How to soften steel

[SteviegtrParticipant @steviegtr]

Toolposts

[SteviegtrParticipant @steviegtr]

I have purchased 4 tool posts to go on my Myford super 7B These are to fit a wedge type quick change I have ordered from the states. Being the clever twit I am I watched a few vids of people modifying the cross slide tool post bed. I had 4mm machined of mine. surface ground at an engine builders. Watched Steve Jordan doing it. The big but, is that they were all fitting the 250-000 holder . I decided to go for the beefier 250-100 which is around 3" square. Much larger than the 000. All good until the posts arrived & are much deeper than the 000. So even with the 4mm ground of the cross slide (is it called a cross slide???). So that I can fit up to 13mm tools in the slot the height is still too high. It means I need to grind/ mill or whatever 4mm from the base of each tool holder. No problem as they are very thick at the bottom so I see no problem with strength. I gave one to a friend with a huge milling machine. Not a beaver but as big. (Story. The council where he got it & his Colchester lathe said if you buy the milling tools that we have for that mill, you can have the machine free. He said how much. They said £50. He said yes. He got a huge box of every kind of milling bits you could imagine & a 3 ton machine for nowt.) I digress as usual. So my friend known as Dar of Dar's motorcycles took one of the tool posts & rang me today with bad news. He said they are too hard to mill. To take them to the crank grinders will cost a lot as they charged me dearly for the 1st job. My question to all you guys out there is can I soften the tool posts so he can machine them & then re-harden them. If the answer is yes then please tell me how to. Pretty please.

Steve.

[HopperParticipant @hopper]

Stick with your standard toolpost until you learn a bit more about using your lathe. A QC toolpost is a luxury, not a necessity.

Eventually if you want to soften hardened steel, it can depend on the steel and whether it's case or through hardened etc. But you heat it to cherry red and then cool it slowly overnight, in a bed of lime, insulating blanket, controlled furnace or whatever. Takes a lot of heat to get a lump like a toolpost that hot. Big propane burner and insulating brick hearth required.

[SteviegtrParticipant @steviegtr]

So like cast iron put it in sand to cool slowly. I am used to softening none ferrous coins which require dipping quickly to cool. The only reason I ordered the tool post holder was so that I can set up different tools without having to constantly shim them.

[JasonBModerator @jasonb]

before you try to soften it think about whether you have the ability to reharden it afterwards without any distortion and what will you do about the scale that will form on the surface.

What did your mate try to mill it with? It will probably cut with carbide just make sure the cutter or inserts are rated for harder steels say 60 plus Rockwell not 45. Should also turn with carbide too.

[Tony Pratt 1Participant @tonypratt1]

If you try to soften it you will end up with a distorted & scaled part, as Jason B says use the correct hard metal milling tips.

Tony

[David George 1Participant @davidgeorge1]

I machined my toolholders and found that they were case hardened. It means that once I was through the hard skin it was less problem but with this type of steel is tougher than through hardened steel and less likley to fracture. The core material does harden but not as much as the skin and i found that a 10mm carbide tool machined them with little problem.

David

Edited By David George 1 on 18/01/2020 09:37:50

[SillyOldDufferModerator @sillyoldduffer]

Posted by Hopper on 18/01/2020 01:46:20:

Stick with your standard toolpost until you learn a bit more about using your lathe.

+1 to that. But Stevie, please slow down. Nothing wrong with what you're trying to do but lack of experience is taking you deep into advanced territory. Too many difficulties – Here be Dragons. Dozens of em'

Not a good idea for inexperienced beginners to start with an unfamiliar lathe by stripping it down or making major modifications. Far too easy to do more damage than good, turning a decent machine into a botched dog.

I too am a "Clever Twit", with a successful engineering career behind me. I have every reason to be confident in my own field. But that level of confidence is absolutely not justified in Model Engineering / Home Machining because skill, judgement, timing and familiarity with processes and materials are more important than the theory. Practical skills and knowledge both matter. Although much of what I learned in my day job is relevant, it hasn't allowed me to short-circuit the learning process. For example, although a lathe is a simple beast in theory, getting consistently good results out of one has to be studied and practised, which takes time and effort. Good to have an expert on call – self-teaching slows the process down.

Putting it another way, I've driven a car for about 40 years without causing an accident. I'm some sort of 'Good Driver'. Doesn't mean I can safely jump on a powerful motorbike and expect to win races.

My advice is to start by tackling several straightforward projects like simple tools, and then progress to a simple model mill engine (my favourite is Stewart Hart's PottyMill). Not because I want one, but because the Plans are accurate (can you read an engineering plan?), it's pitched at just the right level of difficulty to challenge a beginner without leaving him in the dust, and getting it to run requires accurate measurement, reasonable finish on a number of different parts in Aluminium, Steel and Brass, fettling and assembly, clearing faults and reducing friction, and then adjusting the valve gear. Making one will teach many lessons about your lathe and its Operator's shortcomings. One lesson learned will be that – for many home projects – you don't need a QCTP. It will also highlight what's good and bad about all the tools used, such as why a Milling Machine is so highly desirable. Knowing from experience what needs attention on a lathe or elsewhere in the workshop is much better than guessing. Spend a year or two using the lathe before deciding if a QTCP is worth fitting. Then tackle the awkward problems caused by wanting to machine a hardened tool-post! It might be easier to cut your losses…

Dave

 

Edited By SillyOldDuffer on 18/01/2020 10:37:06

[SteviegtrParticipant @steviegtr]

Thanks for the comments. The reason I was going to change the tool post was that when I bought the lathe it came with a box of parts. In there were about 20 cutting tools, all 1/2" square. There were 3 small ones between 8 & 10mm square. 1 is chipped. So that's the reason. If I leave it for a few years as advised, until I am up to scratch with working it. I will have to buy some more cutting tools of the smaller size. Is that the way to go.

[SteviegtrParticipant @steviegtr]

Posted by Tony Pratt 1 on 18/01/2020 09:07:00:

If you try to soften it you will end up with a distorted & scaled part, as Jason B says use the correct hard metal milling tips.

Tony

Unfortunately my mate has come back to me saying he cannot do the parts as they are too hard. The truth is when I gave them to him I got the feeling it was a job he didn't want. Last night I put a fine file to one corner & it filed so cannot be that hard. They are the ones from either China or India. Someone suggests they may be case hardened. Some replies are not to fit it just yet. So the softening part is a no no. Thanks for the info. If I decide to go ahead. I am left with 2 options, 1st is to set up the milling attachment that came with the lathe & buy some mill drills. Or just take them to the engine grinders as I did with the top slide.

Steve.

[duncan webster 1Participant @duncanwebster1]

Take the top slide off and replace it with a solid block, you can then make the height to suit you bigger toolpost. However, 3/8 sq tools are plenty big enough for a myford S7,

[JasonBModerator @jasonb]

Stick the toolpost in your 4-jaw chuck and try one of those brazed carbide tools that you have on it, a lot better than trying to mill it on the Myford

[not done it yetParticipant @notdoneityet]

Posted by duncan webster on 18/01/2020 15:18:28:

Take the top slide off and replace it with a solid block, you can then make the height to suit you bigger toolpost. However, 3/8 sq tools are plenty big enough for a myford S7,

Duncan, don’t forget he has doubled the power of his motor.🙂. But I know what you mean….

[Neil WyattModerator @neilwyatt]

Wait!

I had this issue with the SC4.

I found that an ordinary badsaw was quite capable of slicing about 3mm off the bottom of the toolholders.

After discussion with Ketan at Arc Euro, he's had custom toolholders made.

He hasn't named them after me (unless I take up the nickname 'Slim&#39 so I'm sulking.

http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathe-Accessories/Tool-Posts/Model-100-Slim-Toolholder

Neil

[Neil WyattModerator @neilwyatt]

Also… it may surprise some but the 7-series lathes are very similar to mini lathes in terms of capacity and tool size.

A 100 or 111 toolpost is way too big for one IMHO.

There's no benefit from either the increased tool capacity or mass/rigidity – I would have kept the metal in the cross slide where it can do more good.

You're using up space on the cross slide that could be better kept for workpieces.

You really need a 4"+ centre height lathe like an SC4 or a Boxford to be worth using a 100/111.

Neil

[JasonBModerator @jasonb]

Neil, he needs the TOOLPOST to go lower as there is already too much air between topslide and the underside of the holders so cutting them won't do anything..

may be possible to fit longer studs to the height adjusters so the tool holders drop lower but you are then gripping by the end of the wedge.

[SteviegtrParticipant @steviegtr]

Posted by Neil Wyatt on 18/01/2020 17:52:19:

Also… it may surprise some but the 7-series lathes are very similar to mini lathes in terms of capacity and tool size.

A 100 or 111 toolpost is way too big for one IMHO.

There's no benefit from either the increased tool capacity or mass/rigidity – I would have kept the metal in the cross slide where it can do more good.

You're using up space on the cross slide that could be better kept for workpieces.

You really need a 4"+ centre height lathe like an SC4 or a Boxford to be worth using a 100/111.

Neil

The benefit of the tool capacity is the lathe came with a box of them. They will not fit in the holder I have. The size of the new one is higher but only 1/2" larger on the footprint. A bit confused about your comment about having space for workpieces. on the cross slide. The holder fits on the upper slide. Which permanently resides on the cross slide.

[SteviegtrParticipant @steviegtr]

Posted by JasonB on 18/01/2020 15:22:48:

Stick the toolpost in your 4-jaw chuck and try one of those brazed carbide tools that you have on it, a lot better than trying to mill it on the Myford

Good idea. Probably much better than using a milling cutter. I might wait until I sort out a backplate 4 the 4 jaw. Thanks.

Steve.

[SteviegtrParticipant @steviegtr]

Posted by JasonB on 18/01/2020 18:31:29:

Neil, he needs the TOOLPOST to go lower as there is already too much air between topslide and the underside of the holders so cutting them won't do anything..

may be possible to fit longer studs to the height adjusters so the tool holders drop lower but you are then gripping by the end of the wedge.

Yes I see your point. The problem is the QC post is somewhere between here & the USA. will know better when it comes. But if I sit. No I'll post a picture. Paints a thousand words.

[JasonBModerator @jasonb]

Posted by Steviegtr on 18/01/2020 18:49:24:

. A bit confused about your comment about having space for workpieces. on the cross slide. The holder fits on the upper slide. Which permanently resides on the cross slide.

 

The QCTP you have once fitted with toolholders will overhang the topslide which in some instances means you can't get the cross slide in as far eg when using tailstock support.

The original Myford was not supplied with a 4 way toolpost like you have, the tool would simply have been placed on packing and stood directly on top of teh topslide with a simple clamp arrangement to hold it, you could do the same with the tools you have.

Edited By JasonB on 18/01/2020 18:59:23

[not done it yetParticipant @notdoneityet]

Even though your 1/2’ cutters may ‘just’ squeeze into a 12.5mm gap, you may find the centre height is too high. I think you may be needing to grind off a mm or so from those cutters.

You need to investigate that – little point in altering the tool holders if it is more sensible to be reducing the cutters.

It is a bit like altering the spindle to take a single backplate or altering the backplate to fit the spindle? One is sensible, the other may make the lathe unsuitable for the rest of the backplates used, for ever and a day!

[Neil WyattModerator @neilwyatt]

Posted by Steviegtr on 18/01/2020 18:49:24:

A bit confused about your comment about having space for workpieces. on the cross slide. The holder fits on the upper slide. Which permanently resides on the cross slide.

The toolpost + holders sticks out a lot further from the toolpost, you will see when it comes.

[Neil WyattModerator @neilwyatt]

Posted by JasonB on 18/01/2020 18:31:29:

Neil, he needs the TOOLPOST to go lower as there is already too much air between topslide and the underside of the holders so cutting them won't do anything..

may be possible to fit longer studs to the height adjusters so the tool holders drop lower but you are then gripping by the end of the wedge.

The standard toolholders will happily drop well' below the base of the toolpost with the standard studs.

Quite probable it will overhang the topslide more than enough, but may not be possible to use it angled.

Tomorrow I will do a comparison of 000 and 100 on my mini lathe.

Good point from NDIY:

| You need to investigate that – little point in altering the tool holders if it is more sensible to be reducing the cutters.

Neil

[JasonBModerator @jasonb]

Sorry I read it as the post was too tall. reading again it's the thickness of the bottom of the holders on what is too big a QCTP for that machine.

[SteviegtrParticipant @steviegtr]

All points taken. Some pictures 4mm too high. Someone told me porkies too. That steel is not that hard,see where I filed it.

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