RepRap: Blog

We're having technical difficulties with the RepRap Wiki, so I have worked on the manual on the Github RepRapMicron Wiki for now. First stab at documenting the axis construction is complete and you can access it here https://github.com/VikOlliver/RepRapMicron/wiki/Maus-C-Build-Process

 The finished driver looks nice, but I have yet to test and post final V0.03 STLs - worn out for the day!

Labels: axis, manual, reprapmicron

# posted by vik-olliver @ 4:29 AM 0 comments

I believe I now have all the parts needed for a functional design. I've started an assembly manual of sorts on https://reprap.org/wiki/Maus_C_Build_Process which I am also using to test the final version prints before releasing them. Got the lightbox running, and so here's a complete set of printed parts for one axis driver (3 required):

Labels: fab25, manual, reprapmicron

# posted by vik-olliver @ 4:55 AM 0 comments

The microscopes are a pretty important part of operating the RepRapMicron, so it is very useful to have them arranged in a way that can me moved in and out of position. I've printed a posable clamp that can hold one or more USB microscopes on a single 16mm aluminium pole. This gives a top and side view of the probe, and the microscopes can be swung out of the way just by turning the pole.

This setup allows me to get this kind of view of the work area on my desktop. Side view for adjusting rough probe height is the inset top left, main screen is the downward view:

Labels: microscope, reprapmicron

# posted by vik-olliver @ 10:14 PM 0 comments

The endstop is nigh. I needed a small switch, independent of manufacturer types, with no click and a quick reset. What better choice than a couple of bent bits of wire a la drone. I'm using 28ga 316L stainless ("Vape Wire") here because I bought a bunch for my official (licenced) pyrotechnic endeavours a few years back. So a short length of this gets twisted 8 times into a piece of hookup wire, as you can't solder stainless with 40/60 solder:

 This end gets bent round 180 degrees so that the stainless wire points forward, and to stop it coming undone, 10mm of suitable heatshrink gets put over it.

Two of these wires get clamped against grooves in the drive motor pillars with a 2-hole Metriccano strip, and the free ends are folded over the strip's edge so that they cross but don't touch. You need to shove the strip upwards to take out any slack in the screw holes. I'll update the 3D printed parts in the next couple of days as part of the upcoming V0.03 release.

 

Labels: endstop, reprapmicron

# posted by vik-olliver @ 3:37 AM 0 comments

After much mucking with magnets (just buy 30x10x3mm ones if you can) I've removed and replaced the Stage with the UV source in it (glowing futuristically in the image below). This required far too much faffing around with forceps and flying M3 nuts, so I have added captive nuts to the complementary axis mounting strips in the design.

The UV LED strip is soldered to curly wires with a 680R in series so that the 5V strip runs off the 12V Coolant Flow output from the RAMPS board and can be switched on/off with M8/M9. The curly wires reduce potential drag on the XY mechanism. There is a channel under the Stage Top layer to accommodate the leads, and the LED strip is secured in place with a small dab of hot glue just to make sure.

I've replaced the magnets that go on top of the slide with wide M8 washers because the new magnets are so damned strong using magnets on top was (a) overkill and (b) going to strain the XY Stage when you pull them off.

 Now I have the physical separation and so forth sorted out I can play with timings to see how long I need to set the resin. With that sorted I'll make another batch of slides with resin reservoirs and we'll see if we can deposit a couple of layers.

Oh yes, those of you waiting for a set of printed parts, I'll be working on some mise en place STL files of parts for you while doing all that. Busy, busy.

# posted by vik-olliver @ 6:35 AM 0 comments

The stage for clamping slides to on μRepRap uses magnets. I have a few 30x10x2mm magnets ordered years back, so I used them. Now I need to make another stage, but turns out in NZ/Australia ordering magnets in that size is nigh impossible. It's almost as if there's some stupid restriction.

Anyway, I can order 60x10x3mm magnets. So cut one in half, right? Now cutting magnets is a bad, bad idea. They tend to explode, shatter into sharp fragments, generate toxic dust etc. In other words, my everyday life.

Apart from protective gear, you need non-magnetic tools. I marked out a cut line by scratching in Sharpie marker, having measured with plastic callipers. Score both sides so that if it cracks (and it probably will) it splits cleanly.

Next, out with a fine Dremel cutting disc and the everything-proof filter mask. I used Gaffer tape to secure the magnets to a strip of scrap steel. This stops things flying around, gives clamping area that won't magnetize my clamps, and acts as a heatsink - magnets lose strength when overheated.

It was a very sparky cut, done in many small passes. Looks like I missed the scratch, but I realised a mistake and corrected the mark.

After the cut, two magnets. Clean off fragments and magnetic dust with more Gaffer tape.

Finally, fit into the XY Stage. Damn. Forgot the old magnets were 29mm long, so this is going to take a bit of forcing or a reprint. Still, you get the idea.

# posted by vik-olliver @ 2:23 AM 0 comments

A single LED from one of those cheap UV LED USB strip lights does indeed cure eSun Standard Resin in 5 seconds or less through a glass microscope slide. From directly under the glass it cures a patch 4.6mm x 3.6mm in a little lozenge.

The curing zone might spread out a bit when held further away, or at least I hope so because I need to cover a 4mm x 4mm working area. So I'll fiddle around with the right resistor to make it work with 12V and connect it to the RAMPS board on the output GRBL uses for a coolant pump. It shouldn't be too hard to fit between the two parts of the Maus XY Table, and then I'll have what I need to automate multiple resin layers.

[Update: At 5mm spacing below the slide, the UV LED sets an 11mm diameter patch of resin in less than 10 seconds.]

Now, how to get the bloody stuff off the glass slide...

# posted by vik-olliver @ 8:35 AM 0 comments

So the "Maus" RepRapMicron mechanism still works, and the electrochemically etched nichrome tip that I bent stood up to it all. That's a relief. I could deposit at much finer resolution in resin as I can get down to 15-20μm per pixel with that rather than the rather ragged 30μm pixels that the mechanical process of chipping away Sharpie marker creates. Not so visible for debugging but.

Still, this PNG to GCODE converter works well enough. Might be a convenient way of testing the conductive/semiconductive resins for arrays of LEDs or sensors etc. when I finally get hold of some.

Here's the Maus in the process of doing the print. I'm using the mechanism described here and Arduino/GRBL electronics.

# posted by vik-olliver @ 7:26 AM 0 comments

Just testing out the png_to_gcode generator I've put up on github at https://github.com/VikOlliver/RepRapMicron/tree/main/png_to_gcode and thought you might get a kick out of the "Hello World" I did with it to get my eye back in after a long absence. The points are on a 30μm grid, and Hello World takes 43 pixels, so that's [does maths] 1290μm - about 1.3mm in smug units, 5 one hundredths of an inch in Bronze Age units.

"Hello World" about 1.3mm wide

 

I did bend the etched tip and will have to make a new one, so I don't feel so bad about using the bent one to chisel away a layer of Sharpie marker in these tests. It actually worked well despite the kink, and I'm experimenting with it some more. Stopping the probe tip 10μm above the surface and lowering slowly the rest of the way definitely improves output quality.

# posted by vik-olliver @ 6:16 AM 0 comments

Alright. Relatives visited and recovered, art commission finished ("Kaleidoscope" opens 24th April at Aratoi gallery in Masterton), and other than blowing up the 100W laser cutter life has returned to 'normal'.

Art project required some nifty small UV LEDs, which I have subverted a few of for the μRepRap to see if they will set resin. Just haven't got round to trying it.

I've also created some code to turn a PNG bitmap into GCODE point plotting, which currently doesn't have the dip pen stuff in it but I'll put that in under testing. Monochrome only at this point, though there's no theoretical reason why we can't use multiple resin types.

# posted by vik-olliver @ 11:56 PM 0 comments