FYI ... I purchased an aluminum plate for the Prusa i3 from RepRapSource. It is as flat as I can perceive when checked with the edge of an aluminum scale held across the faces. No visible light peeks through.by TC - General
For some time I've been trying to find information about the viscosity of melted ABS. I kept searching on viscosity but tonight I discovered "material flow rate". My first couple searches turned up the following: ASTM D21398 Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer And this I also found this plain english explanation of "Melt Flow Index" from here.by TC - General
See these links for LinuxCNC (formerly EMC2)... https://en.wikipedia.org/wiki/LinuxCNC http://linuxcnc.org/by TC - EMC2
I wrote this months ago. I acquired a bunch of material for experimentation but haven't been able to work on it. So, I thought I should stop sitting on the idea and contribute it to the RepRap community. Might be a really bad idea, or might have merit. Either way, I hope this will make for some interesting discussion. Motivation ++++++++ I’ve been wondering about the possibility of using infrareby TC - General
Chelsea - QU-BD Wrote: ------------------------------------------------------- > Is it a huge difference vs. the > Makerbot heatsink, no, however it is noticeable. What differences are noticeable?by TC - General
Don't forget that with quadrature you get 4 edges per line. A 1000 line encorer gives you 4000 edges per revolution. TCby TC - Stepper Motors, Servo Motors, DC Motors
I'm in the Lowell area. I'm currently planning a build of PursaV2 + linear bearings. A friend up in the Merrimack NH area may be doing the same. I'm on the fence re: electronics and software. I'm seriously considering R2C2.by TC - Massachusetts, Boston RepRap User Group
I'm thinking about doing the same thing. I like the challenge and learning of trying something like this. If successful then it will also give great insight into the performance of the motor and drive electronics. The lowest cost optical encoders I know of is from Renco: Renco R35i encoder If you know of lower cost alternatives for an optical encoder I'd appreciate a pointer. You could look aby TC - Stepper Motors, Servo Motors, DC Motors
The .pdf of the schematic posted in the GitHub repository has R11/R12 at 1K, thus my comment. At 10 ohms your asking for more current from the AVR than the 20ma rating of the IO pins (no calculations needed - it's in the datasheet). To stay within the limits of the AVR's IO pins would need a 250 ohm resistor. So, this goes back to my original post here. The design would benefit from a high cuby TC - Next Wave Electronics Working Group
Are any of you following the adventures of Hoss over on CNCzone? He's converted his Prusa to dual heads. http://www.cnczone.com/forums/3d_printers/146896-hosss_3d_printers-41.htmlby TC - General
Traumflug... I don't know why you are so put off by 'information' and why you think what I posted was 'opinion'. If you do a few calculations based on the information I posted along with some basic knowledge of IC device IO parameters you should be able to determine that there is a simple zero-cost improvement you could make to your design. Benefit, less heating in the FETs you've already selectby TC - Next Wave Electronics Working Group
A couple of things to pay attention to when using N-FETs for low-side load switching (i.e. the N-FET connects the load to GND). 1) devices designed for high-current and low on resistance typically have significant gate capacitance (a few thousand pf). You need to drive the gate with a lot of current to turn them on / off fast (Igate = Cgate * dV/dt). If the fall / rise time of the gate voltage iby TC - Next Wave Electronics Working Group
Just to echo the comments others have already made I'll suggest you read through this series of blog posts if you haven't already. http://blog.ponoko.com/2010/11/16/ten-rules-for-maker-businesses-by-wireds-chris-anderson-%E2%80%94-rule-1/ This is sound advice. I hope you'll find your way to success. TCby TC - General
This is a low cost (i.e. $40) general purpose Molex crimp tool. While not as easy to use as the higher grade crimp tools it gets the job done when used properly. Molex part number 63811-1000... http://www.molex.com/webdocs/datasheets/pdf/en-us/0638111000_APPLICATION_TOOLIN.pdf The Molex datasheet above lists the variety of crimp part numbers (series) that it supports. Check to see if it will doby TC - Reprappers
I'd recommend reading this paper (or ones similar to it from other vendors) to familiarize yourself with the issues related to oscilloscope bandwidth. TCby TC - Controllers
Ethernet cables (CAT-5e is typical) have four twisted pairs and were designed for differential signaling and with matched driver output and receiver input impedances (i.e. 100 ohms differential). The signals on the stepper motor controller really isn't a good match for this. The signals are single-ended and don't have matched termination impedances. Taking two single ended signals and twisting tby TC - Controllers
Thanks for the follow up posts to my questions about BEEF. I'm pretty sure at this point that I do fully understand what it is, and what the objectives for it are. TCby TC - Controllers
Is there documentation on BEEF besides the Wiki? I've read the Wiki on multiple occasions over the past several weeks. This is largely because I am having trouble assessing BEEFs merits, and not because I don't understand the material on the Wiki. I seriously don't want to detract from BEEF or interest in it and I hesitate to post questions as a result. I do see the need for a modular platforby TC - Controllers
I'm not looking to detract from BEEF but since I learned of it a while ago I've been trying to think about the pros and cons of the approach. I thought by posting this note the people closest to BEEF development would be able to argue the points more crisply. If you stand back from BEEF and look at it objectively how is it different from the current electronics? I think the main thing is the paby TC - Controllers
There clearly are many ways to partition a system like RepRap from electronics, firmware, and software perspectives. My own view is that a microcontroller will be embedded in the RepRap machine. Ultimately, I think that it is hard to predict how simple, or complex, the firmware embedded in the RepRap will need to be. Future capabilities may require more computing resources, and not less. I beby TC - General
I think it is important to look beyond the electronics issues and to also consider the firmware required to make it all work. Unfortunately, the firmware appears to be complicated by the use of a resource-constrained and underpowered micro. I think a cleaner firmware base is needed and the way to get there is to migrate to an ARM-based system.by TC - General
plasmastor A couple of us are working on an LPC1768 based solution. We have decided to start with an MBED module (even though it has some limitations) for an initial prototype. We are in the process of building the prototype hardware that goes around the MBED module so there isn't any significant progress to report yet.by TC - Next Wave Electronics Working Group
martinprice2004 Wrote: > The reason I am trying to promote this way of > thinking is that for many people its the > electronics that are the biggest headache for most > people when building a reprap. PCBs are tricky to > assemble and built up units are expensive and hard > to come by. If we could come up with some > effective way to drive steppers directly from the > PC tby TC - General
I'm trying to get all the parts to do a Mendel build (my first). Does anyone know if it is okay to use dual shaft stepper motors for Mendel? Are there any mechanical interference or other issues that might be of concern? I wasn't able to come to a conclusive answer from the WiKi or the forum posts that I searched. Thanks! TCby TC - Stepper Motors, Servo Motors, DC Motors
I agree that to make the controlled current source practical the voltage supply would have to be varied to avoid wasted power, and in the end PWM of a voltage supply will be easiest. So the question them comes down to temperature measurement, and if we want to use the resistance of the etch to derive temperature, and effective way to measure the current. Thus my suggestion of the current mirrorby TC - General
FYI - I got one of these today... Grex Tritium Nozzle 0.5mm - Overall length from nozzle tip to the other end is about 9 mm. - Inside diameter on the threaded end is about 7.5mm. - The 0.5 diameter hole in the tip is about 2 mm in length. - Above the tip the inside diameter slopes outward to about a 3.5 mm width within about 2 to 3 mm. I'll have to see if I can figure out what the spby TC - General
I certainly appreciate the keep it simple approach. However, I believe that simplicity is easier to recognize after exploration of alternatives. A current mirror MOSFET is hardly cutting edge or rare. Use of such a MOSFET would likely simplify the measurement of current which is necessary to determine the resistance if PWM of a voltage supply is used (measure V, measure I, calculate R). We needby TC - General
aka47 - It wasn't clear what prompted your KISS comment. If there is something specific you find complex it would helpful to know what it is, and hopefully, what you think is a simpler approach. TCby TC - General
If the right solution is to PWM a voltage supply across the zones then use of a current mirror MOSFET might be worth investigating. These devices have a second source/drain junction that will sink a fraction of the current on the primary source/drain junction (a fixed ratio like 1:250th). Connecting this mirror pin to a known resistance and measuring the voltage across it would let us to calculby TC - General