Only 15 minutes! Wow. I think I'd rather go with a compression fitting, because I think a rigidly mounted extruder is pretty important for having an accurate build. My concern is, yeah - would the glass withstand the pressure? Perhaps if it's not screwed too tightly. The printing puts strong lateral forces on the extruder tip, so I think it's very preferable to have it rigidly mounted.by jbayless - General
Interesting extruder design, with integrated filament guide. I wonder if there's any feedback on that DC motor, or if they're running it Makerbot style.by jbayless - General
Also, as to how to mount the glass nozzle... I wonder glass would do in one of those compression fittings? Just as an example, McMaster-Carr 5949K61 (although it's slightly larger than ideal).by jbayless - General
Yes, I expect they will be quite expensive. Still, it's worth asking. How long do you expect it will take you to make a glass nozzle, on average?by jbayless - General
Because not all of us have glass-making experience, I'm searching around for scientific industries that can make glass extruders, with the hope of having a small production run to sell on RepRap stores or via Makerbot. Pegasus Glass (http://www.pegasus-glass.com/) indicated that a part like this is considered "precision" in the glass industry, and they wouldn't be able to do it. They referred meby jbayless - General
Excellent. I really think glass is the ideal material for an extruder nozzle.by jbayless - General
Really? I thought a rigid cable would be worse, because it needs to flex as the extruder moves around, and a rigid cable would introduce drag on the print head (especially with a multi-head system). Has anyone tested it?by jbayless - General New Machines Topics
What McMaster-Carr tubing are you talking about? Do you have part numbers? As I was discussing here, McMaster PTFE tubing is very cheap. Brand-name Teflon: 5239K11 ($1.09 per foot) Semi-transparent PTFE with colour bands: 53935K221 53935K222 53935K223 53935K224 53935K225 ($1.25/foot)by jbayless - General New Machines Topics
Hmm... good question. I hope they haven't been lost during the twiki conversion! Here's the DXFs. I suppose we could use these to create PDFs?by jbayless - Darwin
If you have sophisticated control electronics, it is possible to measure the back-EMF of the motor to determine its speed, which lets you get away without having sensors. But I think that technology might be somewhat out of our reach at the moment. At least, I don't know where to buy any off-the-shelf motor controllers with that capability - I just know of the technique.by jbayless - General
Do you have a drawing of the idea? I'm finding it hard to picture. But it sounds interesting!by jbayless - General
There's also Mica and Micalex. But like I said, I think using machinable glass mostly plays against the advantages using glass... A more elaborate Bowden cable extruder could use one of these to join the PTFE tube to a stainless steel tube. This would also let it screw into a mounting plate (up to 0.5"/12.7 cm thick). For a thinner plate, that also provides room to file a hole and install a soleby jbayless - General
Machinability isn't my main concern. I really like the idea of glass because it can be drawn into a fine, precision needle-tip without having to use micro drills. Continuing my attempts to put together an off-the-shelf extruder nozzle, the following are proposed designs and have not been experimented with yet. All prices and part numbers are from the McMaster-Carr catalog. Extruder A: (1) 6710by jbayless - General
Copy of an email sent to Pegasus Glass (http://www.pegasus-glass.com/) QuoteDear Pegasus Glass, I have a question about the cost and minimum order size of custom glass pieces, and would be very grateful for your assistance. I've attached a drawing of the necessary part. I don't have any previous expertise in glass drawing, so I'm not sure whether this part is easy or difficult to make. Unlabeleby jbayless - General
SimonRafferty Wrote: > The heater wire and thermistor will be wound on to > the little bobbin and the hexagonal brass bit is > drilled with a 0.4mm hole. > Make sure you have a good thermal contact between the bobbin and the tube, then!by jbayless - General
At least for me, the Darwin has a lot of dead space, and can't use nearly as much of the platform as it looks like. But that might just be how I've set it up.by jbayless - General
Thanks! You can also buy Luer Lock tube fittings from McMaster-Carr that mate to the needle. They call them "quick turn fittings". The trick is finding the right combination of parts to put together, because they don't have much variety... Right now I'm thinking of this combination: orby jbayless - General
You could also try using Belleville washers (disk springs).by jbayless - Mechanics
These are probably even better: Luer-lock stainless steel dispensing needles, 1/4" (6.35mm) long, in diameters as fine as: 0.016" = 0.4mm # 6710A72 0.012" = 0.3mm #6710A74 0.010" = 0.25mm #6710A76 Just $2.61 each. I'm now determining whether the Luer-lock fitting is appropriate for use in an extruder, and what other parts would be needed to mate with it.by jbayless - General
There's also these, although at ~$10 they're a little bit pricey: (Precision tube orifices from McMaster-Carr, in sizes down to 0.016" = 0.4 mm)by jbayless - General
You could give edrawings a shot: It might be able to open and view your .dxf files. In general, there is no standard for CAD the way there is for computer code. So while you can open a C++ project in Eclipse, Microsoft Visual Studio, devC++, notepad++, or notepad, and have it all be essentially identical, that's not the case for a 3D CAD file. DXF is an industry standard 2-dimensional vectorby jbayless - General
Hello, I found this free tool, from the company that makes SolidWorks, to be quite useful. It can open and view a fair range of 2D and 3D files from various CAD programs, including many proprietary formats (especially .SLDPRT). Not only that, it can export them to STL. You can use this program as a way of converting files from SolidWorks, AutoCAD, SolidEdge and Sketchup to STL data. It's quby jbayless - 3D Design tools
This is an edited version of a list from UBC's mechanical engineering department. I haven't personally checked all of these sources, but my university trusts them all enough to recommend them. Looking for stuff to build a RepRap, or similar projects? Can't just order everything from McMaster-Carr? Here's some good local places: ---------------------------- General Supplies Princess Auto (15by jbayless - Canada, Vancouver RepRap User Group
Wade made his springs by hand using piano wire, I think. I wonder, if you can't find springs, could you use Belleville washers?by jbayless - Mechanics
If you just use the screenshot method it's not the same result, because end-users can't edit the formula.by jbayless - Administration, Announcements, Policy
I don't understand why you would want to make your own smooth rods. The stock metal you'd buy to put into your lathe should already be a rod (or else it would be very difficult and dangerous to machine). All the lathe could possibly do is reduce the diameter, and alter the surface finish... but smaller diameter rods are generally cheaper, so it'd almost always be cheaper to buy the finished rod tby jbayless - General
That's a good write-up! Thanks! FUNdaMENTALs of Design also goes into a lot of detail on compliant mechanisms. It might be worth skimming through and transferring some of that knowledge up to the compliant mechanisms page as wellby jbayless - Look what I made!
To clarify, most RepRaps can only print one colour at a time although that can be any colour of plastic that you feed into the machine. There are a few experimental multi-print-head RepRaps that might be able to do multiple colours in a single print. But this is rare.by jbayless - General
Interesting, I didn't realize that imperial hardware would be easier to find than metric in Brazil.by jbayless - General
Looks like a lot of good work! My main concern is, you might be needing some more structural support for the X axis assembly. Right now it looks like it's just supported by the two nylon screws. Are those going to be stiff and robust enough, when the x axis is moving back and forth?by jbayless - General