it retains it's hardness at high temperatures – even to red heat. The oxidation colours you mention are well below the harmful temperatures. I do tend to cool my HSS bits from time to time but that's only so I can continue to hold them in my bare fingers! Plain carbon steel however is a different matter.

cheers,

Rod

[mark costello 1Participant @markcostello1]

There is (or was) a tool grade called "Red fury." Stellite is supposed to be harder at elevated temperatures than at room temperature.

[AjohnwParticipant @ajohnw51620]

Posted by Roderick Jenkins on 20/08/2015 11:02:06:

Posted by John W1 on 20/08/2015 10:14:57:

The usual problem with HSS is getting it too hot when grinding, If it shows any colour – blue pale straw etc it basically is unlikely to be any good there after.

I'm afraid I must disagree with you there John. The whole point about High Speed Steel is that it retains it's hardness at high temperatures – even to red heat. The oxidation colours you mention are well below the harmful temperatures. I do tend to cool my HSS bits from time to time but that's only so I can continue to hold them in my bare fingers! Plain carbon steel however is a different matter.

cheers,

Rod

I have to disagree there Rod. It's pretty complicated stuff and is usually double tempered as outlined here

**LINK**

Toughness as well as hardness comes into it. They also mention a more realistic cutting edge temperature.

Tool bits are also generally heat treated away from air – none reducing atmosphere is the usual term. So personally I will stick with not allowing them to colour at all. It just takes a little longer. Much depends on the grade of grinding wheel used. For instance the white aluminium oxide wheels the Axminster sell work well on 6in machines. The only problem in that area is cheap grinders with wobbly wheels. The wobble from my experience makes it more difficult to grind a tool well and it's so bad on some it's very difficult to dress out.

I was just about to do my return 200ml trip when I posted earlier. ( Artics seem to travelling at very slightly over 60mph on my speedo which I am sure reads high) Otherwise I would have mentioned green grit wheels for carbide as an alternative to diamond . They do the job rather well so brazed tip carbide tools are an alternative but as they are generally a cast iron grade clearance and rake angles have to be low. I did use these a lot at one time.

Brazed tip HSS tooling is also available. One well known brand was superweld.

Personally if I buy HSS toolbits I go for 5% cobalt types also sometimes referred to as HSSE. M42 which contains more cobalt tends to be rather more expensive and not worth the extra cost in my view.

I would have also included a link to 9mm raked carbide tips

ttp://www.shop-apt.co.uk/carbide-tips-hobby-use/pack-of-2-tcgt-090204-alu-ak10-carbide-tips.html

Some one mentioned stellite. That has an unusual problem. If it gets rather hot and if cooled rapidly it fractures so it's not used with a coolant. It can be ground in the same way as HSS and really does have high red heat hardness. Carbides have more or less replaced it. There are several grades around but I do not know what these signify. I'd guess some are more robust than others. There are still modern forms of it about such a crobalt and tantung g etc. These are more available in the US than the UK. Some people prefer this sort of material to HSS. Sometimes batches of old HSS tooling contains some – easily picked out with a magnet as it's none magnetic.

John

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[Roderick JenkinsParticipant @roderickjenkins93242]

John,

From you very informative link, metal turning tools are tempered at 500C whereas even dark blue colouring occurs at only 300C – quite a bit of leeway there. However I have to agree that care is necessary because it is quite easy to seriously over heat a thin section or a sharp point. I also agree with your recommendation for cgt type tips for ally – very good for a fine finish on steel.

regards,

Rod

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