Is CNC cheating

[Bill PudneyParticipant @billpudney37759]

I was fortunate enough to be involved in the transition of a mainly (90%) "manual" workshop, to an almost 100% ( one Hardinge toolmakers lathe) CNC short run and jobbing workshop. The Hardinge was used very little, maybe 1/2 hour a month.

The operators were certainly not button pushers, they were very highly skilled people who could and frequently did prepare their own 3D models, devise a production process, write their own programs, machine first off's, produce compliant parts in the quantity required etc etc.

What they were doing was using the best tools available to them, at that time, to produce highly complex very high quality components. In this regard I can see little difference between the Heroes of yesteryear to the operator programmers I was fortunate enough to know. A couple of the few differences are that modern parts tend to be less variable and cheaper than comparable manually produced parts

Sure there were a few whoopsies, but in general the scrap rate was far less in the CNC workshop than the manual one.

My workshop is fully manual, partly because I cannot afford CNC but also my personal learning curve would be too steep and too long. However if I was 20 years younger, with deeper pockets it would be at least partly CNC!!

There is a place for everyone in this largely solitary hobby……..

(whether or not they hate electronics and acronyms!!)

cheers

Bill

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Michael Horner on 31/08/2016 22:36:04:

When you use a DRO or a jig are you then not just a monkey turning the handle?

Just a thought.

Cheers Michael.

Hi, you might as well say that about graduated dials, as John A. S. has pointed out, some early ME lathes didn't have any at all. The one I had inherited from my father had none and only a single line on the fast forward/reverse saddle moving handle for screw cutting.

Regards Nick.

[John HaineParticipant @johnhaine32865]

Posted by fizzy on 31/08/2016 21:12:48:

Im of the opinion that if your loco or whatever is made from CNC derived parts then you cant in all honesty claim to have made them yourself. You may have designed and mounted the material yourself but it is the then automated machine which has made the part (I apreciate it isnt as simple as that!). I take total satisfaction from hand operating all of my machinery and wouldnt even dream of using CNC as it wouls remove all the pleasure and satisfaction for me. What do others think (and im not knocking those who do CNC their parts, each to his own).

You say you wouldn't dream of using CNC. Well, don't knock it until you've tried it. You "appreciate that it isn't as simple as that" – my friend, you don't know the half of it!

[HopperParticipant @hopper]

Electric motors! That's where the rot set in! If you don't treadle it yourself and soak the job in your own sweat, you haven't really made it yourself! Maybe. Or not.

To me, CNCing is like playing an Isle of Man video game compared with throwing a leg over a bike and actually going for a ride.

But if others enjoy it and teach themselves the CNC programming skills which I have not the patience to be bothered with, I respect that. I'm happy they are happy. I think the last issue of MEW contained a good example of how CNC can be right handy to make a complex curved shape for a wheel nut lock key. But for most of what I do, one-off bits and pieces of a simple nature, mostly of a "try and fit" nature there is no point in CNC finery.

And it does seem like corner cutting in something like say making a nine cylinder radial engine where you make one tool path, get it right then crank all nine cylinder heads out while sitting back with a cup of tea. Are they handcrafted parts in the way individually manually made ones are, each with its small hidden errors or near errors or covered-up errors? No they are not. They are mass produced by a machine. The program that made them is handcrafted, though.

Is the resulting model any better or worse for the method used? Not from any practical point of view. But from a sentimental point of view, I have more respect for the craftsman who had the patience and the skill to make nine cylinder heads manually, each one a long exercise in gently turning dials just so at just the right time and judging tools and feeds and speeds and coolants and so forth to perfection, or close to it.

Getting the human mind/body to perform at or close to perfection repeatedly is an achievement indeed. Hence the Olympics, for one. Getting a computer to perform at perfection, once the initial bugs are worked out, is an everyday occurrence, nothing to excite me at all.

To each his own.

Edited By Hopper on 01/09/2016 07:23:50

[JasonBModerator @jasonb]

Posted by julian atkins on 31/08/2016 22:46:42:

However the point you raise is highly relevant. The standard ME exhibition judging will cause you to loose points if parts are disclosed to be pre-made/pre-machined.

Julian

Not quite so, it actually says "Parts not the outcome of their own work" so if you have drawn the part from measuring the original, done the program and cut it on your CNC I doubt you will be down marked. Really applies to buying in completed items.

The interesting thing is that you could probably gain marks by making an original design which is more likely to suit CNC work than just bashing out yet another LBSC design.

JS, As Fizzy was asking about cost of castings the other week I think we can assume he is not mining his own iron ore. Just hope the castings he buys did not have their patterns cut on a CNC machine or 3-D printed

Its a pity we don't get many CNC users posting their work here ( or manul ones for that) iof you follow their builds you will get an idea of the amount of work that actually goes into the models

[MWParticipant @mw27036]

Posted by Hopper on 01/09/2016 07:20:06:

Electric motors! That's where the rot set in! If you don't treadle it yourself and soak the job in your own sweat, you haven't really made it yourself!

 

Yes! I knew they were the work of the devil! Them motorcaring city folk just don't know whats good for em anymore.

Seriously though, if i can teach someone with no machining experience to run a cnc program, then surely, even the proponents have to tell you that there is obviously a descrepancy between the two. You can't argue they are equal skills. 

Michael W

Edited By Michael Walters on 01/09/2016 08:27:19

[Neil WyattModerator @neilwyatt]

If you have a role in the creative process of a mechanical object, it's model engineering.

What does anyone gain by 'excluding' activities such a building from kits, CNC or even running a loco built by someone else? They all require a degree of skill and understanding.

The abilities of someone to make a glass-case model from scratch entirely by hand is remarkable, why should they need to dismiss the achievements of others to make theirs seem greater?

It's rather like a painter saying photography isn't art.

Neil

[Bob RodgersonParticipant @bobrodgerson97362]

I have heard this argument many times. Until a couple of years ago I had an all manual workshop, I have built several Model Locomotives and model IC engines using manual machines. My first Locomotive (Simplex) was made using a lathe and pilar drill as the only machine tools.

I know I can make anything I want using hand tools and manual machine tools and there is a lot of satisfaction in doing so, however I felt that I needed a challenges decided to give CNC a try.

There is a lot more to using CNC machines to making stuff, as has been pointed out here. For a start you have to be able to draw in 2D using any of a multitude of drawing programmes. Then you have to take that one stage further and generate a 3-D drawing/model using software of your choice. If you are a masochist you then need to learn how to translate that 3D drawing into G-code, (basically telling the machine where the tip or end of a cutting tool needs to be using machine coordinates in X-Y & Z axis) or more likely you will use a CAM programme to generate tool paths.

I believe there are skills in getting from concept to part. It shouldn't be forgotten that the machine only does what it is told to do and that it still takes the practical skills you have learned on manual machines to detect when the CNC machine is not happy or about to break yet another cutting tool. It sometimes takes several attempts and changes to the programme to get it right.

I Have chucked more bits in the scrap bin since going CNC than I ever would have using manual methods though the scrap to success ratio is improving.

I am happy that I can produce something using hand skills but if I can avoid blisters I will and I don't think there is any the less skill in arriving at the finished article by whatever method.

[Raymond AndersonParticipant @raymondanderson34407]

I don't see it as cheating, It's just a different SKILL set. and you most certainly don't learn to load and use a Cnc lathe or mill quickly. especially if it is a multi axis machine with live tooling and a sub spindle. where 2 tools could be running at the same time. There in lies the road to disaster if anyone thinks they can learn that quickly.

[nigel jones 5Participant @nigeljones5]

I am sure that someone who has designed and created a part entirely 'electronically' would be just as happy with their work as the man who has hand filed it from solid, it is just different. For me building a model myself is about emulating how it was done way back, and that is where I derive my satisfaction. Once it has been tested and steamed I have absolutely no interest in the model other than a financial one. I have yet to build a loco from castings (indeed a full set of Speedy castings have sat in the workshop untouched for several years) but this would in no way be a down side as the original builders used castings. I would however think it extremely unfair if one of my creations were being judged along side a CNC model. I couldn't ever hope to match the surface finish and accuracy and for that reason would class it as cheating. Like I said, each to their own and this debate has been very insightful thus far.

[MuzzerParticipant @muzzer]

When I started working in industry back in the early 80s, mechanical drawings were still mostly drawn up on drawing boards using paper, film, pencils, ink pens, scalpels etc. I was fine with the practice myself and was able to put the BS308 exam behind me pretty quickly. However, what you will notice if you compare the scenes from a typical 20th century drawing office and today is simply the sheer number of people that were involved in those days and the level of effort required just to make changes. Today it's incredible to think how complete aircraft, engines, gearboxes etc were all drawn on paper and to consider how much work was involved in doing so. It certainly required a lot of skill.

Nowadays the same work is done in 3D CAD but anyone who believes that it doesn't require a lot of skill to do it effectively doesn't know what they are talking about. You can still be sloppy and slow and produce a load of rubbish. However, in the right hands it's enormously more powerful and productive – and flexible. Admittedly I'm talking about manual drawing vs CAD here, rather than manual machining vs CAM/CNC but it's a very similar situation in many respects – and of course they are becoming increasingly integrated. These can / could all be very technically demanding but the difference is largely the resulting work rate which represents a staggering technical advance.

It's worth bearing in mind that it was engineers that created all these CAD, CAM and CNC technologies and made them what they are today, taking us all the way from before Maudsley up to today's state of play. It's been a journey that continues furiously to this day and isn't about to reach a final destination any time soon. So the thought that any particular point along the way represents the "correct" or most respectable situation or practice just doesn't stand up.

I'm not a model maker myself and almost certainly never will be. I prefer to design and make my own things (in CAD these days!).

Would it not be "better" to actually design your own models rather than copy somebody else's and squabble over the way they were made? Just asking.

Murray

[Mike PooleParticipant @mikepoole82104]

If I were building a V12 or 18 cylinder radial engine I would be wishing I had CNC. I enjoy doing a job once but repetition gets a bit boring. The time invested in learning CAD and using a CNC machine would probably pay dividends in the long run.

Mike

[Mike Palmer 1Participant @mikepalmer1]

I am in my 49^th year of model engineering and have made many models over the years using traditional methods, about five years ago I bought a CNC milling machine and learnt the process of drawing the part in CAD writing Gcode and operating a CNC mill a daunting task, but I can tell you I never had so much fun. CNC is like having a third arm it gives you more scope to create models in a way the traditional process cannot.

For instance making a box for a mechanical lubricator you draw the part to be folded, with a 90deg centre cutter you cut a grove around the base roughly two thirds the thickness of the material then cut out the whole box, fold up the sides and silver solder.

Parts for valve gear like expansion links and matching die blocks can be milled out in a very short time. I think you need to experience the process at first hand to appreciate the possibilities.

Mike

[Michael CheckleyParticipant @michaelcheckley34085]

I don't believe anyone genuinely believes you can just download a model, press a button and the part falls out??

Don't forget there is a significant difference between industrial CNC machines that some will have seen as part of their job and on youtube and the machines that the average model engineer has access to. I doubt many model engineers have a 5 axis machine with a carousel loaded with exotic tools driven by the latest CAM software with all the bells and whistles and full support from the supplier.

I have a mixture of both in my workshop and upon entering CNC I had to do a lot more 'technical' research and calculations for feeds, speeds and types of cutters compared to machining by feel/trial and error. The engineering skills I have allowed me to convert this theory in to practise as an alternative to years of practical machining experience (I had some). I would argue that this is an additional skill and by no means a less demanding task.

I have been stuck with the same jigs and fixtures on the CNC that I use on manual machines. Working as a design engineer I get parts made all the time and tooling charges are still the biggest expense. There are some clever clamping systems about but most machine shops don't have them or don't use them if the jobs are 1 offs or small batch.

I rarely make use of the 3D machining capability I have with CNC as it takes too long to machine and is not required for the majority of my work. Don't forget to make the most of this you also need the skill of using 3D CAD, a skill that many have tried and failed to master.

Judges need to ensure they have a general knowledge of all manufacturing methods available to the model engineer to ensure that they truly appreciate the effort that has gone in to making a part.

Also, with respect to all machine operators out there, there is a big difference between machine operators and CNC programmers. As model engineers using CNC we have to be both.

[Chris GunnParticipant @chrisgunn36534]

What an interesting thread, here is my twopennorth, Like Bill I was brought up on manual machinery, and turned the handles for myself, and continue to do so now to create my miniatures. I do use DRO's now to maintain accuracy as the ability to see as good as I did at 21 diminishes slowly. The next generation will surely use the machine tools they are familiar with, probably CNC controlled equipment, provided they can afford them. At the moment they would have to do their own programming, so would be using a different skill set than us old boys are familiar with. Surely that does not diminish the results of their endeavours. To my mind we should be pleased that there is another generation following who will continue the hobby. I wonder if in the future the suppliers will offer a set of machine code to produce all the parts to make a loco or traction engine instead of the drawings? I am more than happy to take advantage of what modern technology can offer, for example I would rather buy laser cut spokes for my next traction engine than carve them out myself, as I can make much better use of the time available. I know I could make them, but choose not too. I feel the skill in building the wheels using the spokes is more indicative of what I can do than tedious repetition. I know some folk like to do everything from scratch, from measuring up a prototype to pattern making to making the parts, and good luck to them. However this is very time consuming, and I do not have the time needed to go through this, so I took advantage of the parts available to shortcut some of this and as a result I have built 2 traction engines and have had years of fun running them as well.

Chris Gunn

[Anonymous]

Posted by fizzy on 01/09/2016 10:00:07:

I would however think it extremely unfair if one of my creations were being judged along side a CNC model. I couldn't ever hope to match the surface finish and accuracy and for that reason would class it as cheating.

I expect my manually machined parts to be to the same degree of accuracy and finish, where appropriate, as those that are CNC machined, so if you're not matching those parameters you need to up your game rather than denigrate methods you don't use and don't understand.

Personally I found the original post insulting, and it is a good example of why I no longer post in the 'Workshop Progress' thread, or discuss other things I am working on.

Andrew

[JasonBModerator @jasonb]

Posted by fizzy on 01/09/2016 10:00:07:

……….. . I would however think it extremely unfair if one of my creations were being judged along side a CNC model. I couldn't ever hope to match the surface finish and accuracy and for that reason would class it as cheating..

Most judges would down mark you if you had machining marks left on the work so it would still come down to hand finishing unless there is a CNC draw filing machine about or you have a robotic paint sprayer

J.

[Roderick JenkinsParticipant @roderickjenkins93242]

It seems to me that the concept of cheating implies that there is a competition. The only model engineering competitions I know of are at the exhibitions so it is probably best to ask the judges. What are their criteria?

In the past though, sheer volume of work seems to weigh heavily in the competitors favour, so a 9 cylinder radial engine will always out impress a single and gain considerably more marks even though no more skill has gone into making 8 more cylinders than went into the first. CNC just decreases the labour, not the skill.

Rod

[John HaineParticipant @johnhaine32865]

I'm with Andrew, I found the original posting somewhat insulting, as well as showing a great lack of understanding of what CNC involves.

[SillyOldDufferModerator @sillyoldduffer]

Posted by John Haine on 01/09/2016 12:04:19:

I'm with Andrew, I found the original posting somewhat insulting, as well as showing a great lack of understanding of what CNC involves.

I think fizzy started an interesting and informative debate. Surely he has the right to express his opinion about a technology of interest to Model Engineers without being accused of gross insensitivity, insolence, and contemptuous rudeness? Especially as he raised the issue in a way clearly intended to allow others to disagree with him.

Dave

[HopperParticipant @hopper]

Posted by Roderick Jenkins on 01/09/2016 11:38:40:….

even though no more skill has gone into making 8 more cylinders than went into the first. CNC just decreases the labour, not the skill.

Rod

I'm not so sure on that Rod. Keeping on going for eight more cylinders and keeping up the concentration to get them all as right as the first one is a skill on its own.

That's the skill they were teaching apprentices back in the day when they made them file 4" square blocks of 1" steel steel plate perfectly flat and square then cut a perfectly square hole in the middle of it and file another block to a perfect fit in it.

By the time my younger brother came to do his apprenticeship, the cheeky blighter used to jump on the surface grinder while the apprentice instructor was away at lunch and knock his steel block down nice and flat then throw a few draw file marks on it for good measure. He got full points for the finished product. Some would say he cheated. He says he got the job done, the smart way.

[Ady1Participant @ady1]

If you view this thread as a tongue in cheek one then it can inspire lively debate

[JasonBModerator @jasonb]

It would be interesting to know if Fizzy thinks it is cheating for model engineering only or all forms of home shop machining? Are those who may be making parts for motorbikes, RC models etc also cheating. And what about those making tooling, machines and parts for them who may never get round to making models.

If it does only apply to Model engineering what about those who like to model modern things where CNC may well have been used on the original item so are those diesel loco and V8 engine builders cheating if they use the same methods as the original constructors used?

J

[Anonymous]

Oddly enough I find it offensive to be called a cheat.

Andrew

[MWParticipant @mw27036]

Posted by Andrew Johnston on 01/09/2016 14:52:49:

Oddly enough I find it offensive to be called a cheat.

Andrew

That could be interpreted to mean, you are CNC? If Cnc means cheating and you are a cheat, hypothetically, that makes you "a cnc".  Like a robot?

I would be ONC, organic neural control! Can't beat that faulty memory. 

Michael W

Edited By Michael Walters on 01/09/2016 15:47:57

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