RepRap: Blog

I've been making a few new probe tips. Keep 'em all safe in a little box like this:

You can't tell with the naked eye what the tip looks like. I thought I'd try making a couple consecutively and see how different they are. I've experimented with just running the electrolysis on the probe wire until the tip just falls off, as in this picture:

And letting it run for a just bit longer like this:

 

Both of these are 0.29mm 306 stainless wire from the same batch, etched in 5% salt solution with 3xAAA batteries in the same jig, and the photographs have been taken at the same magnification with the same microscope and lighting.  While the first one has a much longer thinned shank, it is interesting to note that the tips end up coming to much the same size and sharpness.

Frankly I was amazed at the difference in profile from much the same process. I do not yet know how this will affect the probes' resin-carrying ability, but I suspect the thicker probe would deflect less when used to mechanically interact with items on the print bed.

 Better make some new print beds and test them out...

Fast approaching the point where μRepRap is going to need an interface for direct manual manipulation rather than micron precision. Using conventional CNC jog interfaces just won't cut it (ahah). It's going to need a more complex motion control system, and I say gamers know about that already. So enter pygame.org

The idea here is that this is a widely used platform that's relatively easy to use. μRepRap seems to have fallen into python somehow anyway so may as well make the most of it. The graphics we'll need are pretty minimalist as the user will mostly be looking at a microscope, and pygame provides interfaces to the joystick/controller of your choice.

That's the vision, commentary and criticism welcomed. Two things need to be done before I start on that: FAB25 μRepRap presentation in Prague, and demonstration of multiple layers. So if I'm quiet on the blog for a bit, it's because I'm flat out doing that.

 

That day in 2008 when we announced successful replication to the world. Made a bit of a splash.

 

The plan: Get some of this fine fake gold foil, which is basically ultra-thin brass, and burnish it onto a glass slide like I do 30μm aluminium foil.

Then carve into it with the probe tip to make conductive traces, either in lines or little dots much as I've done with Sharpie marker. I have already poked holes in foil, and others have made macro scale circuits from fake gold foil, so the principle is sound. You can even solder onto it.

If I do all this near manually scored lines, I should be able to construct contact pads. Then I can use the probe to do things like add ionic gels or active resins etc. across conductors and create circuits. With gels that would be done by diffusing the copper into the gel electrolytically. Other options include creating photosensitive components from copper sulfide and so forth.

It's on my Amazon wish list...

 

The previous Flexure Coupling was a bit too stiff, and also perched the connecting nut right on top of the coupling. This in theory allowed a bit of play for self-centring but but in practice this needed a lot of manual (and physical!) adjustment. As I noted when building a μRepRap for someone else with proper limit switches etc., it also tends to strip when you hit the limit, and have forgotten to connect the switch. Amazing how your attention focuses when you're actually going to hand something over to someone else. So, new version:

 

This one completely engulfs the nut in the tapered cavity, and has much thinner flexures. This gives more lateral play for removing wobble. Note that this flexure design doesn't tend to twist and introduce backlash. Quick test shows they centre pretty well, so I'll install a set on Maus #2 and see how they go.

The buttpain here is that the coupling now needs to be printed with a brim as it is too delicate to stay on the bed otherwise. So I have to redo all the build files in git, rebuild and upload the build plates, take new photos, and update the build and calibration documentation. Damn.

The Maus C needs to be mounted on a baseboard of some kind to provide additional rigidity. I'm using lasercut acrylic for the top because I want to see in, and MDF for the bottom because it's cheaper. I'm using two layers so that I finally have somewhere to tuck the electronics, and remove the Bloody Great Chunk Of Plywood from its resting place on my desk for the last year or so.

I made my boards a little too short, and have added a couple of extra holes to the ones on Github. I'll add the pillar and feet designs when I'm happy with them.One "Gotcha" is that the Z motor needs to come off to install the pillar in that corner, but that's not as hard as it sounds and I'll live with it for now.

I've been adding up the Bill of Materials on Amazon, as ordered from New Zealand (to be honest, a really crappy place to order things from) and it came to about NZ$300, or €160 without the USB microscopes. You could do those for around $120 if you go for bare minimum resolution, and I'm assuming you've got a few wires and minor items around like glue etc.

 I was pleasantly surprised to see that you can still get the RepRap RAMPS kits for around NZ$33!

Quick update. The FAB25 RepRapMicron talk schedule is up:

RepRapMicron - Micrometre scale 3D Printing from scratch

RepRapMicron is going to be presented at MIT's FAB25 in Czechia in July, which involves me doing a presentation, show and tell, and two workshops. Hence lack of blog posts while I sort that out.

Anyone else going? https://fab25.fabevent.org/

With an astounding total of 253 fasteners, the Maus C Alpha "Bill Of Materials" has arrived to accompany the build docs and full release of pre-built STLs.

https://github.com/VikOlliver/RepRapMicron/blob/main/maus/Maus_C_V003_BOM.csv

 

The construction section of the manual is now on the GitHub Wiki here https://github.com/VikOlliver/RepRapMicron/wiki/Maus-C-Build-Process and will be transferred to the RepRap Wiki as things progress. So that means I've had to build another one in order to document it and work the bugs out. I also didn't like the Z Tower so I redesigned that. I still have to upload the as-built OpenSCAD files and STL print sheets. Here's the happy couple:

 

And in case it's not clear from the photo, that new Z Tower (will upload tonight after housework is done) which replaces the god-awful assemblage of brackets and Metriccano beams: