How do I learn machining ?

[paul1956Participant @paul1956]

My error, I picked up the wrong bar, it’s 8mm square not 10. But definitely 8mm from bottom of tool post to centre. I’ve found a cheap TCT set on Ali, so they should arrive with some other bits in about 10 days. I won’t get chance to actually get turning for a couple of weeks, so that time delay should be fine.
I’ll also have a go at grinding some of the HSS bar into lathe tools. From all I’ve read and watched it seems a pretty simple task compared to grinding the complex compound curves on woodturning gouges.

A copy of the ‘The Amateurs lathe’ has arrived from the library to read, although it looks like it’s come out of a museum display. Last updated in 1960.

[JasonBModerator @jasonb]

That will be the one with the Whale oil in it!

If all else fails a woodturning scraper will cut metal rather well, I use mine for the odd freeform curved surface. They wil be ideal for things like smokebox doors, chimneys and steam domes on your small loco after roughing out the shape with conventional lathe tools.

 

 

 

[bernard towersParticipant @bernardtowers37738]

Blimey Jason resorting to hand turning!!!!

[HollowpointParticipant @hollowpoint]

TCT or HSS?

Get both, they’re cheap enough. But I would say that having carbide tips helps a beginner eliminate one very common problem. – Poor finish produced by badly ground tools.

One of the very best sources for learning I have ever found is the MIT YouTube series below:

[Martin of WickParticipant @martinofwick]

It was a huge relief to me when TCT XXGT tooling became available at modest cost. I never got to enjoy grinding HSS. I still use both types, with TCT being the general purpose bit of choice now.

By the time TCT became available, I had simplified the process for using HSS by some of the following approaches:

• Use of a pair of left and right tool holders sized for 4mm HSS. These can the bit beck and to the left or right. These require a simple grind on two faces only and re-sharpen on one face (unless worn right back). I have not seen these around for a while but am sure they must be available somewhere.
• Use of a tangential tool holder – easily made to whatever size you wish and only requires a grind and re-sharpen on a single face for which a simple jig is made.
• Avoiding back rake altogether where possible – usually ok for brass and aluminium, sometimes ok for steel. Again, only grind and sharpen two faces and avoids having to repack the tool height every re-sharpen as required when back rake is present.
• If uber fine finishes are required, a vertical shear tool bit is also easy to grind and maintain but is restricted  to fine cuts.

The older books eg. Sparey illustrate all sorts of weird and wonderful forms of HSS tool bit. In reality a simple knife, V, and round will get you a long way. For parting, use a dedicated parting blade and holder. I find that in general on small lathes, really sharp HSS parting blades are easier to use than TCT, which are rather wide. I did break a few while learning though!

I see no particular benefit in wasting time covering your workshop in grinding dust just to use HSS as a learning process, unless you particularly enjoy it. Bear in mind grinding HSS for metal cutting is a much tougher  process than grinding carbon steel chisels. The cut faces on a toolbit for metal should be a single clean facet at the desired angle, resulting in a cleanly defined linear cutting edge. Sounds easy huh?

Go to it, you are your own best teacher!

 

[paul1956Participant @paul1956]

[Dave SParticipant @daves59043]

With a very simple rest and ER16 collets the Unimat is quite good for hand turning

[HollowpointParticipant @hollowpoint]

[paul1956Participant @paul1956]

[HollowpointParticipant @hollowpoint]

You can find black and white footage of WW1 uploaded to YouTube yesterday. The footage obviously predates YouTube. 🙄

It was just a suggestion. I personally found the videos very informative. You aren’t compelled to watch them.

[JasonBModerator @jasonb]

I was corresponding with the person sorting out the workshop series books in the week about getting them updated. As I said to her anyone coming into the hobby now is not going to be attracted to small grainy B&W photos and old blokes wearing workshopcoats, collar and tie. Infact they are not even going to be that interested in books when there is Youtube or forums with big clear colour photos and the ability to ask a question and get a reply almost instantly

As to relevance yes some is but some is not.

Take the typical old advice for someone with a Myford or Drummond when wanting to turn say a 7″ flywheel casting. “select slowest backgear and take a good cut to get under the skin”.

What help is that to the guy with a far eastern machine? He won’t have backgear but may work out that the slowest spindle speed is what they were saying even though he cant get as slow as the old iron. So he goes at it with a decent depth of cut using that HSS tool he spent the previous 4 weeks perfecting. The lathe is likely to stall, but he keeps going with more stalling as that is what the book said. Then he either smokes the motor or board, or if a minilathe with plastic gears he could strip them. Not helped by the fact he has not noticed that his HSS tool has lost it’s edge due to chill around the parting line and running several times faster than the backgeard machine would have.

What he should be told is to use a carbide tool that will not only stand up better to the chilled casting but allow him to run the lathe faster using the vari speed which will get the motor running at a speed were it has more grunt, cooling fan also works better and lastly take lighter cuts as the carbide is not worried by the skin and the lighter cut puts less load on the weaker varispeed and less rigid machine. Job gets done in the same time but the lathe does not get damaged and user does not become dejected and find another hobby.

I doubt there are any far easter hobby machines in the MIT series just like they are missing from the majority of teh WS serie sbooks.

[paul1956Participant @paul1956]

[HollowpointParticipant @hollowpoint]

Jason, as someone who consistently gives good advice and one of the few forum members I find myself agreeing with often. Have you considered writing a book? I’m not being sarcastic in case you’re wondering.

While you’re at it, perhaps a section dedicated especially to me. “How to air ones opinion without upsetting people”. 😅 I  don’t know why but I seem to have that affect on people! 🤷🏼‍♂️

[paul1956Participant @paul1956]

[Dave HalfordParticipant @davehalford22513]

[Howard LewisParticipant @howardlewis46836]

The advantage of reading books, as opposed to videos is that they are always available for reference. (No one, AFAIK, has made a video of equating to Tubal Cain’s “Model Engineer’s Handbook”.

Learning to grind a HSS tool is learning some of the basics (About clearance and rake angles) and then for any tool, to mount it so that the cutting edge is on centre height.

You can regrind HSS at 8 p-m on a Saturday night, after chipping the last spare TCT insert.

But it won’t cut hardened steel well, TCT will

Horses for courses

But only change one parameter at a time, whether, speed, feed, depth of cut or tool geometry.

(Don’t  use excessive angles, 10 degrees is more than enough most of the time. You will probably survive quite well with 5 degrees)

Above all, mount the tools as rigidly as possible (Same goes for measuring equipment)

You won’t get consistent, or good, results if everything is waving in the breeze!

How to choose which is part of the learning process.  Now unless a member of a Club, and able to learn from other members, experience has to be gained the hard way from one’s mistakes!

It is better to make one’s mistakes on relatively simple, cheap material, such as Mild Steel, rather than an expensive casting from a kit.

The time spent facing the end of a 12 mm bar and gradually reducing the diameter to 5 mm will give useful experience, and confidence.

The confidence gained will allow expansion of horizons.  Bigger and more complicated work can be attacked, armed with experience and confidence.

Nothing succeeds like success.

If there is a problem; ask advice, of other club members or on here; but be quite clear in your questions, otherwise it could lead to further confusion.

NOTHING beats having a good mentor!

Howard

[JasonBModerator @jasonb]

Hollowpoint, while I may not be able to help with your own specialist subject I have done a book which is largely based on the series that was in ME. Even after that finished subsequent articles have been written more about using the modern benchtop machines some of which I have also uploaded to this site for those that don’t subscribe, they can be found in the Workshop section of this site see the power feed oneand  four part “getting the most….”

I might even think about adding the one which was in Dec/Jan about modern methods used to take a fag packet sketch to completed parts.

The WS series book on CAD was one I suggested to the publisher should be binned, Yes it is hard to keep up but who in their right mind would pick up a book with this cover image expecting to learn CAD (Nigle excepted) almost more out of touch than whale oil. But it is not just ‘puters that have moved on a lot in the last 25-30yrs. so at the very least new chapters are needed for many and other chapters could be significantly reduced.

[HollowpointParticipant @hollowpoint]

Ah, my apologies, I had no idea! I might even have that one already. I have quite a few.

I see what you mean about the CAD book. The cover does look very dated indeed.

[Bill PhinnParticipant @billphinn90025]

[steveh2024Participant @steveh2024]

I consider myself a little further along than a newbie having owned and used (when time permits) my new Warco lathe for 18 months. I am at a stage where i feel reasonably confident of being able to machine a part to a required size and finish more often than not. I have read most of the books often recommended and spent more than a few hours practicing on the lathe but the 3 most useful aids for me has been Carbide Inserts, high quality youtube sites (like blondihacks and Mr Pete) and this forum (thanks to those who so generously share their expertise).  The books help but, as others have pointed out, they are somewhat dated and the illustrations are often very poor quality. Poorly sharpened HSS tools were a major frustration to me at the start.

[paul1956Participant @paul1956]

[Julie AnnParticipant @julieann]

[JasonBModerator @jasonb]

I suppose “right kit” is part of it as many a cheap bench grinder won’t have a particularly good rest. hough that has not stoppe dme, but I often use a small bench sander rather than the grinder.

 

As well a stop rake that Julie mentions you may get some rubbing with that tool when turning upto a shoulder. The end is generaly angled back 5-7 degrees to give clearance so you can face and turn with out the end rubbing

[SillyOldDufferModerator @sillyoldduffer]

[cedric 1Participant @cedric]

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.

Of course in those days most of us had already rebuilt countless bicycles scavenged from the tip, overhauled a moped engine or two at home, and helped Dad put new piston rings in the Austin A40 so were not exactly mechanical neophytes.

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