How do I learn machining ?

[SillyOldDufferModerator @sillyoldduffer]

I went to a Grammar School, where, alas, practical skills weren’t a priority.  Syllabus academic and intense, aimed at getting us into University or a Profession, not jobs.  80 minutes maximum of woodwork or metalwork per week up to age 16, then none unless an individual has a special talent.  (In my year 1 of 120 did advanced metalwork, and 0 did advanced woodwork)

Basically two streams, humanities and science, with cross-over allowed if the timetable permitted it:  a friend did A-level Maths, Physics,  Russian and Economics:

• Both streams did Maths and English plus French or German up to age 16, then we specialised.  Plus games, which I hated, not least because they injured me doing Physical Education!  My parents should have sued – it affected my life.
• Arty boys focussed on languages (often two or more, ancient and modern), Literature, History, Economics, Art, Music, Drama, Politics, and Geography
• Scientists focussed on Maths, Physics, Chemistry, Biology, and Geography.
• Many introductory support lessons (no exams) : I did Technical Drawing, Art Appreciation, Maths for Scientists, Civics, Debating, Computing, Logic, Economics, Ethics, Politics and Philosophy.
• Very little space in the timetable for hands-on.

We were taught to think rather than develop practical skills.  Rather than learn how to sharpen HSS, I was told to read Machiavelli’s “The Prince” and other challenging texts.  The school taught research, how to assess evidence, logic, and the need to apply rational thought to decision making.   Not righty-tighty, lefty-loosy!

Children who failed the Grammar School entrance exam (the 11+ taken at age 11) went to a Technical School or a Secondary Modern.  These emphasised vocational rather than academic skills, and spent much more time on hands-on.   Technical Schools cherry picked children who did well on 11+’s maths/technical side, but were weak on English/arty stuff.   Technical Schools focussed on educating for industry, skilled trades, applied science (lab technicians), engineering, building, carpenters, machinists,  electricians etc.  A good idea that didn’t work out, possibly because they couldn’t get enough skilled teachers.  Many areas didn’t have them.

An unfortunate side-effect of the British Grammar/Secondary Modern system is that it drove a wedge between techies who should have been in the same team.  Grammar school trained engineers tended to see themselves as an elite to the point of despising “mere artisans”, a serious mistake.  Equally bad is the tendency for non-academic engineers to see graduate engineers as a bunch of practical incompetents, allegedly unable to work a screwdriver, and hopeless in the real-world.    Very unhealthy, because engineering requires people who can think AND people who can do. Not closing the gap is the next best thing if you want to damage British Industry as leaving the EU with no viable trade alternative.

Merging Grammar Schools and Secondary Moderns into Comprehensives didn’t seem fix the wedge problem, and if my friend’s and nephew’s experience of Academies is typical, they’re broken too.  (He was school technician, they were pupils.)  One issue, they thought, was not enough teachers understood technology, in practice or theory.  Not the teacher’s fault; they have to be recruited and trained in large numbers, which “the system” struggles to do.

Plenty of extra-curricular interest at my school in motor bikes and engines, though much less than chemistry, electronics and radio.  Model aircraft were popular.  There was maths club!   None of us sharpened HSS, or knew about carbide inserts…

One formative experience.  I was mucking about unsupervised in the metalwork room, when a group of older yobs crashed a Colchester’s saddle into the chuck at high-speed.    Lathe still worked apart from making a noise like nuts and bolts being flung about inside an oil drum.  We all left in a hurry, looking angelic, and the lathe was still broken 3 years later.   A good example of a previously wonderful lathe that no-one should buy second-hand.  It’s why I tell everyone who will listen than “condition is everything” – Colchesters are not boy-proof!

🙁

Dave

 

 

[cedric 1Participant @cedric]

We did much the same. Woodwork or metalwork once a week for a few hours. Don’t remember if it was as much as half a day or not. We also did Maths 1 and 2 , Physics , Latin, French, Chemistry or biology, and the usual smattering of English, history,  economics etc.

Joy oh joy when I escaped school at 16 I got to do more maths and more physics at tech college one day a week throughout my 4 year toolmaking apprenticeship. Along with metallurgy, stress and strain etc etc as “workshop science” .

Then later in life when I went to uni I got to do the maths and physics again!! As part of the general requirement because the pointy heads did not recognise “practical” education. Can’t say it was any more enjoyable the 3rd time around than it was at the high-school I fled at 16. Be careful what you wish for!

These days I don’t even remember most of it. But I can still sharpen a lathe tool bit.

[cedric 1Participant @cedric]

<p style=”text-align: left;”>PS, your mention of Chemistry and electronics reminded me how every boy had a chemistry kit, playing with sulphuric acid etc. My pride and joy was a Phillips Electronic Engineer Kit with 3 transistors! Hi tech stuff. Until we graduated to working unsupervised on 240 volt “valve” radios scavenged from the tip. Not to mention flying control line model planes unsupervised with monster 10cc finger-chopping glow plug engines. (I still have that McCoy Redhead engine and I’m still scared of it!)</p>
Child welfare would have a fit today!

[cedric 1]

On cedric 1 Said:

In high school metalwork class I don’t remember a single 15-year-old boy who couldn’t grind a lathe toolbit. We were given a handout sheet with diagram, teacher reiterated it on the blackboard then demonstrated it on the pedestal grinder. Then we all just did it.

The salient point here, surely, is that a teacher demonstrated the technique to the class and everyone then had a go, with a teacher on hand to guide anyone who was struggling. Sat at home with no previous experience and no one on hand to demonstrate the technique or guide you, learning to grind the tools is not always an easy thing to do. I can do it now, after a fashion, but it took a lot of time and error to achieve. As a beginner, I found, and still find, it really discouraging when someone glibly says that something is easy to learn.

James.

[cedric 1Participant @cedric]

One trick might be to use 1/4″ square HSS. It is quite quick and easy to grind. The bigger 3/8″ stuff can take a lot of grinding so correcting mistakes or trying experiments can be slow, laborious and frustrating.

Another is to keep a big tin of water, 500ml or more , at the grinder. Keep dipping the HSS in it and swishing it around regularly, before it turns blue and loses the temper. If it starts feeling warm on the fingers  dip it.

And use at least a 6″ grinder with 1″ wide wheels, well dressed wheels  coarse for roughing and fine for finishing. And a bench oilstone or diamond lap for final edge finish and radiusing the point.

[PeteParticipant @pete41194]

“Keep dipping the HSS in it and swishing it around regularly, before it turns blue and loses the temper.”

Sorry but this really is something that literally should have died out back in the beginning of the 1900’s when HSS tool steel was first invented. Steel on average will start to turn blue at around 280 – 315 C, or 540 – 600 F. High Speed Steel cutting tools begin to lose there temper at approximately 550 – 600 C, or 1022 – 1112 F. And at those temperatures, its getting a bit past the dull red color range.

That statement about the blue color is of course quite true for high carbon tool steels. But it’s just about physically impossible to over heat a HSS lathe tool to where it’s temper might be affected at all when grinding them since even the tool shank would quickly become too hot to hold and guide it against the wheel.

[SillyOldDuffer]

On SillyOldDuffer Said:

….engineering requires people who can think AND people who can do.

Some of us can do both. 🙂

Julie

[Pete]

On Pete Said:

“Keep dipping the HSS in it and swishing it around regularly, before it turns blue and loses the temper.”

Sorry but this really is something that literally should have died out back in the beginning of the 1900’s when HSS tool steel was first invented. Steel on average will start to turn blue at around 280 – 315 C, or 540 – 600 F. High Speed Steel cutting tools begin to lose there temper at approximately 550 – 600 C, or 1022 – 1112 F. And at those temperatures, its getting a bit past the dull red color range.

That statement about the blue color is of course quite true for high carbon tool steels. But it’s just about physically impossible to over heat a HSS lathe tool to where it’s temper might be affected at all when grinding them since even the tool shank would quickly become too hot to hold and guide it against the wheel.

That contradicts what the qualified metallurgist wrote in his extensive article  on HSS in MEW several years ago. Being an office bound expert he recommended to never dip HSS in water but to sit it down and let it cool naturally in air every time it felt hot when grinding.

Shop floor types who have to get a toolbit sharpened pronto get around this by dipping it regularly before it starts to blue.

By the time you see the blue colour spreading out from the edge, the very very edge in contact with the wheel is most likely red. You just can’t see it easily.

Overheated HSS still cuts, but not for as long.

[Julie Ann]

On Julie Ann Said:

On SillyOldDuffer Said:

….engineering requires people who can think AND people who can do.

Some of us can do both. 🙂

Julie

Not sure why there is this perceived dichotomy between “thinkers” and “doers “, aka SOD’s much-maligned “practical men “.

SOD seems to not realise that any “practical man” doing an engineering apprenticeship must attend technical college one day a week, or equivalent, and study some pretty serious maths, physics, applied science, metallurgy, tech drawing, machine design etc that these days is recognised as equivalent to about the first year of an engineering degree. Many apprentices go on to do post-trade tech college study that gives them a certificate, then diploma and even a degree in mechanical engineering. Many become associate members of the Institution of Mech Eng etc. Many others go on to “higher” careers in management or other fields

So they are certainly not some kind of unthinking beasts of burden. To say so is an insult. Perhaps a result of ancient grammar school boy prejudices deeply ingrained in a bygone era?

And remember , when working with your hands, they do only what the thinking brain tells them to.

 

 

[John HaineParticipant @johnhaine32865]

Going back to the original requirement about how to learn machining, the OP might do worse than to contact (and join) SMEE

If within “commuting” distance of London their HQ is reasonably accessible by train.

Apologies if this has already been suggested.

[John Haine]

On John Haine Said:

Going back to the original requirement about how to learn machining, the OP might do worse than to contact (and join) SMEE

////

Apologies if this has already been suggested.

My first post said that the SMEE appear to have stopped running courses now from what it says on their web site. It was one of the first places I looked at.

From what I’ve read I don’t think there’s anything running any more like the old model engineering evening classes, which would have been ideal. A short course at Axminster would have been good, but again, sadly no longer happening.

I’ve now read all the recommended books, watched lots of recommended videos and feel moderately confident that I can start work when the rest of the tooling arrives.

[John HaineParticipant @johnhaine32865]

Paul, I just sent you a PM.

[cedric 1Participant @cedric]

Sorry to hear the SMEE classes are no more. Difficult to find people with both the skills and the time to run them I suppose. They have joined the legion of evening classes that used to run in high school and tech college facilities when not otherwise in use. Shame but a sign of the times I suppose.

Yes  books and YouTube are the modern way unless you can find a local mentor, which perhaps is where online forums could play a role in finding likeminded people near you.

[Roger HartParticipant @rogerhart88496]

You seem to have more than enough information to go on. Don’t overthink it, turn some brass and aluminium and plastic. Then some silver steel, easier than it looks. Fix a few things round the house, find something you fancy building and have a go. Our grandfathers and great grandfathers (and mothers) didn’t go to school much, they learned by doing.

The person who never did anything never made a mistake. Also that job takes longest that is never started. Possibly don’t start with an exhibition quality 5″ loco but don’t feel obliged to do something so simple it is boring. Something that takes your fancy. If you get a few sore fingers or bruised knuckles and scrap metal too bad, put it down to experience. Eyeshields are worthwhile, A&E is a boring place to sit, dodging the brass shower is an art.

If you get the chance visit some Third World countries and wander the backstreets. You will likely see some traditional machinery being used in its traditional garb – muck and oil. Sometimes on the pavement! Sometimes they show up on YouTube. That is how we used to do it before (say no more or I’ll get into trouble). Above all, enjoy yourself.

[John HaineParticipant @johnhaine32865]

According to “From the Chair” note in the latest SMEE Journal they are hoping to restart the courses.

[SillyOldDuffer]

On SillyOldDuffer Said:

I went to a Grammar School, where, alas, practical skills weren’t a priority.  Syllabus academic and intense, aimed at getting us into University or a Profession, not jobs.  80 minutes maximum of woodwork or metalwork per week up to age 16, then none unless an individual has a special talent.  (In my year 1 of 120 did advanced metalwork, and 0 did advanced woodwork)

 

Dave

 

 

Hi, I’m glad I failed the 11plus then, and ended up in a Secondary Modern. I only did one term of woodwork, which I was pleased about, as my interest was in all things metal, which lead me to a good job and earnings. I actually hated school, all though I only missed about two weeks in the whole of that time, but that was due to illness alone. I’ve never looked back and wished it to be any different, and yes, I did have to do a lot of thinking in my jobs that I had, and every thing else as well, and I still do.

Regards Nick.

[Sonic EscapeParticipant @sonicescape38234]

With the confidence and ignorance of a diletant I would dare to say that learning machining on a hobby level is pretty easy. Just start to use you lathe and watch good quality videos when too tired to work. That is all you need.

Some books are interesting. But many times the details mentioned there are really redundant. You can figure them out by yourself.

In contrast to my long lasting hobbies, electronics and programming, I found that machining just for fun is way more simple and intuitive. For the first one it took me years to really enjoy it. My RF circuits simply refused to work the way I wanted. In contrast, my short experience in machining is way more satisfying from the beginning.
About three years ago I bought a big industrial lathe. Until then the most complex tool I had or used was a bench drill. Before buying the lathe I just watch some videos and I read various forum threads. When I was in front of the machine for the first time everything made sense and was very intuitive. Yes, it takes me way more time than normal to do everything, parting and knurling is still difficult, but I have no doubt that if I put enough time I’ll figure out how to do it all by my own. Most of time intuition and common sense is all you need. Many years ago I could not said the same about my circuits that were oscillating when they shouldn’t. Or about some bugs in my FFT software that remained a mystery to this day.

[cedric 1Participant @cedric]

Sonic, Don’t feel bad, parting and knurling are always tricky on a small lathe  even for the experienced!

[John Haine]

On John Haine Said:

According to “From the Chair” note in the latest SMEE Journal they are hoping to restart the courses.

Thanks for that John. I’ll keep an eye on their web site to see if and when they resume their courses.

I always liked their exhibitions at Seymour Hall, a real shame this sort of event seems to have almost stopped in the South.

 

[John HaineParticipant @johnhaine32865]

It might be worth dropping an email to the chairman to ask – his note said that they might be trialling the new course, maybe get in on the trial?

[paul1956Participant @paul1956]

Thanks John, an email now sent.

Thanks to everyone for their help and encouragement. I’ve finally been able to put tool to metal and got everything working pretty much as I think it should.

An initial trial with some brass suggests the HSS tool I ground (pictured earlier) works well, possibly better than the TCT tooling I’ve got. Although that might be due to the TCT tip’s bult in rake being less suitable for brass.
Certainly it’s an encouragement to grind more of my own HSS tooling.

[paul1956]

On paul1956 Said:

…An initial trial with some brass suggests the HSS tool I ground (pictured earlier) works well, possibly better than the TCT tooling I’ve got. …

Good start, the HSS tool is cutting well.  You have aptitude!

By TCT do you mean these?

If so, I’m wary of brazed Tungsten Carbine Tipped tools after experience exposed problems.

• I suspect they cover a use-case I don’t have, which is rapidly roughing out tons of difficult materials like chilled cast-iron, hardened steel, work hardening stainless, and abrasive composites such as fibre-glass.   As these nasties rapidly blunt HSS and are liable to chip expensive inserts, a resharpenable carbide tip makes sense.  No point in using them on Brass or Steel.
• Not always supplied sharp,  guess what I bought. Not obviously wrong, but left a poor finish no matter what.  Check before using.
• An advantage is they can be sharpened and shaped on a grinder, but only if it has a green wheel.   The grey wheels used to sharpen HSS are too soft for carbide.  I’m not rushing to waste money on a green wheel to just grind TCT.
• For what I do, inserts do 90% of what I need with no fuss.  Advantages: identical, precision made, with 3 or 4 cutting edges / points, that can be rotated or exchanged in the holder without disturbing the set-up.  Convenient, fast and easy.  Industry love inserts because carbide also cuts metal up to 15 times faster than HSS, and they reduce reset times dramaticallu.  There is a catch!  Carbide can be more fussy, especially when the rake and other angles are optimised for industry to remove metal flat-out and get a good finish in one pass.  The optimum speed, depth of cut and feed-rate recommended for industrial cutting are rarely available in our workshops, so not all inserts are suitable. That said, many perform well at hobby rates, and so would TCT if the angles were ground right.  But the machinist may have to experiment to find carbide’s sweet spot.  It’s not difficult.
• HSS does everything else!

Comparing HSS with carbide at the same speed as shown isn’t conclusive.  HSS gets a good finish across a wide range of cut depths and feed rates.  Carbide is fussier, and probably does better going in harder and faster than HSS.  Finding out what works is done at the lathe and doesn’t require a grinder.

I can do either HSS or carbide.  I find they perform equivalently, but inserts are more convenient, especially when the material is tough or hard.   HSS is mostly kept for form tools and specials.  And no need for a QCTP – all that’s necessary to set insert tooling to height is a pre-cut shim and a bog-standard tool-post.

My advice, try stuff and see what works for you. Much depends on the type of work done.

Dave

 

 

[SillyOldDuffer]

On SillyOldDuffer Said:

• I suspect they cover a use-case I don’t have, which is rapidly roughing out tons of difficult materials like chilled cast-iron, hardened steel, work hardening stainless, and abrasive composites such as fibre-glass.   As these nasties rapidly blunt HSS and are liable to chip expensive inserts, a resharpenable carbide tip makes sense.  No point in using them on Brass or Steel.

 

 

 

90% of the turning on this was done with brazed carbide, works fine on all common model engineering metals and not just roughing cuts. Though I think Paul mentioned having an insert tool holder.

 

[paul1956Participant @paul1956]

It’s just a cheap set of tools with replaceable inserts from China;
https://www.aliexpress.com/item/1005006075857182.html
They seem to be OK from what I can tell. Performance might be better with different inserts, but an acceptable set to start with.

I’ve no intention of going down the sharpening carbide route, it’ll be either disposable inserts or HSS here.

[JasonBModerator @jasonb]

Paul, as meantioned right at the beginning of this thread get some of the inserts intended for aluminium and other non ferrious metals, that includes brass they will give much better results.

The holder on the far left of your set is the one to use and the inserts are DCGT 060202 the G being the bit that makes the difference.

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