Wednesday, July 20, 2011
This is Gregor Mendel's 185th birthday:
Saturday, July 16, 2011
Surface-Oriented CAD, Math, & Telescopes
One of the many projects eating away at my time has been an alternative approach to programatic CAD that I'm calling "surface-oriented CAD" (as apposed to CSG based CAD, like openscad). Loosely based of the code I had for generating models of mathematical objects, the sorts of things that surfcad makes easy to make are very different from in something like openscad. For example, this is easy:
You can read more at my original post. Some people may be most interested in the final section, in which I discuss my attempts to 3D print a telescope (designed with surfcad, of course) and the problems I'm running into.
Labels: cad, math, surfcad, telescope
Around the RepRap Community 07/15/2011
E0 & E1? Wait does that mean that RepRap now has Hardware side support for multiple extruders? Ohh no, what evil things could this community do with 2 independently controlled extruders? I am sure I will be posting about that in the next month. :) Ramps 1.3 by JohnnyR (His webstore is at Ultimachine.com) has many upgrades over the 1.2 version of Ramps.
-Independent power inputs for the cartesian bot (5A), and the heated build plate (11A). This allows you to plug both sides of the heated build plate into the electronics instead of having 1 line to the D8 and the other to the PS.
-Dual Extruder support, need I say more?
-Unfortunately this is the 1st Ramps that is not made to be etched, but with that loss you get a much easier to work with board. The spacing on plugging in stepper motors on Ramps 1.2 was VERY tight, on 1.3 it's not so tight, not dead easy like a Sanguinololu, but much better, especially considering there is a lot more on the board.
-Marked Servo ports. Ramps does not kill your access all those extra ports on an Arduino, but Ramps 1.3 is the 1st to mark those on the shield to remind you that Ramps really needs 5-6 servos and 2-3 accessories added. Maybe a sd card reader?
Greg's Hinged AccessableWades
The Wades Extruder has been the gold standard of strength and efficiency in the RepRap community for over a year now. I would say 80%+ of all the RepRap in the world run it, mostly because it works GREAT, doesn't slip unless you did a poor job on the hobbed bolt, and is quick to print.
Greg Frost has took this design and brought it into 2011 with a complete ground up redesign. It takes a lot of tricks that we have figured out over the last year and applies it to the Wades.
- You can very securely hold a stepper motor by 3 screws instead of 4, less printed mass, easier to print.
-1 spring on a lever is plenty to tension the extruder, less materials needed
-If your bolt is hobbed correctly there is no need to support the top of the plastic being fed, so it gives you easy access to the pinch point
-It just looks cool
Support Material Manual
RepRap wiki dev Madscifi has done an amazing guide on how to use clay as a support material. The write is up top notch, lots of photos and step by step instructions. I love the original use of skeinforge's new perimeter function!
SD Card Reader for RAMPS and Sanguinololu
Kliment, of Pronterface, Sprinter, & Prusa Mendel fame, has done something really awesome. He has designed and is selling a fully functioning SD card reader for the 2 most popular electronics in RepRap, RAMPS, and Sanguinololu. Many people in the RepRap IRC are using it and I have not heard a single complaint yet.
Printing from SD gives you
-Ability to print independent of your computer (You use a computer that has never been used for 3d printing before, download pronterface and kick start your printer, this can be a life saver)
-Much less pause do to communication, this is not nearly the issue it once was, but people have found that their build quality is even better using SD than with Sprinter alone.
If you want one just message Kliment in the RepRap IRC, or order it though Ultimachine.
StepStick, In The Wild!
Anyone who has been in the community for a while remembers the great stepper driver drought of early 2011. I am not kidding, RepRap production all but shut down for a few months because demand for the Pololu 4988-4983 completely outstripped Pololu's ability to produce them. In responce to this Joem, the guy that designed the Sanguinololu also made an open source alternative to the 4988. I have mentioned them before, but the reason I bring it up again is they are now available on ebay for $14, $1 more than the Pololu with free shipping (from China). Considering their shipping is free and Pololu is $5 minimum, that would mean that it's actually $1 cheaper to get the stepper off ebay than Pololu for a simple 4 axis RepRap. Win for open source!
Tuesday, July 05, 2011
There may be life in the Darwin after all...
Let's see. We have a $19.95 six wire NEMA 23 rated at 0.5 amp/phase wired in series and driven by a low capacity Allegro driver chip with a max rating of 0.75 amps. The whole thing is driven with a $19.95 24 volt power supply.
What you get is 65 mm/sec transition speed on the y-axis with a stepper motor and driver that wouldn't melt the ice in your whiskey. No heat sinks or fans required. The Allegro chip is cool to the touch.
Do you want to read more?