my repstrap’s first printout!

February 24, 2011

In the past few days I’ve tested the hotend (pla is melting nicely from 200 degrees C upwards) and I’m happy enough with that. I’ve also installed and leveled the dibond bed – this post has good pointers to help. I’ve setup the opto-endstops and I have a build envelope of  approx 195x135x100. I’ll post photos in a few days.  At the end of all that today, I managed to print a small 10 mm cube (designed in 3 seconds in openscad):

This was printed onto kapton tape (heated bed not yet setup) and obviously theres plenty of fun optimisation to be done…. but its nice to finally print a solid object 8)

Printer settings were mostly Araspitfire’s with a feed rate of 5, flow rate of 10 and max z speed of 2 (all mm/s I believe) as I didn’t want to push things too hard just yet (i have heatsinks to bond to the pololu drivers for doing that!).


hotend assembly

February 16, 2011

I’ve commenced work on the hotend. I had to drill out the 5mm hole in the Al heater block to take the >6mm  5.8 ohm resistor. In addition I had to drill a hole for the 0.8 mm thermistor. Not having a 0.8 mm drill bit, I turned to my trusty laser which did the job nicely.

laser drilling of Al heater block (material ejection and plasma emission visible):

laser drilled hole + thermistor alongside:

After that I followed Arcol’s excellent assembly instructions – hope he doesn’t mind 🙂

Resistor in heater block:

thermistor + fire cement:

I’ve left the fire cement to set overnight. There’s probably too much of it but I was trying to encaspsulate as much of the crimped section as possible for strength. I’ll test it tomorrow. One worry is that the resistor protrudes from the heater block. I’m afraid of hotspots where the temperature rise outside the block may exceed the limit and fry the resistor… but we’ll see tomorrow.

improved z-axis

February 14, 2011

With the exception of the extruder and a lens, all was taken off the z-axis today. This has lightened the load and cantilever problems and its moving much more freely now. I’ve mounted the mirrors in a fixed position and I’ve placed the RAMPS electronics on this as its more convenient for the cable runs, particularly the y one which has a long range.

I’ve rescued a beer can for the opto flags, and the axes need to be squared and calibrated…. but I’m keen to start working on the hotend and melt some PLA!!!

y z?

February 11, 2011

Laser cut some mounts for the y and z axes yesterday and glued them up. Tested them today and y works fine but I haven’t pushed it beyond 8 mm/s.

Z, however, is more troublesome. At 1 mm/s the gear came off the motor spindle (it had been wood-glued on like the others). It seems the professional stage is quite a bit harder to move than my homemade ones! I oiled the leadscrew to free it up a bit but I suspect that there may be too much mass supported by the stage and there is a cantilever action due to the mirrors I added which probably isn’t helping.

I’ve re-glued the gear onto the spindle. I’ll try it again tomorrow and if it fails again I’ll cut off all but the extruder from the z-axis to reduce weight and cantilever effects…

Still no response from the overworked aluminium printbed vendor (who supplied me loads of other cool, working stuff). So today I got some dibond material for the heated printbed from a signmaker in a nearby town, thanks guys. So I hope to get that running once I’ve got the hotend working.

git da motor runnin

February 9, 2011

Mounted the x-axis motor and figured out and set theoretical steps/mm value in the firmware for a leadscrew driven axis (afterwards I found that Josef Prusa has a calculator for this purpose). I’ve only pushed the pololu driver to 25% current so far and it runs at >8 mm/s, going to higher values and steps are missed. I have an old (broken) ATX supply which I intend salvaging the fan from. Hopefully a fan-cooled, higher current pololu driver will get to higher speeds but if not, I’m happy enough, otherwise I can try cutting and mounting some heatsinks but I dont have any adhesive…

I’ve also hobbed an M8 bolt and assembled the Sliced Wade’s Geared Extruder. It seems to be working fine although it hasn’t been tested with a hot-end attached. Both X and E will need calibration.

Currently working on mounting the y-axis motor. Hoping to complete that tomorrow and the z-axis the following day. Then its on to the hot-end assembly. One thing that might be an issue is that the aluminium printbed I received isn’t flat. I’ve emailed the vendor but no response yet…

toys arrived

February 4, 2011

The past few weeks I’ve been waiting patiently for electronics, motors etc.  The RAMPS diy kit and Pololu drivers arrived 2 days ago so I’ve soldered that up.

The motors/hotend/PLA/printbed/thermistors arrived yesterday. Today I’ve prepared an ATX power supply to drive the RAMPS and motors by putting a switch on the green “power on” wire, a 10k pot/LED on the grey “power ok” wire so I know its happy and another 10k pot/LED on a 5V red wire to simulate a load so its happy!

I’ve also laser cut some mounts for the motors. I’ll test the motors in the coming days…