Solidoodle 3: Broken belt loop

We're in the process of adding belts and pulleys to the store. You should see the official Solidoodle belts and pulleys in our store in the next week or so.

to correct the Belt tracking you will need to adjust the drive motor.  The axis of the motor and the driven axis MUST be parallel in order to keep the belt tracking properly.  Check the StockDriveParts web site for a tutorial on belt tensioning.
Switching to a V-belt will result in a major loss of precision in your prints, this is why toothed timing belts are used.

http://store.solidoodle.com/index.php?r … uct_id=104

We also sell the belts directly.

Whats the difference between an MXL and GT2? I just went by counting and measuring the teeth and measuring the gap between each tooth then measuring the width of the belt. The last time I printed something (3 months ago) it seemed to be printing the same as it was before the belt failed.

Edit: Nevermind... i googled.
Sorry for the wrong info folks... Honest mistake...

Looks like I'm gonna be changing my belts again... or changing to GT2 pulleys.

Thanks for the tip Ian.

I discovered the same issue when I followed the video on adjusting the belts. Since the rod floats back and forth, the motor not being parallel to the rod is the culprit IMHO.

I stacked a thin washer between the motor and the frame on the top two bolts. My SD3 prints almost perfect circles now.

There must be a better solution to reducing play in the Y axis system.  I also have spent countless hours fiddling with belt tensions and aligning rods...and the end result is never quite satisfactory.  I still have noticeable backlash and imperfect circles.  I remember reading about some people (I think Lawsy was one) using cable or fishing line instead of belts.  I think the idea is that there is less play  and stretch and requires less tension on the shafts.  Has anyone successfully installed this and does it work?

I think friction between the Y carriage bearings and the shafts has a huge effect on backlash since switching directions makes the carriage temporarily stop.  Even with tight belts, restarting motion means there is a static friction threshold to overcome.   While tensioning the belts helps overcome the carriage friction, it also creates more friction in the bearings on the rear rod as well as the idler pulleys which adds to the problem and creates misalignments.  I think the way to go is to replace all components with low friction components (LM8UU bearings for carriage, ball bearings to replace bearings in the back rod, maybe different idler pulleys...) thus requiring less tension in the belts to achieve the same drive reaction.  Thoughts?

Ok, here is how I solved the problem:

1) Diagnose if your y-motor is level or not (parallel) with the y-axis or not. Here is how I do it: I look at the y-motor from the top of the printer and try to align the edges of the motor with the edges of the cage through my line of sight. If the y-motor is not level the edges won't align.

2) Diagnose if the cage sheet metal where the y-motor attachs has been bent (flexed). Take a ruler or any straight edge and put it on the sheet metal and see if the sheet metal is straight or not.

3) If the y-motor is not level, and the sheet metal has been bent, then put washers between the y-motor and the sheet metal to level the y-motor.

4) Don't push on the motor down too much when you are screwing it in; the belt needs to be in tension but it shouldn't flex the y-axis too much.

I hope this helps!