CNC - arguements please

[Mr T]

Hi

A collegue of mine is seriously thinking of using a CNC machine for making fine furniture. I also know that Waywood http://www.waywood.co.uk/ are using one. My collegue is interested in the accuracy that can be achieved with CNC. He argues that the test of a good craftsman is accuracy, if CNC can be more accurate why not use it.
My gut reaction is to resist this. However I cannot come up wth a good argument against it, any suggestions?

Chris

 

[wizer]

CNC's can be very very accurate, if not perfect.

It's a tool, use it. As long as it's not all churned out to be exactly the same, then I see no harm. It'll still be bespoke furniture.

 

[RobertMP]

No experience of CNC for wood but I do have for metal.

I'd say it is just as skilled but different skills. Skill in designing for the available processes, skill in programming the code (even with cad/cam graphic software) and skill in setting up and operating the machine to give its best. Quality tooling for CNC is always worth the money - buy cheap and get problems.

If you are new to CNC don't expect to be up and running at maximum efficiency too quickly as there will be a lot to learn. Once it is running efficiently there is no beating it with manual processing

 

[JonnyD]

I think CNC is capable of being extremely accuarate. The problems I see for a bespoke cabinet maker is justifying the cost. Its probably easier and much cheaper to sub out the work to a specialist rather than investing many thousands in a machine. A CNC machine really needs to be working most of the time to earn its keep.

Jon

 

[Paul Chapman]

There seem to be a few top makers increasingly going over to a more machine-based way of working because the type of work they do demands it. One such person is Robert Ingham. I saw a YouTube clip of him recently where he described his work as "engineering in wood".

For many workers I think the "engineering in wood" approach would be far less satisfying than a more hand-based style, but if you look at the sort of work people like Robert Ingham are producing, it would be difficult to produce without the use of very accurate machinery.

Cheers :wink:

Paul

 

[BradNaylor]

In my view the end result is all that matters. How you get there is completely irrelevent. A piece has no more inherent 'quality' or 'worth' if it is hand-made rather than fashioned on a machine.

Of course a CNC machine is a valid addition to a furniture maker's arsenal. I'm bloody sure Grindling Gibbons would have leapt at the chance to save himself all that tedious hand carving if he had been able to and what's more, would no doubt have come up with designs even more impressive than he actually did.

My only worry about the 'engineering with wood' concept is that wood is such an unstable material. What's the point of being accurate to a hundredth of a millimetre when wood can move that much in an hour?

Cheers
Brad

 

[Boz62]

Surely it all comes down to good design and understanding the raw materials. CNC is not itself an answer if you are using inappropriate joints or wood - it just gets you to the failure faster. A designer needs to learn the basics first, and then needs to make a business case for whatever tools he feels he needs. He then needs to learn how to make the most of those tools in his environment.

The more expensive the machinery, the harder it needs to be worked to pay for itself. So he also needs to consider the market, and whether it will stand the large batch manufacture that results from that.

Good luck to the guy if he can get the numbers to balance.

Regards
Boz

 

[StevieB]

I think there are two sides to this - a business side and a hobby side. The business side says use whatever you can to get the product to the point of sale as fast as possible without compromising quality. The hobby side says if you use a machine then you lose the skills that most of us enjoy ie the actual hands on making of something. Sure, programming a CNC is a skill, but its not the same as the skill of cutting a dovetail by hand or making something from scratch - is not simply a labour saving device for a hobbyist/craftsman, its a manufacturing device.

I would bet that when PTs became cheap enough for the general man to afford the same argument was had versus hand planing. Heck some hand tool guru's seems to think if you haven't grown, managed, cut and seasoned your own timber you are missing the point of woodwork as well! My gut reaction - it stops becoming woodwork and starts becoming furniture production when you move to such an automated process. Doesn't mean I dont like to see big tools in action, just that for me, its not something I would consider skilled craftsmanship to produce something using a CNC. It would take away the pleasure of woodworking for me.

Steve.

 

[Calpol]

I would love a CNC machine but like most folk I don't think it'd be used constantly. I do have access to a small one and it's good for templates, engraving and whatnot but I wouldn't like it to be the main machine...

So long as the customer knows that's how it's done I wouldn't see a problem with using it in a business, even though it seems most customers don't really care how thing are made, everything gets called handmade now :?

 

[BradNaylor]

So long as the customer knows that's how it's done I wouldn't see a problem with using it in a business, even though it seems most customers don't really care how thing are made, everything gets called handmade now :?

I don't think any customers give a flying fig how their furniture is made, and I certainly don't see any reason why they need to be told that a CNC has been used in the production process.

'Handmade' is a pretty ludicrous term anyway in woodworking, and not one that I like to use. Everything is fashioned with tools, not with hands. Even componants machined by CNC are assembled by hand however, so where do you draw the line?

Ultimately all that really matters is the design, the quality of the finished piece, and whether the customer is happy or not.

Oh, and whether the maker has turned a profit!

:lol:

Cheers
Brad

 

[Calpol]

That's what I was saying Brad, the customers don't really care how things are made but even with machines furniture is still 'crafted' to some extent, with a CNC it's really just assembly...

The line for handmade is probably before a CNC machine though, certainly in my head :?

 

[wizer]

The line for handmade is probably before a CNC machine though, certainly in my head :?

Everyone's view of this is different. To me, Handmade\crafted means that the product was largely conceived, designed and made by one person and is a single piece as opposed to a production run. What tools you used to get there is irrelevant IMHO.

 

[j]

"Hand Made" Pah
I cut mortices with my teeth and do intricate carvings with my toenails.

 

[Calpol]

I'm sure it's a personal thing, there'll be people who say it's only handmade if there was no electric tools used at all... I agree that what everybody on here probably does is handmade (don't know anybody though :lol, just I think a CNC is a step too far

 

[dicktimber]

The question is very difficult to quantify, let alone answer.
CNC machining comes in several forms, depending how many axis you want to machine.
Deciding what you want to use it for, is of paramount importance, and purchasing one is only the start.
Programming cost can be huge depending on complexity of parts.
If you decide to use sheet material, material utilization will be high, whereas machining single stock pieces will under utilize the machine.
What about tooling costs? Regrinds?
Checking the first off programmes, for dimensional correctness the list goes on.
CMC machines can be purchased from tens of thousands of pounds for a basic model, to millions depending again what you wish to manufacture.
BAE have the largest I have seen for machining the wing skins for the Airbus family of aircraft.
For reproducing thousands of components, CNC will pay for itself.
To be used as a machine to, tinker about on, it will not.
However, we must remember that it's not too long ago that we were reading about the Japanese having them installed in their garages.
They would load the machine in the morning, set it running and then go off to work.
In the evening they would pack the parts and have them delivered to whoever they were making the components for!!!!
Now if you could strike a deal with a big furniture manufacturer to make, components and then tinker when it's not in use, then you will have the best of bothworlds??????

Mike

 

[CNC Paul]

Hi

A collegue of mine is seriously thinking of using a CNC machine for making fine furniture. I also know that Waywood http://www.waywood.co.uk/ are using one. My collegue is interested in the accuracy that can be achieved with CNC. He argues that the test of a good craftsman is accuracy, if CNC can be more accurate why not use it.
My gut reaction is to resist this. However I cannot come up wth a good argument against it, any suggestions?

Chris

Chris,

Does your friend have an established business? How many people does he employ? What type of work does he produce?

There are many reasons to use CNC machinery, usually output, accuracy, repetition, speed and quality.

The most basic a workshop would use CNC is on a panel saw rip fence and crosscut, but really only nessacerry when used all day for cutting sheet material. The same would apply to a CNC spindle.
Then you have the CNC router, these vary in price from £10K to £100K for woodwork, usually the larger the company the bigger the outlay by way of the machines features and size. There are machines far costlier than £100K but I think they would be irrelevant to your friend’s requirements.

A small cabinet company will benefit greatly by having a CNC router. My situation was brought about by employing 15 people with all the problems that it creates, at that time I was sub contracting my CNC machining to another company, until I found out that they were stealing my designs. I now work on my own with my assistant that never comes in late, never goes home early and never asks for a rise, outputs the same quality Monday to Friday.... His name is Merlin my CNC router. I now make more money than before, with none of the stress. I can do far more in less time than the vast majority of workshops from basic cabinets to 3D carving. If I choose to go to Ireland fly-fishing for a month I will go, I put my phone on divert and if someone calls wanting something done I tell them 6-8 weeks delivery.

Merlin will machine cabinet parts while I can build cabinets or design the next project etc. I can have a job with say 30 sheets of material, I load the sheets one by one, then the CNC process will drill shelf holes, hinge and drawer runner mounting holes, cut dado’s, grooves for backs, toe kick notches and cut out all the parts. The software also has the ability to produce jointed face frames and dovetailed drawer boxes from sheet material; it will even mark the parts for identification.

Is there a skill in this?....... Yes, you need additional skills in CAD, CAM programming, learning the capabilities of the machine and work holding. The more complicated the shape the easier it is to turn to CNC
CNC will Never replace the skill and dexterity of a carver like Grindling Gibbons or latter day carvers such as Ian Norbury. I can produce 3D carving in a very short time where hand carvers will have a backlog of many months, but to me CNC carving does not have the vitality of hand carving. I can use carving to add features to a project very quickly; even the ability to add simple stopped flutes in Maple or Cherry without any burn marks is a joy.

One of the greatest problems for a workshop is quality of staff, as a generalization the good makers are working for themselves, CNC machinery will NEVER replace them, but will greatly enhance the capabilities of a workshop.
There are few fine furniture makers that can exist solely on making one off pieces; most makers will fit in a kitchen or a library to fill the schedule. I met Robert Ingham one of the greatest makers around at a craft fare last year, he was selling beautiful wooden boxes, which I expect are made in small batches. The use of engineering quality lathe and milling machines are prominent in his workshop.

Your friend would benefit reading the “The furniture fabrication factory” or any of the books by Ken Susnjara.

That is my 2p worth.

 

[BigShot]

When making high end furniture (I don't speak from experience here, just a general understanding) does the craftsman not choose his cuts carefully to make best use of the grain, patterning and so on?
I've heard several woodworkers say things like "you do what the wood tells you to do" and also "work with the wood and you'll be fine, try to force it and it won't work".
Generally working in a way sympathetic to the wood's patterning, grain and so on is a part of what produces a high quality product. Right?

I can see that being very difficult to achieve with CNC. A machine can't see the kind of variations a person can see in that respect.
Sure, you could line the wood up in such a way to get the grain running nicely, but once the cutting has started you can't change your mind without scrapping the wood in the process.

This discussion has been had at length in the custom surfboard world. The general consensus seems to be that CNC's strength is in repeatability.
For really high end, performance boards a surfer can ask for the exact same board as he had before with just a few mm taken off, moved or whatever with everything else unchanged. Pretty much impossible with traditional shaping but not with CNC.

On the other hand, those boards tend to be short lifespan. The other way is custom shaping in a more hands-on way. Not as repeatable, but producing some great boards.

One shaper I spoke to about it said something along the lines of "Making a wooden board I read the grain and work with the wood. A machine can't do that, it works the wood in an unsympathetic way. Even in foam* not all blanks** are the same. I can stop when I see I need to and remove stock from the other side, a machine would just keep cutting. That can give you a weaker board that could break in a bad wipeout."

*polyurethane and polystyrene
**boards pre-shaped to a specific dimension in a mold and then taken to finished board by a shaper


So "horses for courses".
CNC definitely has a place, but I'm not actually all that sure bespoke furniture (like custom surfboards for all but the elite few who notice millimeters on their boards) is that place.

I'm certainly not opposed to CNC. I'm actually planning (pipedreaming at the moment more like) to make a CNC router for a few projects I have just beyond the horizon.

I suppose I think it's much better suited to production than to craft. If someone could find a way to put CNC to good use in a bespoke environment though, more power to them. It'll be pricey though.