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MK5 Wade's-Style Tensioner by ScribbleJ is licensed under the BSD License license.
© 2011 by ScribbleJ
Instructions
FINAL FILES UPLOADED. This is a working design in production use now. If I make any improvements, I'll post them under a new derivative. The -final files are the complete design, which differs from the photos only in that the space for the 608 has been /slightly/ enlarged, leaving a window for it in the back of the idler block.
Other required bits:
4 springs; I am using 1/4"x1/2"x.035 compression springs which I picked up for a couple bucks at my local Ace Hardware. They just fit a M3 bolt head, something a shade thinner might be even better. You can go to the Ace, get your bolts, then just go to the springs and see what fits, if you have any trouble. If you get springs that fit the right width, the length is not too important; you can use aviation snips to cut them to size. You can also use a nut or washer to help hold them under the bolthead if you're worried they are too thick.
4 M3x40mm bolts, (x45mm or x50mm will make assembly and filament changes much easier)
4 M3 NYLOCK nuts. (my photos are normal nuts but I'm sure they will come loose someday)
-- ALTERNATIVE (not tested): 4 6x32 2" bolts, plus matching nuts.
1 608 bearing (rollerblade/skateboard)
1 m8x25 bolt.
IF you are using a narrow STEPPER motor mount like mine, or TheRuttmeister's, you may want to make sure you have 2 M3x10mm on hand to fit behind the idler block. If you are using the DC motor, you might want 4 of them to fit the motor on with.
You should be able to find all the above parts between your local Ace Hardware and your local skate/rollerblade shop. The "Play It Again Sports" near me sells the bearings for $1/ea!
This part is a bit thicker than the original, to make room for a nice thick idler block. This means your pusher gear needs to be moved up a bit on the DC motor shaft. There should be just enough room left to seat the end in the bearing. I took a photo to show the clearance I've got, which you can see on the side here. (Incidentally, the 'NOISY' sticker? That's the way it came to me from MBI, I didn't label it.)
I think I took enough photos for you to see how to put it all together. After you've got it in place, if you used the M3x40mm bolts like I did, you might need to use a screwdriver or something to wedge the idler block to the side to fit in your motor, and the filament. That's how I did it. You might otherwise make sure you put the motor and shaft in BEFORE attaching the 608 idler block, but I dunno if that'll have it's own complications.
