I don't think the ATMEGA8 will work in the extruder controller in place of the ATMEGA168. Particularly if you want to use the Heated Build Platform hack which uses A6 for thermistor input. I don't think the ATMEGA8 has an A6 analog input. Another reason to replace it: ATMEL says the ATMEGA8 is "Not recommended for new designs: Replaced by ATmega8A"by JohnWasser - Reprappers
The chip on my Extruder Controller 2.2 (purchased assembled from MakerBot) says: Atmel ATMEGA168 20AU 0919 It is possible you were shipped an old ATMEGA8 by mistake. What else does it say on the chip? I'd expect something like "16AU" which I think is the same package type as the ATMEGA168-20AU.by JohnWasser - Reprappers
The "RepRap Motherboard" uses an embedded Sanguino. The Extruder Controller 2.2 has an embedded Arduino. I think you may have gotten the two bootloaders confused.by JohnWasser - Reprappers
I found out the hard way that the MOSFETs on the Extruder Controller (V2.2) cannot handle 3A @ 12V for more than about 20 seconds before they overheat and shut down. They work fine at 2A but with 6Ω of nichrome (two stretches of 12Ω in parallel) my heated bed is taking a LONG time to heat up to 110°C, even with a potholder over the top as insulator! I guess I should use the MOSFET to control aby JohnWasser - General
I've found that the description of the A6 and A7 headers on the Extruder Controller 2.2 does not match the circuitry. Is there some formal mechanism whereby such errors can be reported and thus corrected?by JohnWasser - Controllers
Hmmm... I was just thinking: Laser printers use a fusible plastic toner. I wonder if you could: 1) Print the layers of an object on paper with a standard laser printer. 2) Put the stack of pages in a heated press to melt the toner and fuse the pages. 3) Use a water bath to dissolve the paper not coated in toner I suspect that thin paper and an extra-heavy coating of toner might be necessaryby JohnWasser - Mechanics
McMaster-Carr (mcmaster.com) has 0.5mm drill bits. They even go as small as 0.05mm! It's not a size you will find at your local hardware store but your local metalworking supply company should have them. Perhaps a metalworking shop can tell you where they would order some.by JohnWasser - General
Stoffel15 Wrote: ------------------------------------------------------- > That cant be... i have an alu-plate 200x120mm x4mm > i need 2,6 Ohm to get 70° C 24000 sq mm = 0.024 sq mm 0.024 * 1000W = 24W to maintain 100°C 2.6Ω at 12V = 4.6A at 12V = 55W You're right. The math does not work out in your case.by JohnWasser - General
nophead Wrote: ------------------------------------------------------- > Yes you need about 100C for ABS to stick to kapton > and about 1kw / square meter to hold that > temperature. At least twice that to get there in a > reasonable time. OK. 100x100mm = 1/100th sq m. 1/100 x 1,000 W = 10W So minimum of 10W (0,83A @ 12V)) and preferably 20W (1.7A @ 12V) or more. That would <by JohnWasser - General
Another data point: With the nichrome cut down to 13Ω (0.9Amps / 11 Watts)the temperature of my 1/2" slab of aluminum gets up to 60°C... barely... after about half an hour. ABS did not stick to the Kapton. Definitely need MORE POWER. :-)by JohnWasser - General
The original Arduino bootloader would wait up to 10 seconds after a reset for a possible "download this new program" command, before turning control over to the previously downloaded program. Newer Arduino models reduced that wait to 1 second (and provided a means for the host to force a reset). Perhaps the bootloader in your Sanguino chip is the older variety? That's just a guess. On the motby JohnWasser - Reprappers
Rick Pollack Wrote: ------------------------------------------------------- > John - why are you using a 13mm slab...that seems > awfully thick/heavy. I would have preferred using 1/4" aluminum plate (6mm?) but I could not get a 100x100mm square out of the scrap pieces of 1/4" aluminum I had in my shop. The 1/2" stuff (13mm) was the only scrap I had from which I could cut a full 100x10mmby JohnWasser - General
I put 20Ω (about 900mm) of MakerBot nichrome on the bottom of a 100x100x13mm slab of aluminum using Kapton tape. Hooked up to 12v it only got to 40°C. Looks like I'll have to shorten the nichrome.by JohnWasser - General
nophead Wrote: ------------------------------------------------------- > The problem I have found with the parts is that > the STLs are generated from AOIs, which are > considered to be the masters. I think it is even worse than that: My understanding is that the originals are created in SolidEdge (not to be confused with SolidWorks) and then imported into AoI so that they can be manipuby JohnWasser - General Mendel Topics
I'd like one unit (10 pounds) of blue up here in Massachusetts 01754by JohnWasser - For Sale
"RS232" should mean +/-12V serial "TTL" should mean 0-5V serial Is there a term that implies 0-3.3V serial?by JohnWasser - Controllers
The eBay auction ended with a winning bid of $255. This means that at least one person would probably have paid about $340 if the set had been complete and not just 75% complete.by JohnWasser - Wanted
Current (I) in Amps = Voltage (V) in Volts divided by Resistance (r) in Ohms I=V/r V=I*r r=V/I To drive one Amp (I=1) through 1.2 Ohms (r=1.2) you need 1.2 Volts (I*r) A 12V supply can drive as much as 10 amps through 1.2 Ohms (I=12/1.2) but he driver chip provides current limiting so it's OK to use the higher than necessary voltage.by JohnWasser - Controllers
Best improvement so far is switching from Darwin cube to Mendel A-frame. I think the addition of a heated build platform to control warping and eliminating the need for a 'raft' is a major upcoming design improvement. If the RP'd rack & pinion drive works out, and eliminates the need for expensive timing belt, that will be a big step forward in self-replication. On the software side, incorby JohnWasser - Reprappers
spacexula Wrote: ------------------------------------------------------- > No one is going to print Mendels at less than > minimum wage consistently I hope that eventually a printer (MakerBot, RepStrap, or RepRap) will be reliable enough that it can produce parts mostly unattended. Since there is no "minimum wage" for robotic workers and no Mechanical Workers Union (yet, see ) I can seeby JohnWasser - Wanted
Currently on eBay someone in Oregon is selling an approximately 75% complete set of RepRap Mendel parts: (The calculations I did to determine how complete the set was are based on build time and extrude volume for the parts included and for a full set of Mendel parts.) When the auction completes we'll have an approximate street value for a full set of RepRap Mendel parts: WinningBid/0.75 Actby JohnWasser - Wanted
You should find out the printer's build area first as you may not be able to get all copies of all Mendel parts in a single print. You should also make sure the parts they can print are strong enough to use in a RepRap. This YouTube video by "prusajr" shows how to do it in Blender: Basically he creates a very thin base plane, sets all the parts on it, and merges them into a single object. Aby JohnWasser - Reprappers
We could print something like a Digicomp (plastic toy programmable computer from the 60's): I had one as a kid and enjoyed programming it to be a three-bit binary counter. It would probably be more practical to laser-cut one from sheet plastic.by JohnWasser - Let's design something! (I've got an idea ...)
Likely retail sources that are fairly local: You-Do-It Electronics 40 Franklin Street, Needham, MA (take Exit 19A off Route 128/I-95) Open 8 AM to 9 PM M-F, 9 AM to 6 PM Saturday, Closed Sunday Electronics Plus 480 King Street (Route 110), Littleton, MA Website doesn't bother to list business hours.by JohnWasser - Rhode Island / New England RUG
FYI: the threaded ring on the nose of a Dremel tool is 3/4" x 12 tpi but the thread is so short it works in a 3/4" National Course (10 tpi) hole.by JohnWasser - CNC Routers, Mills, and Hybrid RepRapping
It is a sort of a duplicate. A pointer to Bruce Sterling's "The Kiosk" was posted two years ago (by SebastienBailard): This version is an AUDIO podcast with a reading by Peter Cavell. It starts at 10:30 into the podcast. While looking for the text of this story I found a mention of a similar story by Cory Doctorow titled "Printcrime". You can read that one on his blog here:by JohnWasser - General
Gizmodo also picked up the HP/Stratasys/$15,000 3D printer story: (They use the same RapMan picture.)by JohnWasser - General
From the admesh 0.95 ReadMe file it looks like the "volume" is in the same units as the "size" values. If the STL is in CM then the volume would be CC. I don't know if STL files have an implicit or explicit scale. If the scale is implicit I would expect the Mendel parts to be in mm. ================= Results produced by ADMesh version 0.95 ================= Input file : sphere.stl ===by JohnWasser - General
And by "(relatively) affordable" they mean $15,000. The desktop units are to be made by Stratasys. The picture used to illustrate the article appears to be of a RapMan (RepRap Darwin variant made of laser-cut acrylic).by JohnWasser - General
Looks like the relevant change was on December 16th: "Revision 3396 Modified Wed Dec 16 12:19:19 2009 UTC by adrian-bowyer Improved version of the extruder motor bracket. It's thicker, and so the pinch-bearing screw is less prone to moving through the bracket's distorting." It sounds like a worthwhile change if the piece had a tendency to flex. Just another example where a change in one placeby JohnWasser - Mechanics