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| Joules:
vtsteam, you raise some interesting questions. Number one PLA is a consumable, whilst I hate throwing things away at least this one is biodegradable, eventually. One ring gear and pinion weighs 9gram. Printing with wax, I guess the problem is wax has a low viscosity when fluid and would be harder to meter from the head, it just doesn't behave like molten plastic. That said you could do a rubber mould of the printed part then shoot wax for lost wax casting, just seems a lot more work unless you plan on making many of them. Now the tricky bit. Printers... The technology has taken many years to reach the point we are at now, yes there has been obsession with getting the machine to make itself. I am not at all interested in that side of things, I am an end user with applications. The printer for small parts usually has to be an order of magnitude more accurate than a hobby cnc router, but at a push you could use one. Having an enclosed cabinet helps the consistency of layer building no end, it keeps the heat in and the drafts out that can cause warping and delamination. Again the printer is a huge compromise, you actually want a very light weight printhead so you can move it about rapidly without shaking the machine all over the place. Add to this the need for as close coupling of the feed motor to extruder. Bowden fed extruders are a lot more difficult to control than a direct drive, especially with flexible filaments where they easily compress. Printing has loads of variables that must be balanced to achieve good printing, it really is juggling with jelly that we tend to take for granted now the hard work is done. Hit a snag and you are back on the learning curve of how this all works, this is why I concentrate my efforts on PLA and work within its constraints for now. Printed nylon does not have the same characteristics as moulded or machined nylon, it may be touted as stronger but it ultimately depends on your end use and understanding of its limits, and we are back at compromise. picclock, the results of my morning in the workshop. Brass splined shaft made ready to fit pinion. Partly mated, they are a tight fit, I can remove the pinion without the printed splines being torn out of the pinion. This is a test part and something new I am trying, I am very happy with the result so far. The gear is centred with no slip on the shaft. Next up is design the bearing carrier for the two gears and then start load testing them. I have about 2 years 3D printing experience with current hobby machines, about 10 months on my Createbot mini. In my collection is a deltabot that I play with, but it is a whole different beast to this current one. Don't fret over some of the details in printing. That first layer is usually your most inaccurate as you are trying to lay a foundation layer that is usually thicker than those to come. A microswitch is adequate for sensing the bed home position. Granite slab, great idea that should be standard for ALL 3D printers and bolt them too it. Always plan how you are going to print something before you print it, each print in effect has grain that can work against you or for you in some applications. Don't be afraid to print something at an angle with support material, or break up a model into parts and weld them together at the end with a soldering iron. Like the above example. Guy's this is what I have learn't about printing and printers. It's my experience and my journey, yours will be different, always happy to answer questions where I can or just comment on what you see. |
| vtsteam:
Joules, I wasn't suggesting wax per se, but that a printer medium be deveoped that could be melted out of an investment mold before casting. Otherwise, the claims for using a low cost 3D printer to make accurate thin metal molding patterns for complex small parts like gears via "lost" plastic molding is uhhhh, let's say on "optimistc" side of the truth. I'm sure you can make simple shapes with a machining allowance, but then, you can do that with just about any pattern making method, and a lot quicker and cheaper the trditional way. When I was suggesting welded square steel tube base rather than the flimsy construction I've seen on some of these printers, the reference to router bases had nothing to do with precision. I was talking about simple constructional stiffness. the ways and bearings determine positioning accuracy, not the base that supports them. And for the moving gantry and parts I was talking abut reducing mass, not increasing it. I haven't seen very impressive work in the design of machines themselves in terms of an understanding of stiffness and damping. I've seen a lot of futuristic maker-culture design, which often seems to hint at a lack of basic design and manual metalworking fabrication skills. I think these mchines are fine if you enjoy modeling in plastic, but when people start talking about producing machine parts, I think there needs to be a shift in design understanding, not necessarily cost. I do believe that a machine to produce strong long wearing mechanical parts could be designed better, and not necessarily more expensively, and that was what I was suggesting. |
| awemawson:
:bugeye: Well I've signed the pledge :bugeye: Just signed up as a backer for the BigBox full works dual head jobby :ddb: Hopefully they start delivering in December but I reckon that's a date that might well slip a bit as these things do. Speaking to them they seem a nice crowd but the proof is in the product when it arrives :scratch: |
| PekkaNF:
I have never been really excited about these hobby 3D printters. Too much hype. There are some mention and reference to anual make magazine 3D Printing Shootout, I found pretty nice "test". I don't knw how many makes are test. http://makezine.com/2014/11/07/how-to-evaluate-the-2015-make-3dp-test-probes/ Unfortunately this is in Finnish, I could not simply click "English" to have these articles English, maybe google translator would do some kind of job? http://www.minifactory.fi/yleinen/minifactory-3d-tulostin-ja-make-magazinen-tarkkuustesti/#more-2877 http://www.minifactory.fi/uutiset/minifactory-tarkkuustesti-osa-2/#more-3456 This was interesting though "The structural strength of Carbon Fiber PLA is around 90% of the structural strength of traditional pure carbon fiber.": http://www.minifactory.fi/en/news-articles/minifactory-took-part-worlds-largest-3d-printing-event/ Hard to believe it. Maybe someting lost in "translation". End of this page there is shor mention about casting: http://makezine.com/volume/guide-to-3d-printing-2014/ Pekka |
| tom osselton:
Here is some more about 3d / lostwax casting. http://makezine.com/2015/02/02/new-3d-printer-filament-brings-lost-wax-casting-to-your-desktop/ |
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