Bending HSS

[Peter G. ShawParticipant @peterg-shaw75338]

Hi folks, this is just an idea!!

 

Ok, I don’t like TCT. Sometimes it’s ok, and other times it seems to chip even before it’s touched the work! But ok, I understand it’s probably best for getting underneath the skin on cast iron, but….

 

So I’m thinking about, no definitely am, doing back to HSS, and even carbon steel, even to the extent of converting an old file or two. (I’ve already used an old 4″ file to make a parting off blade!)

 

Now, I’d like a bent tool in order to get closer to the chuck jaws, and it struck me that I might possibly be able to use the blowlamp with a fine flame, heat up where I want a bend, and then bend it. So can I actually do it? And is it likely to have a negative effect on the hardness of the tool.

 

I stress this is just an idea, a wild thought even, because the easier and alternative method is to cant it within the tool holder and also twist the toolholder round slightly, but I did wonder.

 

I have actually found that Amadeal has some square HSS going fairly cheap and I’d wondered about experimenting a bit, but if it’s a no-no before I even start, then there ain’t much point in experimenting.

 

Many thanks in anticipation.

 

Peter G. Shaw

[Peter G. ShawParticipant @peterg-shaw75338]

[adyParticipant @ady]

You’re better off finding ways of improving your stiffness and sticking to carbide IMO.

 

A bigger leadscrew nut.

A more acute angle, text book guidelines aren’t always right, chances are they’ve been copied from somewhere else.

My best carbide tool is the “parting” tool which seems to be indestructible.

Cast iron. Stainless which makes cast iron seem like a doddle.

It aint very sharp now either but I just shove it in there, there seems to be enough material there to support any cutting part and it doesn’t fracture.

 

The ones with the tips are very vulnerable, the thick chunky bits are surprisingly strong.

And try a bit of torque instead of speed, live a little.

 

Actually…now I think about it, I actually try to use those tuff jobs as an opportunity to put a bit of an edge on some of my carbide tooling, a standard grindstone is useless.

Anything which can flatten hss like a bit of aluminium must have it’s uses…

Edited By ady on 18/09/2010 21:48:22

[Ramon WilsonParticipant @ramonwilson3]

Peter,

You will need a fair bit of ‘localised’ heat to get HSS ductile for the purpose you intend. I would think that the average blowlamp will not be up to it and have a much too ‘open’ a flame to put the heat in a small area . That said however, the heat needed to put a bend in it should not affect the hardness properties as the hardening temperatures for HSS are far higher than for carbon steel.

 

However, have you thought of getting some HSS in bar section? eg 1/4 x 1/2 or wider. By using this it can be ground away down one edge to leave a left or right joggled end enabling that ability to get close to the chuck. Takes a bit of time on the offhand grinder and a bit messy but it is viable. I’ve had a very cheap 6″ grinder for many years now and that handles a roughing job like this with ease (though it is soon to be upgraded to an 8″) and use a small 5″ grinder for final facing and touching up tool edges.

 

I know many advocate carbides but personally I much prefer to use HSS. That’s not to say TC is not a viable proposition – just a personal choice based on my lathe and the power available.

 

The big bonus of HSS is the control you have over tool shapes and the ability to change them with relative ease. Carbon adds to that as well of course providing the speed is kept well down and the tool kept cool

 

Hope this helps in some way

 

Regards – Ramon

[Keith LongParticipant @keithlong89920]

Peter

Rather than trying to bend HSS another alternative is to look at using a tool holder that fits into the toolpost to carry the HSS tool bit. The holder can be mild steel and shape limited only by your own imagination. The holder gives you the bends and offsets that you prefer and then you just need a short straight length of HSS clamped in the end to do the cutting. The tool holder can also give you some of the rake angles to simplfy the grinding of the HSS. It has the advantage of allowing you to use smaller sections of HSS but still keep good overall rigidity because the tool holder can be as chunky as you can accommodate. Chester list some holders in right and left hand cranked form as well as straight and I think I’ve seem similar in the Chronos cat. as well. The older patterns from makers such as J&S and Eclipse come up regularly on EBay as another source.

Keith

Edited By Keith Long on 18/09/2010 22:31:58

[John OlsenParticipant @johnolsen79199]

Make the bendy part of  the tool out of whatever is convenient, then braze (silver solder) a small piece of HSS to the end. When it eventually gets ground too small from sharpening, heat it up, take the old bit off, and braze on a new one. You can make all sorts of handy tools like this, including cuttters to do t-slots as for a vice swivel base and the like.

 

I use both HSS and tips, they both have their uses.

 

regards

John

[John Stevenson 1Participant @johnstevenson1]

Yes you can bend it but you need red heat for it to move without cracking.

The heat will not affect decent HSS.

There are uses for carbide just as there are uses for HSS and a lot depends on the machine and machine rigidity as regards slides and supported area’s.

 

No idea what leadscrew nuts have to do with it, my capstan doesn’t have any leadscrews but rips metal off faster than lady Gaga’s knickers.

 

It can also be forged with good success to make swan neck tools etc. A short while ago I wanted to make a very stout slotting tool with the tip right at the end for a blind keyway. This was for a 10mm keyway so the usual slot or hole with the grub screw was out. I bought a length of 10mm x 12mm HSS with the idea it could make 10mm and 12mm tools.

 

Cut a 10mm slot across the bottom of a piece of 1″ square and brazed a cut off piece into it, sharpened the front edge and checked the size and it was 9.8, checked the bar and it was 9.8 x 11.8 duh…

 

So heated it up on the end whacked it a good one with a large hammer and left to cool, measured it and it was now 10.4 regrind and touch up to size and now got a nice 10mm slotting tool.

 

John S.

[Clive FosterParticipant @clivefoster55965]

Peter

For HSS bits its prolly best to use an Armstrong type holder in a four way or single slot block tool post.  If you are using one of the smaller lathes, say under 5″ centre height, the odds are you will have to make the post as the standard issue probably won’t be high enough to take the holder shank.  Fabricated construction is fine.

 

Use the bent to the right holder for normal turning.  This lets you get close into the chuck without endangering the saddle. Set the business end 90 degrees to the bed and put the angles on the tool bit.  Don’t mess with pivoting the post.  Although the American lantern type tool post is allegedly suitable for Armstrong holders its propensity to move in approximately 65 directions simultaneously if you are careless with the clamp bolt coupled to sadly inadequate rigidity will soon convince you that it’s an invention of Beezelbub to improve the profit ratio on workshop swear boxes.  If you must try one pull the boat and flip the washer over to give a flat mounting surface, as advised on page 27 Newnes Complete Lathework Vol 1.

 

When using carbide on the smaller lathe its worth considering the angles and shapes given in the older books, like the Newnes set, written before negative rake and inserts became de-facto standards.  Modern inserts of all types are designed for high speed cutting with most of the energy dissipated in the chip and pretty much don’t behave unless the chip is short, curled and blue.

 

Clive 

[Sam StonesParticipant @samstones42903]

Peter,

Just a quick word about HSS hardness. I can imagine that there will be some change to the hardness of HSS should you reach its critical temperature.

An occasional task for me while an apprentice was to machine (turn) a short length of `raw’ HSS, say about 150mm and about 15mm dia. (we were in inches in those days). The prepared conical blank was then fluted to form a tapered reamer. Prior to grinding, the blank was suspended in an electric furnace at something like 1200C, (I can’t remember the actual value), then it was quenched in oil.

If you have access to a copy, Machinery’s Handbook stipulates more precise details.

Good luck,

Sam

[Axel BentellParticipant @axelbentell]

Sure you can bend HSS, its like any other steel, but you need to follow makers advice on heat treating!

 

Files are queched in mercury I belive to recieve optimum hardness. Ive been told modern HSS of some makes can be red hot w o loosing hardness or get microscopic cracks. Ask the manufacturer!

[chris stephensParticipant @chrisstephens63393]

Hi Peter,

You could make yourself, or buy, a Tangential toolholder which will do both sliding and facing cuts with ease, and right up to your chuck.

If you want to get under the skin of Cast iron you could always put a piece of square TC in the holder instead of HSS.

chriStephens 

[Peter G. ShawParticipant @peterg-shaw75338]

Ooh, what a lot of suggestions. Many thanks. I’ll not use names – instead I’ll just talk generally. Does that make sense? I know what I mean, even iff you don’t!

 

TCT.

I quite agree that TCT does have some advantages, but for me generally it’s usefullness is outweighed by the need to spend a lot of time honing etc to get back to an unbroken tip. In any case, TCT cannot have a sharp corner which means HSS/carbon for that purpose alone. I did have two parting off tools – one broke the first time I used it (the tip parted company from the parent metal), whilst the other created so much chatter it was useless. I also cannot easily get a fine finish, due I suspect, to the lack of a broad enough tip, although my grandson the first time he used TCT produced a perfect finish! Anyway, enough of that – I’ve tried it, and now I want to go back to HSS/carbon.

 

Lathe stiffness.

I have had some concerns about this for a while, and now that I have found that the lathe is not turning parallel, I have decided to do a full overhaul/lubrication, adjustment and setting up of the machine. This should improve matters. 

 

Bending, or not, of HSS.

To be honest, I had forgotten that HSS can be silver soldered – which is a bit remiss of me since I already have a bit of HSS silver soldered onto an angled  mild steel shank & ground up for aluminium cutting. This, I think, is the way I shall go especially as it will enable me to get the cutting edge nearer the centre line without recourse to loads of packing . 

 

Tool Holders.

Sounds good, but here I would like to make my own rather than buy.

 

Tangential Toolholder.

Yes, could have a go at that.

 

There is one thing I would like to say. And that is that my interest is in making the tools wherever possible myself. Which is why I have a couple of large scrap files waiting to be cut, cleaned, and reground. Also why I have some square “silver” steel waiting to be used. Trouble is, as some of you will have realised, I have no engineering training as such, hence a lot of what I want to do is learning by experiment, ie am I able to do it.

 

So, there we are, question duly answered (Yes, HSS can be bent), but as I initially said, it was just a wild idea and I knew there were other possibilities. At least I now know the answer even if I don’t do it.

 

Many thanks to one and all,

 

Regards,

 

Peter G. Shaw

[adyParticipant @ady]

I was actually wondering the other day whether HSS would make the ultimate samurai sword.

 

It seems to have amazing strength but isn’t too brittle.

[John Stevenson 1Participant @johnstevenson1]

Drop Harry Kari an email to see if he can help ?

 

John S.

Edited By John Stevenson on 20/09/2010 00:14:49

[John HaineParticipant @johnhaine32865]

Martin Cleeve’s little book on screwcutting in the lathe has a few words about heat treating HSS.  He says that they should be heated to 1250 degrees C before quenching, where “sweat drops” will be seen on the surface (!)  Heating with an arc flame recommended rather than acetylene.  No tempering after quenching.  “Bending, or end-cranking for internal tools, must be done at a good bright heat” (presumably red rather than white).

[Axel BentellParticipant @axelbentell]

what does he use for quenching?

[John HaineParticipant @johnhaine32865]

Paraffin (he says)….hmm.  He also says “once hardened HSS is very difficult to soften by any means likely to be available in the average workshop” – whether that means that you can’t bend it either I don’t know.  Some brave soul should perhaps have a go!

[Sub MandrelParticipant @submandrel]

I understood that HSS was normally air-hardened – that’s with a concentrated blast of cool air, not just leaving it to cool.

 

Neil

[Axel BentellParticipant @axelbentell]

No dont blow on it, just leave it in still air. Reynolds makes the most famous of air hardening steels, and I never heard of anyone blasting them with cool air! Sounds like a good way to distort the peice, adn even create cracks.

[adyParticipant @ady]

You could practice on a piece of 1/8 toolsteel with one of those gaz blowlamps.

[Ian S CParticipant @iansc]

Tryed this last night, here goes. To Anneal airhardening HSS (Novo & Blue Chip)

   Pack the piece to be treated in a steel tube with powdered charcoal and plug the ends. Heat to cherry red, and hold until the temp is right through. Put in a sheltered place to cool, it will then be OK to machine or bend.

 

Bath for hardening.

A mixture of table salt–1lb per gallon of paraffine oil. Heat the steel to a lemon colour, and plunge it into the mixture, keep it moving until cool, the steel should be a grey colour. Good for most steels.

 

When it comes to heat treatment of HSS, its like asking how longs a bit of string, there are air hardening ones, some require water or brine, others oil, and some have the job done annealing hardening and tempering in a salt bath.Ian S C

[Sub MandrelParticipant @submandrel]

I don’t know where I got the air-blast idea from. perhaps I dreamt it?

 

I thought it might be in Radford’s Improvements and Accessories for your Lathe*, the only work I have that mentions making your own tools from annealed HSS. He says heat to red heat, then quickly to blistering yellow with the oxy-acetylene (is this the same as ‘sweating’?) and plunge into oil (and run away?)

 

Neil

 

*Funny how some people say similar books for ‘mini lathes’ prove they are no good, yet Radford was writing about Myfords…

[Anonymous]

Neil, I don’t know where you got the idea for air blast cooling from either! But the following is a quote from “Machinery’s Handbook”, so whatever else, you were not dreaming:

 

“Many high-speed steel tools are quenched in air, either in a stream of dry compressed air or in still air. Small sections harden satisfactorily in still air, but heavier sections should be subjected to air under pressure.”

 

Regards,

 

Andrew

[adyParticipant @ady]

–I don’t know where I got the air-blast idea from. perhaps I dreamt it?–

 

Probbly read some historical blast furnace stuff at some point.

http://en.wikipedia.org/wiki/Blast_furnace

[Peter G. ShawParticipant @peterg-shaw75338]

Hi folks,

 

Just a follow-up on what I did.

 

Cut off a 25mm length of HSS from a 125mm x 10mm x 10mm length from Amadeal. Cut a length of mild steel bar, bent it and shaped it to form a ledge. Ground it and the HSS to fit and silver soldered together. Ok, it took a couple of attempts, in part due to running out of gas, but it eventually worked.

 

Ground up the HSS to make a tool. Some very ugly pictures on page 2 of “Tip Build Up”.

 

Cleaned it up this afternoon, and tried again on some other steel. Again I think it must have been either a hard, or hardened steel. Anyway, the steel was eventually ruined by tearing when using other tools, but the HSS was worn circular. Set about cleaning it up again, and thought about trying to file it. Yes, I have managed to soften the HSS whilst brazing. So that was a waste of time.

 

I tried the file on the remaining part of the HSS bar and sure enough that is still hard. Which suggests that this particular HSS is not suitable for brazing onto mild steel shanks and then using to cut steel. I suppose it may be suitable for aluminium and other softer metals. Interestingly, it did seem to try to work on the tube I was trying to turn (see “Tip Build Up” thread).

 

Oh well, back to the drawing board.

 

Regards,

 

Peter G. Shaw

[Author]

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