'average model engineer'

FWIW...I'm part way through (OK, very early days) CNC'ing a Chester 20V - using good quality components - with an estimated total cost the same as adding 3 good quality magnetic sensors and a DRO...

Jason - good point - posting before coffee is maybe not a good idea. (sigh)

Ok - I don't keep accurate costings, mainly because shipping to Canada sometimes doubles the cost of the item, so it is not a good indicator. Maybe I'm not the one to ask, but here's my last completed project.

Lets look at my little Unimat CNC conversion.

1) Stepper motors. The ones from Printrbot.com are more powerful than the ones I used, and about the same price. $15.00 US each.

2) Power Supply. I'm using an old 48v power supply, but many use an old computer supply for small machines.

$0.00 US to (say??) $50.00 US.

3) CNC breakout board + stepper drivers. I used a Gecko G540 that I had from another project ($300.00 US) but others use ones from EBay - John Stevenson would know more, but $100.00 tops??

4) Computer with parallel port. Free. Just ask around. Same with old VGA flat screen monitors, and mice and keyboards. Last couple of VGA flat screens were either a) free, and b) $15.00 at the local "recycling" store.

5) Unimat lathe. Mine cost $0.00, but I have some machining to do for a friend. Some year.

The CNC controller is the most expensive part, but I could use the inexpensive "stuff" 3D printer people use, not the G540, which is obviously overkill for this project, but I had it sitting on a shelf… Maybe someone can take this comment and run with it?

Does this help anyone?

Thanks John, So with a bit of begging and borrowing you could be up and running for say $500 on a small scale, maybe $1000 for something larger than the Unimat or 3 axis on a small mill.

$500 say £300 seems quite reasonable to me same cost as say a Myford vertical slide or brand name chuck at the same price which many in the hoby seem to be able to justify.

J

I see lets just cobble a load of old bits together, that may be OK for some but I have found it can be a false economy.

I was thinking more of a decent size CNC machine for making the parts for say a 7.25 loco that doesn't need twenty passes to get to the correct dimension. To me a 4mm cut is not unreasonable on my lathe or my bigger mill, little one may be 1mm but that one is simply not ridged enough for large metal removal.

There is a sizeable chunk of hobbyists who don't have great wedges of cash to throw around, or simply don't have the space for anything bigger than 'benchtop' machines.

"It ain't what you got, it's what you do with it!"

As for me, I'm about to turn some paper sketches into a Turbocad 21 design. Learning the CAD skills will be rewarding, just as making the actual parts will be.

Neil

CNC can make things impossible to make manually, I watched a Marwin machine a one piece turbine rotor about 2 feet diameter and around 10-12 blades from a solid blank, it took about 6 weeks. I would be amazed if anyone could make that on a manual mill.

Mike

Numerical control was driven by the needs of the aircraft industry after WW II. I think the American military funded much of the original research. The toolroom where I worked as a sparky had some very interesting examples of early numerical control when players like EMI, Ferranti, Olivetti and even a Cincinatti Acramatic 1 grafted on to a massive Hydrotel Mill. These were R&D projects to investigate the viability of making automotive press tools without the use of copy mills which need precision patterns to be made before you can cut the castings.

Mike

Just looking at the Christmas "double issue" of ME from 1958, things haven't changed much. Complaints about the reducing number of tool stalls at the Model Engineering exhibition, "pointed" remarks at Martin Cleeves for proposing Steel rather than cast iron castings, worries that young people are not engaging with the hobby any more.

The biggest difference is that there was very little actually making anything in the magazine. A bit of a difference with today's magazine. Loco's predominate. There was an article on a model ship and the design for a brass candle stick (The author claiming that anyone turning from solid instead of casting the components was idle...)

Oh and a Myford ML7 was £55 - about two months wages for a skilled man, A decent Warco is probably about 2-3 weeks pay for a skilled bloke these days. This is why I made the earlier point that the average model engineers budget hasn't changed - it just that you can buy a lot more with it.

Steve

Bob;

Two things I have found about CNC since I started machining 45 years ago:

1) small end mills rule. Reason: you keep the tool moving; reduces distortion from machining loads, and heat. You end up with a finished product that is on size, at a fast turn of speed;

2) CNC mills climb mill, reducing heat, tool wear, and producing an incredibly nice finish.

Yes, I was surprised at the above. Yes, it did take me a while to figure out #1 especially.

I think 3-1/2" gauge is the best gauge there is, and if you work it out, it's about 1/8 the "envelope" of a 7-1/4" gauge locomotive, so, *all* tools need to be larger for your 7-1/4" work than my 3-1/2" work.

Regards - JohnS.

> Just looking at the Christmas "double issue" of ME from 1958, things haven't changed much.

In 1956 someone was complaining "why do people still insist on using number drills, surely they will be obsolete soon"!

Neil

Steve,

1958 was a bad year for ME as Vic Smeed had taken charge. this led the following year to LBSC giving up and the circulation of ME dropping considerably till the mid 1960s when Martin Evans took over as editor then managed to persuade LBSC to return to 'Ours' around 1965. in the intervening period articles on model boats abounded and H Tuplin's much criticised 'Hackfly' appeared.

cheers,

julian

According to his tribute page Vic Smeed was nowhere near the ME magazine until 1965

There was an executive editor called C. E. WALLER who popped up occasionally

Edited By Ady1 on 21/08/2014 22:30:39

Vic Smeed was one of the MAP people who saved ME and reinstated LBSC, apparently

hi Ady,

my 'inside knowledge' paints a rather different picture im afraid. Vic Smeed was instrumental in the sanitising of LBSC's writings from the mid 1950's onwards , and Vic Smeed was one of the main reasons LBSC left in 1959. Vic Smeed excercised a control over ME far earlier than your above links suggest. it was Dickie Laidlaw and Martin Evans who persauded LBSC to return to 'Ours' due no doubt to rapid circulation decline, plus offering LBSC a much larger fee! Dickie Laidlaw sidelined Vic Smeed, and left Martin Evans to control ME without Vic's influence, hence circulation resumed it's pre Vic Smeed influence in the mid 1960s and no more model boat building articles!

Vic Smeed was by all accounts not an easy person to get on with or work with, and the direction he sent the ME in the mid to late 1950s proved disastrous commercially. i had few a great late friends who knew all the personalities at the time, and Vic was certainly portrayed as the 'Evil King'!

cheers,

julian

Edited By julian atkins on 21/08/2014 23:17:24

I'm pretty much self taught thus proving the axiom "we learn by doing".

It's human nature to dismiss anything we don't do ourselves and to be annoyed (partly with ourselves) when we come to suspect we were mistaken.

I may not be of watchmaker class myself but after the best part of 45 years of (both tutored and self-taught) manual and machine practice, I believve I have a reasonable level of machinist skills. I resisted looking into 3D CAD and CNC until the last year or so and now kick myself for being such a complete Luddite, despite the fact I like to think of myself as a technophile.

Engineering companies used to have vast drawing offices where parts were laboriously drawn up using slide rules and drawing boards (I know - I remember them well). The reason they have vanished is that a small handful of CAD engineers can do the same job much quicker and better - and print out automated part and assembly drawings, BOMs, GAs etc in minutes. What is wrong with that? I passed my BS308 test years ago but wouldn't dream of going back.

CNC isn't for mass production only. When you take into account that some one-off jobs require the work to be repositioned and moved from vise to rotary table etc many times, you are keeping yourself very busy - and working hard to avoid human error. Given the choice I don't see anything particularly admirable in persisting with manual methods unless you have an inverse snobbery complex going on. CNC's there if you want it and really the cost isn't the barrier.

Having said that, I don't think anyone here has actually suggested that beginners should shell out for big expensive CNC machinery, unless I've missed something. I think you'll find that most of the CNC users on this forum are actually pretty handy with traditional manual machining techniques but see CNC as another productivity tool (and possibly good clean fun - is that allowed??). Take a look at some of their photos if you need convincing.

Murray

Fun....FUN you expect to have FUN.................outrageous.

cheers

Bill

I've just started using Turbocad in anger. Previous half-hearted attempts at 3D CAD didn't get very far, and I still have some major things to crack (how do I weld shapes or lines together?) but the main hurdles took a couople of good sessions and a I swallowed my pride and looked at the tutorials

Neil

CNC would be great for repetition work but not much fun for "making" stuff since I would simply plug the cutter and workpiece in... then go off to do the gardening

3D printing will eventually make us all luddites IMO, and throw CNC onto the manual lathe scrapheap

RAF jets fly with 3D printed parts

Won't stop me enjoying the hobby though

Where it WOULD come in handy would be for big projects.

Gerald Smith spent 6 years of his life making his rotary marvel

Edited By Ady1 on 22/08/2014 10:09:22