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Rostock, Kossel, Simpson, 3DR, and more. See: http://reprap.org/wiki/Category:Delta. Previously named "Delta Robots and Stewart Platform"
Re: BOM Generator -> Part Lister - 15 years ago
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
Re: Aluminium instead plastics and CNC milling - 15 years ago
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
Re: Simplification opportunities - 15 years ago
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
Re: Stepper Motors - 15 years ago
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
Re: Using other cam programs - 15 years ago
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
Re: Extruded filament diameter - 15 years ago
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
Re: Testing PowerComms - 15 years ago
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
Re: Testing PowerComms - 15 years ago
Yes it is quite common to get TX and RX swapped with RS232 but I have never known it damage anything.by nophead - Controllers
Re: Extruded filament diameter - 15 years ago
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
Re: JB Weld alternative? - 15 years ago
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
Re: Extruder drive screw soldering instructions - 15 years ago
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
Offset extruder v older design - 15 years ago
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
Re: Extruded filament diameter - 15 years ago
By hemisphere I assume you are referring to the acorn nut version. Mine is the older design which looks like thisby nophead - Mechanics
Re: Testing PowerComms - 15 years ago
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
Re: Extruded filament diameter - 15 years ago
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
Re: Extruded filament diameter - 15 years ago
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
Extruded filament diameter - 15 years ago
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
Re: Extruder drive screw soldering instructions - 15 years ago
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
Re: JB Weld alternative? - 15 years ago
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
Re: temperature swinging - 15 years ago
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
Re: Extruder drive screw soldering instructions - 15 years ago
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
Re: Extruder drive screw soldering instructions - 15 years ago
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
Re: Extruder drive screw soldering instructions - 15 years ago
Well the crossed version lasted about 20 mins before it broke. The solder didn't really penetrate into the castellations much as it doesn't wet the SS it's probably a surface tension thing.by nophead - Mechanics
Re: Extruder drive screw soldering instructions - 15 years ago
Well no surprise it did break again after extruding about 300mm of HDPE at 200C. I switched the motor off and left the heater on. When I switched the motor back on the filament would not move so I tightened the springs and the joint broke. I will try Richards idea of cutting a cross in the top of the screw next. I read that it is possible to solder stainless steel with ordinary tin lead solderby nophead - Mechanics
Re: JB Weld alternative? - 15 years ago
JB Weld is supposed to be good up to 315C. I have had my extruder heater up to about 250C and it has changed from gray to dark brown. Is this to be expected or have I got some inferior counterfeit product?by nophead - Mechanics
Re: temperature swinging - 15 years ago
Thinking out loud here but putting a resistor in parallel with the thermistor probably helps with making it a bit more linear. It would certainly tend to cramp up the high resistance low temperature end where the resistance is changing rapidly and have negligible effect at the high temperature end.by nophead - Controllers
Re: temperature swinging - 15 years ago
Well my thermistor goes from about 2K at 20C to 20 ohms at 200C. To cover that range with a 10 bit A/D only gives you 10% accuracy at the 200C end. If you are measuring time, as long as your timer is fast enough to get good resolution at the high temperature it is no problem slowing it down with a prescaler to get similar resolution over a very wide range indeed. I suppose in this case we are noby nophead - Controllers
Re: temperature swinging - 15 years ago
Forrest Higgs Wrote: ------------------------------------------------------- > Oh Lordy! You're right! I remember now. Struck > me as a lot of bother to go through at the time so > that you wouldn't have to change PIC chips. There > are, after all, a lot of inexpensive 16F's that > have A/D. Actually thinking about this while measuring the thermistor englewood sent me it isby nophead - Controllers
Re: ALTERNATIVE SOURCE FOR MAGNETIC SHAFT ENCODERS - 15 years ago
If you have an index then the end stop only needs to have a precision of less than one turns travel. When you see the index you round your count to the nearest whole revolution. When you see the end stop you take the remainder of the count divided by a revolution. Once you have seen the index once and the end stop once you should always know you position absolutely to the resolution of the encoby nophead - Controllers
Re: A question about the RS22 cable - 15 years ago
The connector on the powercomms board uses those three but it also loops 4 to 6 (DTR-DSR) and 7 to 8 (RTS-CTS). I.e. it effectively converts a straight through cable into a null modem cable.by nophead - Controllers