Is CNC cheating

I use small machine tools(and welders, hand tools, etc) at home to make and repair parts for things to support my hobbies. Bizzarely 'Model Engineer' has become the English term to describe this; the American 'Home Shop Machinist' seems so much more sensible to me. Being able to produce the part is what matters to me, I'll cut and file a small piece, but I've also drawn them in CAD and had them laser cut when it's been a better solution.

I started with a mini-lathe, then bought a mini-mill. A couple of years ago I upgraded to a WM250v lathe and the ability to easily take 3mm cuts in steel has dramatically improved my productivity. Doing the same with the mill would probably be even more effective, but I simply don't have room for anything bigger. Converting it to CNC so it cranks to and fro shaving off little bits of metal while I do something else could be almost as good.

mick

I'm also a G code man, but if cnc is cheating I must be a bigger cheat than you as I also use a few M codes. !!!!!!!

Emgee

The most satisfaction I've had in my (short) model engineering career to date is after I'd machined a motor mounting plate for a CNC conversion on a tiny mill fitted with a previous version of the conversion.

In the process, I'd designed (and redesigned) the motor mounting system and gone through 3 sizes of motor (cut and try!), built the electronics to control them (admitedly from modules), written an arduino program from scratch to drive the motors, invented my own G-Code like language to run on the arduino, built a PC program to drive the arduino and written an 'Iain Code' script to carve out the mount.

I would refute any suggestion that machining the mounting plate was cheating, given how much 'proper' engineering it took to get me to that point! I use the term 'proper' in my case with tongue firmly in my cheek!

I shall derive even more fun from improving the CNCness of my mill. I still have to add a Z axis, make the mill more accurate and I have a revised version of 'Iain Code' and driver in the pipeline.

Iain

But I can teach someone with no machining experience to drive a manual machine tool. I see no intrinsic difference between twiidling a handle so many turns plus so many divisions and telling the computer in G code to do it. You still have to know appropriate speeds, depth of cut, feed rate etc, and don't think you can just let the machine get on with it under computer control with an unskilled man supervising, seen what happens when the unskilled guy didn't know it wasn't supposed to make that noise, ruined tens of thousands of pounds worth of components. Sensible management puts skilled guy on, just gets more productivity.

I presume all the naysayers refuse to use the leadscrew when screwcutting, as that would be taking the skill out of it.

I presume all the naysayers refuse to use the leadscrew when screwcutting, as that would be taking the skill out of it.

Hand chasers only for the highly skilled boys, much faster for producing threads too

Don't know if anyone who did that is still about though

I had a try.

I didn't feel the need to share the results

I sometimes find myself telling people I am a model engineer in spite of the fact I don't make models but it is the easy way to explaining what sort of workshop I have.

Ian P

To some, it's not so much the destination that matters but the journey undertaken to reach there.

Horses for courses at the end of the day.

Gordon.

How can you cheat at something that is non-competitive?

N.

I am a Luddite, and used to be unwashed and proud... Now i'm married i'm still a Luddite, but unfortunately now un-unwashed...

I've been thinking about this quite a bit.

The comments of those denigrating CNC really seem to think it is like using a bread maker. You throw in the right quantities of steel, brass and cast iron, turn the dials to 'Loco'; and '5" gauge', then press 'GO'.

The core of this is Fizzy's claim that CNC is 'cheating'; cheating requires deceit so for a start you can't be cheating unless you claim CNC-made parts were fashioned manually. I'd be 'cheating' if I claimed the loaf from my bread maker was a hand-made artisan loaf. Now I find kneading dough as therapeutic as the next fool but I'm rather glad it's no longer a daily chore and don't think it's cheating for me to use the bread maker if I just want a loaf of nice, fresh bread.

WHERE THE EFFORT LIES

The same amount of effort is put in, but like many things in the 21st century there's more mental application required and less physical.

If not going into competition, they how can people be cheating? If entering a competition and declared it is hardly cheating either; indeed the CNC user should get some credit if they drew up the plans themselves rather than downloading them - just as I hope I get credit for making patterns for the castings for a model even though someone cast the parts for me.

WHEN IS THE SKILL LOST?

I admit to enjoying the process of cutting metal with a machine under my direct control, but having spent a couple of weeks testing a power feed on my mill I'm getting used to it. I have a pile of 13 change gears and counting, even in nylon the endless handle turning would have meant much slower progress.

In the old says someone did exactly the same job (in brass not nylon) indexing with Myford change gears and using a super-duper Adept as a shaper. They used an optical projector to hone their cutter to shape.

I ground up a 20-degree tool and made a rack-form cutter out of silver steel. Even the 20-tooth gears run smoothly and appear indistinguishable from moulded ones.

I used a spreadsheet to tell me how to set the dial on the rotary table. I could have made and used division plates or worked it out in my head.

I could have used the dial to set the DOC was exactly one turn (1.50mm) after allowing 0.01mm for winding in until the cutter touched the work. But it's easier to see the DRO when sitting down than to take my glasses off and peer over the handle.

It isn't hard to imagine an automatic arrangement where the mill table winds the cutter past the blank and then back again. That would have stopped my left wrist getting sore from being awkwardly posed over the reversing switch.

I could add a stepper motor to turn the rotary table and have avoided several; scrappers where my eye fell on the wrong line of the spreadsheet.

This would totally automate the process, but still isn't CNC - setting two travel stops then having something generate X pulses every time one of the switches is triggered isn't 'computer numeric control'.

That said, moving to full CNC would replace the switches with virtual ones and give me a more flexible interface.

So at what point on the route from shaping brass gears by hand to CNC does it become cheating?

To my mind the critical point where the skill required dropped was when I chose to use the multi-point rack cutter method. Having made lots of gears using single point cutters the rack form one took less than a quarter of the time to make and less skill; I also only need one to cut both 20 and 80-tooth cutters, rather than having to make a set.

Counter-intuitively, making the gears wholly by CNC would probably require greater skill. There's really barely any skill in the mechanical method other than getting the DOC and angular turn correct - with the rack method you don't even have to have the cutter exactly on the centreline of the blank to get usable gears.

WHY IS CNC DIFFERENT FROM OTHER AREAS OF PROGRESS?

I have made a box, effectively just like CNC, and once I have set up my telescope (which requires as much skill or more as setting up to take a cut, it will point at what I want to photograph and follow it (Interesting point - I set the roatry table to an accuracy of 10 arc-minutes, the scope demands arc-second accuracy). A little controller takes 120 pictures for me. A computer program chooses the best of these and stacks and averages them. I then spend time processing the image, aided by some automated scripts and advanced filters.

I was looking at an old coffee-table book yesterday, it had a picture of the Andromeda Galaxy taken by the Palomar 200" telescope. The core was burnt out baldy, and although the greater aperture meant the surrounding stars were a bit smaller and sharper, there's vastly more detail in the pictures I took last week.

Quite simply, without the help of computers it would be impossible to produce an image of that quality (and by the standards achieved by others it is far from remarkable). Yet by the arguments above it is clearly 'cheating'.

... to be continued

Part the second...

SO IS CNC CHEATING?

No it isn't cheating to use CNC - only if you don't explain what you are doing, which is no different to declaring bought-in parts or where someone gave you a hand with painting or an oversize part.

I think the real problem is the 'Palomar Effect'.

Those who achieve things by manual skill and dexterity fear that those with CNC will produce better work than they could ever achieve and that when judged side-by side with the product of the CNC user will be deemed to be superior. And if the person has skills developed over a lifetime of manual machining, they fear that someone with few skills but having a 'magic box' can make their work seem crude and unfinished.

So at the bottom of all this is suspicion, fear and jealousy. Suspicion that people will 'cheat' by not declaring they use CNC; fear that their own work will be less appreciated or valued; and jealousy that those less skilled can achieve better results with less effort.

The answer to all these is for everyone to be open and transparent about the methods they use, a long standing tradition anyway; to value and evaluate work in context; and to appreciate where the skills and effort lie in every piece of work.

Neil

If Shaun Wainford was making his Barbarian Motorcycle by hand I think he would still be a long way from completion. The great thing about CNC is that it pushes the boundary of what can be made on a mill or lathe. I don't have any CNC equipment at the moment and enjoy hand control but power feed is close to being fitted as this produces a better finish than I can, even when I concentrate. I once watched an NC Marwin make a 2ft diameter turbine, it took about six weeks to make. That was 38 years a go, to make it by hand the customer would probably still be waiting.

Mike

Edited By Michael Poole on 02/09/2016 10:00:27

In fairness to Fizzy he doesn't actually claim that anything is cheating, he asks if it is. Asking is not the same as claiming.

He does go on to set out his own view, and some of us have expressed different views. Such is life.

My hand made paper is hanging to try, and my goose-quill pen is sharp. I just have to finish grinding these oak galls, and I will be ready to add the (home made) green vitriol. Then I will be able to prepare a letter to give to the common carrier as he passes on his way to Birmingham, and I hope that Mr Boulton will kindly reply with permission to begin a model of one of his fire-engines. Have I broken anyones 'rules' yet?

Cheers, Tim

A very thoughtful essay, Neil ... and possibly more than fizzy's question deserves

... Unless I am very much mistaken; fizzy uses oxy-acetylene welding equipment

You will probably find parallel discussions on the needlework forum

... I think these "questions" are usually just tossed-in for the sport of it.

MichaelG.

A short time ago I made a part using the manual data input (MDI) of Mach3 to do the work. I thought it would be interesting for all the manual machinists to look at the half-way house of CNC that is MDI so wrote up the process with a parallel commentary of what a manual process would entail for comparison. I think it would help some of the people who may be interested in dipping their toe into CNC but are daunted by talk of 3D CAD and CAD/CAM/CNC with POST processing and all the other abbreviations that can be bandied about. It may also enlighten some of the people who think CNC is just pressing a button and sitting down to wait as to what may be entailed. Due to the limitations of this forum there may be some loss of quality in the prints.

Martin

In a later post he is pretty unambiguous though:

"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've now added an anonymous poll, to see the results you have to vote.

Neil

Crikey this has gone a bit mad....when I first posted the question I was referring to cheating in the sense of 'do you feel that you have cheated yourself if you use CNC?'. I was looking only for opinions of a persons own sense. I certainly wasn't putting down anyone who uses CNC and if by doing so I offended anyone then I profoundly apologise. That was never my intension and unfortunately for me it now feels like it has now escalated to a 'fizzy bashing' exercise. I stand by the premise that I wouldn't be happy having my work judged along side something produced in CNC but not for reasons of fear and jealousy as Neil suggested, but simply because it would be (in my mind) in a different class. I dont enter competitions and so the question was merely academic but I thought it would be interesting to gauge others opinions, nothing more, nothing less.

Thanks to Neil for taking the time to summarise his take on this.

Apologies if I missed a point already made in his two-part post but I would add that it's only cheating if you do it in a competition AND you deliberately break the rules of that competition.

Curiously enough my breakfast read today was the September 19th 1966 issue of Model Engineer. In it there is strong reaction to a claim by K.E. Wilson that: "the vast majority of prize-winning locomotives cannot even raise steam and haul their own tenders: I would make it compulsory for every engine that qualified for a prize of any sort to demonstrate its working powers before receiving any award". Presumably he felt there was a bias against his work in competitions.

The same issue contains the article "My Purley Locomotive Works" by LBSC. In it he describes his workshop. No CNC of course but I have to say LBSC was exceptionally well equipped. For instance he mentions three machines "which are the sole examples in this country, to the best of my knowledge and belief." I don't suppose anyone would suggest that LBSC owning and using better tools than average meant that he was "cheating".

Dave

Why do I only spot mistakes after hitting the button?

Edited By SillyOldDuffer on 02/09/2016 11:01:45