Finished MakerGear Heated Build Platform
I ordered a heated build platform kit from MakerGear before MakerBot started selling a pre-assembled one. The MakerBot one is cool, but I think MakerGear's is pretty solid. (not to mention half the price) It does take some time to put it together, though! The provided instructions are great, but I ran into a few gotchas. Below are the notes I took while building it as well as a bunch of pictures of the build process...
Since I have big fat fingers, I find it frustrating to handle tiny bits like the small lock nuts. The top ones need to be screwed into the tight end first. This is hard to do because it's so tight. However, if you screw it in once in the opposite side, it will make threads in the insert. Then you can turn it around and screw it in the other way more easily. I found it best to hold the bolt still with the allen wrench in my palm in one hand, screw on the lock nut, then use pliers to turn the nut around the bolt.
To rough up the washers, I put tape on one side of the washer to have something to hold on to while rubbing it on sandpaper.
It's best to take the small ring terminals off and solder the wires seperately instead of soldering them on while they are pressed against the magnets on the bolts. The magnets could lose strength when heated up by the soldering iron.
The Y stage and ceramic plate mounts are keyed. The 2 that are wider appart are for the thermistor, the ones closer together are for the nichrome.
I had a hell of a time with the crimps. It seems I'm incapable of crimping. Crimps are my arch nemesis. I really need to get a good crimp tool instead of trying to use pliers or this cheapo multi-tool wire stripper/crimper I have.
I couldn't get the nichrome and thermistor wires to push into the solder in the ring terminals by pressing my soldering iron on the wires like the directions say. They just wouldn't get hot enough. I ended up holding the soldering iron against the bottom barrels of the rings for a few seconds till the solder inside got soft enough for the wires to slide in. I was able to do it quick enough so as not to melt the solder under the washers.
When I epoxied the rings to the ceramic plate, I found that I had put too much epoxy on the nichrome too close to the holes. This made it impossible for the rings to lay flat against the ceramic tile. It was already cured and hard as a rock so I had to get out my dremel and grind some of it off here and there.
Lightly sand the kapton film to get better adhesion.
Unfortunately, the yellow kapton film makes it a little hard to read the temp stickers.
To test it, I unplugged my extruder and plugged in the platform nichrome and thermistor in their place. I set target temp to 50C and it heated up and stayed at the target nicely. Then I tried setting the target to 90C and it seemed to get stuck at around 65C and then took about 30 minutes to get to 80C and wouldn't go any higher. That's when I noticed it was buzzing. The plate itself was making a very faint high pitched buzzing sound. Rick suggested that the rings aren't making good contact and to make sure it's level and try rubbing it with an eraser, but that didn't help.
It was then suggested that I loosen the bolts under the magnets. (I had them tight so that nothing could move) That helped a lot. The magnets can now flex a bit to make better contact. It now got to about 70C in 15 minutes, but no higher.
So I tried doing a test print anyway. I plugged my extruder back in and moved the platform heater to the fan port (thats the 3rd port C to the right of the normal extruder heater port). Went into replicatorg and checked the fan box and BAM it hit 90C in about 15 minutes and would have probably gone higher. I'm thinking there's PID control on the B port that was causing it to fail to heat up correctly.
Now I need to figure out how to build a plug to attach the second thermistor to the extruder board. That or buy one of the temp sensor boards.
I'm also thinking of a way to attach a handle, perhaps in the acrylic platform mounting holes that I had Makergear drill in the ceramic plate. Maybe use a bit of a coat hanger to make a hook or something. Since a MakerBot endstops aren't reliable, I have to center the platform by hand and I just know one of these times I'm going to reach in there and forget to use a hot pad!
Everything seems to be working quite nicely. I tried doing a test print, but it failed. Not because of the platform, but because I didn't have it leveled quite right. However, it's getting late and that will have to wait till tomorrow...
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