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Very compact MK7 Upgrade

by makedave, published

Very compact MK7 Upgrade by makedave Nov 17, 2012
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16782Views 1758Downloads Found in 3D Printer Extruders


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 ø.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.

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Where did you get your filament extruder gear? The sharp tooth gear tightened down on the stepper shaft.

I got the extruder gear at: http://store.qu-bd.com/product.php?id_product=18http://store.qu-bd.com/product.... But I would recommend my latest setup over this original design. I just uploaded my changes to: http://www.thingiverse.com/thing:152499http://www.thingiverse.com/thi...

Extruder Upgrades

That was really why I created this thing. With this and not using the groove end on the toothy gear and I can get some pretty consistent extrusions. The problem is that you can see the arm flex as it goes over the set screw so it is not perfect. But, it is pretty consistent at the slower speeds I am going for now. I think I will replace the toothy gear and/or the nozzle, if I am going to print much faster

im glad someone got one of the mbe extruders to work, mine is not at all, so i ordered the best one i could find, that has a really great warranty, he wont refund your money, he will just make it work, which is what i want.

Does it work in a dual setup? It doesn't look like you left enough space on the side of the unit, and the idler will stick out when it is released, so there's not room to put another one up against it. It's also missing the rear clean-out that mine hase. Nice idea, though!

I could see it interfering, I could easily update the arm to ensure it does not extend outside of the body profile when the button is pressed. Would that allow it to be used in the dual extrusion setup?

Is the clean out area on yours to clean the pusher gear of all of the buildup? I will have to see if I can incorporate that. I asssume on dual extrusion I would need to reach the pulley from the spring side so that the extruder heads are close to one another.

Sorry for all the questions, I do not have dual extrusion. I am still  kicking it old school with a cupcake.

I uploaded a new arm specifically for dual extrusion.

Looks pretty interesting, but I don't quite understand exactly how it's assembled. Would you mind taking a picture of it all assembled and in place without the fan and heatsink? I think that would answer all of my questions.

I've been using the minimal Mk8 very happily for a while. Your  design's use of a button is very nice. But I have to say - the only problem I have with the minimal Mk8 is that it's a bit tricky feeding filament straight from the top, through the arm, past the gear, and into the extruder. Do you think your design would help?

With this design, I was trying to maintain the same overall shape of the extruder to save space for a future upgrade idea. I can work on more pictures. When I originally posted it was pretty late. I figured I would get some more details sometime soon.

I noticed that I had a few tries where the plastic did not get fed into the heater barrel and came out of the sides of the extruder, I found that while looking at the extruder from the side it was pretty easy to align as there is a gap that you can see the top of the heater barrel. I was thinking about tightening some tolerances on the arm to help guide the filament better. And maybe another guide after the pusher, but I am not sure if that is to close to the heat. Let me know if you have any ideas.