Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Right and Left Minimalistic Mk8 replacement - Modded

by Doogiekr, published

Right and Left Minimalistic Mk8 replacement - Modded by Doogiekr Oct 13, 2012


Just a modified version of the original mk8 upgrade to allow me to use things that I had on hand instead of ordering / waiting for parts.

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I am away from my home comp right now... will try to split it up once i get back.


Would you split the Screws item to one file?

did you ever get it to work with 628s?

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Update 2: Added versions for 623 bearing use (I do not have any 623 bearings so can't test it myself... please let me know if it needs to be different).

Update: Create one for the left side for those that have dual extruders and want to do both.

I was in my machine doing repairs for a thermocouple problem and noticed that my delrin plunger was worn. I did not really want to order parts and wait for them to come in to fix it so I modded the "Minimalistic Mk8 replacement" to fit what I had around the house.

I removed the spring and put a spot to use 3 "binder clip" arms to give the needed spring loaded pressure. I also adjusted the bearing area to allow for a 605 bearing (I had several in a bin full of RC helicopter parts), and made a printable pin that is a press fit through the arm and the bearing. I added a bit of a guide for the filament to make it easier to guide it in when loading.

Printed at 0 extra shells, .2mm layers and 100 infill. After it printed I cut the support away from the bearing area, installed the bearing and then put a drop of superglue on each side of the pin to make sure it didn't move after I installed it.

Have made a few test prints so far and it seems to be working quite well.

I only did the right side because I rarely print with my left extruder.


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jyeh_tw on Nov 8, 2013 said:


Would you split the Screws item to one file?

Doogiekr on Nov 10, 2013 said:

I am away from my home comp right now... will try to split it up once i get back.

jkiv on May 9, 2013 said:

I've been hitting my head against the wall for a few weeks trying to get my once working Replicator to print a piece I need; most of this time was spent adjusting the plunger!

Luckily, I was able to print a decent copy of this Thing and it's printing a lot better (but not perfect yet).

I didn't have any bearings handy but I did have quite a few brass screws and nylon washers. I managed to make the hole for the screw large enough by carving at it with larger and larger hex keys and tapped it for a 8-32 screw. I used a hex set-screw instead of a normal screw as the latter stuck out and made contact with the heat sink of the print head, preventing its reassembly. I used two nylon washers (sized "large enough") in place of the bearing and it seems to work okay!

Thanks so much!

Doogiekr on May 11, 2013 said:

Glad its working out for you... If you need it to be different, let me know and I will see what I can do.

pottiepie on Mar 18, 2013 said:

I think my fix is slowly melting away...

pottiepie on Mar 18, 2013 said:

I think my extruder fix is slowly melting away...

Doogiekr on Mar 18, 2013 said:

I have heard of issues with people making them in PLA... I made mine with ABS and they have been running strong for many months with no issues.

pottiepie on Feb 28, 2013 said:

Turns out it doesn't fit my MakerBot Replicator 2. =(

Doogiekr on Feb 28, 2013 said:

Yeah... if I had a Rep2 I would ask MBI for a free www.thingiverse.com/thing:5312... since they know its a problem

boredpilot on Feb 15, 2013 said:

Any Chance you can do me a modified Left version, I have a 628 (8x24x8) bearing I was just about to make a similar extruder but as you appear to be a few hours ahead you could save me the ear ache from the miss's :).

Its only a single extruder from a Rapidbot so I think its the same size stepper motor having a quick look

duotang on Oct 10, 2013 said:

did you ever get it to work with 628s?

Doogiekr on Feb 16, 2013 said:

I will give it a shot

pottiepie on Feb 14, 2013 said:

How to you fit this together? Does it require additional hardware parts or is everything printed?

Doogiekr on Feb 14, 2013 said:

For the original version (the one I use) you need a 605 bearing for each side as well as 3 of the binder clip arms (as shown in the pictures). There is also the version for the 623 bearing, but I never tested that, it was a request from someone in the comments.

mejarhed on Jan 11, 2013 said:

This is awesome! Thank you so much. My replicator is working like a dream again. Don't have to watch it like a hawk waiting for a jam.

Doogiekr on Jan 12, 2013 said:

Happy it worked well for you... it has been working well for me since I installed it on my Rep1.

mar-x on Dec 24, 2012 said:

as luck would have it.. I was looking at these mods for the exact same reason .. started printing with PLA and BAM.. no more ABS for me at the mo.. this printed out amazing .. I had the exact bearing from a Dremel teardown and it all snapped together flawlessly. Doogiekr, you are a champion.. I had the Bull clips handy and was able to make this without spending a cent!! well done on a great idea!!

Doogiekr on Dec 24, 2012 said:

Glad it worked out for ya...

Chaceb94 on Dec 20, 2012 said:

you need to post the .scad or whatever you used so that we can change the bearing parameters

Doogiekr on Dec 20, 2012 said:

Added my original files as demanded...

latigerlilly on Nov 2, 2012 said:

Where's the file for the plastic pin hinge you used to put the two pieces together?  Thanks.

Doogiekr on Nov 2, 2012 said:

 Thanks... Emmett is the real genius, I just took his design and made it work for what I had on hand and needed it to do.

laird on Oct 13, 2012 said:

Very clever! The binder clips look like they're probably more secure in position than the springs (which, at least for me, don't feel securely in place), and are certainly easier to source. It's odd that while bolts and nuts are standardized, springs appear to be randomly designed by each manufacturer. And binder clips, while not technically standardized, are easy to pick up for almost nothing at any office supply store. Yay!

And adding a 'guide' for the filament is great. The only problem that I have with the minimal extruder is that it's a little fiddly feeding new filament in, and this might help.

Huge thumbs-up, you made a good thing even gooder! :-)

Doogiekr on Oct 13, 2012 said:

Yeah, the binder clips are very secure... there is no way they are coming out of the arm without alot of help from the user. I never made the original one, so not sure how much different mine will be, but I read somewhere on the makerbot operators group that a little more filament guide would  be nice so I went ahead and added it while I was doing the other changes. I rounded a few corners and changed some spots that looked they could benefit from being stronger as well.

Doogiekr on Oct 13, 2012 said:

was asked what size binder clips i used, not exactly sure so I just took some pictures with a cm/mm scale for ref

mkeveney on Oct 13, 2012 said:

love the binder clip idea. Got me thinking about using the clip part somehow...

Doogiekr on Oct 13, 2012 said:

My first thought was the spring from a clothes pin, but couldnt figure out how to get enough pressure from it. The binder clip arms have alot of spring pressure, so they were my next choice.

g33zer on Oct 13, 2012 said:

Very nice and practical improvement! This should encourage people to  try it with easily sourced parts. 

Doogiekr on Oct 13, 2012 said:

That was the idea, well for me anyway...

Doogiekr on Oct 13, 2012 said:

Made a left one for those that want to do both sides

Austin on Oct 13, 2012 said:

Interesting source for springs!

Doogiekr on Oct 13, 2012 said:

like I said... using what I had around my house =) ... they work very well for this purpose (and others,I  love binder clips)