RepRap: Blog

We needed a clock in the RepRap Lab at Bath University. So, of course, we made one.

It's shown mounted on the MDF build platform from ARNIE - the very first prototype RepRap that we made. See RepRap history at:

blog.reprap.org/2007/02/arnie-gives-it-shot.html

Naturally the hours are in binary...

Full build details and all files are here on Thingiverse.

This is not a new idea (indeed, it's so old that I've forgotten if it was Simon or Nophead who first suggested it; apologies to the true originator if it was neither of them...). But a simple way to improve build quality is to start and end the outlines of parts from within the solid area that they surround. This avoids dwell problems at the start and finish of the outline, and wipes the nozzle on the interior of the part itself as the head moves off to the next outline. All the slightly dodgy blobs, dribbles and so on are left buried in the fill, and don't appear on the outer surface.

At the end of last week Ed and I realised that a simple way to do this is to use the hatch that fills the interior as a guide to what is needed. I've now implemented this in the Java Host software and checked it into the repository. On the right is the new code building my handy SMT-measuring tweezers. This type of object with its thin sections is notorious for generating lots of spurious bumps and string. As you can see there is the occasional lump (easily removed with a fingernail post build), but the quality is much better than before. And it works even better on chunky things like the coat hook.

The way the code works is to identify the extremal corner of the profile in the hatch direction. It then finds the nearest point in the hatch to that. From that hatch point it tracks through the hatch until it finds a reasonably long hatch line (where "reasonably long" == 10 mm or so). It then adds the hatch lines from the middle of that long segment to the outline polygon and deletes them from the hatch. There are other heuristics to deal with cases where it can't find a long bit and similar problems.

The effect of this is to start the outline within the solid (and the middle of a "reasonably long" hatch line is likely to be a sensible distance from the perimiter for that start), run to the outer edge having left dwell blobs and draggy starts in the middle of the solid, run neatly round the outline, and then move back into the middle again (without extruding) to finish.

It's always nice when you can make things better just by changing the software...

I'll play with it for a bit to check it works OK, then do a release.

Labels: blobs, build quality, heuristics, string

Back in March I had a visit from Marcin Jakubowski, the founder of Open Source Ecology. He was over here in Manchester presenting at a conference and asked if he could come and see HydraRaptor, as he wants to use RepRap machines on Factor e Farm. Like RepRap, his project also aims to change the world.

He asked lots of questions and made a couple of videos of my answers for his blog, which you can see here.

I volunteered to print a set of Darwin parts to help get Factor e Farm up and running with 3D printing. I was confident that I would have my Darwin running in time to churn out the parts. However, because I spent a lot of time experimenting with extruder designs in an attempt to get something more reliable, I ran out of time and had to print the parts on HydraRaptor.

Here they are, all 109 of them: -



More details here: hydraraptor.blogspot.com/2009/07/hydraraptors-second-child.

Labels: Open Source Ecology, OSE, repstrap

I had another nutty idea all of a sudden. Would cable ties work as a precision track? So I rolled a very funny-looking gear by hand and found it might. I put a section of it in the jig we use for making Darwin gears, and it came out a little strange but definitely worked.


As you can see, I didn't break the jig or anything - the polymorph (yes, I dyed it black with candle soot) was just a little too cold. Stabbing it with the wrong size screwdriver for a shaft didn't help either. However, it is getting late and I must away. And soe once more to bedde...

Vik :v)

Labels: cable tie, pinion, rack, track

After a long wait, ReplicatorG 0005 is finally available for your printing and simulating enjoyment. Most of the changes have been stability fixes and tinkering under the hood, but there’s also a bunch of changes that should make your life a bit easier (especially if you were using 0004):

* ReplicatorG is now much smarter about serial ports. When you select a machine type that uses a serial port, it will automatically scan all available serial ports to try to detect a working machine.
* You can now explicitly tell ReplicatorG which serial port to use. There’s a “Serial Port” submenu in the “Machine” menu that allows you to select any available port. If you forgot to plug in your serial cable when you started ReplicatorG, you can just select “rescan serial ports” after you plug it in and the port should appear in the list.
* You can now run multiple instances of ReplicatorG on the same machine and have them connect to different serial ports. This means you can now run several 3D printers simultaneously from the same computer! (Pretty handy if you have to, say, print out three dozen pulleys in a hurry.)
* There’s been a little bit of consolidation of the status displays; we’re down to just two separate status bars on the main window now. :)
* The “stop” and “pause/unpause” functionality is now more reliable. However, a word of caution: a stop or pause is not guaranteed to halt the extruder as well; a fix for this will be in the next firmware update.
* There should be far fewer situations where the program blocks; for example, you should be able to exit normally after hitting the reset button on the machine.

You can download ReplicatorG 0005 from googlecode.

Be sure to leave a comment and let me know how 0005 works out for you, and let me know about any changes you’d like to see in 0006.

via the MakerBot Blog

If you run your RepRap on a resonant surface such as a table, you may notice a strange thumping noise. That noise is your neighbours in the flat below banging on their ceiling with a broom-handle.

There are two solutions to this:

1. You can make four of these, or
   
2. You can murder your neighbours, dismember them, and distribute their remains in sealed plastic bags round the wastebins of the nearest large city.

The first option is the recommended one.

These spring feet decouple the mass of the RepRap machine from whatever it is resting on. That considerably reduces the transmission of the vibrations from the machine.

Details and file downloads are here on Thingiverse.

I had a daft idea the other day: It started off with a double-decker RepRap, and ended up with a vision of RepRaps in a 19" rack frame. The RepRap below was building the RepRap above...

In theory, RepRaps should work upside-down or even in zero gravity. The extrusion is forced out in contact so doesn't need to fall anywhere. So, time to get 2 Darwins running simultaneously in the workshop and then get creative with some 2x4. Anyone near Auckland with an unused 19" rack who really likes RepRaps?

Vik :v)

Labels: 19 inch, rack, reprap, stack

I've finally finished a Windows app for stripboard design. If you want to play with it you can read about it and download it here. Have fun! :-D

Looks like we're up again, but the changes may take some time to filter through the interwebs so I'll leave the original alert in place.

---8<-------8<-------8<-------8<-------8<-------8<-------8<-------8<-------8<----

For reasons unproven, our web server has keeled over. Brave technical wizards are hard at work pumping backups through the thin tubes of the international internet. Resurrection will be attempted. Meanwhile:

http://203.96.60.151 contains a temporary old site.

The pages everyone on reddit is trying to look at are cached here (sadly without pictures and frame formatting like there is on the site link above):

Google Cache: http://74.125.93.132/search?q=cache:_vO1qm-t8PsJ:reprap.org/+reprap&cd=1&hl=en&ct=clnk&gl=us&client=firefox-a

And the video is on on vimeo here: http://vimeo.com/5202148

The voting page for the Sourceforge Community Choice Award is:

https://sourceforge.net/community/cca09/vote

There is also an IRC #reprap channel on freenode.net

Vik :v)

Labels: outage, web site

Some were a little puzzled as to how the interior of the no-lathe extruder works. As I'm putting a few together, I took a photo showing how it combines the ideas of a simple locknut thrust bearing and a chopped-up drilled nut being used as the bearing behind the filament contact point. Files now online at http://www.thingiverse.com/thing:765.

Vik :v)

Labels: extruder, reprap, tamiya

Zach's new extruder controller was first used to control DC-motor extruders, as used in the MakerBot Cupcake (and also older versions of RepRap). But it is also capable of driving a stepper, which will allow it to be used with the new RepRap extruder too.

You can find details on the Builder's Wiki here.

Labels: controller, extruder, stepper motor