Ru Wrote: ------------------------------------------------------- > So, commercial extruded plastic prototyping > machines use a support material. It evidently does > the job very well. > > Does anyone know what this material actually is? > If so, why have you chosen to hide it from us all > over the last year people have been asking about > support materials? Because it'by Joshua Merchant - Plastic Extruder Working Group
Interestingly, there is an epoxy with boron nitride and aluminum oxide , which is used for... well, I don't know, but the company makes heatsink pastes (they say that this specific epoxy "IS NOT intended to be used between a CPU and the CPU heatsink"). Boron nitride is a dielectric with a higher thermal conductivity than aluminum oxide (AFAICT) which can be added to ceramics (it can also be addedby Joshua Merchant - Mechanics
Interesting Viktor, thanks for the advice. Looking at your pictures gave me an idea: perhaps I could wrap the leadscrew/motor shaft with some material (perhaps electrical tape, which was used for the captive nuts , or something similar) to increase the diameter of the shaft and leadscrew so that they fit more snugly in the hose/tubing, instead of using an adapter to change the motor shaft diameteby Joshua Merchant - Reprappers
Ru Wrote: ------------------------------------------------------- > Evidently such a material exists, but absoluetly > no-one has any idea what on earth it could > possibly be, and we aren't really short of clever > people on the project. Say what? What about PVOH ? You even replied to the post about it! There is a question as to whether it will set fast enough to work as a supportby Joshua Merchant - Plastic Extruder Working Group
Has anyone thought of using PVOH/PVA as the raft material? It was the most promising support material (AFAIK). I think the biggest worry was that it wouldn't dry fast enough during building, but I don't think this would be as much of a concern when making the raft (which is before building). I don't recall whether anyone reported any success in adhering it to our plastics (or adhering our plasticby Joshua Merchant - Mechanics
jgilmore Wrote: ------------------------------------------------------- > I was going to try zip ties too, but realized > before I put it on that the bulge wouldn't fit. I > twisted a bit of bailing wire around it and then > clipped of the twisted bit. Hasn't come off yet, > and it's plenty small enough. If I was posting > from home I could even post a picture of it. > >by Joshua Merchant - Reprappers
There seems to be a bit of a interest in linear sliding mechanisms lately (e.g. the posts in the builder's blog and Viktor's post on this forum). Sort of related is something I've used for my plywood McWire. The basic McWire design has, on each stage, 4 of 1/4" thick strips of PTFE (1 in each corner). Under each stage are two parallel aluminum U channels, each of which has two of the PTFE stripby Joshua Merchant - Mechanics
I ran some tests this morning and basically: 1) The RM2 has it's pinion gear attached in a different way than the RM3. I don't think this is a problem, but just to be sure, I took it off and reversed it. It's a simple matter of pulling it off and putting it on the other way (after doing so, it looks just like the RM3's shaft). 2) The RM2, when mounted in the GM3 and powered by the DC Motor Driveby Joshua Merchant - Reprappers
I just installed the X motor on my McWire and started testing it, and I need some help with of the problems I'm having. The 1/2" OD, 1/4" ID silicone tubing from McMaster has a snug fit on the motor shaft, but just slides over the 1/4" leadscrew. I took a zip tie (those plastic cable control things) and tightened it around the portion of the silicone tube with the leadscrew in it, and while I cby Joshua Merchant - Reprappers
Ian Adkins Wrote: ------------------------------------------------------- > I have a proffesionally made (CNC'ed) nozzle with > a 0.5mmby Joshua Merchant - Mechanics
Forrest Higgs Wrote: ------------------------------------------------------- > Ain't no way I'm going to be wrapping nichrome > around an aluminum barrel, anodized or not. Uhm... why not? Type II anodized aluminum (which I will probably be using) has a nonconductive surface (according to a few non-wikipedia sources found via google). Of course, I would take a multimeter and thoroughly tby Joshua Merchant - Mechanics
Wait a minute, I'm using an aluminum barrel... why can't we (I! I mean I, really!) just anodize it? says anodising can be used to increase the thickness of the natural oxide layer (which in aluminum is normally very thin). We'll have a dielectric coating between the aluminum barrel and the nichrome wire which also happens to have a high thermal conductivity (well, at least for a dielectric: 40 Wby Joshua Merchant - Mechanics
Ceramic?by Joshua Merchant - Mechanics
Forrest Higgs Wrote: ------------------------------------------------------- > Joshua Merchant Wrote: > -------------------------------------------------- > ----- > > About how hot do you think it will get, and why > > doesn't it conduct well enough to the barrel to > > maintain an approximately equal temperature? > > > LOL! What part of epoxy is a pretty goodby Joshua Merchant - Mechanics
About how hot do you think it will get, and why doesn't it conduct well enough to the barrel to maintain an approximately equal temperature?by Joshua Merchant - Mechanics
Ru Wrote: ------------------------------------------------------- > Remember that the JB weld will perish. It would > suck to have a big build fail because the heater > wires popped loose. That's an argument against > soldering, anyway. What do you mean it will perish? The packaging on the stuff I have says it's maximum temperature is 600by Joshua Merchant - Mechanics
Just to cite it: > Forrest: the previous one leaked, as it says. The > problem is getting the crossing point in the middle > of the flow. -posted in comments by Adrian Bowyer here Also in those comments: > Hi > > Could you use a wire with a larger diameter and > just drill across a plain nozzle? The increase in > diameter being enough to cope with the inevitable > misby Joshua Merchant - Mechanics
I'm going over all the extruder design information as I prepare to build mine (as I watch glue dry on the unfinished cartbot...), and one thing that doesn't quite make sense is that the nichrome wire's ends are sticking out of the electrically insulating heat conductor (in my case and in the standard, JB-Weld high temperature epoxy) (picture and page ). The ends sticking out become hot during oby Joshua Merchant - Mechanics
Brace yourselves! nophead Wrote: ------------------------------------------------------- > Casting is labour intensive, which makes the parts > expensive. The whole point of RepRap is the > machine does all the work, making the parts cheap. > It is slow however, so you need lots of machines. > One person could run lots of machines, but the > original scheme of make two sets ofby Joshua Merchant - General
VDX Wrote: ------------------------------------------------------- > ... i can remember a discussion in last year about > repstrapping repraps and parallelizing the fabbing > capability for speedup. > > The point was to build as many repraps, as you > have place in your basement and then let the > 'overcounted' run with specific tasks > continuously. > > So you canby Joshua Merchant - General
This is kind of off topic, but oh well (I think the discussion of the original topic went as far as it could go, and it is indeed interesting how the thread evolved into a discussion of RP methods for creating SMT boards). As far as desoldering SMDs, I think it might be worth considering putting the heated skillet on the platform (that is, the platform normally used as a build platform), puttingby Joshua Merchant - Controllers
Heh. I'm also a bit obsessive, and, while that may perhaps be a bit of a motivator to build the RepRap in the first place (to get precision, computer-controlled part production), it has slowed my RepStrap progress a bit (more than a bit, actually). Thanks, that's excellent advice. It's nice that it's coming from someone other than myself (my right brain does nag me so).by Joshua Merchant - General
Interesting. So, then, can anyone tell me or point to a tutorial that explains how to use the ATmega168's timers (http://www.atmel.com/dyn/resources/prod_documents/doc2545.pdf says it has 2 8 bit timers and 1 16 bit timer) to implement internal firmware interrupts to allow high frequency checking of encoders (well, obviously, I don't need a tutorial that includes the encoder checking part)? I'vby Joshua Merchant - RepRap Host
nophead Wrote: ------------------------------------------------------- > I process my extruder shaft encoder with a fast > timer interrupt rather than using edge triggered > interrupts. That allows me to debounce the signals > as well. They were too noisy for edge triggering > interrupts because of the close proximity to the > GM3 which generates lots of RFI. > > Code exaby Joshua Merchant - RepRap Host
I'm working on my motors right now, and it has come to my attention that my Arduino Diecimila (I have to look up the spelling on that every fricken time...) has only 2 pins (Arduino pins 2 and 3) that can be used for external interrupts (with the attachInterrupt() function). All the rotary encoder firmware I have seen so far (the magnetic encoder and some other stuff on the blog) has the encoderby Joshua Merchant - RepRap Host
I bought the GM3 gear-motor with the standard 6V RM3 motor before I realized there was a 12V version. I also bought the RM2 at the same time to replace the RM3 to get more torque and speed. I just put a DC Motor Driver v1.1 together, and I was about to connect it to a gearmotor and the Arduino to test it, but I realized it was using a 12V power supply. I've searched around and there is some dby Joshua Merchant - Controllers
sid Wrote: ------------------------------------------------------- > I'm unsure about that advantage, because of the > need of larger parts to be reprapped What larger parts? (Anyway, I don't personally see larger parts as a problem, it just takes a bit more printing time.) > with only one leadscrew for X-Axis, I think i'd go > for a portal mill and only move the table not the > aby Joshua Merchant - Mechanics
sid Wrote: ------------------------------------------------------- > my upcoming cartbot Nice. > still without leadscrews (I guess you'll figure > where they'll go > The two leadscews for the x-Axis are going to be > connected by a timing belt. Yeah, I figured I would have to do something like that if I didn't do it the way I did it (where the x axis moves the y axis and the y axiby Joshua Merchant - Mechanics
Ru Wrote: ------------------------------------------------------- > Now I think about it a bit more, I guess a > no-overhang version might be okay. You might have > to make a few compromises which might limit the > strength of the link, but I guess you can heavily > over-engineer the whole thing and not worry too > much about its strength. > From what I've seen so far, castby Joshua Merchant - Mechanics
Does anyone have ideas on specific setup? The best thing I've come up with so far (now, I didn't say it was "good"; "best" is relative!) is a leadscrew design which has the z-axis attached to the toolhead, the y-axis attached to the z-axis, and the x-axis attached to the y-axis (of course x/y are interchangeable; I imagine this would be in firmware or software). Basically, the toolhead mount canby Joshua Merchant - Mechanics