Tuesday, September 01, 2009
Mendelssohn Y axis operational
Here's my toothed belt design for Mendelssohn using the Darwin-style moulded gear. I've turned Mendelssohn on its side, so you can see the Y axis workings clearly. I'm just using the NEMA17 to drive this at 250mA, so it won't get hot enough to melt the CAPA. The belt is the E-SKY model helicopter belt, and there is just the right length once you've cut the loop.The big silver idler is a 608 bearing and 2x ridiculous washers as per the Z idler. The less heavily loaded small belt guide is an M4 soft, black plastic spacer between two M4x11 washers (plenty of lubricant). The belt is clamped by printed pillars (shout up if anyone wants the design files BTW), each held by 2 M4x40mm screws.
The base itself is 230x230x9mm MDF, supported on 16 x M4x40mm countersunk screws clad in 20mm lengths of stiff rubber tubing. These go into 4 PLA pads, which can also be hand-formed from CAPA. These pads have a very low friction, and can be levelled individually to cope with quite gross manufacturing flaws :) The axis moves at 50mm/s very smoothly with plenty in reserve even at 250mA. Yes, bearings will move much smother and faster with less wear. But this seems to work for now so I'll move on to butchering the X axis.
Vik :v)
Labels: helicopter belt, Mendel, Mendelssohn, y-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
