Monday, March 26, 2007
Darwin's X axis repeatability
Appologies, this has been a bit slow coming - I've had the lurg. The final repeatability test for Darwin: here we're looking at the performance of the x-axis after mouding a gear diectly on to the motor (see the previous "Darwin's X-axis toothed pulley" post). Results are, again, looking promising with repeatability to ±0.025. Again, a further test is needed at a later date to understand how asymptotic the trends are, but as with the other two axes, we're in the right ball park here.
Next on Darwin's todo list.. home sensors, wiring & documentation.
Next on Darwin's todo list.. home sensors, wiring & documentation.
Labels: darwin, gear, performance, repeatability, reprap, x-axis
Friday, March 16, 2007
Darwin's Y-axis repeatability
Firstly, I've been issued with IE7 which means Blogger actually works properly on my computer... I cannot express the joy!
Secondly and more importantly, the toothed pulleys from the previous post were put on the Y-axis. Big thanks to Adrian for sorting out the electronics and the repeatability programming!
Super glue was used to lock the little gears into position on the 8 mm drive bar. [Incorporating flats are on the development list]. The same repeatability test used on the Z-axis (see previous post) was re-used, results below:
After the first ten runs the repeatability appears to be in the ball park of ±0.04 mm. I think that the first few runs balance the tension: this is important because the transmission isn't symetrical:
It's worth stressing that this is not bad, we're still within our targets, but we need more data to pin down excatly what's going on. The next test will need 100+ runs.
Secondly and more importantly, the toothed pulleys from the previous post were put on the Y-axis. Big thanks to Adrian for sorting out the electronics and the repeatability programming!
Super glue was used to lock the little gears into position on the 8 mm drive bar. [Incorporating flats are on the development list]. The same repeatability test used on the Z-axis (see previous post) was re-used, results below:
After the first ten runs the repeatability appears to be in the ball park of ±0.04 mm. I think that the first few runs balance the tension: this is important because the transmission isn't symetrical:
It's worth stressing that this is not bad, we're still within our targets, but we need more data to pin down excatly what's going on. The next test will need 100+ runs.
Labels: darwin, performance, repeatability, y-axis
Monday, March 05, 2007
Darwin makes a move
I tested a bit of Darwin today. I asked the Z to go up and down 20 times, putting the motor through 1000 steps for each stroke. This, in theory, would only move the bed up and down by 3 mm, but there was some timeout error going on in my code, so that's as far as I could push it today. Testing over a big range is on the list, but it's repeatability I'm interested in, so 3 mm will do for now.
The motor torque was at 100%, speed 200 (see exerciser scale - approx 80%), and the results on the caliper bolted to the bed were... well... the graph can do the talking:
Happy days! I guess that puts the resolution at ±0.01 mm. There's still the X&Y to get moving yet, but it's good to know they're on solid foundations ;-)
The motor torque was at 100%, speed 200 (see exerciser scale - approx 80%), and the results on the caliper bolted to the bed were... well... the graph can do the talking:
Happy days! I guess that puts the resolution at ±0.01 mm. There's still the X&Y to get moving yet, but it's good to know they're on solid foundations ;-)
Labels: darwin, performance, z-axis
