Extruder Lever Arm for Monoprice MP Select Mini

by Zakattacks Aug 30, 2016
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Worked perfectly. No adjustments needed for a great fit. Had me back up in running in under an hour! 20% infill and 3 outlines!

I'm wanting to make a spare of this real quick as I just got this as my first printer and have heard that this is the weak point. But I don't have an enclosure for this yet to do this in ABS and I don't want to print in abs until I have an enclosure with air filtration system due to the VOC's, Would this be something that PLA could handle?

Actually PLA would be better than ABS in this example, the higher tensile strength is more desireable than the durability of ABS. I recommend Esun PLA + as it is almost as durable as ABS but without the weak tensile strength or the VOCs. I also think some people estimate the VOCs, while they are dangerous in a sufficient quantity in most cases 3D printers won't emit enough to be hazardous. I did a lot of research a while ago and there weren't any actual studies back then. Good to err on the side of caution though, I wouldn't print ABS around infants or common areas.

Awesome news! I didn't realize that PLA had a higher tensile strength than ABS.

Thanks for your help, and design!

Comments deleted.

Thanks for this, the guy I bought this from broke this exact piece so I've had a hand clamp applying the pressure instead

Thanks for the file, fit perfect in ABS you made my technology class very happy, we were in the middle of printing final projects for their class.
Thank you!

Downloaded this and printed lever and cover to keep as a spare. The original lever cracked yesterday (it did last 7 months). A spare came with my printer, but I decided to use the one I printed. Works like a charm!!! Thanks so much!

You're a life saver! I turned my printer on and tried to figure out why the extruder sounded fine but nothing was coming out... Doy! Currently printing a spare with the first one installed. Hope that pin lasts long enough... would love to mill one of these out of metal.

I had a similar experience with the center pin breaking off two of them - the FIXED version held most of the pin though and it's working now! Make sure you use a clamp to get the bearing to feed the filament correctly, otherwise it has underextrusion issues and won't print right.

Mine broke and I called MonoPrice. They directed me here. I printed it (used a clamp to hold the broken one) and it worked flawlessly. Ran it at 0.2 layer and 75% fill 205C and 50C. Currently making a spare! Thank you very much!

I find it very interesting that a company would direct someone to a online 3d printing community for a replacement part. Seems fitting and all being it's a part for a 3d printer. I wonder if we will ever see appliance companies like Whirlpool, Samsung, LG & Sears direct customers to Thingiverse for parts.

It's because monoprice doesn't stock replacement parts.

Mine just broke after only maybe 200g of filament printed^^ you safed me from the hobbyking Support ;)

3 Things i've noticed after printing at 0.2mm and 100% infill on my Malyan M200 (mp mini select) which i had to "fix" with a tool XD (see pics of my made)

  1. The pin fell off after the first little pressure while assembling.
  2. The pin hole of the cover is too small. My original was still ok and i could see that it is bigger there.
  3. It works perfectly fine without the pin... so that way the cover would work as it is;)

So maybe you could make the hole a bit bigger. Everything else is perfect! Thank you a lot!

I have built this 5 times and each time the bearing spindle immediately breaks. Using Hatchbox PLA. 200/50.

What slicer and settings are you using? I recommend using Slic3r or Cura at 30% infill or higher and a 0.2mm layer height.

Maybe I didn't see those recommendations on Thingiverse.

Using the "Fixed" version, this thing printed and worked perfectly! I printed it at 100% infill after my OEM lever had broken after only 2-3 months. Luckily, I was able to rig up a way to add enough pressure on my broken lever in order to print this replacement piece.

Just a note: The cover in this model is upside down compared to the original. I printed it as-is without thinking, and had a funny result. You will need to flip it in your slicer before printing.

Just fixed that. I am also just getting around to printing these on my MP mini. (I printed the originals on a poorly calibrated printer)

Making the cover now - I'll reply w/ results && post pics in my make.


Long winded, not in the least! I can't thank you enough. You rock! I'm holding my extruder clamp in place with my finger trying to re-print a good one.

Thank you so much! :)


Lever replacement was great, except the bearing pin broke nearly immediately. Need a matching cover for the pin ... and I'm still a 3d modeling n00b. Tried printing the one for the original in your link, but the hole is too large for the modified pin size.

Do you know what size the hole should be modified to?

Thanks again!

The external diameter of the pin is 2.55mm (I got that number from measuring, then guess & check for tolerances). You have to take into account extrusion width (usually 1/2 the nozzle size) and printer inaccuracies. Generally, I add/subtract 0.3mm. So to make a snug fit, we should make the hole 2.8-2.9mm. Since people have a wide variety of printers, the one I post will be 2.9mm. By the time you read this it will probably be uploaded. Sorry about the long winded response, I just want to share my experience.

This worked perfectly for me and was just a drop in replacement for the broken one. Thank you so much, your a life (read cheap ass 3D printer) saver.

Cool! Glad it helped (It's why I post this stuff!)

What's the difference between the FIXED .stl file and the other .stl file? Thanks.

If you have any problems slicing the original file, try that one. I opened it in Slic3r and then exported because someone reported problems with the original. (I was going to use solidworks to re-process the stl but I don't have it installed on this computer anymore)

Also, your instructions say no support, I'm assuming you suggest printing it in the orientation posted, shouldn't I support the hole where the filament is passing through?

The hole is small enough to where support isn't an issue. In general, verticle circles dont need supports but will be slightly flat on the top. This is fine for this print because the hole is much largerthan the filament. Some big circles (more than 10mm) wiol need supports though.

Gotcha. I kinda figured anyway, certainly printing this in ABS and that circle was only at an angle of 50 degrees which isn't awful

Just an FYI, getting this in simplify3D when I slice your STL

It is probably an issue with the export from Onshape. I will open the .step in solidworks then export it from that (like earthwildldie did) and replace the current stl. I have had cura and slic3r do random stuff like this before, so I think it is a combo of the stl not being perfect and the way that s3d processed it. Is there a 'repair model' feature in s3d, and did you run it?

I did, and it only highlighted a small circle near the tip of the dome that the spring interfaces with. The solidworks importer didn't like a single face somewhere and I kinda just ignored it and it detected the features just fine anyway. Sent both STL angle and tolerance sliders to the max and saved it out

and for reference this is the back side

that slot is a hole that goes all the way through the model to where the bonus triangle shape is on the previous picture

I ran the step file through solidworks and exported an STL at maximum quality, S3D is now slicing it properly. Not sure if the best way to supply the file is to post it as a remix or just send you the file so let me know either way works

Hi earthwilldie I just printed one of these and I look forward to printing one from your STL file that you sliced with S3D too. I'm new to all this and at this point have just been using Cura. I have just started looking into S3D. Could you maybe explain to me how S3D slices this model different then Cura? Is S3D slicing it correctly and Cura is not? Thanks.

Well when you slice an STL its basically customized specifically for your printer. Even if we had the exact same machine right out of the box, there's a very high chance we both need different settings. Flawlessly manufacturing something is very difficult and, for instance, the reason why lockpicking works. So, for you to be able to run a gcode sliced from S3D by someone else as a "trial" to see which slicer works better, well that's pretty difficult.

Anyway, S3D is just simply more advanced than Cura and the attention to detail is what would make it slice incorrectly for me but correctly for someone else. These programs use intense math to figure out the most efficient coordinates to direct the nozzle of your printer based on the settings you tell it to use. Better slicers use better math which takes less time both for slicing and for printing. S3D is a no-brainer to me if you plan on printing for a while, check it out