CNC machining....is this a woodworking topic?

[Amateur]

There seems to be quite a lot of cnc questions turning up in one form of another.

Should they be included in Gen woodworking or have their own Topic heading for discussion?
Is it really woodworking or mass production?
Is it a step forward, another string to the bow like any machinery used in our sheds today?
Would it be of interest starting a discussion about how users got into cnc machining at home and where they are now.?
Or is it just another fad for retired engineer\ computer orientated folk?

What do you think?

 

[Jelly]

This has turned into a collection of random thoughts on CNC stuff in terms of both woodworking and hobby stuff.

Random Thought One:

It's very relevant to professional woodworkers in a production environment, but is increasingly in reach for small businesses and artisans if they have a strong use case...​

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I'd suggest that for smaller businesses the speedy, low man-hours personalisation and decoration aspects, is a great way to increase the value of "Bread and Butter" products... With the right software package and setup, they can still be a major productivity booster even working on one-offs or small runs (in fact they're actually better at this; for real serial production, dedicated machines usually still beat generic CNC).​

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Random Thought One "A":

Also having used a laser cutter to cut out parts for intarsia and inlay, I would never voluntarily go back to cutting them by hand, never... It's just a better tool for the job, that produces a better result.​

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Random Thought Two:

I'm not a big fan of the Hobby-CNC mills/routers, because I don't know what purpose they really serve (can't cut steel, not appreciably faster than by hand for letter-carving, not rigid enough to use small carbide d-bit engraving tools, limited multi-axis profiling abilities); but if people enjoy using them and then good for them!​

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Random Thought Three:

It's definitely it's own skill too, and one which doesn't replace hand-skills even for very complex geometries, there are plenty of curved forms which I find hard to produce exactly in even quite powerful CAD software, but could very rapidly shape by hand on a real item.​

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I remember a guy in the shared workspace I used to use marvelling at how quickly I made one of my ball-and-claw feet (must be No.3 or No.4 of a batch because I was well into it) he was saying how long it would take to make one by CNC profiling, as I merrily roughed out the shape in literally minutes with a bandsaw, axe, and spokeshave, then took the waste out from around the ball with gouges (he wasn't there to see the hours that getting the fine detail in took later).​

 

[julianf]

Is it really woodworking

What, working with wood?

Id say no. I mean, getting wood, and working it.... No chance.

People should hand carve with their fingernails. I don't know why people are allowed to talk about chisels here. They're clearly not wood working either.


Don't get me started on motor sport. I mean, using a machine to run a race? What's wrong with feet? And i don't mean those new fangled pogo stick running shoes either. That's cheating too. They should have banned them when they first showed up on the scene.

Bare feet. Running naked with bare feet. And they have the nerve to call all these other things "racing"? I've even seen people sitting on top of horses? Do they have no shame?

 

[EddyCurrent]

There is an excellent forum for CNC here; MYCNCUK , however it's mostly about the machines themselves.

A new topic heading in this forum would be ideal. There could be sub topics also such as;
CNC Hardware
Software
Tooling
Woodworking

 

[EddyCurrent]

Bare feet.

It worked for Alf Tupper

 

[D_W]

Not much reward for a hobbyist in my opinion unless they're looking to avoid doing things or making parts straight from cad files.

On some of the other forums in the states, there are CNC specific forums that I've browsed once or twice (not that stimulating). Lots of talk about dongles and software versions not working on new PCs, etc. I think they come into their own when you start working wood and other materials at the same time (lots of people making resin or plastic or whatever they are, signs, etc).

 

[julianf]

Joking apart,

People who don't know think that CNC machining is akin to pressing print on their computer screen. People who do know cnc know very well that its nothing of the sort.

I could show you how to operate the machines here in an hour or so. Your results would abysmal.

I mean, look at my recent threads. Ive been a cnc operator for years. Ive recently started trying to cut wood, and, whilst im probably doing better than the man off the street, im worlds away from my skill and speed with metal cutting.

I cut mainly 5005 alloy. Even 1000 series i struggle with, as my whole cutter setup, knowledge etc is focussed on 5 and 6000 series.

I do rotary engraving. I grind my own cutters to suit the job. As in use microscopes to measure 20ths of a mm distances at the ends of the cutters.

This is metal work cnc. Its what i know, and what i can talk about. Grinding cutters to custom geometries to work with specific requirements is not the same as hitting "print" on a computer screen.

I would fully expect wood CNC work to have similar learning curves. Which im right at the bottom of currently.

My point -

There is really quite significant human skill involved with CNC work*. This is factual and easily proven. To disregard it through ignorance of process is, well, ignorant.

*i suspect that the level of operator skill goes down as the price of machine goes up. Probably if you bought a machine that cost twice what the house i live in does, and all the accessories from the supplying company, then an amateur could click "go" and get good results, similar to clicking "print" on a printer. But this is an extreme case. The majority of machines in existence are not at this level.

 

[D_W]

Joking apart,

People who don't know think that CNC machining is akin to pressing print on their computer screen. People who do know cnc know very well that its nothing of the sort.

it's a completely different skill and a significant involvement in learning something well enough to become familiar with it. The folks who get a CNC and just start using it quickly without learning much make work that looks like that's what they did.

The world of guitar bodies is a good example of this - you can find guitar body components that look like they were roughed out by shrek (but they come off of CNC). At the best, they just have cosmetic issues, but then they also often have dimensional issues.

The "good" CNC operator who also understands nice work, rather, will spend significant time nailing down the process and turn out a guitar body that needs only sanding and that has no bits about it that need more than some sanding and surface prep. The holes will be in the right places and all standardized bits will fit. If the "good" operator has a higher end machine, the top will also be carved and not instantly scream "made on CNC".

The former will think they'll sell guitar bodies for $300, end up selling them for cost of materials, and the latter will understand ahead of time that he's not going to get rich and sell his wares for just a little under the $300 figure.

I worked in a cabinet factory. Nobody from the regular floor ever went to work on the CNC stuff. If it was that easy, they'd not have paid the operators more than they paid the general assemblers.

 

[sploo]

I've been running a "hobby" CNC machine (1000x600mm capacity, total machine weight ~100kg) for nearly 20 years now. I originally bought it as I was doing a reasonable amount of loudspeaker building. Given that most speaker cabinets are fairly simple cuboids, the CAD/CAM work required to design the panels, rebates, dadoes, and cut out and rebates for speaker drivers is fairly easy and not particularly time consuming. Cutting the outline of a panel would of course be much faster on a table saw, but overall, the timescale (and high accuracy) of being able to produce completed panels unattended made it worth the investment.

I've used it for a number of other repetitive or intricate cutting tasks (wood, plastic, and aluminium) and especially for parts with curved edges it's great.

For one-off items I suspect that often the CAD+CAM+setup+machining+cleanup time is more than it would be to just make a part by hand - however, the accuracy and (relative) certainty that it'll come out correct can be important - especially if you're using stock that can't be replaced. That said, these days I'd prefer to work by hand (or at least, operate individual machines) for hobby projects; but I still turn to it for many jobs.

Given that almost all my use of the machine has been in wood (well, MDF), 0.1mm of accuracy is fine. If you're talking about machining metal to engineering tolerances then that's a whole different ballgame; and not something I'd feel capable of doing.

 

[Amateur]

What, working with wood?

Id say no. I mean, getting wood, and working it.... No chance.

People should hand carve with their fingernails. I don't know why people are allowed to talk about chisels here. They're clearly not wood working either.


Don't get me started on motor sport. I mean, using a machine to run a race? What's wrong with feet? And i don't mean those new fangled pogo stick running shoes either. That's cheating too. They should have banned them when they first showed up on the scene.

Bare feet. Running naked with bare feet. And they have the nerve to call all these other things "racing"? I've even seen people sitting on top of horses? Do they have no shame?

so I take it that's a yes?
Or was it a No.. lol

The only bit I can add is that I worked a punch tape controlled boring machine for six months, back in the early 70s serving my apprentiship.
First article inspection took days referencing everything off the datum before you even pressed the button.

 

[Jelly]

I would fully expect wood CNC work to have similar learning curves. Which im right at the bottom of currently.

From what I saw in industry, doing really good CNC in wood, is largely down to balancing the understanding of the Toolroom and Programming side, with an operator who is observant and knowledgeable about the timber's characteristics and machine operation who can alter the parameters on the fly.

Ironically CNC planer moulders are much much harder to operate well than CNC routers, because there's so much going on, and it's all happening insanely fast.

To do top class production work you need a toolroom which can produce cutters to match your profiles (or to stick to commercially available profiles and send them out), because using surface profiling techniques that work really quite well in metal just doesn't cut it in terms of surface finish.

I do rotary engraving. I grind my own cutters to suit the job. As in use microscopes to measure 20ths of a mm distances at the ends of the cutters.

I have serious respect for you doing that, I've done a little bit of CNC engraving and found it much much harder to get good results than doing the same work on a pantograph machine with templates, faster to produce multiples, but the programming and setup was not nearly as easy as just cutting your templates and sitting down at the engraver.

CNC Milling of more conventional shapes, is less bothersome and opens up lots of interesting design opportunities compared to manual milling; but the skill there seems to be in using a small VMC with a high speed spindle to match a big conventional mill in terms of material removal rate; I'm much more comfortable with the latter approach.

 

[Ollie78]

A cnc machine is just a tool, exactly the same as a planer or a router.

Also brilliant fun and incredibly useful.

Ollie

 

[Keith 66]

I just made a new stock for an Original model 6 match air pistol, standard one was horrible plastic & didnt fit me. New stock & grips took about 2 hours to bandsaw out & rough shape, It took another 6 hours to finish shaping it, another 6 hours to do the inletting for the action which was quite complex, 16 so far, sanding & finishing with varnish, cutting back & oil polishing another 4 hours spread over 2 weeks.
Checkering the grip area at 20 lines to the inch took 10 hours spread over a week then more hours final assembly & bedding of the action.
So it took me about a weeks full time work. Several people have commented, "Thats lovely you could sell them". Not if i wanted to make money i couldnt!
This is where a batch of them might work machined on a cnc machine.
But whoever does it has to measure or scan the stock, draw it up in 3d including the inside complex bits, then set the machine up to do a run, there will be a minimum run below which its not cost effective. I dont have the skill or experience so would have to farm it out.
Then i have to stick my mark up on it otherwise its not worth doing. Be interesting to see what the price would come out at!

 

[Jamesc]

I have a hobby grade CNC and find it great for a few things.
As others have said it is great for customisation, carving lettering and logos has been a godsend.
Templates are another thing I make a lot of. To cut out a complicated shape in say 1" oak on my set up takes forever, However it chomps through 8mm MDF so I make a template and use a bandsaw and router table to make the parts.
The final bonus for me at least is it lets me work on projects during the week. By the time I finish my day job I rarely have the time or inclination to go out to the workshop during the week. I can happily sit at my laptop and design parts in the evening that I can then cut out on the weekend.

 

[akirk]

I have a hobby grade CNC and find it great for a few things.
...

which one do you have? I am interested in one for exactly those purposes...

 

[julianf]

I've done a little bit of CNC engraving and found it much much harder to get good results than doing the same work on a pantograph machine with templates, faster to produce multiples, but the programming and setup was not nearly as easy as just cutting your templates and sitting down at the engraver.

In fairness, that probably is a hardware thing, rather than operator skill.

Your manual pantograph would have been built for the task, and the spindle would have been resting on the surface with a depth regulation nose cone.

A CNC mill used for engraving either needs the same spindle setup, or a time consuming and inaccurate surface profile map added to the tool path.

Fine text is so very dependant on depth of cut that nothing is going to be flat enough and well enough set up to just carve out with a v cutter using the z axis alone to regulate to a constant depth.

Nose cones are the most accurate way, which, I'm sure, the manual pantograph would have used. The down side is that you can't really use then with all materials in all situations, as you'll get ghosting from swarf "dust" trapped under the cone itself. Things like non anodised brushed alloy are the hardest, although that is a poor choice for most applications anyway, so isn't a common "ask".

If you ever want to have another go somthing like the little gravograph wizzard spindle can be purchased bare for not much over £100. Couple it with a small motor and a little ball slide table and you would be well away. The fancier spindles use springs and the like, but the weight of a small spindle and motor on a ball slide isn't far off being right.

 

[Phill05]

After an accident stopped me throwing timber about I was stuck at a desk designing on a computer for a stone company and went on to set up a cnc to cut 3D memorials, fireplaces and many other pieces in stone, I then re-built a cnc for myself cut metal parts out to build other cnc's, made tools for myself, cut out clock parts and dials and played about cutting 3D work in wood my first love.

I still have a pantograph in the workshop that has not been used in years and when I look back at all the work I had to put into making patterns to do the job compered to designing then cutting on a cnc I wasted a lot of my time, but it was very enjoyable at the time.

So I would say YES there is a place for cnc in woodwork if it helps you, if you've not got the inclination to work on a computer and just want to work wood that's great until you can no longer do it, it is just another way of earning a living.

This is the front of a drawer box I will be cutting soon.

 

[D_W]

I just made a new stock for an Original model 6 match air pistol, standard one was horrible plastic & didnt fit me. New stock & grips took about 2 hours to bandsaw out & rough shape, It took another 6 hours to finish shaping it, another 6 hours to do the inletting for the action which was quite complex, 16 so far, sanding & finishing with varnish, cutting back & oil polishing another 4 hours spread over 2 weeks.
Checkering the grip area at 20 lines to the inch took 10 hours spread over a week then more hours final assembly & bedding of the action.
So it took me about a weeks full time work. Several people have commented, "Thats lovely you could sell them". Not if i wanted to make money i couldnt!
This is where a batch of them might work machined on a cnc machine.
But whoever does it has to measure or scan the stock, draw it up in 3d including the inside complex bits, then set the machine up to do a run, there will be a minimum run below which its not cost effective. I dont have the skill or experience so would have to farm it out.
Then i have to stick my mark up on it otherwise its not worth doing. Be interesting to see what the price would come out at!
View attachment 105197

What ends up happening with a CNC (supposing full tooling isn't feasible to run thousands of these) is getting a shape close, an wood that can be pressed will be the choice, so the checking gets pressed into the stock instead.

And, of course, it gets done in a foreign country so that the work that has to be done by hand at the end can be done at $2-$3 an hour instead of 10 times that at the least for skilled work.

Just like powder metallurgy has really reduced the price of a lot of metal parts that don't need to be forged but do fare better if metal and hardened, printing parts is coming along for metal and CNC has replaced a lot of small batch jig making.

Experiments done for the lovely nuance, like the inletting above the trigger guard is being done where scale is large enough (for example, that kind of contouring is cut in large groups on 3D machines with rounded mill/bits by gibson and I'm sure others), but to me, quite a few of their necks feel like they weren't checked by someone who has a hand. The difference is subtle but it wasn't missed on guitars made by a guy finishing the profile with a specialized belt sander. Their savings are probably not more than $3 on a neck, but i'm sure that $3 are important to them. They probably love the idea that the machine won't take disability, though.

 

[Jamesc]

which one do you have? I am interested in one for exactly those purposes...

Hi akirk, sorry for the delay, I took the weekend off from the PC. I have a stepcraft D840. It is not perfet but on the whole I am very pleased with it.
It is self assembly which for me is a bonus (I thoughly enjoyed putting it together)
It is well engineered in Germany and well supported again from Germany.
I purchased mine though StoneyCNC. They have a reputation for outstanding customer service. Maybe I cought them on an off month, my experience was not so good.
I am happy to discus the pros and cons of this machine at length if you are interested