For fun, I found this model on Thingiverse and gave it a go.
It needed extra cooling during the print so I set up some computer fans alongside the print bed to keep a cool flow of air over the part.
The end of the print failed because the printer pulled the model off the bed.
What was happening is because of the short layers at the horns, the previous layer of PLA didn’t have time to cool down enough before the next layer was being printed on top.
This causes the layers to curl at the edges, and this is what happened until the print head pulled on the soft layer.
There is a fix in the configuration of the program where a delay can be added so there is a minimum time per layer to allow the layers to cool properly before continuing. I’ll have to set that.
I finished the print bed. It is a large piece of mirror over 5mm thick sitting on some Hardibacker cement board, with a layer of Painters Tape. The PLA plastic seems to adhere well to the painters tape.
My first run, I purposefully placed the starting point 1mm above the bed. I was nervous about the print head colliding with the mirror face, and I wanted to do a run ‘close’ to the surface and keep an eye on it. The result after about 30 seconds is that blob of plastic you see on the right.
I then set it to the height I thought would be best, and the result is the cube you see on the left!
As a first print, this is utterly amazing. Especially for a printer that isn’t off the shelf.
It is a 25mm cube.
25.00mm +- 0.10mm in the Y direction
25.30mm +- 0.05mm in the X direction
25.50mm +- 0.10mm in the Z direction
The cube isn’t square. It’s parallelogram slightly. I’m pretty sure this is due to backlash. The X-Direction belt does seem a little loose so I’ll have to tighten that up and test again. Failing that, I might have to replace the belts I have with proper timing belts.
The variance in height 25.6mm to 25.4mm is completely in the Y-Direction. This means my bed isn’t perfectly level, and needs to be shimmed up a bit on the one side. Also the extra 0.5mm in height means I need to adjust the Z-Steps/mm, which isn’t unexpected because I just ball-parked the value.
I also noticed during the print a lot of vibration of the entire unit. I will need to push the printer up against the wall and brace it, also the speed and accelerations set in the software will need to be adjusted. They are pre-set for a small light moving machine, and not a large heavy one like mine. So I will have to adjust and tune those values over time as well if I want to prevent a lot of jerking around.
Overall I’m really impressed and pleased with my first print. The temperatures seem to be good, the PLA is sticking to the bed, and the extrusion rate looks good.
I got my hands on a power resistor, and it didn’t work at all. The power supply was still kicking out.
But Invictus Lemming (friend of mine) was kind enough to give me another power supply to try out.
Bad news is, I did something I’ve never done before in electronics. I hooked up the power backwards.
POOF! Smoke came out of my circuit board.
So myself and a couple buddies didn’t get to test out the printer. But we were pre-occupied by Invictus’s Occuls Rift anyway, which is awesome by the way.
Good news is, the thing I fried was just a diode, which I happened to have an extra one, and I replaced.
Printer is back online and working now with the new power supply, and it appears to be stable.
Last part I need to do is the print bed, and the real fun will begin.
So after all this, it looks like I was all ready to get printing. All I needed was my print bed to be in place.
Fail. My ATX Power Supply is now acting up. I guess it’s the combination of the 3-Axis + Extruder + Heating Resistor is causing it to randomly shut-off.
I don’t think I’m pulling too much current. It’s rated for 15A on the rail I’m using, but from what I’m reading online, it appears I will need a good load on the 5V line to make the power supply function properly. It looks like some use a 5W resistor, and others a lightbulb. I have that laptop fan on the 5V line, but it apparently doesn’t pull enough current.
I don’t know if I’m too keen on the idea of dissipating 5W of heat just to make a power supply function correctly, but it’s either pull apart my power supply and put in a few dollar resistor, or go buy a proper 12V 30A power supply for $50-$70.
So good news, I have the Print End together on the Printer.
It’s all wired up, and appears to be good. Before I mounted the hotend, I ran some of my PLA plastic through the extruder and took a look at the steps/mm. Which means that if I ask for 1mm of plastic, I actually get 1mm of it. Surprisingly it was dead on without any changes needed. I even had the extruder wired up in the correct direction first try.
The thermistor is responding well, it appears to be accurate. I heated up the hotend in steps and kept an eye on it. I ran the temperature up to 180degC eventually and I was able to push by hand the plastic through and extrude my first pieces of plastic.
I then allowed the extruder to push the plastic through, and everything seemed perfect!
The large aluminium thing on the left is a laptop 5V fan to keep the top of the J-Head cool.
I also had to get creative with mounting the spool of PLA.
This was the scary part so far. I’ve read a lot of people burning up their hotends, usually due to thermistors not mounted properly and falling out, etc.
So what I wanted was to find a glue or epoxy, that’s high-temperature (>300degC) AND it had to be a good thermal conductor.
The stuff exists, but you won’t find it in your local hardware store, and finding a Canadian supplier online was just proving futile.So I opted to go this route.
I have some Arctic Silver. It’s a good thermal conducting compound for mounting Heatsinks to CPU’s, the problem is it’s only rated for about 200degC, because it dries out, and it isn’t a glue. The other stuff I have came with the hot-end itself, and that’s just standard muffler putty. My worry is I have NO data on how well this muffler putty conducts heat.
So what I did was I put some Artic Silver on the inside of the heating resistor and the thermistor, and I used the muffler putty on the outside to hold them both in place. Hopefully the Artic Silver will allow heat to conduct well, and the muffler putty will keep everything in place.
The good news is the thermistor seems to react quickly and well to changes in the blocks temperature. I brought the block up to ~50degC using a 9V battery, before I noticed the battery itself was getting up to about 50degC too and I quickly put an end to that.
So the program that is loaded into the Arduino is referred to as the ‘firmware’. The firmware I started with was called Sprinter. It is fairly basic, and I started with it as a learning point, and it was easy to get it to do a phantom print by modifying it to ignore the fact that it doesn’t have an extruder/hotend attached.
But I had to upgrade to the more sophisticated version of Sprinter called Marlin. The reason being is my Z-Axis Endstop. The stardard placement of the Z-Axis endstop on most home-made 3D Printers is at the bottom, where the printing table is. Mine is at the top, because, well I don’t have a table yet, and mounting the Endstop at the bottom of it’s stroke AND making it adjustable for when I do put in the table would be a royal pain in the arse.
So I opted with what’s called a Z-Max Endstop, instead of a Z-Min. The bonus of this setup is I also don’t have to monkey around with mechanically adjusting the end-stop to accommodate my printing bed. I can adjust it in the software with just a number. The other added bonus is that when the printer wants to ‘home’ itself, it pulls the printing head up away from the bed and any existing part, preventing a collision. The only danger is I have to be careful about that number I set, or otherwise my print head may attempt to go through my print bed.
But to support this Z-Max Endstop setup, I need the Marlin firmware, and Marlin was giving me a lot of grief initially just to get the axis moving. So I spent an entire evening in the IRC #reprap channel, and two gentlement were kind enough to help me out, and I got it working.
With the Endstops all in place, this means I can actually ‘Home’ the printer. This means instead of just manually telling it where to go, the machine can now know where it is in relation to everything else, and move on its own.
After some monkeying around with the software to get it to ignore the fact that there isn’t a printing head on it at all, I was able to make it do a Phantom Print.
What the printer thinks it is doing is creating a 20mm calibration cube. You will notice it do the outer edges first, and then zig-zag on a 45deg angle to create the interior fill of the cube. You may also notice the Z-axis isn’t moving, more on that in the next post.
I’m lagging behind in my updates, as I’ve hit a few snags. Ok, so where did I leave off. Ah yes, I got the three axis functioning. I then went on to get my optical endstops working, and I ran into trouble. I hooked them up thinking they were industrial proof, and I burnt them out. Who would of thought that these things were only rated for 1.5V. So the 5V I gave them ending up burning out the IR LED that is built into them. I’m also kind of glad I’m not using them, because with some testing I noticed that they respond to ambient light way too easily.
So off to Newark (online electronics supply) I went to order some mechanical switches, and some metric hardware so I could have everything I need to assembly the extruder.
This is when I hit my second snag. I guess I’m not too well versed in how Newark works, because I ordered what I though was basic mechanical switches and metric hardware. With what I found out ‘after’ I ordered it had a 1 month lead time. I wasn’t willing to wait that long. So I went to my local electronics shop ‘Sayal Electronics’ and I picked up three mechanical switches, and wouldn’t you know, they also had metric hardware. I also had to make a stop at Fastenal to pick up a M3 and M4 tap.
Tapping the Mount
So as you can see here, I’ve tapped the Z-Axis to prepare mounting the extruder. I ran into trouble tapping the holes for mounting the new mechanical endstops, but a good co-worker of mine let me borrow his tapping ratchet that made it much easier to tap a hole in the corners. After breaking the M3 tap near the end and much pain and trouble having to actually crawl INTO the 3D printer volume to get at the area’s I needed to. I finally got the extruder mount and all three endstops in place.