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General discussions. For specific printers / electronics / fabrication methods / softwares, please see other sections.
Re: McWire Successor - 14 years ago
BeagleFury Wrote: ------------------------------------------------------- > tools. The most difficult part is to cut accurate > circles in the MDF for the two build platforms, > required because they act as pulleys. How are you doing your cut for this? I've always found circular cuts relatively trivial, using a router compass.by Corwin - General
Re: 95% reprappable repraps
- 14 years ago
Of course, the OCTOR isn't really precise enough for our purposes and uses servo-driven ligaments rather than pneumatic actuators so I wouldn't say it's the best example, exactly.by Corwin - General
Re: Linear Motion Precision - 14 years ago
Viktor, what is your current UV-LED setup? Would something like this help for UV cure?by Corwin - General
Re: Linear Motion Precision - 14 years ago
This whole situation happens every other month or so. Someone new comes in, decides they have a better idea for how to do things, and wants to convince everyone that they should focus on it. Often, they also talk about how they are working on their own fork of the design based on available technology y. You're really, really not the first, goinreverse. Forrest shouts at most of them (insofar as yby Corwin - General
Re: Makerbots can make Mendels, right? - 14 years ago
What it sounds like to me is that if you buy a Rapman and get it working as well as Forrest's, there's not reason why you couldn't cut up a mendel into ~8 hour long prints, then sell the finished kit at $300 now or (hypothetically) $150 down the line. If you did, a single kit of mendel would pay for 30 or 15 lbs of ABS, respectively (based on makerbot price for natural ABS, while consuming only aby Corwin - General
Re: Makerbots can make Mendels, right? - 14 years ago
spacexula Wrote: ------------------------------------------------------- > Corwin Wrote: > -------------------------------------------------- > ----- > > Even if the market for Mendel bits does tank, > > it'll still be more than the cost of the > > materials, which means if your printer is > reliable > > enough that you don't have to put a lot of work > >by Corwin - General
Re: Makerbots can make Mendels, right? - 14 years ago
Even if the market for Mendel bits does tank, it'll still be more than the cost of the materials, which means if your printer is reliable enough that you don't have to put a lot of work into each print batch you can still make it pay for itself. I also think that there's definitely a market for prototypes made on mendels, darwins, and makerbots, and with the help of services like etsy and ponokoby Corwin - General
Re: Printable Linear Bearing - 14 years ago
JohnnyCooper Wrote: ------------------------------------------------------- > I've seen the airsoft bb idea recommended here > multiple times, and although I think it's > inspired, my contribution to it would be to switch > to the steel BB's used for BB guns vs. airsoft. > > These bearings are at least as accurate, are of > smaller size, are virtually the same price, and >by Corwin - General
Re: Is this a dumb idea? - 14 years ago
You definitely could do that, fred, but it means that each machine is significantly less convenient and useful. It also means that you can't multi-task by leaving, say, your printer running while you mill those PCBs. When you consider how long the build times are for these machines, that's a major concern. If you get a printer working reliably (to the point that you can leave it running unobserveby Corwin - General
Re: Plastic recycler - 14 years ago
The wikipedia article on plastics extrusion is actually very good, by the way. It mentions a few rather frightening issues, such as extrusion barrel pressure exceeding 5000 psi and the extruding scews being as much as 6 inches in diameter.by Corwin - General
Re: rack and pinion versus belt? - 14 years ago
I'm not sure that it necessarily follows from having a rack and pinion setup that your x axis needs to sling your y axis around. I would start from the mendel setup for this for that very reason, in fact. One axis of all-thread for z still seems to make sense to me because threaded rod is so good at station keeping - no need to keep the stepper energized 100% in order to stay on the layer. That'sby Corwin - General
Re: Contraptor - 14 years ago
Especially when you consider that all of their example machines use the Arduino GCode interpreter - definitely.by Corwin - General
Re: roller pinion seems very printable... - 14 years ago
One issue I see is that while this may be easier to print than a herringbone rack, it would require more non-printed parts. Even if it doesn't need bearings (which would require quite a bit of testing to determine, since you're talking about seeing how it wears down under longterm use), it does absolutely rely on precise and very stiff rods - ie, metal ones. A herringbone pinion has no need for mby Corwin - General
Re: rack and pinion versus belt? - 14 years ago
I don't know if I would put it as strongly as Forrest, but I have to agree - while a good bit of what you're talking about, especially the problems that Sebastian raises, are important and deserving of discussion... they don't belong in a thread on designing rack and pinion drive systems. Figuring out what should and should not be covered in the wiki, what full releases should be covered, and howby Corwin - General
Re: Dumb Electronics Question - 14 years ago
It is solvable with a windows or linux laptop, but it is actually more difficult to solve it that way than with a cheap microcontroller such as the arduino. The operating systems that we use are not intended for real-time control, so it takes significant work to make them operate in that manner. If you wanted to go about doing this, your best bet would probably be to start with EMC2:by Corwin - General
Re: Ceramic 3D printing - 14 years ago
What they're doing is making open source alternatives to the powder/binder setups used by Zcorp printers. The binder/activator is applied by an inkjet head to the powder, the powder bed drops a level and gets a new layer of powder, repeat as necessary. Besides just cheaper feedstock for ZCorp printers they're experimenting with powders that can be kiln-fired into pottery and glass.by Corwin - Paste Extrusion Working Group
Re: plastic recipes - 14 years ago
stephen george Wrote: ------------------------------------------------------- > Triffid_Hunter () said > don't quote me on this, but IIRC that starch > plastic is hygroscopic, so it swells > up and goes moldy after a while unless you live in > a desert. > > 1) Can you paint it? > 2) Could you use it as a filler ie. ABS outside > with a solid IIRC centre. IIRC is an aby Corwin - General
Re: rack and pinion versus belt? - 14 years ago
Forrest Higgs Wrote: ------------------------------------------------------- > Corwin Wrote: > -------------------------------------------------- > ----- > > > > Chances are you need a gearbox (you definitely > do > > for printed parts, not sure if this is true for > > commercial but bear with me). > > > I would have agreed with you two days ago. Siby Corwin - General
Re: rack and pinion versus belt? - 14 years ago
Forrest definitely has a good point on the impracticality of designing things so that printed and commercial parts are interchangeable. It might not be impossible or impractical to design so that smaller sections of the design change between using printed and non-printed parts, though. For example, say you have a rack and pinion system. Chances are you need a gearbox (you definitely do for printeby Corwin - General
Re: Printable Linear Bearing - 14 years ago
@anton: that looks very good! Yes, the individual bearing balls are quite small compared to the whole setup. The design is based loosely on my observations of a commercial recirculating ball bearing and rail system, which I used in my attempted Repstrap last year (it's languishing back home at the CNC plotter stage, no extruder). Here is a nice picture of a very very similar bearing (mine wereby Corwin - General
Re: Printable Linear Bearing - 14 years ago
@Forrest: I took another look at the amount of material next to the holes and decided to add some more, and while I was at it I thought I'd give it enough to add a third hole for security and to prototype mounting. @anton: I'll see if I can figure a way to do that. Unfortunately the student edition of solidworks has crippled format functionality, it only lets you save as solidworks files.by Corwin - General
Re: Printable Linear Bearing - 14 years ago
Interesting. If there are options to make it not do that, I don't know where they are. Can it be fixed by scaling the stl or does it still come out wrong? I brought up the ASCII file in notepad. It looks like everything is at e-2. That means everything that's supposed to be 1mm is turning out to be .01 mm. If you can scale it by 100 times, might that fix it? Regardless, I'll start digging into thby Corwin - General
Re: Printable Linear Bearing - 14 years ago
Weird. I don't know why they came out like that. I made binary and ASCII stl files this time in case that's the issue. I had to zip the ASCII file for the top, it was larger than 614.4 KB For the new version here, the posts have been replaced by #4 boltholes with counterbores. I also extended the sides into wings to get more material around those holes and allow a third hole on each side for morby Corwin - General
Mostly Printable .25 inch ID bearing - 14 years ago
This is a 4 piece/2 part ball bearing design intended for use with nine 6mm balls. Currently it there is no race for the balls, but the bearing is designed to allow one. If someone tries this and feels it needs a race, tell me and I will whip it up. The ID is .25 inch, the OD is 1.5 inch, and the bearing is 8mm thick. Assembly should be accomplished in the most obvious possible manner. Print twby Corwin - General
Re: Challenges ahead - 14 years ago
@Anton: I share your supsicion about how common airsoft ammo is outside of the U.S. Fortunately, anywhere you go steel balls are less expensive than bearings - the design doesn't care what material they are, and can be adjusted to fit slightly different sizes of ball. The quality of the bearings and whether the difference between them and commercial all-metal bearings is an acceptable tradeoff reby Corwin - Kartik M. Gada Humanitarian Innovation Prize
Re: Printable Linear Bearing - 14 years ago
@Beagle Fury: I don't know if they are round to 2 microns, probably not. And you're right, they would probably break if someone stood on a bearing (mostly because they're hollow, not because they're plastic XD). At $2.50 per machine, you're right that the price difference may not be significant enough to justify the weaker plastic. We'll have to see how that goes. @Viktor: I was joking about extby Corwin - General
Re: Printable Linear Bearing - 14 years ago
@Viktor: Closer how? Do you mean a smaller radius curve on the loop? or should the backside be curved rather than straight? Embedding steel rods in the rail and carriage certainly would enhance the smoothness, lower the friction, and almost certainly greatly increase the rigidity. Also, there would be steel rods in it. As far as I'm aware, a steel rod is rather diffcult to extrude at the same teby Corwin - General
Re: Printable Linear Bearing - 14 years ago
@Beagle Fury: You've got a good point. What the balls actually are isn't really important. However, when you start looking online for parts, the price on precision airsoft pellets is an order of magnitude less than the steel balls. A very, very quick google turns up this: as a good example - $11.71 for 5000 means each bb is $0.002342 per BB, versus 7.66/100 = $.0766 per ball in your example.by Corwin - General
Re: Printable Linear Bearing - 14 years ago
@Victor - I agree that the balls aren't particularly printable, which is why I recommend airsoft BBs as an unprinted element. If you're talking about the carriage and the rail, I'm not sure I agree, though the design is such that a CNC mill definitely could produce the parts perfectly (I'd definiitely want to use screws instead of the posts, though, the current design is very wasteful of materialby Corwin - General
Printable Linear Bearing - 14 years ago
Mostly, and maybe. This is my first draft of a design for a mostly-if-not-completely printable bearing. I can make no absolute claims of printability, functionality, or sanity. The design is in 3 or 5 parts depending on how you look at it (I think the images are fairly self explanatory), plus a number of 6mm diameter balls. 6mm was chosen so that if someone is willing to make my day and try printby Corwin - General