mollwollfumble said:
Or to rephrase the question. Are electric and pneumatic tools only necessary for increased production speed and accuracy? Or are they an essential part of construction?
For example,
- Could an engine block be sand cast or lost wax cast by hand?
- Could the holes for the pistons be machined by hand?
- Could the windscreen be made by hand?
- Could the welding be done without electric power, for example by thermite?
- Could the photo-masks for the silicon chips be etched by hand?
I’m not asking whether it should be done, it shouldn’t. I’m only asking if it could be done.
The reliable & very consistent speed & accuracy of machines simply can’t be matched by a human. Or even three teams of humans taking eight-hour shifts around the clock, so car makers typically try to get as much of the car done by machinery as possible. The more automation there is, the (generally) cheaper the car is.
For higher- end cars though, as they are expensive and usually in far smaller numbers than mass-production cars, more human input is common. As the cars are already expensive it does matter that they add another few grand on the purchase price to give the owner the warm fuzzy feeling that their new car was hand-crafted. It’s not really needed these days but for limited production runs it’d probably be cheaper just to pay some humans to bolt them together.
For example, here’s a Mercedes G63 engine being assembled – https://youtu.be/ri_LFckaT7g
Note that every part of the engine is made on a machine and only (maybe) in some limited & small areas are any of the parts hand-fettled by a craftsman. Cylinder heads are a good example of that, as the inlet & exhaust ports can be quite difficult for a machine to get perfectly right and in an acceptable time frame. A five-axis milling machine takes time to set-up the part, calibrate the start point of the job, then swap over the various cutting tools to get into the tight areas of the ports. So they are often cast as close as they reasonably can (sand cast, usually) then hand-finished by another craftsman. An example of how much difference it can make are some of the various Toyota heads I’ve fiddled with; I can easily get a good 5% – 10% more power and improve the fuel economy as well just by doing a bit of hand-finishing the ports. It’s a shame as they really could make the engines usefully better with just that little more time & effort.
- Could an engine block be sand cast or lost wax cast by hand?
Yes, but that’s very slow as to make the sand moulds takes time to prepare and then clean up. So blocks are almost always die cast instead. It’s quick & accurate.
- Could the holes for the pistons be machined by hand?
Yes, but again relatively slow.
- Could the windscreen be made by hand?
Again possible, but very slow. It’s possible to get custom windscreens made (A mate of mine does them in Brisbane) but it’s somewhat more expensive than a regular mass-production one. Also – When shopping for a new windscreen, try a few places other than Windscreens O’Brien are they are often the most expensive. They do a hell of a lot more advertising than anyone else so that’s often the first company think of when that time comes.
- Could the welding be done without electric power, for example by thermite?
Most unlikely. Thermite can certainly get to very high temperatures but you need to fuse the various metal parts together which means only making them sit in the high end of the temperature that the metal melts at but only for the shortest time needed to fuse them together. It’d be quite difficult to get thermite to do that in the required manner. Machines like spot welders are very accurate and fast, so they are often used to join metal panels. The other advantage of spot welded panels is that in a crash they tend to ‘unzip’ progressively and absorb the crushing force smoother than if the panels were joined by one long weld. Not always the case, but it is very commonly done that way. Mete of mine in the rally scene told me about a Valiant (I think … ?) they built for rallying in the 70’s. To make the car stronger they welded up all the join seams so the spot welds didn’t have to take the entire load. Anyway they crashed into a tree and whilst the car only had limited damage, it’d stopped so quickly because it wasn’t crumpling as the designer intended it to, the driver & navigator had broken collar bones as the seat belts stopped them from moving forwards. So whilst rally cars are still welded-up to improve the chassis stiffness, they are stitch welded, and that is a bead of weld is run for about 20 mm – 30 mm along the seams then that much again is not welded. it still lets the panels crumple progressively but also still be stiffer overall. And because rally cars get a pretty violent time belting around on rough dirt roads it’s not uncommon to get cracks in various parts of the chassis & panels. A single long weld, once it starts to crack has nothing to stop of the crack getting longer. Stitch welding helps stop that.
But I digress – Yes it’d be possible to make the vast majority of a production car by hand but it would greatly increase the price per-unit and also be a lot slower to do. Some mass-production cars come off the production line about 30 seconds apart.
Something like my own racing car is a framework of 20 mm x 20 mm steel tube. It would take me many weeks at best to make a good quality chassis of that type. I have the choice of TIG, MIG, and gas welding to join the tubes together – They all work very well – but for the repair of the front of the car I’ll be tacking the tubes together with a small TIG weld and then doing the final weld with my gas welder, using nickel-bronze as the type of weld distorts the metal less than the localised & intense heat generated by TIG & MIG welds. As the metal cools, the molten pool of metal added by the TIG & MIG shrinks and pulls the tubes a little out of shape. Gas welding isn’t as hot so there’s less distortion, and as I’ve got my arse in the car I want the welds to be very good. I can TIG weld okay, but I’d feel safer with a larger addition of metal that you can get with gas welding, with less distortion overall.
Making the panels is painfully slow. Again it takes weeks at best. Things like the mudguards are fibreglass and so made in a mould I have tucked away somewhere. But that still takes up a big chunk of the day just to make four of them.
With the engine a lot of it is hand-made as I can’t buy the parts & need from anyone. So it’s welding & milling time again to make them.
For sure all that would be much faster if I had a CNC miller, etc, but t’d still be very slow overall.
