RepRap: Blog

Ages ago, I put code to reverse the extruder at the end of plotting a sequence of line segments into the Java host software, thinking, "That might be useful someday." I set the default so that it reversed the motor for 0ms to turn the feature off, and forgot about it. Seeing Erik and Nop's post below, I thought I'd better finally try it out...

Above is the result - perfect! (Ignore the dark splodge in the middle of the square; that was crud on the extruder falling into the build; I should have cleaned it first.) Normally there'd be loads of string between the L-shaped nozzle-wipe bit and the block being made. Now there's none.

I'm running at an XY feedrate of 3000 mm/minute. At that rate setting ExtruderN_Reverse(ms) to 200 and ExtruderN_ExtrusionDelayForPolygon(ms) to 400 seems to work nicely.

The delay figure is how long the extruder runs before starting an XY move; this allows the polymer to move back down the barrel to take up the slack.

... a successful days collaboration, see hydraraptor.blogspot.com/2009/11/hacking-with-erik

Before:


After:


PLA on ABS on PLA:

Labels: ABS, ooze, pla, support

For some time we have intended to set up a RepRap Factory at Bath consisting of four machines that will be dedicated to printing RepRap parts for others. We shall then sell these on at cost.



This video shows this beginning to come together. We could drive the factory machines off their SD cards, but it is more versatile to drive them off host computers. But we don't want to dedicate one computer per machine.

It turns out to be pretty simple to drive multiple machines off one host computer, especially under Linux. I just set up one account per machine. All the accounts had their own copy of the reprap.properties file. These were identical except for the communications ports, which were set to /dev/ttyUSB0, /dev/ttyUSB1 and so on.

I then just opened a terminal window for each machine in a separate desktop, executed xhost +, did an su to the appropriate users in each window, and ran the RepRap host software. I ended up with one desktop per machine (hint: put the desktops in the same relative places on the screen as the RepRap machines are around the computer to avoid confusion). I could easily control them all.

The bandwidth needed to send the G-Codes to the machines is nothing special, so even my weedy old laptop could keep up.

I'm pretty sure one could do the same trick under Windows using the Run As... utility.

Faster production means more RepRaps...

Will RepRap work in space? We did an airmile whipround but didn't have quite enough for one of those fancy parabolic flights. So we took the Russian approach and just flipped Mendel instead...

Here's a photo of prints of the same object file in positive and negative g. I would say which one is which but we muddled the order and honestly can't tell the difference.



So it can print in positive and negative g, I guess zero will just be middle ground?

Just in case you missed it over on the MakerBot Blog, Fynflood proposed with a MakerBot-made engagement ring. His girlfriend said yes :-) I shall presume to speak for the entire community and say we all wish the happy couple a long and prosperous life together.

Labels: love, proposal, Thingiverse

I suggested previously that it might be possible to create PCB's by copper plating wire glue to create a low resistance section of track. Also, parts of the glue may be buried beneath plastic to maintain a high resistance, by preventing the plating process in order to make resistors. Anyway, I made a small PCB on our commercial machine, which consisted of a 3mm diameter channel that was later filled manually with the glue. Anyhow, after connecting the PCB to the positive terminal of a power supply and a small copper pipe to the negative, I left it overnight in some copper sulphate solution, with the power supply left at 0.1A (higher currents do speed things up, but the results aren't as tidy):

Labels: circuit, copper plating, wire glue

Mendel comes in at £395 for the lot (in the UK).

Assumptions are:

- Using RS (UK) for bought in standard stock (fasteners, bearings, bars, studding and belts)
- 4 off NEMA 17s, @ £20 each
- RP parts @ material cost of £20 (assumes no commission)
- Thick sheet cost (inc cutting cost) @ £20
- Electronics are Zach’s Gen3 @ £110

Raw data can be found in the Mendel assembly data sheet on the wiki. A tabular summary is also available on the wiki.

Here’s a graphical breakdown:

Labels: costing, Costs, Mendel

Done. Woohoo! The mechanical solid-model files are now complete which means all Mendel designs (mechanics, electronics, firmware and software) are now totally available on SVN:

https://reprap.svn.sourceforge.net/svnroot/reprap/trunk/mendel



For mechanical aspects:

Mendel cartesian bot files (STLs, and even AOIs*) for printing are in /mechanics/solid-models/cartesian-robot-m4/printed-parts

Mendel extruder file for printing is in /mechanics/solid-models/extruders/pinch-wheel/wedge-604

SolidEdge users check the readme in /mechanics/solid-models/cartesian-robot-m4/

Documentation for the mechanical construction to build your own Mendel (!) is now on the wiki. Documentation for electronics, firmware and commissioning is being written now. It’s all editable by anyone registered. If you’re building any aspects of Mendel please feel free to improve the documentation in true open-source fashion.

Here’s another short video ;-) of some of Mendel's mechanical improvements.

Mendel's improvements over Darwin from Rep Rap on Vimeo.

* massive thanks to Paddy and Adrian for their hard work on tying this up. (And also especially to Ed – AB.)