MPCNC - Belt Tensioner Parametric Remix for US or IE Version by GeoDave

Last crawled date: 3 years ago

Update 4/9/2016
Rev10: Belt Tensioner Plate revised to have option to add reinforcement at the end. I had the previous version break when I pulled the bolt to much to clear the Conduit cap.
Update 3/12/2016
After playing with this design a couple of days, I came up with a change that seems to have solved all my problems I could see with it. I connected the bolt above the belt clamp so I could put a screwdriver on the bolt head while tightening the nut. I also put the open part of the belt clamp to the inside so it would be in line with the belt path. Since the bolt pulls the top part of the clamp more, I added a 15 degree angle to that so the bolt would be close to perpendicular with the clamp. The 1st photo shows it in place. I left the other designs here in case anyone would rather use them. The new files are:
BeltTensionerPlate_Rev8.scad
Bolt_DbleBeltClamp_15deg_Rev1.scad
BeltTensionerPlate_2x_2xBoltDleBeltClamps_Rev8.stl
(print 4 of these for the new design)
Bolt_DbleBeltClamp_2x_15deg_Rev1.stl
I liked this technique for tensioning the belt, but wanted to be able to adjust some dimensions, so I copied the geometry into openscad and made some of the dimensions variable.
This works with: http://www.thingiverse.com/thing:1401177 & probably also the totem mpcnc corner design. I made 2 versions of the clamps. One uses the teeth of the belt to match teeth cut into the plastic & the other uses a double up to a single width for the belt to clamp it. I am leaning towards the double up design, since it is easier to insert the belt & also.
I would print BeltTensionerPlate2x_2xGrooveBeltClamps_2xDbleBeltClamps_Rev5.stl which has both style clamps with it & see which you like best. If you print the belt clamps seperately, I would print at least 2 at a time so each layer of plastic has longer time to cool before the next layer.
There are 3 openscad files included:
BeltTensionerPlate_Rev5.scad
DbleBeltClamp_Rev16.scad
GrooveBeltClamp_Rev16.scad
I am using #10 x 1.5" bolts, but you could also use M5x35 or 40mm bolts. The shorter the bolt the less tensioning you can adjust.
Each openscad file defaults to printing 2 parts. There are several variables in each file that you can adjust. You will need 2 plates & 2 belt clamps at each corner. The belt clamp openscad file have the variable Qty you can set to 1, 2, 4, or 8. I am printing these parts at 40% infill.
The DbleBeltClamp part I hard coded the belt way, so there is less variables you can adjust there.
I used the Groove part from:http://www.thingiverse.com/thing:925911
I used the Bolt Clamping part and tensioning holding plates from:http://www.thingiverse.com/thing:1191395
I used the smooth groove cut from:http://www.thingiverse.com/thing:824458