robbl Posted March 8, 2014 Share #1 Posted March 8, 2014 (edited) Having cleared the cupboards of some my old unmade plastic models and generated some spare cash, I finally splashed out and got a metal lathe, so I thought I might make a couple of notes about it. I am a lathe novice, so if I get terminology wrong, I apologise. My requirements included: Light weight so it can be stored in a cupboard or moved outside for use Able to turn 45 mm diametre (I hope to make a 1/24 scale cannon and a carronade) Able to use a variety of tools Able to take a CNC kit to repeat jobs accurately and to cope with tapers and curvey bits Locally in NZ, the Sieg machines and a lot of clones are available. They are cheap but quite heavy at between 35 and 55kg for the small ones. So in the end I chose a Proxxon PD230 which weighs in at 10kg with its clothes off, can turn up to 56mm, can use small lathe tools (up to 8x10mm tools) and has various CNC kits available on the market. Technical specifications: centre distance: 230mm swing: 52mm height over cross slide: 28mm cross-slide travel: 60mm top slide travel: 45mm steel toolholder: accepts 8mm x 8mm cutters spindle bore: 10.5mm thread cutting capability: 0.5mm, 0.645mm, 0.7mm, 0.75mm, 0.8mm, 1.0mm, 1.25mm, 1.5mm spindle speeds with reduction: 3,000rpm, 900rpm, 300rpm automatic feed resolution: 0.05mm/rev or 1.0mm/rev tailstock spindle: MK1 bore (short) tailstock travel: 30mm internal chucking capacity: 2mm - 35mm external chucking capacity: 24mm - 68mm handwheel resolution: 1 revolution = 1mm feed (40 divisions) mass: 10kg dimensions: 530mm x 250mm x 150mm The lathe came with 3 jaw chuck and live centre and a few bits and bobs for threading and gear cutting, which I do not plan on using. In addition, I got (over the following couple of weeks) splash guard/tray Quick tool change post plus extra tool holders Proxxon's HSS tool set (5 tools) Fixed steady Boring tool set Tail stock drill Tool holder for rotary tools (Dremel etc) Set of 7 indexed tungsten carbide tipped tools (on special from sieg shop here)The 8mm high x 10mm wide tools fit in the tool holders made for the quick change tool post. Out of the box, the PD230 is almost ready to fire up after a quick check on the various fittings. It runs surprisingly quietly, and is very compact (in fact the lathe could sit inside my HMS Blanche). I got some Acetal (Derlin) rod for practising on and created a bit of a mess which pleased me no end. With the tools all adjusted for height and distance from the centreline, it is very easy to swap tools around in the middle of a job. I got used to facing and general turning (the lathe has an automatic feed if required) but the one task I am struggling with is parting and deep grooves. At the moment I am avoiding both tasks by using a saw. The CNC kit came from Ideegeniali.it, and it arrived shortly after the lathe did. They claim it only takes 5 minutes to assemble, but it took me about 10 minutes ... but who's quibbling. Wiring it up wasn't difficult either, and then it was time to consider the control software. I chose Mach3, which requires a PC with an printer port. That took a bit of finding, but after a bit I had everything hooked up and ready to go. Ideegenialli supply configuration files for Mach3, so apart from a couple of minor tweaks the computer soon had control over the lathe, with the ability to make moves in the X and Z axis rapidly or jog tiny distances. With the kit in place, I can still manually work the lathe, although I need to remount the original hand wheels onto the stepper motors to make that easier. I already have a CAD/CAM program, so the next step was to create something. I worked up a drawing of a carronade and a cannon from Wayne Kempson's plans in Allan Yedlinski and his book Euryalus V2 and started testing. The testing taught me a few things about tool selection and pathing, as well as how to cope with the complex shapes, such as the breeches of the cannons and carronades. Under CNC control, the carronade can be turned in one job (several passes) with a single tool, while I am turning the cannon first from the barrel back with one tool, then flipping it in the chuck and turning the breech end using two tools (here the quick change post comes into play). I still do facing, drilling and parting off manually. The jobs are not perfect yet, as I have a couple of issues to work out: When I flip the cannon to turn the breech end, the chuck marks the barrel. I am contemplating leaving a V groove oversized in the barrel to slot the chuck into the barrel, then manually turning that out at the end of the job. The finish is not as good as I would like, which I think is a result of tool choice. When turning from the left or right, it is really nice, but the 55 degree straight tip is leaving grooves. Multiple finishing passes clean these up, but a better tip might be a plan. Parting ... if I can't do something manually, then there is no way I'm going to do it under CNC control. I think I have the height correct (on or slightly higher than centre) and am feeding slowly, but it just doesn't work well for me. This may be due to the plastic bending away from the tip, then trapping the tool as it flexes - brass may be better. Or I am parting to far away from the chuck, or with the part still under pressure from the tail stock it is trapping the tip. Conclusions: Pros: The lathe is more expensive than others, but meets my requirements for space and capabilities. Accuracy of the lathe is impressive, but I can't compare to other brands. The CNC kit works well and lets me do things I think I would struggle with (complex curves and repeat jobs) Both the lathe and the CNC kit worked straight out of the box. I spent (and still spend) a lot of time looking for hints and tips on turning - that is time well spent. Con: The operator is a bit inexperienced and could do with a bit of learning. Overall, a nice machine to have and I am glad I finally took the plunge. CheersRob PS: some wood turned - old walnut dowel from an old damaged kit. Edited March 8, 2014 by robbl mtaylor, WackoWolf, cristikc and 4 others 7 Quote Link to comment Share on other sites More sharing options...
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