Wiring is go. I have checked and double-checked the resistances, and the look fine. I'm concerned about the big black (12 PSU wires together) and whether it's really properly connected and going to stay there. Otherwise, looks good.
More problematic is the extruder hotend. As I mentioned earlier, bits broke off when I was fiddling with it. Having stiff wires coming out horizontally is not really the smartest design. As the photo below shows, some crucial wiring is missing. The wires on the left (which are kind of loose) measure 10 Ohm across them, so that must be the heating element - the thermistor should be about 100 kOhm. I'm slightly surprised to see no hole in the screw inside the right-hand hole. I'll have to try to unscrew it and see what comes loose:)
The X belt on the right also looks... different. Is it really supposed to slant like this:
Time to add the power supply, now that all the wires are hanging prettily out the sides. It's slightly tricky to get it in with the thick bunch of wires coming out the back side. First the washers in the right-hand bracket were in the way, so I had to use smaller ones. The wiggling in and out while figuring that out was enough to break the top notch, so now it'll get fastened with one screw only. By bending a piece at the back and putting the PSU in from the top, I was able to get it in both brackets, but it wasn't happy with going all the way in on the right bracket due to the screws on the fan guard.F Finally squeezed it in with a clamp. Alas, the screws for the PSU mount are neither M3 nor M4, but 6-32 (whatever that means). I just plopped in an M3x20, which should hold up by tension alone.
Don't have appropriate wood screws for the resistors either, so I drilled M3 holes for bolts instead. I hope I didn't get too much MDF dust into the PSU this way. Also, it turns out these resistors are slightly bigger than the ones the holes were placed for (see picture below). The M3x20 screws were almost but not quite long enough for this. Instead, I found some M3x30, but with 3mm hex head, which we don't have a bit for. So screwing in by hand with an overly long L hex. Bother.
The wires on the inside are rather squished. If I were to make another of these, I would make the Y axis a bit longer, so there was room enough for the wires to breathe.
Had to extend some of the wires a bit. Got the big honking power wires set up, and the Melzi mounted. Next time, wires!
My fears were grounded - the wires to the hotend fell off. Need to get a new one, I guess. On the left side (taken from below), the thermistor wires are top-right and bottom-right, and the hole for the hotend itself is on the bottom-left. On the right picture, a lost hotend connector.
Fastened the extruder on the carriage. For lack of wing nuts, I used normal nylocs and a long pair of pliers:
The sideways mounting of the connector on the X motor got in the way. When I tried to move it to live on the top, it turned out FabLab has no PZ1 screwdriver or bit that isn't horribly stripped. So for now the connector still lives on the side, but I need to remove it if I am to remove the extruder:
Adding the fan was a bit fiddly at first, then suddenly easy. Probably by way of bending the thermistor cables.
I lasercut a little piece of wood to trigger the X microswitch before crashing the wing nuts of the extruder into the X axis bearings. My machine now has duct tape on it, as is proper:
The fan connectors from my extruder are wrong, they have red and black on the outer sides of the plug, not lining up with the markings on the X motor connector.
PSU Assembly
The PSU wires are a bit shorter than required, some from previous cuttage, some just from the way they were. A lot of the wires are really thick, I may have trouble getting them into the Melzi (PZ2 bit for scale):
Also, there were fewer wires than expected, but a bonus white one that I have no idea what's for. The yellow wire has a lot of heatshrink on it because I had the piece too close when soldering the tip and it shrank right there. BTW: German for heatshrink is "Schrumpfschlauch" (I kid thee not), but I like to call it "Schlumpfschlauch".
I misread the instructions for the 4R7 and put green on one end and black on the other at first. This gave me the opportunity to try out the solder removal tool that's the right-hand part of the solder box. Worked incredibly well. If I am ever going to salvage stuff again, or just want better soldering irons at home, I want this.
All in all, good progress (except, of course, the hotend). I really hope it's easily replaceable.
Actually, same quality rods, just smoothed out with a metal sponge. I might need to go back to the other rods and do the same.
Y Axis Assembly
Fastening the final nut for the right-hand bearing is quite tricky, since there's limited space, not even enough for a hex wrench. But I got it fastened. It doesn't move very smoothly, but reasonably so.
The hole for the Y idler was too far back - I must have cut the belt too short. Drilled a hole further in and fastened with a 4x20 wood screw. I'm a bit concerned about the idler slipping over time, though, and also that the belt is somewhat far out on the motor pulley.
The ribbon cable for some reason is way too long. I must have cut it wrong - looking at this example, there shouldn't be any spare length at all. But that's not critical, merely messy, so I'll leave it like that for now.
X Axis Assembly
Using a good metal saw is really a lot faster, easier, and more accurate than a Dremel. And doesn't eat the disks, either. And hammering the ends a bit make them nice and rounded for going into the linear bearings.
Re-did the Z axis smooth rods to be smoother. So nice and shiny now!
Tightening the X axis clamps, I hope they're meant to bend a little. Only enough to be visible when seeing a reflection on them. This is the first time I've had a reason to use three hex bit extenders in series:)
Again, the belt is too short. This time, the only solution is to have fewer teeth showing at the ends.
Turns out the adapter holder on the extruder motor was on the wrong side, so had to flip that. At least that allowed me to add a washer I'd forgotten.
Why am I surprised anymore that FabLab doesn't have any M4 wing nuts? Anyway, something is odd: There is a nut trap on the underside of the X carriage, yet the other side gets wing nuts. I guess I have to run a bolt through from the nut trap side. Weird, and not clear from the manual.
I hope I haven't damaged the wires from the hot end by all the manipulation and schlepping around.
My extruder is a slight variation in design from the one the manual expects. I'm going to have a bit of overhang of wing nuts over the edge of the carriage, about 2cm. I should add a bit to make the microswitch trigger earlier.
A very merry Yuletide to all! I hope you are excited about what the new year will bring. For me, if all goes well, it will bring a working printer: at the rate I'm going calibration should start in January and real printing (knock wood) in February -- surely to be rudely interrupted by our upcoming move.
In the meanwhile, since I'll have some downtime away from Internet for several days around New Year's, I'm collecting some educational reading on modelling software - having learned that I can't effectively just try out a few things and then move on to complex tasks with success. So far, I've checked out:
3DTin: Looks somewhat primitive in comparison with the above. Manuals only in video form.
MakerBot Customizer: Sounds interesting, but when I log in I hit a login loop :(
OmNomNom Creator: Only 2D to 3D conversion.
ModelBuilder (Mk2 seems incomplete?): Geometry library. Docs only in raw HTML form, fairly impractical on a ChromeBook.
Google SketchUp - I have tried it and found it initially useful, but prone to difficult gaps.
Sculptris: Possibly too artist-oriented for me, and doesn't have downloadable docs.
Art of Illusion: Aimed at graphics, but supposedly useful for design, too. Has a downloadable manual.
CadQuery: jQuery for CAD programs. Has documentation, but not in a readily downloadable format.
ShapeSmith: In-browser parametric CAD, but no downloadable docs.
Wings3D: Erlang-based subdivision modeler. Interesting concept, no downloadable manual.
123D Design: Commercial, but has a free version (I'd rather not pay until I have an idea what I should pay for). Only video tutorials, though.
...and many more. 3Ders has a long list but with no indication of which ones are the most useful for 3D printing, and includes a lot of graphics-oriented software. reprap.org's list is even longer. And even those are not complete. This is a big field.
Print Bed Assembly: The hex pillars I have just have a hole straight through, so I use M3x30 bolts to fasten them. A bit unclear which side of the PCB was up, but an image shows the side with MK2a turned up, I'll trust that.
It was a bit tricky to get the cable in right. Looping the cable loosely through the clamps before putting bed and dibond together would have been easier.
Again using that weird misdimensioned multicolored Conrad ribbon cable instead of polypropylene. I hope it doesn't cause weird electromagnetic effects.
Y Axis Assembly: Twisted green wires are a little short, but the manual says "about 750mm".
My microswitches have a little "blade" above the button. If it turns out to be a problem, I'm still orienting the button as indicated. Slotted screws are stupid. Throw rocks at them.
I don't see a mouse hole in the right stay (except for the one the motor is using). Around the side it is.
Great! The Y motor wires are way too short. Fix later.
Unclear which way the belt should be threaded through the idler. Does it matter? I know not yet.
Attached rods. The carriage does not slide lightly back and forth. If I don't hold against the frame, the entire machine moves along. That cannot be right. I suspect the odd matte rods I got are too rough, maybe. Could also be a side-effect of the holders not being fastened yet, but I would expect the manual to mention that. Also, the right-hand bearing was to be loose until now, but fastening it while on here is difficult.
Check out in this video how the frame moves along:
Additionally, the Y motor wires come out the top, where they would be better off coming out the side. I guess I misunderstood "downwards", but now at least I have an excuse to take off the motor and extend the wires.
I notice the right-hand rod holders were missing screws. Added, but since those rods were also of the bad kind, I didn't move further on that.
One of the first things to print would be more cable ties. I like a well-organized cable setup, and the printed parts only come with the bare minimum.
Current state of the machine (which should get a name soon):
With that, since I won't have time to do more work the rest of the year, I will just wish you a Merry Christmas (or whichever) and a Gutes Rutsch.
X Motor Assembly: With the M3x45 screws acquired from Schrauben Preisinger, I can now properly fasten the remaining part of the motor holder. Required 4 nuts to span the gap. Due to the hole in the motor being just between a nut trap and a too smal for a nut, I added a washer, but it also kept skittering around the edge, leading the screw to go slanted and push against the holder instead of going nicely in. On my second attempt, keeping it more straight, a crack appeared in the screw holder. Removing the washer made it work, but now there's a big gap around the nuts - one actually dug up into the holder - so that already-cracked piece is now going to get unexpected stress. This piece is now first on my list for replacement once I can print. I can probably offload it a bit by putting some open washers in after the fact.
Fastening the microswitch was a bit tricky - No2 screws are unknown here, so I got slightly bigger ones. Also, Schrauben Preisinger seems to have a predeliction for slotted screws rather than Phillips or hex, which makes it fiddlier. Would be nice to have a slotted bit that fit over the outside of the screw, so it couldn't slide.
Splicing together the wires, I re-learned how to do a good inline splice thanks to this Instructable.
Y Motor Assembly: Since this will be under tension, I re-fastened all board connections with M4x20 screws, adding extra washers to compensate for the extra length. This ain't going nowhere now!
Z Motor Assemblies: Took some of the extra wire from the extruder motor (it has meters and meters!) and extended the left-side wiring across to the right-hand side where the electronics is. Much faster to splice now that I know what I'm doing. Also, putting on the heatshrink before stripping insulation is a lot easier. I'm still not sure which cable ties go where. I'm leaving them loose for now so I can swap them when I can see it.
Extruder Motor Assembly: Finally got the remaining screws. All fastened and good to go.
Z Axis Assembly: Added microswitch and threaded it. Almost stripped the Z markers on the home-cut end of the threaded rod. Somewhat confusing instructions on the couplings, but then my shaft has no flat. Everything of this now mounted and tightened.
Y Carriage Assembly: Got the last two LM10UUs in. Slightly funny that the bearing holders have slots instead of nut traps, maybe that's just an older version. Using M3x20 in general since my M3x16s are slotted. Doesn't look like it'll affect anything.
Print Bed Assembly: Stripped and soldered on the 26-way flat cable. Stripping worked incredibly well with this little snipper - notice the flat piece of metal along one edge.
This one is a Knipex 78 71 125. I may need to get one of my own.
The 2x12 twisted-together pieces need to join with the 32/0.2 red/black wires. I don't even know that designation. It's 0.2mm copper (sensibly) overall diameter 2.5mm. I guess the 32 is strands. Need 635/620 mm of these. I guess another trip to Conrad is in order. My time here tonight is up, anyway.
