Thanks for the clarification Kempy. I had read through some of the threads, but not all. Last I had read there was still a desire for an inert gas environement, using argon, nitrogen, or hydrogen, with a preference for the later two since they can be generated on site. Do any of the current professional machines work in a vacuum? I wonder about the added strength of the chamber. And especiallyby rocket_scientist - MetalicaRap
I looked and did not see anything posted on this subject yet, and I feel like I have just had a brain storm and wanted to see if it is already old news. With the desire to have high precision parts I saw 5u spot size being mentioned. To get the full accuracy in the Z axis you will want each new layer to be not much thicker than 5 microns and very uniform. I imagine that drawing a squigie acrosby rocket_scientist - MetalicaRap
brnrd If you have access to a lathe, drill press, or even just an electric drill, you may be able to put the rods in the chuck, and use sand paper running up to 400 or 600 grit to first reduce the diameter slightly, then smooth the rods again to make them less tight and still be able to use all the bearngs. If you have access to a leathe, be careful not to take too much off and make them looseby rocket_scientist - General
Considering the very long time constant of a heated bed compared to the hot end of the extruder, a 1hz PWM, which is basically a bang/bang style anyway, should work fine. It all depends on how accurate you need to be, and how sensitive you temperature measuring device is. If the thermistor has an LSB of less than 1 degree, then the bang/bang with probably cycle within +/- 2 or 3 LSBs. If you slowby rocket_scientist - Next Wave Electronics Working Group
Milly, another point that I did not see when skimming though the thread is that thermistors are notoriously not accurate. When you initially said that you were getting 19C on the thermistor and 23C from a room thermostat. my first thought was "wow, you already have it dialed in!". Thermistors change resistance over several orders of magnitude, and not linearly. Sometimes not even uniformly. Thaby rocket_scientist - General
Not dangerous at all. 18 Gauge is thicker than 20 gauge ( gauge numbers always go backwards, smaller number means bigger item). I suspect that even the 20 gauge is generous, unless the extruder heater and/or bed heater are powered by this board as well. Don't worry, 18 will do fine! Mikeby rocket_scientist - General
I have not yet tried, but the specs look good for using high temperature silicone for insulation. I bought an oven mitt made from blue silicone. It is supposed to be good enough to dunk your hand in boiling oil. I cut multiple disks and punched out the center hole so that when the time comes, I can slide the disks over the hot end and secure with Kapton tape. The oven mitt was quite inexpensive,by rocket_scientist - General
It sounds like the 1.75mm filament is more expensive per pound/kilogram than the 3mm. I would want to see some real advantages before increasing the base cost of raw materials. Mikeby rocket_scientist - General
David, I am hoping to buy a digital scope kit at some point, but right now my own madscientists workshop has a Tektronix 455 'scope on it. It is very old, only 2 inputs plus trigger and the A input level shift pot is going, and it only works up to 60Mhz. But it is a Tektronix 'scope and should be a clean, honest 60Mhz, which is all I need for ATmegas, Arduinos, and other microcontrollers. Hereby rocket_scientist - Controllers
As far as RF interference goes, a little bit of googling and Wikipedia point out that for frequencies lower than 100Khz, shielding is best done with high permeability magnetic metal rather than just a Faraday cage. I found a listing on Electronic Goldmine for a sheet of 'ultraperm' that would not only block outgoing interference, but if wrapped around the induction heater, might improve the magneby rocket_scientist - General
Ben, I think the internal shredder, cutter, shear, whatever inside must remain stationary with the outside world, while inside a rotating drum (similar to the squire cage fans of evaporative coolers for those who have seen them). This means that a structural member that holds the lawn mower cutter must go through a hollow axle and bearings of the outer drum. Worse, to power the spool of bladesby rocket_scientist - General
Ben, Would it help if one of us lucky ones in the States bought one for you and then shipped it out? Things can be sent as 'samples' through customs without major charges or problems from what I have heard. To help advance the reprap world state of the art, I would be willing to act as go between myself. I have been looking at push lawn mower ideas. They have the best potential for taking wby rocket_scientist - General
Ben, When making your own custom, giant blender, make sure you use the correct bearings to support the drive shaft. The standard bearings used in repraps are ball bearings. They can handle large radial loads, but have very weak side load ability. Tapered roller bearings can handle both radial and axial loads, and should work much better, and be much safer for holding your whirling blades of milby rocket_scientist - General
When I first realized that the boro-silicate glass nozzles would work well up into the liquid aluminum range I kept wondering what great things can be done with that. I would also suggest that FDM when applied to metals might not include welding with electric arc through the filament as that has no corresponding process when working with plastics. So I was looking specifically at extruding alreby rocket_scientist - General
Rob T, as I was fading in and out of concisousnous napping earlier it occured to me that your design would expand well into something I was thinking will be required for long range universal fabricators. In science fiction stories, they have Von Neumann Machines that take in any kind of raw material, process it into building materials, make all the components and then assemble them to produceby rocket_scientist - General
Cefiar Wrote: ------------------------------------------------------- > FWIW: The Melbourne RUG wiki page lists local > suppliers in Australia for a lot of stuff, which > includes some of the generic places you're used to > (like Element14, Mouser, Digikey, RS, etc) who > have a presence here. > > I urge all the RUG's to actually do the same, > regarding suppliers. There'by rocket_scientist - General
Cefiar, sorry, I do tend to suggest without thoroughly researching. However, you have just been guilty of doing the same. AndyMark supports the FIRST Robotics Challenges, which are international. If you had checked the shipping instructions link on the first page of the website you would have4 found that they ship internationally, and a flexible as to what type or carrier of international shippinby rocket_scientist - General
WOW. that looks like several step in the right direction! I did not get a clear view of the virgin HDPE pellets he was using, but I think that sending milk bottle sides through the paper shredder multiple times would get something close enough. I could not tell of the auger was made from a meat grinder or wood boring bit set into a custom diameter match aluminum chamber block. It would be niceby rocket_scientist - General
Andrew, In answer to your first question, even ABS rods suffer from creep. Over long periods of time, the plastic acts like, well, plastic, and the straight rods become straight no more. I am currently brainstorming how to make something thicker and more rigid than rods, but even for that I am hoping to be able to put fiberglass threads throughout to further stiffen it and prevent or reduce creby rocket_scientist - General
AgingHippy, We are talking about levels of protection here. A normal input pin for any microchip should only take fractions of a milliamp whether being driven high or low. It is common practice to tie unused inputs on a quad gate to ground with no resistor. On chip selects, it is often tied directly to +5V or ground ass appropriate. However, if the stepper shorts out internally and becomes damaby rocket_scientist - Controllers
Buback, I have attempted to make to make the type of glass nozzles you requested. Some have a lip slightly up from the end so that two plates can sandwich the lip between them. Others have a flange at the end that I worked harder on getting perfectly flat and perpendicular. I also chucked several of them in the lathe and tried to square up the rounded edges and and make the addition more circulby rocket_scientist - General
Looks very exciting Casainho! Looks I may soon have more electronics kits than intended machines to use them in! Mikeby rocket_scientist - Next Wave Electronics Working Group
Should I add that I plan on making a new board using toner transfer this weekend? I am willing to decide to use it myself, and even teach it to students, because I have done it before and have some idea of the difficulty. But when recommending it cold to someone I can not give hands on instruction to, I tend to be more cautious. And yes, I am looking forward to when repraps can make their own douby rocket_scientist - Controllers
Yes, a power resistor (or several) would be adequate. Use one that will pull at least 10% of the rated 5V capacity. Even better is to pull at least as much as the 12V supply does at max. Let us assume that you have a 450W PC power supply rated for up to 21A at 3.3V, 20A at 5V, 18A on two separate +12V, and a small -12V and 5V standby connections. I pull 10% of the +5V supply, you would need toby rocket_scientist - Controllers
In my limited experience so far, toner transfer printing of one sided boards with home equipment (standard laser printer, clothing iron, pool acid and hydrogen peroxide) is iffy enough that you may need several go rounds before you have a board with no opens or shorts. If you do it more than once or twice, try the PCBfab-in-a-box with special transfer paper and laminator. That makes singled sidedby rocket_scientist - Controllers
I would still look more towards using the arm to pick and place parts so that small assemblies can be built. In particular, SMD devices can be mounted on pcbs using an arm like that. The next question is can we redesign the arm to make it printable by a reprap?by rocket_scientist - General
Hazuki, you might also look at the thread on glass nozzles. It eliminates the problem of using soft PTFE to hold the hot brass. Although we are still working on the best way to heat the tip and measure the temperature of the plastic. Mikeby rocket_scientist - General
I have been looking into using a 32bit micro running Linux and EMC2. On closer inspection, the website lists the hardware requirements as X86 based processor. So at this point in time, they have not yet cross compiled it to run on other processors, let alone the completely different hardware I/O, PWM, and hardware timers that 32bit microcontrollers have to offer. It may some day be a good step upby rocket_scientist - General
Lanthan, The TIP-120s are power darlington transistor pairs. If you look at the spec sheet, you will see that for currents of several amps, the collector-emitter voltage is over 1 volt. If you needed 4 amps to drive the stepper motors (the maximum that this device can handle), that would be 1.1volts times 4 amps = 4.4watts dissipated across the device. That is equivalent to the MOSFET's on resiby rocket_scientist - Next Wave Electronics Working Group
I just ran a plastic milk bottle, HDPE, through a home/small office paper shredder. I cut the milk bottle into a bottom piece and 4 sides. Cutting through the handle took a bit of work ! When I passed a side piece through the shredder, it came out in one large piece still, but with deep lines between the cutter blades, and little cliffs where each tooth tried to shred it to confetti. So I ran itby rocket_scientist - General