Very strange. With the values you've got, you shouldn't get stuck at 107C. It's almost as if the heater isn't getting hot enough. Any way you can measure the actual temperature? I used a meat thermometer shoved into the heater barrel as a sanity check.by degroof - Controllers
For mounting the PCBs on my Darwin, I picked up a bag of nylon P-clips at the hardware store. Like this: I ended up using 1/2" ones which were slightly too small but workable. Something similar could be used to attach panels to the existing frame. The picture I have in my head is acrylic panels mounted on the frame, with plastic corner protectors covering the gaps at the edges.by degroof - Mechanics
In the current Darwin design, at least 4 of the 12 bars used for the edges of the cube are also used as guides for moving parts. Replacing them with angle bar might be tricky. > The current design is great because it has tolerance for bars which have > not been precisely cut. Any ideas on how to design a similar tolerance > using angle bar? The first thing that comes to mind is: - cby degroof - Mechanics
> I've got a piece of 3/8" diameter bisque alumina on order Just got notification that the package is "out for delivery". I should have it in time for the weekend. Let's see how many tool bits I can break on it... > Can you get PTFE sheet about 0.5mm thick? Would fusing a bunch of strips of PTFE tape together be viable?by degroof - Mechanics
How much would the target machine's attributes affect the slicing process? For example, two nearly identical target machines have extrusion diameter of 0.6mm and 0.5mm. Wouldn't the compiled file for the first one contain fewer slices?by degroof - RepRap Host
Motors: I might have to pick up one of those GM17 motors. The GM3 I've got seems very unhappy. Polymer guide friction: I was toying with the idea of adding some sort of roller bearings. First thing that comes to mind is getting some pieces of metal tubing or standoffs and mounting them on pins or bolts driven through the extruder body.by degroof - Mechanics
That's the Z axis flag adjuster. Took me a while to figure that one out too. Here's my take on it:by degroof - Plastic Extruder Working Group
Maybe someone could take a kit, dump it in a bucket of water and measure the displacement. That'll get you volume and you can work out mass for each flavor of plastic.by degroof - Plastic Extruder Working Group
Here's the calculator: I think a Darwin's RP parts are roughly 1000cc (anyone have an accurate measure?). CAPA's density is about 1.1 g/cc. So 2kg will get you 1800cc. You might be able to squeeze 2 Darwin's out of a roll.by degroof - Plastic Extruder Working Group
Wait a minute. It looks like the threaded rod for the Z axis goes up through the top corner brackets. I didn't think it was supposed to do that.by degroof - Reprappers
I finally broke down and replaced my old vernier caliper with a digital micrometer. It says the extrusion from the pencil tip is 0.65mm, compared with 0.55mm for the pencil lead.by degroof - Plastic Extruder Working Group
Some random thoughts based on my experiences so far: - In the current design, the flexible shaft and PTFE barrel appear to be the primary weak spots. - I've got a piece of 3/8" diameter bisque alumina on order, just to see how it holds up to pressure and temperature. I have fantasies of machining a one-piece barrel out of the stuff. - It's difficult to tighten the extruder body so that the drivby degroof - Mechanics
I like this idea. You'd basically be compiling the model into machine code before building it. I'd expect that, in addition to the above advantages, you'd also be able to run the actual build on a much simpler machine. For example, you could have a fairly hefty desktop machine compile a set of models to machine code, then distribute the compiled code to one or more smaller machines (e.g. sub-noby degroof - RepRap Host
I pretty much just heated up a blob of polymorph (actually ShapeLock) in some hot water and cranked it through. The machine has 9 thickness settings. I picked one in the middle. It does tend to curl a bit, so I flattened it on the bench and let it cool.by degroof - Plastic Extruder Working Group
I ended up using one of these: Works very well for extruding sheets of polymorph and it has adjustable thickness.by degroof - Plastic Extruder Working Group
Anyone have any experience with bisque alumina? It sounds like it can be machined and used as-is or, alternatively, machined and fired at 3100by degroof - Paste Extrusion Working Group
Yeah, I'm starting to realize that the PTFE barrel just won't take the stresses involved.by degroof - Plastic Extruder Working Group
I had something similar happen. It turned out to be bits of ground-up plastic stuck in the threads.by degroof - Plastic Extruder Working Group
I've got a Mk II with the flexible shaft removed, a pipe clamp on the hot end of the PTFE and deck screws through the cold end. It managed to hold up for a while but eventually came apart at the pipe clamp. Currently rebuilding it.by degroof - Plastic Extruder Working Group
Here's a closeup of the extrusion, along with a 0.5mm pencil lead.by degroof - Plastic Extruder Working Group
I was experimenting yesterday and came up with this: It's a mechanical pencil tip in an acorn nut. I drilled a hole a bit narrower than the widest part of the pencil tip. The pencil tip is from a 0.5mm Scripto P200. Tightening the nut on the barrel wedges the pencil tip into the hole. As you can see from the photo, it actually managed to extrude some plastic. Advantages: cheap, easy to make,by degroof - Plastic Extruder Working Group
I just tried an experiment using a 1mm sheet of polymorph as a base for an HDPE build. I only did a single layer as a test. Here's the result: The HDPE sticks well to the polymorph. To remove the build from the base, you heat it up and peel it off. You can also reuse the polymorph for additional builds. The problem I've got now is that I need a way to make sheets of polymorph that are thin, fby degroof - Plastic Extruder Working Group
Another hack. I ditched the flexible shaft on the extruder, shortened the motor mount and added a filament guide (paperclip).by degroof - Reprappers
For flexible shaft couplings, compression springs work well. I'm not using any on my Darwin build but, on past projects, I've used a spring from a retractable pen as an improvised U-joint.by degroof - Reprappers
I might have to start using a reel. It's amazing how much filament you can go through, just running tests.by degroof - Reprappers
One thing I've noticed is that, once you've run to the end of a piece of thermoplastic filament, starting a new one is a serious pain. If you just feed it in behind the last piece, it almost invariably jams when the gap reaches the top of the PTFE barrel. Right now, I have to take the extruder apart and manually push the old piece far enough down to start the new piece. Anyone come up with a soby degroof - Reprappers
I've run into the same thing here in NC. I needed a 1cc syringe to give oral meds to a budgie. The pharmacy had them but they couldn't sell them to me because they came with a needle attachment and I didn't have a prescription. Nevermind that I didn't actually need the needle.by degroof - Plastic Extruder Working Group
I recently had a couple wisdom teeth pulled. One of the things they gave me was a Monoject 412 syringe to keep the sockets clean. It looks like this: It's 12cc, with a curved, tapered nozzle. It looks like it would be handy for extruding paste. I did a search on "monoject 412" and found that a lot of craft places sell these: While looking at that, I also found something called a "needle boby degroof - Plastic Extruder Working Group
As I've been (slowly) building my Darwin, I've deviated from the standard design in a number of places: - used metal gears for X, Y and Z axes - used metal couplings for Y and Z motors - added a tensioner on the Z belt - omitted the backlash springs The first two were done mainly for the sake of durability. The other two were an attempt to get the Z belt to stop slipping. Has anyone else doneby degroof - Reprappers