For the last few days I’ve mostly just been doing research into how I’ll actually build the frame and the rest of the machine. I found a really cheap welder (stock clearance) which I almost bought but I’m glad I didn’t now. As I mentioned in the last update I decided to weld some of the frame to cut down on the number of bolts I’d need to fit. Unfortunately though that’s looking like it won’t be an option.
The problem is that a MIG welder with enough power to weld 4mm box section will set me back about £350 and then on top of that I’d need to buy wire, a mask, gloves and an apron. In total I think it’d set me back the better part of £500 and that only gets me doing gasless welding. If I wanted to do gas shielded welding (which everyone says gives a better result) then I’d need to get a gas conversion kit (about £40 normally) and source a supply of gas which means hiring a bottle etc etc. All told I think gas shield would probably be another £100. On top of that I’d need to find somewhere to store a 40kg welder after the job was finished and I’d still need to buy a pillar drill for other parts of the frame and build. I’d really like to weld some of the frame but I don’t think it’s an option at the moment. Once we get the workshop built and I move the CNC down there perhaps I’ll invest in a welder but for now I think the machine will have to be bolted together.
As for the other parts of the machine I’m getting a bit concerned about shaping the aluminium plate that I’ll need for the various parts. I’m flipping madly between shelling out for a small milling machine and trying to route it by hand. The problem with the milling machine is basically cost, even a fairly small cheap one will set me back about £650 (although I could possibly pick one up second hand) and then I’ve got to find somewhere to put it. I could probably (just about) justify £650 as it would also be used as a pillar drill but on top of that I’d have to shell out for a rotary vice and various measuring tools all of which cost a fair bit and that would only allow me to mill fairly small pieces.
As well as the cost though the milling machine seems like a step in the wrong direction. I’m trying to build a strong CNC machine that can mill aluminium so buying a machine that can do that in order to build one seems daft to me. The other option is to try routing the aluminium plate by hand. I’ve read comments from a lot of people who have claimed to have done it successfully but there’s surprisingly little hard evidence online. One of the best videos I found was this where I think they are routing 1/4″ plate very aggressively with a top bearing bit. They mention doing 4 plates at a time although they don’t show this, certainly the router bit they are using is large enough. There’s also this video where the guy cuts a slot.
The trick seems to be to drop the speed of the router down as low as possible and take light cuts. WD-40 can be used as a lubricant if needed. My main concern with these videos is that none of them are cutting really thick aluminium.
A poor mans milling machine, this is an ingenious idea and could be knocked up fairly cheaply I think. The cross slide vices he uses are about $100 (although only in the US it seems) and the rest of it is mostly wood and scrap. I’ve also discovered this which shows a pillar drill milling what I think is steel (it looks like an engine block so I’m guessing it’s not aluminium). The guy takes as massively deep cut in one pass, probably a couple of millimetres, so with lighter cuts I’m fairly sure a pillar drill could be used as a not very good milling machine.
I’m currently thinking about combining a ED16B2 pillar drill with a CT1 compound table. The pillar drill is the one I’m going to go for whatever so the compound table is the only real risk and that’s about £100. Even if it doesn’t work as a mill it’s not the end of the world as I’m sure the table will come in useful. I’m a bit concerned the table won’t be accurate enough but I only need mostly accurate I think.