Err... of course there's different levels of skill!
Compare the carvings of Grinling Gibbons with someone pushing a bit wood through a saw. Even though things like how fast you feed the bit of wood makes a difference, how is that on the same hierarchy as the works of Grinling Gibbons?
Having worked in sawmilling (a planing mill producing finished and semi-finished products from imported softwood) in a previous life, I'd say custard is bang on the money, and your implication in the second part of the section I quoted is dead wrong.
Wood Machining is not somehow less skilled than working with hand-tools... But it is a completely different set of skills, many of which are not related to hand-work or joinery at all.
If you ever have the opportunity to watch a skilled operator running a 4-sided planer-moulder you'll get what I mean, from the second they pick up their job-sheet and cutter set from the toolroom, they've got to start thinking about how to set up the machine for best performance, considering dozens of questions and constantly making and re-evaluating decisions about how to run their job
- What timber are they receiving?
- Is it slow grown material from a russian mill, or faster grown from further south?
- Does the timber come from one of the mills which consistently uses old-growth logs, or is it plantation grown with more reaction-wood and less dimensional stability?
- Is the mill that produced your pack of timber one which has good kilning facilities, or should you expect lots of deformations from overly agressive drying?
- How long since the timber was delivered, will that be long enough for it to have fully equalised with the local environment or is it likely that there's a moisture gradient in the timber?
- That then dictates how to set up the cutter heads:
- If you've got material with lots of reaction-wood, then you ideally want to remove the minimum amount from as many flat faces of the profile as possible to help keep the boards from warping so:
- You need to set the initial feed rollers and pressure shoes to a relatively high pressure, to help with feeding through the rest of the machine, even though this is not ideal.
- You'll set at least two of the leading heads to take a pass just deep enough to get a planed face and a straightened edge,
- your next set of rollers and pressure shoes should be set at high pressure to ensure the timber feeds true to the new faces.
- You'll then set the next two heads to remove almost all the material down to near finished size, but not to finished size.
- You'll then set your feed rollers and pressure shoes in the middle of the machine, to exert very light pressure so that they don't push out any warping which does occur in the first set of cutters.
- The next two cutters will be set to cut the top and bottom of the profile to finished size and shape, hopefully straightening any warping.
- the next feed rollers will need heavy pressure to keep the profile locked in place, but the pressure shoes need to be light still, to ensure that the edges remain straight.
- the final two cutters need to be set to cut the profile on the sides to final size.
- If you've got material which is likely to be deformed, then you most likely want to cut the profile from as close to the center of your board as possible to eliminate all those defects:
- Your first feed rollers want to be at a light pressure, to maximise the amount the boards are trued up,
- you're going to want to take a cut with your first two heads which is no more than 1-2mm away from finished size, cutting into the heart of the board
- next two rollers and shoes want to be a medium pressure, not high enough to push out major deformations, but enough to ensure the timber is gripped firmly to avoid vibrations as the board passes over the preceding cutters which will marr the surface finish
- next set of heads need to again take almost the whole cut, to give a true, rectangular section, just big enough to take the finished profile from.
- the next two sets of feed rollers and shoes can be set with heavy pressure, and the cutters will again be set to go to final size.
- What if it's both?
- You've got to run a couple of boards and experiment with compromises between the setups until you're confident that you're going to get consistent results that are in spec, at a reasonable production rate.
- The more experience you have, the better you'll get at this, and the less likely you'll have to call the shop foreman or production manager for advice.
- Oh, and don't forget the profile itself:
- If you've got a deep cut into the timber, (say an architrave or panel moulding with large beads at each edge, connected by a sloped surface, meaning one cutter has to take most of the timber out), you're going to want to minimise the extra material that profile head has to remove, which can be an issue in scenario one above, so again you have to develop a compromise.
- If you've got profiles on multiple sides, and you're feeding warped timber, how much do you choose to offset your profile cutters relative to your straightening ones, and in which direction?
- Too much and you risk taking the boards which were not too badly deformed undersize.
- Too little and you'll end up with sections which don't clean up on one edge.
- So you've got the machine set, now what?
- You need to decide where you want to monitor the process from, and what the critical steps will be:
- With heavily deformed timber, you need to be monitoring the infeed, and manually controlling the initial feed roller and shoe pressures by hand, adjusting by eye for each board as it comes in to get it to feed, whilst maximising initial straightening.
- With timber that's prone to warping during machining, you want to be in the middle of the machine, watching to see how boards are reacting, and adjusting to ensure you don't go undersize.
- if you're running a larger 12 or 16 head machine, this likely means being inside the sound cab whilst the machine is running during setup, which requires you to concentrate very carefully in an environment which is full of vibration and dust, whilst wearing a dust mask, goggles and ear defenders, then using a small picture on a video-screen to remotely monitor once the machine is running.
- Feeding itself has a world of complications:
- Depending how you've set your cutters, you need to feed the machine with the deformations against a specific face of the feed table to ensure they clean up.
- At the same time, with a heavy profile cut into thin boards you need to ensure that you have the annular rings in a specific orientation relative to the profiling heads to ensure that the boards don't cup exccessively.
- Oh and if you have delicate mouldings on part of the profile, you need to try not to feed any knots on that side of the profile.
- You're making these judgements and correcting the orientations, whilst feeding a machine which is processing timber at anything from 20-300 linear meters a minute.
- Even if you have a team of people on the infeed to do this, when running at full pelt it's still a back-breaking job which simultaneously requires a good eye for timber condition and consistent concentration.
- You're running, great!
- But you're also running so fast that the wood will blunt your cutters in a matter of hours, so you have to make judgements about the cutter life in order to minimise downtime and maximise production.
- How long do you wait until you run a hone in place cycle on the profile cutters?
- Do you do it each time you see signs of cutter wear, minimising the risk of producing off-spec material, but increasing the likelihood of removing so much material from the leading edge of the knives that they'll loose their edge geometry necessitating a time-consuming cutter change part way through the production run?
- Do you hang on as long as you can, then opportunistically run it during some other slowdown or upset like a feed problem, so that it doesn't stop production, trying to nurse a set of cutters through your entire shift, and quickly strip the machine ready for the next shift to do a full cutter change and setup?
- How's your extraction performing?
- Are you seeing excessive dust or shavings buildup in the cab, which can become a fire risk?
- If you're seeing poor extraction, have you over-faced the hood on that cutter, or is there a clog or blockage?
- If you have over-faced the hood, can you get away with adjusting the blast gates on the other hoses to give it a bit more flow, or can you radio the fitters shop and ask one of them to go out to the air handling units and adjust the VFD's on the blowers to pull a higher flow on your section of the system?
Oh, and if you're doing that, you're also almost certainly trained to run circular and wide-band resaws, which require similar levels of attention to detail to run effectively, in order to maximise throughput whilst meeting a minimum quality standard, and there's a good chance that you're trained to setup CNC crosscut saws, double ended tenoners etc too, and are expected to support and mentor the semi-skilled operators running those machines whenever they hit a problem which is beyond their current level of understanding/knowledge; potentially trying to problem solve for or teach them whilst still also running your main machine.
If you're good at it you may even have to oversee a chain of multiple machines with a couple of less experienced operators to assist you; I've seen a team of three run: 4 huge bandsaws, a massive 16 head planer moulder, a cnc-crosscut saw with automated length detection and cut optimisation, two double ended tenoners and a shrink-wrapping line all at the same time.
That's not only highly skilled, but highly varied, detail oriented and extremely challenging to do, not
just well,
but consistently well for 8 hours straight.
Sure most of the guys who work in sawmilling (be that primary conversion or a planing mill like I described) aren't going to make fine furniture (or any other fully finished product), but don't belittle their skills and experience...
Because unless you're felling and milling your own trees, then highly skilled wood machinists and sawyers are the only reason you're able to pursue woodworking at all!
"the matrix" would end pretty abruptly after 5 mins when he refused to take it ..............
