The original y-axis belt anchors broke so I designed better replacements. These are stronger, and have a ribbed slot for the belt ends to fit into, so will never slip.
It's a tiny part, but vital!
Please leave a comment if you like...
Edit: Improved y-axis tensioner: http://www.thingiverse.com/thing:2249773
Print two, obviously!
I used PLA, and they came out perfectly first time. ABS will work just as well if you allow for shrinkage, you might need to experiment with scaling to get it right.
First, I glued the broken pieces back together so I could measure them with a digital caliper.
I started by sketching a rectangle on the XY plane, same size as the width and length of the original. I added sketch fillets to the corners, exactly half the width so I get nicely rounded ends. The centres of the fillets then are the exact centres for the screw holes, and I added circles at these points, slightly larger than the nominal screw diameter (4mm).
Then I extruded the sketch profile upwards to the height of the original.
Next, I sketched a row of 5 circles on the YZ plane, 1mm diameter, 2mm pitch, to make the profile for the belt. I joined the circles along their centres, extending the ends beyond the width of the clamp, and joining them with lines to form a section of the belt.
Then I extruded that sketch symmetrically, by 6mm, to cut groves in the clamp.
I finished by adding chamfers to all the outer edges -not necessary, and probably not even visible in the finished object, but, as they say, 'the devil is in the detail'. :)