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Is CNC cheating

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Q: Do you think the use of CNC equipment in model engineering constitutes cheating?

YES ALL  
4%

 
 

IF NOT DECLARED  
11%

 
 

NO  
85%

 
 

(127 votes)


Muzzer02/09/2016 20:06:52
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2904 forum posts
448 photos
Posted by Tony Pratt 1 on 02/09/2016 19:39:03:
It is a common but false misconception that CNC is only good for multiple parts.

Indeed, try machining an oval cavity, domed surface, non-circular curve etc on a manual mill. Some CNC operations take minutes to set up (see Tormach "conversational" for example). Even if you managed to half-bake the job manually, you'd spend hours setting the work up for each different operation.

JasonB02/09/2016 20:07:48
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25215 forum posts
3105 photos
1 articles

A lot would also depend on the part, simple rectangular hole may not be a lot of difference but as mentioned earlier if that hole were eliptical the CNC would win hands down for a single and just get better the more there were

 

Edit Muzzer beat me to it

Edited By JasonB on 02/09/2016 20:08:36

Neil Wyatt02/09/2016 20:34:00
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19226 forum posts
749 photos
86 articles
Posted by NJH on 02/09/2016 14:40:47:

Then your "poll" Neil is meaningless. Outside competitions there ARE NO rules hence there cannot be any cheating.

I made a post saying just that but i don't think anyone read it

Neil

john swift 102/09/2016 20:37:33
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318 forum posts
183 photos

with so many demands on our time these days

the use of CNC tools could make the difference between embarking on a new project

or deciding you don't have enough time left in this lifetime


John

Mark P.02/09/2016 20:37:41
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634 forum posts
9 photos
I did.
Mark P.
blowlamp02/09/2016 20:42:58
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1885 forum posts
111 photos

Is this router cheating?

Martin.

Boiler Bri02/09/2016 20:46:32
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856 forum posts
212 photos

Not cheating at all, did the early model engineers say using a lathe was cheating rather than use a file to shape something?

Bri. 21 century convert 👴🏻

Michael Checkley02/09/2016 21:12:17
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121 forum posts
66 photos

From experience it is just as easy to produce a part with poor surface finish and poor accuracy on a CNC machine as it is on a manual machine, quite often with costly consequences to the machine and tooling!

I haven't seen many (if any) libraries of parts that one can simply download and machine to produce a model of any kind. Therefore to produce a part on a CNC machine the engineer will have to program the part in G code or model the components in CAD and let the software generate the G code then produce all the fixtures as normal. To do this they will need all the knowledge of the materials and tooling to ensure depth of cut, feeds and speeds are correct as the machine wont back off if it 'feels' its not quite right.

In my opinion it takes more engineering knowledge and skill to produce a good part on a CNC compared to a manual machine. Those that consider it cheating don't have the appreciation for the amount of prep work required before the machine starts to cut. The most used machine tool in my workshop is my manual lathe, the CNC lathe hardly gets used!

Sadly I do not believe that the enormous effort required to get the CNC machine going will be taken in to account in judging at competitions just the same as the effort that goes in to 'own design' projects and engineering drawings e.t.c....needs further consideration to ensure new creations are brought on to the exhibition scene but this is another subject for debate...

JA02/09/2016 21:41:16
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1605 forum posts
83 photos
Posted by Ketan Swali on 02/09/2016 17:43:38:

I wonder what purpose this thread really serves, other then to create heated arguments in places, setting one person against another?

I wonder if the opening posters objective has now been met. If so, would it be appropriate to request one of the moderators to consider closing this thread, before it really gets out of hand?

Ketan at ARC.

Here, here.

This is enough! If this was a real tea room you could have been chucked out for brawling (punch-up is too good a word).

JA

PS. Contributors  have raised good comments but............................. [this is my edit]

Edited By JA on 02/09/2016 21:43:45

julian atkins02/09/2016 22:06:04
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1285 forum posts
353 photos

Fizzy (Nigel) is one of the nicest guys you could ever know in model engineering. We have corresponded for quite a few years.

Lets get down to brass tacks.

Not that I ever exhibit, one of my locos is hypothetically along side another loco in an exhibition. My tender has been cut out by me with a hacksaw from brass sheet and fashioned. The cab is also a steel silver soldered fabrication cut out from steel sheet. All the valve gear and coupling and conn rods are milled in a very antiquated vertical mill and finished with a file. The frames were hacked out of 3mm steel sheet with a hacksaw and file. The boiler is to my own design, in copper, and silver soldered by myself in my workshop with all flanging plates made with my own hand made formers.

Apart from the pressure gauge, all the cab fittings are tailor made and as close to scale as I can make them. I have made my own injectors.

Alongside is a similar loco but with a commercially built boiler bought in, CNC frames, CNC valve gear and coupling rods and conn rods, a Malcolm High brass kit tender and cab, and all commercial cab fittings and commercial injectors.

How do you judge both?

Cheers,

Julian

Michael Gilligan02/09/2016 22:10:47
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23121 forum posts
1360 photos
Posted by julian atkins on 02/09/2016 22:06:04:

How do you judge both?

.

... as I said on page1 : By the rules of the Competition.

MichaelG.

John Stevenson02/09/2016 22:33:43
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5068 forum posts
3 photos

This one is is for the hard / easy brigade or not sure if they have the skills.

OK I'm sitting in the bar of a hotel In Luxembourg with the delectable Dr Debs about 1,000 Km from my workshop and all attendent trappings. In a recent post called Florid Script, one of the members is after a binks and Bullows bage for a bike he's restoring.

Another poster put up some script that is very close. So given all i have is a crap hotel computer I took this picture, processed it in a mid priced CAD/ CAM software i have web access to and this is what I got. Sorry you will have to look in my album as I don't have passwords with me to log on to my web space. As I say 1,000 clicks away with no gear.

Now I could post G Code for this but I have no idea what size the finished article is, surround on this one is 40mm x 40mm but even that size could be loaded into Mach 3 and scaled.

Now if you will excuse me i have far more interesting things to do with the delectable Dr Debs,.........................................

julian atkins02/09/2016 22:58:28
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1285 forum posts
353 photos

Hi Michael,

That was a bit of a 'cop out' of a reply?

(I think we will pass over John S's contribution above in the interests of good taste and forum rules. I dont really want to know what John at a foreign bar does with 'interesting "delectable" Dr Debs'.

Cheers,

Julian

Neil Wyatt02/09/2016 23:08:12
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19226 forum posts
749 photos
86 articles

I think it's a given that at model engineering exhibitions it is not so much the quality of a model that is being judged but the skill, originality, ingenuity, fidelity and finish achieved by the maker. This makes documentation, particularly of complex items, important.

It does create the interesting situation where, as Julian describes, two utterly identical models may 'score' totally differently - assuming the maker and the assembler have both been honest about their input.

Neil

Ed Duffner02/09/2016 23:10:58
863 forum posts
104 photos

If he's in Luxembourg, probably drinking a pint of Stella.

Michael Gilligan02/09/2016 23:20:38
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23121 forum posts
1360 photos
Posted by julian atkins on 02/09/2016 22:58:28:

Hi Michael,

That was a bit of a 'cop out' of a reply?

.

On the contrary, Julian ... It was my honest opinion, as already expressed.

If there is a Competition, then the Rules of the Competition prevail.

Beyond that, I think it's all been said in the last seven pages.

MichaelG.

Neil Lickfold03/09/2016 00:45:07
1025 forum posts
204 photos

This is an interesting thread with loads of varying opinions. It seems to me that a lot do not realise how much skill is required to make something cnc and to make it accurate and have the really nice finish. There is the design or cad skills as well as the cam or cutter path skills. Of course to a great extend the shape as ling as the tool can access it, it will create the geometry. Accurate things need cutter compensation and radius compensation, if not on the machines controller on the cam package making the part. If you can measure the geometry of the tools being used, and create a cutter library with the tools of the correct geometry, then the cam side will create the compensating code. Depending on the equipment being used but the path may need to be modified to compensate for the idiosyncrasies of the machine tool itself. I make stuff on my myford with no digital read out is one end of the scale and make parts on a cnc lathe or a cnc wood router. There are some precision parts that just can not be made by hand and do require the control of cnc equipment to generate the geometry to the level of precision that is required.

The final answer has to be how to you weight the varying skills to make the same item ?

What weight do you give to the person who can 3d draw a propeller with the correct sections and geometry and then program a machine tool and create the tooling and method to make it over someone who hand carves an approximation of the same propeller . The hand carved prop will be not be as equal in performance and will not have the same precision in it's manufacture. The person who used the computer and cnc has a far greater skill set than the person who just carved one up. In this example I know as I have done the hand carved props and they are way easier than the skill set to learn to draw it all up and then create the cutter path. I just don't have the cad skills to draw the props, but do have the cam skills to create the part from a solid model if it were supplied to me as has been done on my cnc router at home.

Which leads to the next part, if you do not make the cad models yourself, then in reality, you have just copied a part and got it produced which is essentially my cnc made carbon props.

Neil

Hopper03/09/2016 02:14:46
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7881 forum posts
397 photos

I think the poll needs a fourth option: What a bloke does in his shed is his own business.

Bill Pudney03/09/2016 03:11:47
622 forum posts
24 photos

Beautiful work Shaun......wassitgolike??

cheers

Bill

Steven Vine03/09/2016 04:24:32
340 forum posts
30 photos

edit - removed post

 

Edited By Steven Vine on 03/09/2016 04:33:49

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