The only POSSIBLE advantage is that the Gumstix is roughly equivalent to a PDA, therefore should be quite low power. Perhaps the Linux mini-notebook environments (Eee PC running Linux or perhaps the Everex mini PCs with gOS) would be a good high level controller.by SOI Sentinel - Controllers
I might as well toss in my two cents. I wanted to hold off on this until I determined if it was feasible, however. PIC24FJ256GB106/108/110. TQFP 64 through 100 pin packages. 16 MIPS 16 bit MCU with USB On the Go and available FAT 16 and Host Mode Mass Storage code to start with. , Remappable digital peripheral pins and a charge time measurement unit (CTMU) connected to the 16 analog IO. 16by SOI Sentinel - Controllers
Yes, encoders can be expensive. To get the same resolution that's already in Darwin on a cheaper, lower resolution stepper, you'd have to go to a microstepping driver. Not bad, but possibly not the simplest approach. The advantages of having an encoder option as an incremental upgrade I see is like this: 1) Simplest is using it for position verification. This will become more important as Reby SOI Sentinel - Controllers
I've been thinking on closed loop motor control a bit. While I'm working on some fairly beefy DC motor drivers on and off, I keep worrying about them somehow destabilizing a computer PSU's switching control loop. Brushless is somewhat nicer to the PSUs, but are a bit more expensive and require at least 50% more hardware to run. They both get great speed, but pay for that starting torque in higby SOI Sentinel - Controllers
A switcher would be nice, but they're usually require more parts and you have the possibility of adding noise if you don't have the outputs filtered. Nophead's also right in that the power pull is so small that it won't be missed. I'd guess about 50mA at 5V for the logic going up hill with a headwind.by SOI Sentinel - Controllers
Gosh it's been a long year... and nothing to show RepRap wise (life + work...) Anyway, I thought someone would be interested in this. If you can handle TQFP-64 chips at least. Rabbit RIO. With a 40MHz input clock, it can operate at 10MHz. SPI mode. 8 channels that can be configured in many ways but most importantly as a full H bridge per channel with short circuit protection and 16 bit Pby SOI Sentinel - Controllers
If the ground connection is pulled from a PC PSU, you can parallel the PSUs safely. HOWEVER, especially with DC brush motors, your standard switching PSU may have an overcurrent fault develop. This will definitely vary with peak torque/amps of your setup vs the rated ability of the PSU, however. Unregulated Linear power supplies (transformer-rectifier-capacitor) are recommended usually for motby SOI Sentinel - Mechanics
Ack, no. He's looking for a replacement material for the PTFE thermal barrier for the extruder. Right now the RepRap is thermally limited from attempting to extrude some of the traditional engineering plastics as the required temps will melt the PTFE. Shell foamed ceramics may be useful as the air space will improve the thermal isolation. I suddenly have an urge to go and find a lava rock.by SOI Sentinel - General
That's actually what popped into my mind when I first saw it. Unfortunately, it's not something that's going to be self-replicatable anytime soon. No matter, it's an idea. I might have to see about picking one up. This is exactly how the Stratasys does it after all. Although I don't think you'll be pulling a turkey out of one anytime soon. I think the biggest thing that makes me wish thatby SOI Sentinel - General
I do believe that the only appropriate support material would then be... stuffingby SOI Sentinel - General
I know that the RepRap must be able to duplicate its own parts and must be able to work at room temperture but I live in the land of Menards home improvement stores and their odd selection of afterthought items, and they just put an 18 quart turkey roaster on sale for $20. I'm almost tempted to get it and build a frame for an XYZ head out of alternative material to fit within its envelope but wiby SOI Sentinel - General
I've read the posts over on the Hydraraptor blog about using a toothbrush head and a knife to clean up the expanding extruder material. nophead's now partially melting his toothbrush, and it still requires you to trek halfway across the machine to clean up. Not a concern when you only do it once or twice a part, but I can see issues if you need to clean up when doing discontinuous extruding. Hby SOI Sentinel - Mechanics
Wait, you haven't FDM'ed yourself an auto-lube system yet? Yeah, I'm probably high on my nut calculations, and I'm working on an Excel sheet (although I should probably move it to an OS Matlab clone) for testing out different efficiency ratings of various thread types and pitches. I'm actually thinking of working with 3/8-16 rod. Higher inertia will absorb vibration better and it's capableby SOI Sentinel - Mechanics
There will probably be a small bit of vibration. That's normal for non chopper/non microstepping driver setups. The torque/current is high at the edge of a step and it drops as it centers, and it'll usually oscillate past and back again due to the rotor inertia. I'm planning on a Tomellise 1.0 style design. I have other uses for the structure beyond RepRap, so the structure has several advantby SOI Sentinel - Mechanics
A 15x10" work area? Pretty decent. Congrats and good luck! (BTW, my only personal issue with the Mcwire based designs is the vertical stiffness of the Z axis, just keep an eye on it!)by SOI Sentinel - Reprappers
Hi all, thought I'd post a picture of our old (and 2nd hand) Hermes engraver. The pictures are 1.3MP, so I'll leave it to the bored or broadband to select. Cross slides are sleeve bearings on one side and roller bearings at the other end.by SOI Sentinel - Mechanics
If you're building a machine from the start, with known machining tolerances and mechanics, you can determine your torque. Here I'm looking at what people have found useful in their Repstrap experiments. We also have to look at torque for the extruder, something that's being experimentally gathered. I look at various drive mechanisms. Now, the losses in Acme and related screws are well docuby SOI Sentinel - Mechanics
Inversely, you COULD use the RepRap software to run a CNC machine. All voids would have to be fully accessible from the top. You'd have to take and boolean subtract your object from a block. The only other software modification I can think of is that the system would have to bring the tool to it's Z+ starting offset whenever transitioning from one "extrusion" start to another. RML-1 and PLTby SOI Sentinel - General
Rock, While they need to be tested, It's now apparent that most PC PSUs can be series and physically stacked safely if the case ground is severed. Old article, but it should still hold steady. I'm starting with the old AT PSUs I have laying about to verify this first. Many modern ATX PSUs have multiple 12V rails that can be tied together (parallel, not series). The rails usually average 15Aby SOI Sentinel - Controllers
I'm poking around asking my search for good motors, but it's got me wondering, how much torque do we need? How much do we want? 1kg-cm = 98 mNm = 13. oz-in = 0.87 in-lb There's two different drive methods in common use. One is the Darwin belt drive, the other is the threaded rod drive. Solarbotics motors are doing something like 40rpm and 100oz-in before clutch slip. Nanotec steppers are doby SOI Sentinel - Mechanics
I think I'm going to have to track down my local ACME rep. We've used them before at work as a good but not excessively expensive transformer supplier. Their 24VAC transformer line goes up to 1kVA. 40A continuous is definitely capable of support anything I think we'll see and this shouldn't exceed your standard recommended single phase loading or outlet loading. They're even 120/240V input. Iby SOI Sentinel - Controllers
That is exactly what I'm expecting. Plus, as RepRap adds new head capabilities (coughzachandhislaserscough ) I suspect we may start seeing random failures from voltage glitches if run on DC brush systems. Could always split the difference, low cost 7.5 deg/step steppers run in high pole count brushless DC mode with the right controller and an encoder. Thoughts for the future, be it quiet andby SOI Sentinel - Controllers
I took the cover off a 200W AT pSU I have sitting around. Single sided (as expected) and several safety/noise parts have been removed and replaced with jumpers. Found out that the mounting screws are the only connection of ground to case. I'm working my own electronics design, with the motors and probably the heater going on a separate power bus than the electronics. The mains transformer iby SOI Sentinel - Controllers
Sharp blades belong to nophead so far. I think a small milling bit in a 30krpm rotary tool works just fine. Or for even more fun, a fiber reinforced cutoff wheel. There's a lot of discrete parts in that PSU. Figures. Nophead's idea may work, and I think we'd all love it if it does. Anyone have an ATX they want to crack open and look at? I have access to several AT supplies here, so I mightby SOI Sentinel - Controllers
mmm... lunchtime It would work for testing, but yes I'd not want to touch that system as "production" either. If the grounds can be separated (possibly), then we're safe. I know this is possible if they're using a full bridge topology switching power supply. This would also transformer isolate one side. Anyone know where we can take a look at schematics? I'm almost tempted to look into builby SOI Sentinel - Controllers
Viktor: Yeah, I figured that may be the only way to clean up the system emf: What you did with the ATX supplies may work fine actually. I'll have to tear into one later and see if the grounds are shared. If they are, it could have been you got lucky by not having the supplies grounded to each other. If this can be easily "broken", it would be great. As for brushless, a lot of the RC brushlby SOI Sentinel - Controllers
I've been poking around power supplies for a while and have been seeing what I can get for amperages. A lot of higher torque DC motors pull a LOT of amps for 12V models (60A stall for the ones I've found new so far, but they also top out at over 20000rpm, too), and I think "low cost gearbox" is an oxymoron. I'm waiting on testing of the strength of RepRap'ed gears before final judgement on thatby SOI Sentinel - Controllers
Dissection time! 1) See pin 18? P1_INT. External interrupt pin for my dsPIC. 2) The pair of resistors are there for 2 bit slot addressing of the I2C EEPROM plus whatever else I need it for. 3) Well, I'm considering another chip select, but since this is not hardware defined on my platform, I can use any of the IC/OC/PWM pins that aren't used for motor control as a CS line. 4) The card is rby SOI Sentinel - Controllers
Actually, the suggestion is to use plastic and fill in with a layer of powder or crystals. Sebastien does have a point, unless the plastic touches other plastic, it will slide as the filler will act like a greased surface. You'd have to almost use some fast/safe solvent-solute base system to melt away. Dissolved sugar is an example, but it'd take too long to resolidify and would leave a mess.by SOI Sentinel - Mechanics