You could reuse the motors,so "almost everything" is just a bunch of rods, studding, pulleys and belts plus a lot of FDM parts.by nophead - General
I did order some M3 wingnuts but they took 10 days to arrive due to a postal dispute here in the UK. There is just enough room to spin them as long as you keep the others vertical and don't tighten one a lot further than its partner. Still a bit of a faff, but kinder to the fingers than my home made knobs. Making the extruder a bit wider and making the nuts on the other end captive would be worthby nophead - Mechanics
That looks far more sensible to me than 7ft RJ11 cables.by nophead - Controllers
I think the work Mike and Fernado are doing with resins and fillers is the most likely route to making a machine solid enough for milling. A lathe is another desirable product that requires, I would guess, even higher rigidity.by nophead - General
Well the deal is on receiving a set of parts you use them to make a machine and use that to make two sets of parts to pass on to two other people. That way we conquer the world in a short time. That's if it works!by nophead - General
I have a Darwin extruder attached to a reliable cartesian robot. It will probably take me a couple of weeks to find out whether it works. If it does I will make parts for people at cost but I suspect that the current part designs cannot be made with the current software and HDPE.by nophead - General
I do have AC in my work room but summer hasn't happened here this year so it wasn't needed, so no excuses there. I have a working positioning system and an extruder which seems reliable but the filament is a bit larger than I like unless I run it slowly. The remaining work to be done is to build some electronics to control the extruder and then modify the host software to drive my completely nby nophead - Reprappers
Well the design consists of relatively complicated plastic parts, which are hard to make, other than by FDM, and off the shelf items like rods and studding which are cheap and easy to get hold of. That means that if it can self replicate it is both easy and cheap to build. If not, it is quite hard to make, you need to either be skilled at metalwork or have a CNC milling machine, etc., or you caby nophead - General
I think you must live in an alternate universe where there are more hours in the day than mine, or a multiverse where there are more Zachs.by nophead - RepRap Host
I don't think so. I learned the hard way just how stiff you need to make even a small milling machine, with a Dremel type spindle, able to mill plastics. I naively thought that as long as you didn't feed too fast you would not need to apply much force so the worst you would get is a small deflection and loss of accuracy. What actually happens when it is not stiff enough is that the tool "snatcheby nophead - General
The Darwin design is the way it is because it it designed to be self replicating as much as possible. It is designed to be made by FDM. If you are fabricating it by other means then you would not design it like that at all. The basic requirement is a steady frame to support some rails, motors and bearings. It doesn't require a milling machine to make a frame. It is much easier to make an open siby nophead - Mechanics
Yes but you can make a one line change to the firmware to use half stepping which will get you the same resolution with a 200 step motor. Edit: But with about 1.4 times less torque.by nophead - Mechanics
The mechanical side of RepRap is not rigid enough for even light milling. The electronics could drive a small milling machine but it would be a bit on the slow side. The software neither inputs or outputs G-codes at the moment. I don't think adding G-code output would be too difficult for anybody proficient in Java. It would be useful to allow people to add extruders to existing 3D machines toby nophead - RepRap Host
Well I tried around 160C and the filament was bigger at lower speeds and it started slipping when I tried higher speeds. I had to raise the temperature and push it with pliers to get it moving again. So for now I think it will stick with 200C, 5mm / second giving about 1mm diameter filamant and see if I can get the software hooked up to make something. I think I will switch over to the acorn desby nophead - Mechanics
Ok, I will have a go. I would like to get to the bottom of Kai's problem first though. That's a real puzzler.by nophead - Controllers
Yes it is quite common to get TX and RX swapped with RS232 but I have never known it damage anything.by nophead - Controllers
Another possibility is that it is the temperature, rather than nozzle geometry, that is the cause. I am using temperatures around 200C and above, while most of Forrest's figures are substantially lower. I don't know anything about non Newtonian fluid mechanics, or Newtonian for that matter, but perhaps the hotter the plastic is the more compressible it is and hence the more it will expand when reby nophead - Mechanics
Yes mine has gone almost completely black now and apart from a little cracking where the wires exit it is holding up fine so far. Edit: Actually mine is also acting as the insulation as I am using bare nichrome. That may be a bad idea because the wire has no room to expand.by nophead - Mechanics
That might work but it would be have to something like M1 or M1.5 if that exists as my cable is only 2.5mm diameter, the recommended one is 3mm. It would also have to be headless, i.e. a grub screw otherwise it will catch the incoming filament.by nophead - Mechanics
I think the aim of the offset extruder was to allow the use of a wider range of materials by allowing stiff rods to be accepted. Its a clever design but it does have a few disadvantages: It's harder to build and requires an extra material: steel cable. The cable winds up, so when the motor stops it sometimes slips backwards unwinding the cable but sometimes it doesn't. That implies the motor doby nophead - Mechanics
By hemisphere I assume you are referring to the acorn nut version. Mine is the older design which looks like thisby nophead - Mechanics
First of all I wouldn't be too worried about the voltage on pin 11 when there is nothing connected to P3. It is an input to the max chip with a 400K internal pullup resistor to 5V. The voltage you get will depend on how good your meter is, i.e. how much current it takes. The wiki should probably say 4 to 5V depending on your meter, or just not mention it all. Pin 13 having close to zero on it isby nophead - Controllers
Hmm, reviewing your data against mine on the face of it there is not a lot in common. You have are getting a much lower temperature for an equivalent power but a much higher flow rate. My thoughts of possible reasons why your temperature is less: - 1)I think your barrel is a bit longer, mine has only 30mm exposed. 2)You have a plate at the top with a large surface area acting as a heatsink. 3)Yoby nophead - Mechanics
The head was high above the table and I was letting it fall under gravity. I have not tried laying it down yet. I think I am extruding at a little over 200C. That is the temperature of the plastic inside the nozzle around where the heater is. I think the actual nozzle is a bit cooler. The rate of extrusion was ranging from about 3.5mm per second to 5mm. Increasing the motor speed does not increby nophead - Mechanics
I am using a nozzle with a 0.5mm hole in the end. From what I had read I was expecting the extruded filament to expand up to about 0.8mm. I was a bit disappointed to find it was coming out at more like 1.2mm. After a bit of playing around I found that the amount it swells is related to the the pressure it is extruded at. I reason the higher the pressure the more it is compressed as it goes throuby nophead - Mechanics
I have tried to combine all the advice in this thread and some from the JB Weld thread. I cut a cross in the end of my screw thread. I roughed up the inside surface with a small spherical grinder. I stuck it with JB Weld and held it in alignment in my lathe. After letting it cure at room temperature for 15 hours I then baked it in the oven for two hours at 200C. So far, touch wood (or should Iby nophead - Mechanics
I just used some JB Weld again. The instructions say it can be handled after 4 hours and it can be put to use after 15 hours if the room is above 50F. I would say it was still a stiff liquid after 4 hours. After 15 it was soft and flexible. I.e. I could dent it with my fingernail and bend a piece 2mm thick. The room would have been no lower than 20C so I don't know what I am doing wrong. I usedby nophead - Mechanics
Yes putting a fixed resistor in parallel with a thermistor can make it almost a straight line over the range we are interested in. In my case I used 100 ohm across a thermistor that has a resistance of about 2K at room temperature and 20R at 200C. I have put some graphs up on my blogby nophead - Controllers
Yes that was the page I saw. I have not been able to find a source for the flux. I think I will try JB weld next as Eric M has had some success with it. If that fails I think I will make a new shaft from zinc steel. I don't know why I didn't do that in the first place as it is available cheaply from the local DIY shop B&Q.by nophead - Mechanics
The cable is no problem, it's a bit I had left over from a garage door opener but it solders very easily. It's the drive screw that is SS. I bought the parts a while ago when the design did not include soldering. I could only get stainless from Farnell at the time. I was worried it would be too hard to machine but that went ok. When the design changed I thought no problem I have some cable, I diby nophead - Mechanics