Greetings all, I like the ease of use of Arduino, but (like others), I find Arduino somewhat limiting in CPU speed and I/O. The Arduino mega provides more I/O pins, but the processor is still not that fast. Several folks here (my self among them) are experimenting with 32-bit processors, but doing that requires breaking with the Arduino code base. It appears there are a couple projects portby Larry_Pfeffer - RepRap Host
Greetings all, I've heard back from the two US suppliers of Ingeo brand PLA resin I contacted. I have preliminary pricing, which varies by resin type and grade. In small quantities (under a pallet, ~~ 1600 lbs) The more expensive resin *granules*, would cost approx $1.88 / lb (at the factory dock) and the lower-cost material is $1.30 / lb. At these prices, the cost of shipping (granules),by Larry_Pfeffer - Plastic Extruder Working Group
Greetings Admin(s) et al, Is the search function broken -- or am I doing something wrong? I tried searching on the single term PLA (for all forums and all times), but I get zero results. However, this string is in both message subjects and messages in the last month. Is a three letter string too short for our search function? (If so, ABS is in a similar boat.) -- Larryby Larry_Pfeffer - Administration, Announcements, Policy
Curlup, A related question: Would your employer be willing to venture an estimate for a set of parts, if they were to be printed on an as-available basis, (e.g. using up slack time/bed space on various machines), and not necessarily all made out of the same material? Thanks, Larryby Larry_Pfeffer - Reprappers
Greetings all, I haven't heard anything about a US supplier for PLA, so I did a little digging. This website lists some suppliers: I emailed two of the US suppliers (Ashland and Jamplast), who both source NatureWorks Ingeo brand of PLA in the US: I believe they supply in granule form, so we'd need somebody (New Image?) to make it into 3 mm rod. Is anybody else looking into this (Zacby Larry_Pfeffer - Plastic Extruder Working Group
Greetings all, Since I'm still sub-expert with the various CAD tools (gotta work on that), I would be very interested in such 2-D projections, especially if they had critical dimensions added. Until I get some form of CNC "making" machine built, I'll be manually machining parts. Thanks,by Larry_Pfeffer - General Mendel Topics
johnrpm Wrote: ------------------------------------------------------- ... imagine a bracket that can > measure the forces on it, or a 3d lattice that > could twist or bend according to the energizing > pattern? The electrical properties of piezo materials (capacitive + slow leakage resistance) means that they can't really be used as sensors for steady (DC) forces, after a couple time cby Larry_Pfeffer - General
Yes, there are piezoelectric polymers. Google says, " Results 1 - 10 of about 1,670,000 for piezoelectric polymer" Apparently Polyvinylidene fluoride (PVDF) is one such, see: From what I recall, they have a strong piezo effect, and can be used both as sensors and actuators. The wikipedia article says: "In 1969, the strong piezoelectricity of PVDF was observed by Kawai et al. The piezoeby Larry_Pfeffer - General
Greetings all, I agree that MDF, plywood (or LVL scrap) would be better than plain wood, due to grain effects. However, humidity-related distortion should be somewhat less of an issue for Mendel (vs. Darwin), since the bearing kinematics is forgiving of slight bowing/misalignment of the guide rods. The one place that it isn't very forgiving is the spacing of trios of bearings evenly about oneby Larry_Pfeffer - General Mendel Topics
There's a company that builds a metrology system that uses this principle: http://www.arcsecond.com/ Not sure if they have patents covering it.by Larry_Pfeffer - General
aka47 Wrote: ------------------------------------------------------- > Don't know about you guys but this looks to me > like a mechanical design (Structural Engineering) > challenge rather than a challenge that needs a > software repair. > > Making up for poor mechanics via software strikes > me as being a false economy. Tony, et al, This is a matter of opinion, howeverby Larry_Pfeffer - General
merlz Wrote: ------------------------------------------------------- > One easy possibility for eliminating the sag is to > use rotating arms. A long horizontal arm that > rotates in the xy plane will have the same > droop/sag no matter where it rotates to (being the > same distance to the end of the arm no matter how > you rotate it). Unfortunately, your assertion (constantby Larry_Pfeffer - General
Greetings all, I think this is an interesting notion, although getting a team of buildbots geometrically coordinated (well enough to make useful parts instead of scrap) is certainly a challenge. A team of robots is one approach to making objects bigger than any one robot/machine; I find this an interesting idea. One idea that could make it easier to coordinate a team of robots is to provideby Larry_Pfeffer - General
Christopher, To be able to advise re your machine's motors, I suggest: Copy down any model number or related info printed on the motors Take pictures of both the motors and whatever electronics they connect to. Closeups of PC boards would be most helpful. Count the motor leads, trace them, label where they went and disconnect Measure lead-to-lead resistances Caveat, if some of the leadsby Larry_Pfeffer - Reprappers
@Hazel, In my first test, I turned the toaster oven up from 150 deg F, to its max ~450 deg. F, without even opening the door, so there was no exposure to moisture between steps. I didn't keep it at 150 for as long as specified for drying granular feedstock, and I might have help it at ~450 for too long -- I'm not sure which one was responsible for the discoloration. I'll have to shred moreby Larry_Pfeffer - General
Greetings all, Apparently, moisture in some plastics causes worse problems than steam voids. If you look at the literature for molding (or recycling) PET plastic (used for 2-liter soda bottles and many other containers), moisture while melting leads to a chemical degradation of the plastic. I tried melting some PET shreds after approx. 2 hours of drying (at approx 150 deg. F), and the plasticby Larry_Pfeffer - General
Sebastian, Thanks much, -- Larryby Larry_Pfeffer - Administration, Announcements, Policy
RE: Grinding/shredding PET plastic (like soda bottles) Several people have suggested trying to recycle PET plastic (used in many containers, such as plastic bottles for soda and water) into filament to feed reprap extruders. I rinsed out some 2 liter soda bottles, and cut away the tops and bottoms, leaving cylinders of plastic. I slit the cylinders, leaving a flattenable sheets. These areby Larry_Pfeffer - General
@Christopher: What info do you have on the motors themselves? Stepper/Servo, Peak voltage, peak current, etc. The reprap hardware is set up for stepper motors with around 2 amps peak current. (Again, this depends on which generation of reprap/makerbot stepper boards you have.) There are other options, such as using an arduino/sanguino/motherboard together with some higher power stepper drby Larry_Pfeffer - Reprappers
Christopher, That's one heck of a nice hardware starting point! If the motors and their amps/controllers are still functional (and you can work out how to command them, you'll be over a mahor hump. IMHO, you top pripority should be fuses/breakers to prevent repeat electrical damage, and limit switches to help safeguard the mechanicsAre you doing this solo, or do you have team-mates? IMHO, deby Larry_Pfeffer - Reprappers
Greetings forum admin(s?), The green reprap logos (top left corner of all forum/subforum pages) used to act as a link to the main reprap webpage, . That's no longer the case. Some forum pages (e.g. the one on the top-level, ) no longer function as links at all. Other sub-forums, like do have logos that still function as links, but they seem to link to the TL forum page, rather than to tby Larry_Pfeffer - Administration, Announcements, Policy
Viktor (et al) Interesting speed numbers. What drivers are you using that can handle 60 volts for full/half step? That's considerably (5x) higher than the 12 volt rail used by the stock reprap stepper boards (both current and prev generations) and a bit higher than the H-bridge chips I've used to date. I'm looking for a different power supply so I can try running my steppers faster. -- Laby Larry_Pfeffer - General
PET needs a fairly high temp to extrude. If I recall, it's above the (stock) thermister's range, so using it would require a thermocouple (or a platinum) temp sensor. I think PET welding rod is available; don't know if anybody's tried it yet. As for recycling, many have talked about making a machine to melt/reform bottles/other PET disposable items, but nobody has gotten that working reliablyby Larry_Pfeffer - Plastic Extruder Working Group
Ryan, Google is your friend; learn to use it! your Dura-Lar is apparently a polyester, as is Mylar, if memory serves. I suspect your professor is correct; Mylar is a trade name, and I suspect that Dura-Lar is also. Here is an MSDS for Dura-Lar, which gives some composition details: HTH, Larryby Larry_Pfeffer - RepLab Working Group
@Lionel, The meat grinder notion is an interesting one. The old-style ones were all metal, which would be good for heating. (I'm a bit concerned that once heated, you'd have to always heat it to get the parts moving again, since the re-solidifyed plastic is quite strong.) I'd try that, but the only metal meat grinder I have is one of the few things I have from my maternal grandmother, so I dby Larry_Pfeffer - General
Greetings all, One way to increase max. step rate is to increase the voltage used. A higher voltage rail gives a faster rate of current increase (for a given inductance.) However, first check what your drive circuitry can handle (though it's probably substantially above the +12v that the current reprap designs use.) HTH,by Larry_Pfeffer - Mechanics
T3Aguy Wrote: ------------------------------------------------------- > Thanks for the nice reply. > > My real concern is the work volume not weather it > can replicate itself. > > Does Forests RepStrap have a workspace close to > 30x30x30 like the one in the picture I showed? @Forrest: did you mean 28x28x160 cm or 28x28x16 cm? 160 cm is huge (but I've learned that youby Larry_Pfeffer - Reprappers
T3Aguy, First off, glad to have you with us, interested in RepRap. Forrest is too modest to toot his own horn, but I'd particularly recommend reading his blog. His machine is an alternative to the Darwin design. It's a repStrap, so its design goal is not to be a machine that can replicate its own parts exactly. However, it uses parts that are inexpensive and readily available. (uses woodby Larry_Pfeffer - Reprappers
Greetings all, I like the idea of a prize (or series of prizes) to help motivate the development and wider adoption of making useful things (e.g. via reprapping.) As far as prize criteria go, it is unfortunately quite hard to design explicit prize criteria that do not motivate behaviors we don't want. (Assuming, for the moment, that we even agree that secrecy or adding a massive, otherwise useby Larry_Pfeffer - Kartik M. Gada Humanitarian Innovation Prize
T3Aguy (and anybody else who has seen this warning), With what version of Firefox (and on what O/S did you get this warning? FYI, Firefox 3.0.12 on LINUX (kernel 2.6.9-78.0.13.ELsmp) doesn't give me any such warning. -- Larryby Larry_Pfeffer - General