Very compact MK7 Upgrade
by makedave, published
I purchased a MK7ish extruder and could not get it to extrude consistently. All of the boards were talking about the whosawhatsis' Minimalistic Mk7 replacement. That design inspired me to make a new design with the same basic concepts but much more compact. And a simple push button to release the plastic.
I have not gotten a lot of mile on it yet, but it seems to work pretty well so far.
Let me know if there are any issues getting this to work on an official makerbot MK7/8. As I bought mine form another company.
Only four items required:
1) Spring 10-12mm in diameter and about 25mm long. (I used a Ã¸.43" x 1.00" long spring from an 84 piece Everbuilt brand spring assortment box I got from Home depot.)
2) 5mm bolt longer than 10mm
3) 5mm x 11mm bearing that is 4mm thick. (these were readily available at the local RC car hobby store. They were also the cheapest on the shelf)
4) a 3mm washer to go between the body and the arm
1 body (ensure it does not need mirrored for your extruder. The solid side of the assembly goes against the servo)
2 arms (one as downloaded one mirrored)
1 button (I switched to red plastic for the button)
1) Clean up corner holes to ensure a 3mm bolt fits into the hole
2) Cut the 5mm bolt head off leaving a 10mm long shaft
3) Thread the 5mm shaft onto one of the arms
4) Place bearing on shaft as shown in picture
5) Thread mirrored arm onto the threaded shaft of the assembly
6) Place button in larger hole of body
7) Place arm assembly into the body
8) Place the spring onto the aluminum bar opposite the hot end that the servo is mounted to.
9) Slide body over the spring and the extruder drive.
10) Attempt to thread bolts back through the fan, heatsink, arm, body and servo while fighting back the spring. Place the 3mm washer between the arm and the body.
11) tighten it up and your ready to go.
12) just press the button on the top to release the filament and the filament pulls right out.