I once saw a guy in the local maker space spend a couple hours programming a CNC milling machine & arranging a complicate series of clamps and shims to hold a work piece he intended to drill. 15 seconds into his run the drill bit bound up in the work piece. Since the mill was set to pulse drill on the up stroke it snatched the work piece out of the jig that was holding it. On the next downstroke it totally obliterated his jig and then hurled the work piece across the machine shop. 15 feet away there was a set of collets that would have worked way better than the printed ABS widget he was using to hold his workpiece. There was also a bog standard drill press standing next to the table the collets were on. If this dude had simply chucked his piece in a collet and walked over to the drill press his parts run would have taken 15 minutes, likely with no ballistic interludes. The really shocking part was that he was in the machine shop at all. Normally it, the welding stations, and the wood shop were deserted and there was always a line (sometimes hours long) to access the laser cutter, 3d printer, and CNC router table. The three tools in the shop that could be controlled with a laptop and that required no direct tool use on the part of the operator. That always bothered me for reasons I can't fully articulate.
I'm in the target market for maker-spaces but everything about the "maker" community puts me off. The obsession with "hi-tek" is a huge part of it. They think I'm crazy for using a crosscut saw or a metal file, even when it's the best and most straightforward tool to use.
There's also a general smug condescension to real craftsmen too; like they're hopelessly out of date because they actually know a thing or two about the materials they're working with. I was talking with a guy who wanted to make a model boat. I pointed him towards the model boat building community -- which is large and can produce amazing work. He was really put off anything to do with them, or buying plans from a real naval architect for something that will actually move through the water well. He was entirely focused on the electronics he wanted to add to it.
This strongly reminds me of a phenomenon I've witnessed on several occasions. I occasionally teach blacksmithing lessons and have found that new students can be pretty neatly grouped into two categories.
There's the "I want to be the blacksmith" crowd. They are far and away the most common type of student to show up for one of my lessons. The defining characteristic is they have little prior aptitude and even less interest in the hundreds of hours of work required to develop strong fundamentals and build up a toolset. They're perfectly happy to mash hot metal into gross approximations of a given shape and then post pics of the resulting catastrophe all over social media. They romanticize the mere act of tossing a chunk of metal into a fire and then hitting it with a hammer and are disinterested in end results.
The second group (maybe 1 out of every 10 students) are folks that want to make forged things and are concerned about achieving good results. These folks generally have some kind of background with basic tool use and typically blacksmithing isn't their first craft.
I teach the same material to both groups but after about the third lesson there's a distinct drop-off for members of the first group as we progress away from "yay I make metal hot whack-whack-whack" kitsch items like s-hooks and bottle openers and start getting into more serious work like making simple hand tools and tongs. The transition from 15 minute projects that are functional even if they look like hammered cat shit to 1-2 hour long projects that have to be right to work at all is normally where the first group drops out.
I've used a CNC mill as a drill press when drilling a hole crosswise through a small tool steel shaft. Drill presses have too much slop in the spindle bearings for that. I'd tried doing it in a drill press, but couldn't get it centered precisely enough. On the mill I could use a machinists vise, V-blocks, and position precisely.
(A useful setup I had back in my DARPA Grand Challenge days was a drill press with a cheap calibrated hand-crank X-Y table. When you need patterns of holes to mount something, that's an easy way to get the holes in the right places.)
A hand crank X-Y table with a digital read-out is halfway between CNC and manual, you can do incredibly complex work with a setup like that if you're patient.
When I was in high school metal shop, back in the stone (iron?) age, a fellow student forgot to take the key out of the chuck before turning on the lathe. That key shot across the room and punched a neat hole through the wall. It could have easily killed someone.
Making dangerous mistakes is hardly confined to CNC machines.
Chuck rules are the day #1 instruction item for a reason. I've seen that one replay many times over only a couple of years but always with inexperienced machinists. The older ones all have their ritual before engaging the 'on' switch of the spindle drive, which usually includes a nice 360 on the main spindle by hand to make sure it all runs free.
While it is definitely true that making dangerous mistakes is not limited to CNC machines GP has a point, with CNC machines the potential for accidents is quite a bit larger because of the much longer time the machine will spend with the workpiece during which even a trivial change in setup will cause serious damage to workpiece, machine, operator and the environment. And because a proper trial run will take as much time as making the workpiece and people get overconfident accidents are all too common, especially when you put a bunch of inexperienced machinists and very high power tools in the same space.
It's a pretty harsh way to learn that servo motors don't actually care about you at all.
That experience taught me never to stand radially to rotating machinery.
Some old Bridgeport mills I used had power feeds, and if you weren't VERY careful you'd wreck your piece, and the mill, and everything in the vicinity. I hated using those machines. I don't know how they remained in one piece.
Hence the joke of windmill enthusiasts 'real confidence in your prototypes is shown by standing in the plane of rotation'.
Power feeds are scary, to me even more scary are very large servos. Those things will act up in entirely unexpected ways when blocked. (Including shearing off shafts, ripping their own mounts and turning the servo housing rather than the shaft if the situation allows for it...)
At my school, one of the teachers had fixed a spring to each chuck key, to make it impossible to leave in by mistake - you had to press the key in to open/close the chuck, and as soon as you stopped pressing it in the spring would make the key pop out. I'd have thought such a simple way of improving safety would be pretty standard by now, but I've not seen it since, at least on any of the home tools I've used.
I've only used a small number of low budget tools on a very infrequent basis since. A quick search on the internet suggests that safety mechanisms are common nowadays, with keyless chucks and chuck guards seemingly the most common. I guess I was just impressed with both the improvisational nature and retrofitting of the spring solution.
Yes, but a drill press is so low tech... Anyway, it's a 'right tool for the job' kind of problem. We see the exact same thing in IT. Learning how to use hand tools properly and efficiently takes time, learning how to use a CAD program properly takes time too. When you've invested your time in the latter without first doing the former you'll end up trying to solve all your problems in terms of that particular solution.
The proper time to use CNC gear is when:
- you need multiple units of something
- or you need one single extremely complex workpiece
- when the accuracy required is beyond your ability to achieve with a manual tool
- when you don't have the manual tool
For most people you sketched above #3 translates into 'or when you don't know how to use the manual tool at all'...
Which is understandable, after all a lathe or a mill are a lot more up close, personal and intimidating than a CNC instrument but it would be a mistake to think the CNC version is safer in the hands of someone that doesn't understand what they're doing.
If you want to make half decent CNC workpieces you have to know the basics and you should be comfortable with the manual version of the shoptools before you graduate to CNC.
You'll be safer and produce much better work.
BTW: I'm very much not a fan of hold downs that are not made out of steel with a nice T bolt running through it to a solid base but I've seen a fairly powerful rig pull a setup like that apart like it was made out of plastic so even there you're not always safe. Turns out the shear forces on the clamp bolts were overcome by the mill, retrospectively it kind of figures (large diameter workpiece, clamps in the center, mill geared down considerably). Under the right conditions anything will give.
Vacuum and magnets can be used as hold downs for certain workpieces, it all depends on the setup. 3D printed clamps would probably need to be oversized to get any strength at all negating much of their advantage and with hold downs it's much better to be safe than sorry.
I know this article is more about "maker spaces" than "wood shops", but there is also somewhat of a renaissance in traditional hand-tool woodworking going on. A new community shop opened in Toronto which is based entirely on hand tools: http://www.theunpluggedwoodshop.com/. I'd like to see more people realize they don't need $1000s of high tech machines to build the same types of furniture we've done by hand for centuries.
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[ 4.2 ms ] story [ 60.8 ms ] threadThere's also a general smug condescension to real craftsmen too; like they're hopelessly out of date because they actually know a thing or two about the materials they're working with. I was talking with a guy who wanted to make a model boat. I pointed him towards the model boat building community -- which is large and can produce amazing work. He was really put off anything to do with them, or buying plans from a real naval architect for something that will actually move through the water well. He was entirely focused on the electronics he wanted to add to it.
There's the "I want to be the blacksmith" crowd. They are far and away the most common type of student to show up for one of my lessons. The defining characteristic is they have little prior aptitude and even less interest in the hundreds of hours of work required to develop strong fundamentals and build up a toolset. They're perfectly happy to mash hot metal into gross approximations of a given shape and then post pics of the resulting catastrophe all over social media. They romanticize the mere act of tossing a chunk of metal into a fire and then hitting it with a hammer and are disinterested in end results.
The second group (maybe 1 out of every 10 students) are folks that want to make forged things and are concerned about achieving good results. These folks generally have some kind of background with basic tool use and typically blacksmithing isn't their first craft.
I teach the same material to both groups but after about the third lesson there's a distinct drop-off for members of the first group as we progress away from "yay I make metal hot whack-whack-whack" kitsch items like s-hooks and bottle openers and start getting into more serious work like making simple hand tools and tongs. The transition from 15 minute projects that are functional even if they look like hammered cat shit to 1-2 hour long projects that have to be right to work at all is normally where the first group drops out.
(A useful setup I had back in my DARPA Grand Challenge days was a drill press with a cheap calibrated hand-crank X-Y table. When you need patterns of holes to mount something, that's an easy way to get the holes in the right places.)
Making dangerous mistakes is hardly confined to CNC machines.
While it is definitely true that making dangerous mistakes is not limited to CNC machines GP has a point, with CNC machines the potential for accidents is quite a bit larger because of the much longer time the machine will spend with the workpiece during which even a trivial change in setup will cause serious damage to workpiece, machine, operator and the environment. And because a proper trial run will take as much time as making the workpiece and people get overconfident accidents are all too common, especially when you put a bunch of inexperienced machinists and very high power tools in the same space.
It's a pretty harsh way to learn that servo motors don't actually care about you at all.
Some old Bridgeport mills I used had power feeds, and if you weren't VERY careful you'd wreck your piece, and the mill, and everything in the vicinity. I hated using those machines. I don't know how they remained in one piece.
Power feeds are scary, to me even more scary are very large servos. Those things will act up in entirely unexpected ways when blocked. (Including shearing off shafts, ripping their own mounts and turning the servo housing rather than the shaft if the situation allows for it...)
The proper time to use CNC gear is when:
- you need multiple units of something
- or you need one single extremely complex workpiece
- when the accuracy required is beyond your ability to achieve with a manual tool
- when you don't have the manual tool
For most people you sketched above #3 translates into 'or when you don't know how to use the manual tool at all'...
Which is understandable, after all a lathe or a mill are a lot more up close, personal and intimidating than a CNC instrument but it would be a mistake to think the CNC version is safer in the hands of someone that doesn't understand what they're doing.
If you want to make half decent CNC workpieces you have to know the basics and you should be comfortable with the manual version of the shoptools before you graduate to CNC.
You'll be safer and produce much better work.
BTW: I'm very much not a fan of hold downs that are not made out of steel with a nice T bolt running through it to a solid base but I've seen a fairly powerful rig pull a setup like that apart like it was made out of plastic so even there you're not always safe. Turns out the shear forces on the clamp bolts were overcome by the mill, retrospectively it kind of figures (large diameter workpiece, clamps in the center, mill geared down considerably). Under the right conditions anything will give.
Vacuum and magnets can be used as hold downs for certain workpieces, it all depends on the setup. 3D printed clamps would probably need to be oversized to get any strength at all negating much of their advantage and with hold downs it's much better to be safe than sorry.
https://www.folkschool.org/