I haven't gotten one completely right from memory yet, but... IIRC, the first thing that doesn't always work is getting the serial chain to sync. This is usually a problem seen during checkout of the boards. Second, there's often a small delay in transmitting a move around the ring, causing delays and possible "bloat points" in the extrusion. That is probably the biggest reason to investigaby SOI Sentinel - Controllers
Hi all, just trying to jog my memory. I know we've seen PLA, polyactic acid (?), CAPA, and HDPE as materials printed so far. I know that ABS has been on the materials list, but either I'm searching wrong or I haven't found much documentation on any testing (although I think I remember references in Forrest's blog about ABS but no results). I know that RepRap will move into a bit higher leaguby SOI Sentinel - Mechanics
They've made one part, and IIRC the dimensional accuracy wasn't quite up to par without some manual adjustments. A lot of current research is on consistencyby SOI Sentinel - General
OK, TIME OUT. Much of the work being done is for a future upgrade to the RepRap system. Yes, some of us are going different directions, but we're also trying to get this right. nophead and I do NOT have the idea of a pure reprap. It's gotta be robust, and those parts it does not make itself must be easy to work with. It's meant to do additive parts production. Zach and the main dev team iby SOI Sentinel - Controllers
Not a bad idea nophead. I'll be doing the same myself after this post (probably). I have a different method to my madness than the normal RepRap group. I know Forrest has migrated to a single PIC18F processor. I'm aiming for what may be the start of an open source generic machine controller someday. I've seen several start off as a "cool project" on the CNCzone boards but they've always disaby SOI Sentinel - Controllers
IIRC, in CAN, you count your ACKs to the transmission since all CAN communication is broadcast, it depends on the reciever to filter the messages to see if they're appropriate for the node. In most integrated solutions, this filtering is fully automated. THAT is the primary advantage of CAN. A disadvantage is that it was made for engine work. It's meant to be fast and deterministic. It onlyby SOI Sentinel - Controllers
Thanks for the feedback, Here's what I've decided on in the meantime (subject to change upon final routing requirements/headaches).by SOI Sentinel - Controllers
It's a lot of inverse kinematic math, Russ, and some closely synchonized motors. Not necessarily hard, but to keep things moving slowly you'd have to probably do all the motor control in a single higher end embedded CPU. Adurino might do it, a dsPIC definitely would.by SOI Sentinel - Mechanics
Eh, anyone know a bit about inductive sensors? I've heard excellent results from these guys and the basics are fairly simple. Ball bearings + plastic tube + electronics + plastic reader head (notice how this tends to follow Darwin here...) and we might be able to get a good position reading out of this.by SOI Sentinel - Controllers
Stuttering steppers? Since the Nanotec models are dual shaft, try attaching a flywheel. It helps the telescope makers keep their systems moving smoothly. Doesn't seem to affect accuracy too much but it DOES affect top end useful speed. (Addendum) Whoops, forgot to mention it increases top end useful speed.by SOI Sentinel - General
Hey Zach, I've been reconsidering the RepRap cabling issue for future use over the last month. I can't say what you want to do will be optimal, but let's look at an example from my projects. I started looking into CAN networks for highly deterministic communications between my modules (ack I need a design team). There are two standards of connection for this, DB9 (Devicenet) and RJ45. Both tby SOI Sentinel - Controllers
Hi all, This isn't a critical question right now, but let me explain what I'm looking for some feedback on. I'm mucking around with a design for an SBC for RepRap. Power conditioning will be done offchip and final conditioning on-chip. My current board is using a dsPIC33, but an ARM chip could work for someone else. I'm planning on four "slots" on this board. Each slot will be capable ofby SOI Sentinel - Controllers
The Darwin basic mechanical design, while not 100% ideal, is very sound. Once running, the Darwin will proliferate quite quickly. Still, I can think of two good reasons and one other reason to be doing RepStraps: 1) Seed sites. It's much easier to get a RepRap passed around within the borders of your local principality rather than international. If RepRap part kits are made in several sites,by SOI Sentinel - General
You're right, modern engines are still done that way. They specifically use the lost foam method for high initial tolerances.by SOI Sentinel - General
I'm still in favor of a positive displacement rotary pump (aka take a hub, put on pliable rubber slats, and put in a chamber) for metering material into the system and to allow for airspace to act as the primary insulator between bulk and working reservoirs. Just a different delivery method. Testing is neededby SOI Sentinel - Mechanics
I Was just thinking as I work on a motor control test board schematic. Several of the chips I'm using (DSP, motor driver chips, FETs, LDO's, etc) are surface mount. Some very fine pitch, some coarser. Darwin has a stated accuracy of 0.1mm. Using solder paste this is accurate enough to place most parts. As an example, a multi-use head of a solder paste dispenser, a 2 DOF vaccuum tool (vertiby SOI Sentinel - General
the one shown? Starch. Not kidding. The Z-Corp printer (not E&MS) uses a starch based fill. The inkjets provide adhesion and coloring. These things are HIGHLY hydroscopic and need a laquer coating. If you bring an unlaquered part outside on a high humidity day, it gets kinda... squishy. They have decent strength but are very brittle. Their newer, higher end units handle what appearby SOI Sentinel - General
These are just about as expensive, but this might be a more accessible option for RRRF. I'm looking into their other motors (brushed DC and brushless DC) for my own projects. One thing is that they're willing to play ball with special modifications over their in-stock designs.by SOI Sentinel - Mechanics
From what I've seen in the photos, the bigger problem is the mass of granules. The reservoir needs to be decoupled from the drive auger. I think forming more of a feeding funnel with the cylinder itself plus having the larger hopper above with something similar to an automatic fish feeder dumping rough pre-determined ammounts into the smaller feed funnel at regulated times would work to isolateby SOI Sentinel - Mechanics
Phyiscal gear generation is a serious business. I'm curious how smooth or self-leveling a RepRap'ed gear will be without some postprocessing. You may see some serious binding and it'll almost definitely make a racket. I know Forrest has a program and is going to attempt a gear in HDPE. Now, mind you, I've been living in the Land of the Giant Gears for the last two months (big project at worby SOI Sentinel - Mechanics
Given the want to do "high speed" FDM, the current darwin design has many things going for it. Small table space means you can put it somewhere that most other designs won't fit. I personally prefer #3. This is often called a gantry machine, and Tommelise uses it. There's some simple but interesting tricks that a gantry design allows. Not all of them would be useful for RepRap, but the posby SOI Sentinel - Mechanics
Quadrature isn't your only option on any of these chips. Quadrature is very good for being a generic interface to incremental encoders. Its also great for those high speed positioning systems, especially with semi-dedicated hardware. However, all the various encoders I've seen listed here have an absolute output function. No worries over skipped codes, you can deal with a simple numeric rolloby SOI Sentinel - Controllers
Zach: Premade cables are office environment hardware. They aren't moving constantly as in a RepRap. As for my Combicon solution, the 2.5mm models ARE expensive. There are other manufacturers. They're also keyed so you can't reverse them. We'd still need to make the cables first, but once made they will work fine. Moving to the 3.5mm models are actually quite simple. The "economy" modelsby SOI Sentinel - Controllers
Cables are the main failure point of any system. I've used RJ 45 comms cables before. Yeah, they work, but it's really annoying if you manage to cold work one wire inside. It doesn't bother me because I have a spool of 1000' of wire and a crimper. Most don't. Buying spare cables works, but then you have to keep track of where you put them. A somewhat more expensive option that I favor is goby SOI Sentinel - Controllers
Interesting. The specs and capabilities of those chips appear to exceed those of the Austria Microsystems hardware. They also have a US distributor. It makes me feel like they're a more established player.by SOI Sentinel - Controllers
Ok, I REALLY have to suggest this then (for your sliding torque issues): I'm using a few here at work (the N-027 variety) and they're wonderful for low mass motion. They're also fairly cheap. They'll quote you on the website. The sliding table gantry design of Tommelise is very common in all routers. I've dealt with machines made by at least three different manufacturers (one was a test unby SOI Sentinel - Mechanics
I think I can get STL files of most major mechanical parts from the current manufacturers. They'd need to be modified as most are aluminum or steel, but they can help with correct tooth profile for specific belt types. These have STEP formats available I know I have one somewhere that has STL files, I'll have to dig a bit moreby SOI Sentinel - General
I do not know if you can serially program the dsPICs like you can the 16Fs and 18Fs. Check your favorite package. I personally have an ICD2 from Sparkfun electronics. It's cheaper than the official and does not need that annoying phone jack hardware. They also have a "light" version, see here:by SOI Sentinel - Controllers
Most N2 lasers are DC driven witb the transformers charging a capacitor through a diode. Anyway, I found a few links that the laser wanters would be interested in. I lost these at my last reformat years ago. For galvanometer and driver creation... The math behind an X-Y scanner (courtesy of Delta Tau)by SOI Sentinel - Laser Cutter Working Group
There's still at least one in operation. At my alma mater.by SOI Sentinel - General