Friday, January 3, 2014

Delta Bot Build: Part #2 Belt Tensioners

After initially assembling the frame and trying my first belt tensioner design, I realized that putting the belt tensioners on the moving carriages just clutters up the design and adds additional mass to moving parts. I decided to move the tensioners to the top of the towers instead.

After searching through thingiverse for examples of rostock / delta bot 3D printer belt tensioners, I initially considered mounting the belt idler wheels on an arm that could rotate and thus tension the belt, but as the idler would move in an arc, the belt would possibly rub against the side of the idler mount. Instead of trying to concoct a four-bar linkage that would keep the idler moving in a straight line up and down, I went with a much simpler concept. The idler will be mounted on a plaftform that is moved up and down with three screws, thus tensioning the belt.

All parts are printed with a 0.5mm nozzle, 0.5mm layer height, and 50% fill density. I chose the big nozzle and layer height to maximize part strength. I think fewer layers = better strength, less chance of delamination.

Idler carriage printed and assembled

bottom view- note M5 captive nuts pressed into place

New upper corner bracket installed and belt fed through, ready for idler carriage

idler carriage in place and ready for tensioning

Successfully tensioned!
It seems like this concept works- so I just started printing another set. Hopefully I'll have enough red to finish, this spool is just about finished.

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