First to forth test prints
I have put the E3D hotend together (really easy to do if you follow their instructions) and installed it on the printer. Since then I started to do some test prints. I started with a 20x20x4mm piece. The extruder worked brilliantly however the printer had an issue, the Y axis kept offsetting (see first print above – ignore the waviness, I was impatient and pulled it off the bed while it was still hot). I turned up the power of the Y Axis stepper driver (second print). Same issue, again ignore the blob that was my fault. The Y Axis is quite heavy and I thought that the stepper was still missing steps. The stepper for the extruder has a slightly higher torque so I wanted to swap it for the Y Axis motor.
I removed the extruder motor and then started on the Y Axis. As I removed the motor I noticed that the pulley came off too easily. Oops I forgot to put the screw to clamp it to the motors shaft! So what I think was happening was the motor turned but didn’t have the grip on the pulley to move the mass of the bed. I finished the pulley with the nut and bolt and reattached the two motors. Voilà, it worked correctly as shown in the third and forth prints above.
X Axis pulley slip visible on the left print
While I was writing this I was printing out a 40mm dome. It finished printing and a similar thing was happening to the X Axis. It isn’t visible on the above prints as they didn’t go high enough for it to manifest. A new pulley was printed on my Huxley as the old one wouldn’t take the captured nut correctly. As you can see above there was some significant slippage although not as severe as the Y Axis had.
The last thing, which should have been the first, I wanted to do was to do a bit of PID tuning for the hotend. Using the auto PID command M303 in Marling I was able to set the PID to: P 26.84, I 2.48, D 72.57 should anyone be interested in using them as a base for their E3D hotend.
Just in case anyone is wondering the domes were made with Faberdashery’s Aurora UV colour changing filament.
Just had an email to say that the hotend, from E3D, for my printer has been posted! On holiday this week so should be able to get the printer finally up and running!
For some time I have wanted to design my own printer. Partly so that it will be able to do what I want and secondly for the challenge. Obviously it is much easier these days given the number of designs out there. For my design I had several things that it must be capable of:
- More than one extruder
- Use as many of the same vitamins as possible
- Be simple to construct with the minimum of tools
- Use as many printable parts as possible
- No Bowden tube
Now I am not above thinking that some of those ideals may have to be altered but so far, in the planning stage, I think I have hit all of them.
So taking each point in turn:
It currently has space for two extruders – I wanted at least two so that I can leverage Slic3r’s ability to have one extruder for the shell and another for infill. That way I can use Faberdashery’s great colours for the shell and a cheap bulk black or white for the infill. The current extruder/hotend design means that only around 50mm of Y axis is lost when using both extruders.
Each axis uses the same linear bearings, all the printed framework attaches using M4 bolts, bearings used in the belt idlers as used in the extruders and so on. I want to not have a BoM as long as your arm and be able to order from only a few places. Personally I think this is the ideal that will change as the build progresses.
The tools that I think will be needed are screwdrivers, allen (hex) key, wire cutters and a wrench. Again this will probably change as the build progresses.
All structural support parts are printed, only the obvious items aren’t (frame, smooth rods, threaded rod etc).
No Bowden tube for the extruders are used. The current design is for a direct drive extruder – the hobbed bolt is directly attached to the stepper – which reduces the size of the extruder and reduces the need for large gears. The actual reason for no Bowden tubes is purely down to I want to print flex-polyester and I haven’t been able to get it to work through my current Huxley’s Bowden. I am considering having one direct drive extruder and maybe replace the second with a Bowden system to reduce carriage weight. This would also allow for another hotend to be potentially added.
So there is my design. I have put the files up on Thingiverse and have ordered (and received) the extrusion for the frame. I am currently printing out the main frame components to begin building.