What cutting tools for mini – lathe (HSS or Carbide Tipped ?)

[Chris machinParticipant @chrismachin]

Hi , When looking to purchase some lathe tools for my Clarke 300 lathe i see there are HSS and Carbide tipped tools available in many different types / grades as well as HSS blanks.

 

I will be doing small cuts on brass , mild steel and also stainless steel.

 

What would be my best option for general machining on all these materials , are certain tools better for certain materials ?

 

Also as cost is an issue would i be ok to purchase the blanks and grind my own ?

 

Any advice on basic lathe tooling much appreciated.

 

Many thanks

 

Chris

[Chris machinParticipant @chrismachin]

[colin hawesParticipant @colinhawes85982]

hi Chris: I recommend starting with HSS tools as these are more than adequate for your application. Tipped tools are expensive to buy and use and offer little advantage on most machining operations, the exception being cast iron if you want to remove metal quickly or if it has commonly found hard spots in it.Stainless steel comes in many grades and i’m assuming you intend to use a free-machining type.HSS tools should be kept razor sharp so touch them up on the grinder before you start a job ,making sure you have plenty of rake on all cutting faces and a good finish should be attained on the workpiece.Industrial machining is done with tipped tools to get very fast metal removal with minimum tool wear and the best results are attained on very rigid and powerful machines

Colin

[Russell EberhardtParticipant @russelleberhardt48058]

Hi Chris,

 

As Colin said HSS is the best allround material. A well ground tool will require less power than a carbide tipped tool and give a better finish.

 

Yes you can grind your own, in fact I would recommend it as you will learn more that way. There is a guide showing you how to do it here . You have to choose suitable angles for the materials you are cutting. A table showing the angles required for different materials can be found here.

 

Russell.

[Ady1Participant @ady1]

Try to get both, because sometimes hss won’t cut the mustard and a carbide tool saves the day. In other circumstances hss is far more convenient.

It’s kinda like having a ratchet set and a spanner set

You can usually do without one or the other but sometimes one is a vastly superior tool for a certain task and you will never regret buying both.

 

On cast iron, and with the backgear engaged, carbide is superb, and with the tool at the back like a parting tool you can create a neat mound of iron swarf at the back of the lathe bed which is hoovered up in seconds.

Doing cast iron at higher speeds is seriously messy…

 

…and so on…after a few months get the bigger picture

 

 

[colin hawesParticipant @colinhawes85982]

Don’t get bogged down with “recommended rake angles” my experience indicates you are better off with more rake for non heavy- production work the recommended figures are designed to allow the heaviest possible metal removal with best tool strength and heat dissipation. Our hobby does not create such conditions.Your tools will give a better performance with lots of rake, like a slicing knife rather than a hammer and chisel Try it.

Colin.

[Colin GParticipant @coling]

Most carbide tipped tools were designed for heavy industrial use removing a large

amount of material very quickly. They require high speeds large amounts of coolant

rigid machines where even the final cut is relatively large. They do not like intermittent

cuts or very light final finish or rubbing cuts.If you examine a replaceable carbide tip

they are not sharp to the touch as a hss tool. Also there are hundreds of grades and

specifications for the material , shape and rake depending on the material being cut

and other parameters. When a model engineer wishes to buy carbide tips or tipped

tools none of the above data is available , and would probably be irrelevant because

of the limitations of his equipment.

One of the most efficient ways of removing material that the model engineer uses is

the drilling process. This is at best a two edge cutting process, maybe one edge if the

drill has been ground by hand, there fore equivalent to comparing it to the lathe tool.

How many model engineers would use a carbide tipped drill in their tailstock or drilling machine other than for a hard spot in C.I or on glass/ceramics.

This post is considering the mini lathe and as such will not generally have coolant or the rigidity required for carbide tools. By all means borrow a couple to try and compare but

you should find that the only time that they are of use is to get under the skin of an iron

casting.

Some of the ‘ old school ‘ may even say why not use carbon steel ?

[Ady1Participant @ady1]

I forgot to say.

 

You can also remove the rough stone on a bench grinder and replace it with a green grit one, so now you can grind both hss and carbide tooling.

 

Once you get into the habit you only need to tidy up your tooltips

[Ady1Participant @ady1]

In reply to the post above, all you need is reasonable stiffness and you can take advantage of carbide.

A seventy year old 3.5inch Myford Mseries can munch down a concrete reinforcing bar with carbide, this would destroy a HSS tool.

 

Carbide is just another tool you have to learn to use, it’s not some mystery voodoo material.

Once you suss it out it’s great.

 

[Ian S CParticipant @iansc]

Stick with HSS for now, as you get more experience you’ll know whether you need more cutting power. One of our local engineers has gone back to HSS from carbide, because he could not get the finish he wanted with carbide tooling, hes got a fairly large Dean Smith @ Grace lathe, proberbly about 6″ between centers, and he uses it for building hydraulic cylinders amoung other bits and pieces. He’s also into 12″ to the ft stuff with steam ie., the Lyttelton tug, the Ernslaw at Queenstown, and the steam park in Christchurch. If he thinks HSS is go enough, I’m not argueing. Ian S C

[Derek DroverParticipant @derekdrover32802]

I used to have a Clarke CL300… and I only used HSS tools. As some have already said, carbide tipped tools are great for more powerful cuts, but your machine isnt very powerful. Its ideal for brass and mild steel, but stainless can be a bit hard. Stick with HSS, its much easier to use.

[Ian PParticipant @ianp]

I frequently see people who recommend HSS tooling mention carbide using phrases like, ‘Aimed at industry, Suits heavy cuts, Useless for interupted cutting, OK for hard material’ Does not have a sharp edge, etc etc.

 

Whilst there is some truth in what they say, like most things there are two sides to every story. I use carbide 95% and HSS 5% of the time. I have used a variety of tips (mostly bought off eBay) that have razor sharp edges, some that cope with VERY interupted cuts, and others that don’t seem to mind what material they are cutting, last a long time, and produce a good finish.

 

The only downside is that it is more expensive than HSS.

 

Indexable tooling is like VFDs and DROs, once you’ve used it you will wonder how you managed without it.

 

Ian P

[Douglas JohnstonParticipant @douglasjohnston98463]

I think we have to be careful when talking about carbide tools since there are some that are dreadful on small lightweight machines but others that are superb. I use a Myford speed 10 lathe and have used both HSS and carbide and find both have a place. I have found in recent times that I use much more carbide than I used to and this is because of the types I use. You can get some modern types with good positive rake and very sharp edges that can produce wonderful surface finish. Some of these good ones use titanium carbide which seems to give good results at slower speeds.

 

For a complete novice HSS is a good starting point however since it is more forgiving, is cheaper and easily sharpened. The sharp carbide tips can be quite fragile and you have to treat them with care but they are a joy to use. The simple answer is to try all types of cutters and see what works for you.

 

Doug

[KWILParticipant @kwil]

It is a fallacy that you must use coolant with carbide tipped tools (inserts). Their use is a matter of practice and experience. The specs and other info is available for the model engineer (talk to Greenwood Tools). By the way Colin you can take fine cuts, one of my party pieces is around bar with a 0.0004″ step on it

[Anonymous]

Posted by KWIL on 14/02/2012 09:32:14:
It is a fallacy that you must use coolant with carbide tipped tools (inserts). Their use is a matter of practice and experience. The specs and other info is available for the model engineer (talk to Greenwood Tools). By the way Colin you can take fine cuts, one of my party pieces is around bar with a 0.0004″ step on it

 

Listen to KWIL, he knows what he’s talking about. It may also be informative to read this thread:

 

http://www.model-engineer.co.uk/forums/postings.asp?th=51900

 

Regards,

 

Andrew

[TomfileryParticipant @tomfilery]

Chris,

 

This is the third time I’ve tried to post ot this thread (don’t you just love IE?).

 

My first lathe was a Cowell’s, which was only capable of tiny little cuts. My work was transformed when I was given a set of brazed tip carbide tools (around 30 years ago). I have never gone back to HSS for general use and have used various types.

 

I now have a Myford S7 and am using £7.50 10mm Sq replaceable tip tools from Chronos (includes one three-sided tip and allen key). Although specials, the tools are branded Glanze. A replacement tip is about £3.00 and gives three cutting edges.

 

I regularly turn 3/4″ MS hex bar cylindrical using these tools (without coolant) and without ever having broken a tip (touch wood). I tend not to take too aggressive a cut and they work for me. Obviously, you need to avoid banging them around in the tool drawer to avoid chipping them.

 

I’m sure we’d all like to be expert in hand grinding HSS tools, but presumably, you’d rather be using your new lathe! I can’t comment on the quality of the Clarke tools – presumably others will be able to do so.

 

Regards Tom

[chris stephensParticipant @chrisstephens63393]

Hi Guys,

As Tom says “I’m sure we’d all like to be expert in hand grinding HSS tools, but presumably, you’d rather be using your new lathe!” Well, save the learning stage and go straight to a tangential tool.

Somebody had to say it and it might as well be me!

chriStephens

[gerry maddenParticipant @gerrymadden53711]

Chaps,

 

I recently delved into indexible tooling and bought some of the gold and silver coloured tips from AET. The gold ones were claimed suitable for hard ferous materials whilst the silver ones were stated as suitable for brass and aluminium. I tried both on a variety of materials. I always cut dry as I cant be bothered with the mess of cuting fluids. But I am fussy about finish.

 

The gold ones worked ok in some situations and were not too bad on others. However the silver ones are simply fantastic. Steels, plastics (in addition to brass and alum.) can be cut quickly and effectively with a very good finish and without undue cutting forces.

 

I think that the performance of the silver ones is due to the fact that they are very sharp as they have been ground (after moulding) to a perfect edge. You can cut your fingers on them if you are careless ! I cant comment on their wear life yet but I occasionally inspect them under a microscope and dont see any wear at all so far so I think they will last quite well. But they are for sure fragile. Whilst peering under the mic I did see a small built-up edge. I tried to pick it off with a watch makers screwdriver and before I realised it I had put 3 chips on that beautiful ground edge. Clearly they dont like any force in the wrong direction. Despite the 3 chips they still seem to work well ! I have to say Im a total convert on this particlar tool tip material and its now my ‘standard’.

 

Gerry

 

 

[HasBeanParticipant @hasbean]

Hi Gerry,

 

I’ve found much the same as you have. I know the ‘silver’ inserts are designated as for aluminium and non ferrous but, used with care, I’m very pleased with the finish they produce on steel.

I now have two holders, one with each insert, for general purpose and for finishing.

(But I still really like my tangential tool as well )

 

Paul

[Sub MandrelParticipant @submandrel]

I use HSS on my mini lathe for most things, but have a set of HSS that are useful for castings with a good skin or even chilled sections, and the odd job on hardened steel – such as truing up a dead centre.

 

Neil

[Andrew EvansParticipant @andrewevans67134]

Use replaceable tipped tools is my advice. Personally I find grinding tools is frustrating and I can’t be bothered except for the odd special. Lots of advice says ‘touch the HSS tool on the grinder to keep it razor sharp’, I try that and end up just adding a new angle. Using ready made tips is one less skill to learn as a newbie. I have never had issues with tipped tools, with or without coolant and the price is negligible compared to other tooling costs.

[Sub MandrelParticipant @submandrel]

Oops – I meant I have a set of carbide tiopped tools for the tough jobs!

Neil

[Ian S CParticipant @iansc]

Chris, for a mini lathe (and bigger lathes), tools made of junk box mild steel, or old bolts (8 8 or better if you can find something like that laying around), and an old damaged carbide tipped circular saw blade.Remove the tips from the blade. For a normal tool, a step in the right hand side to take the tip, braze the tip in the step. There is a bit of grinding and fileing to make it look like a lathe tool, and you'll find that the tips are left and right handed in the way they are ground. With a little more work ,a little boring bar is quite easy to make also. Ian S C

[Author]

Posts