M Prime One 3D printer

by diegotrap, published

M Prime One 3D printer by diegotrap Oct 7, 2015
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M Prime One is an open 3D printer intended to be simple, low-cost and easy to build and use.
With the M Prime One, we have designed a 3D printer focusing on three main points:

  • Free design. The printer have been designed from scratch in a free 3D software: FreeCAD. All the files have been published under the less restrictive license we have found (CC BY 4.0). This way anybody can download the files, modify them and use them for their own purposes.
  • Simplicity. The design has few different parts (for example, cold bed, 4 motors, just two types of screws and one type of radial bearings) in an effort to reduce building complexity, cost and maintenance.
  • Documentation. Apart from the files, you can find the printer firmware, list of materials, slicing profiles... in this repository, receive support in our Q&A site and soon read the complete assembly manual.


  • Printing surface: 200x150x150mm.
  • 1.75mm bowden extruder.
  • Compatible with any hotend with 12mm diameter mount.
  • Magnetic bed, easy to place and remove.
  • Auto-level system with inductive/capacitive sensor.
  • Cable management integrated in the design
  • Integrated electronics holder (compatible with RAMPS or SAV Mk1, can be adapted to other boards)
  • Optional LCD holder (compatible with Smart Controller)


You can find the Bill Of Materials, instructions to build an M Prime One from spare parts at: http://mprime.io/how-to-build-an-m-prime-one/

Or if you want to build the printer from a kit, check our M Prime One page.


M Prime One render

M Prime One printing an Stormtrooper helmet

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looks cool im gonna try to 3d print one and the the things in it

Hi very interested in building a M Prime printer. I have a few questions though. Does it have auto leveling capability? Also if I were to print all the parts how much would the remaining parts needed cost? Is there a parts list somewhere I could refer to?

I am currently putting together a spreadsheet with the price, link, and a bunch of other things to make the making of this printer more convenient, for I too am very interested in making this printer.

Comments deleted.

For anyone interested, here is a PDF Printable layout you can use to make the frame out of MDF board.

https://drive.google.com/open?id=0B8x3ulcUdNOvOVBaaE1uQXkzSW8 for 11x17 paper

and here https://drive.google.com/open?id=0B8x3ulcUdNOvV1kxS3hndVZSMGM for 8.5x11 paper (Select Poster when printing)

Hope this helps

Hola. Alguien tiene la orientación para impresión de las piezas sin soporte o no es posible.

¿Podrías explicar a qué te refieres?

hola diego. imprimi la maquina y la use por mucho tiempo pero siempre me imprimia en falsa escuadra.
reimprimi las piezas carro x, carro z y carro y en una createbot profesional y tambien salieron las piezas en falsa escuadra.
Es u error de diseño o estoy haciendo algo mal?

La impresora está diseñada para ser ortogonal (para tener los ejes en ángulo recto). Sin embargo supongo que dependiendo de la calidad de las piezas impresas sí que puede salirte una impresora no ortogonal.

Seguiré buscando el problema.
Igual sigue siendo la maquina transportable mas practica que he visto hasta la fecha.

Good morning Diego, I'm looking to make a modification to Print in 200x200x200 saw that for the y axis must increase the bars to 330 mm and if the z axis would have to increase to 415 mm. Have you ever thought these changes? You think there might be some problem in this project or to work need to modify something beyond the frame height? You have some guidance?

Thanks for the great work!
Quick question though as I found myself a little confused.

Are the parts here updated with the latest?
it would be really great if you can get it up to speed in case it is not, as it'll make things easier for people following you here.

Will start my print as soon as I know I am using the latest and greatest :)


I am very glad that you like the printer! All the latest parts are in the Github repository: http://github.com/M-Prime/M_Prime_One. Enjoy your M Prime One =)

Hi Diego, I noticed that your yz carriage model has an error. The two wholes which are meant to hold screws which hold the two belt pulleys are filled in! It is a small layer that blocks the screws from entering. Can you please fix this?

Those layers are intentional, they are there to help you print better the nut holders. You have to use a 3mm drill bit to remove that plastic once you have completed the printed part.

Actually we are a leading sensors manufacturer. you can used our high quality proximity sensor on your 3D machine. I can be reached by email:[email protected] and whatsapp:+86 13319542018.

This may have been asked somewhere but if we are interested in hand dremeling the body of the printer is there a sketch of how far apart the cuts are and the placement of holes that is not in a CNC format?

You can download the files from the github repository: https://github.com/M-Prime/M_Prime_One. You can use the .dxf and .fcstd files to try to print them or take measurements.

Thanks! I almost have this thing build! Accept, I am feeling like this hot end holder is not super sturdy. Is there a version where the bolts and nuts have a place to lock together to hold the two hot end hold pieces together?



You are right, there is a newer version that you can find in the github repository: https://github.com/M-Prime/M_Prime_One

Hey Diego, it looks like here you are using a jig with a dremel to cut smooth rods http://www.thingiverse.com/thing:879719 ? Is this how you cut your smooth rods to length? Thanks!

Smooth rod holder and stacker

This is the dremel holder that I use: http://www.thingiverse.com/thing:229431. I use it for chamfering the rods, but I am not sure if a dremel is enough to cut 8mm rod. The part I designed is just for stacking several rod kits.

Dremel custom vice


vvdd, I don't agree with your opinion. My printer is working perfectly and so are other user's. I have not complaint about the stability of my printer, although it cannot reach very high printing speeds (I use between 30 and 40 mm/s). Maybe your machine wasn't properly calibrated, assembled or you just made it run too fast.

I work on this project everyday and give support to the users that reach me with questions, I can assure you that the printer works. You can see it with your own eyes in this video: https://www.youtube.com/watch?v=BJROiZyinXQ


Diego, I have a question. When I was building my 2 copies of this, I saw that you had the bed's rods (X-axis) at 295mm (if I remember right). However, I also notice that you have a print size that significantly less in X. I wish to add a heatbed which is 200mmx200mm. If I do, do you see a reason why I should not cut down the 8mm rods so that the X-ends are supporting the heat bed (I would have a metal plate under the heat bed suspending it above the X-ends on spring loaded screws).

On another note, I recall folks having hole sizing issues so that clamping the rods was difficult and I can sympathize. Mine have worked themselves loose somewhat and I will be taping the ends with blue tape to make the fit much tighter. In the next version, Diego, if you consider it, give the clamps more force on the rods perhaps by doing something that does not need to deform the part to clamp to (for example, using the 8mm rod clamps you see elsewhere here). That would compensate for those who generate the parts on different printers with different shrinkage.

SkyRider, thanks for the feedback, I answer your questions/suggestions:

  • You can't cut the X axis smooth rods because you need some free rod length at both ends of the axis. Check with your built printer, the axis moves right and left but the hotend tip won't reach the hole width of the bed/rods (295mm), but only the 200mm in the center, the actual printing surface. If you cut the rods to 200mm, you'll get a travel in X of about 100-130mm, so you won't use the whole heated bed.

  • Other people have also reported this kind of issue. I don't know if I will be able to change the whole design, but I take note. What is the 8mm rod clamps that you refer in your comment?

Cheers SkyRider, good luck with the printer.

8mm Rod Clamp
8mm Shaft Support

can you please post a step file or iges/ igs file???

hey just a heads up just tried that with freecad and it dosnt work it shows up blank in Fusion360

I have downloaded Autodesk Fusion 360, exported a part from FreeCAD to the .step format and open it in Fusion 360. The part has opened fine. I have also downloaded the frame from the repository, opened in LibreCAD without issues. I don't know which problem you are having, it works flawlessly from my side.

I don't have those files, if you are interested you can download the model and FreeCAD and export as step.

the print bed size is 200x150x150mm
looking at possible 200x200x150mm
to get this i'll just match the x and y rod lengths? and change the size in config. h

X 8mm smooth rod 2 295mm
Y 8mm smooth rod 2 280mm (295??)
Z 8mm smooth rod 2 365mm

You'd have to add 50mm to the Y axis, so the measurements would be:
X 8mm smooth rod 2 295mm
Y 8mm smooth rod 2 330mm
Z 8mm smooth rod 2 365mm

thanks again..

No problem. I am here to help :-)

Comments deleted.

measurements and drawing of the frame board please.. do not have access to a cnc.. just a trusty handheld jig saw..table saw

You should use the .dxf file or the FreeCAD file to take the measurements, the project has not a set of technical drawings yet.

ok.. thank you

I just printed all the parts on my Geetech i3, and then I looked on the site for build instruction or a D I Y guide, not much that I can see.

it would be good if this had a build manual, for things like the heat bed, and how things like the belts go on, or that the site says that in the nut and screws used that there are nylon nuts,, where are they supposed to go,, or are they even needed ?

Blueckcrow, there's no manual yet, but we are working on it. In the meanwhile, you can use our Q&A site (http://mprime.io/questions/), Google Plus community (https://plus.google.com/u/0/communities/108084856251985677965) and the FreeCAD 3D model in the Github repository (https://github.com/M-Prime/M_Prime_One/tree/master/3D_model).

Where can I get these parts aside from your website since you only ship to Spain. I want to make sure I get high quality parts


You can get the parts from us (M Prime) if you order by email. The address is [email protected] Give us a list of items and your ZIP code and we will give you a quote.

Ok, I sent an email, also just an idea but, wouldn't the endstop for the y axis be better placed on the hotend piece? Like the one which is attached to the rods but does not hold the Z probe. That way, when a print is done, instead of having the hotend stick out towards the person, it retracts backwards. This means the person has more space to move their hands and don't have to worry about touching a piece of metal.

Actually I think that is a great idea, but there is an easier way to do it. The endstop is in the YZ carriage because it was the simplest way to design the printed parts and because we didn't want more cables in the printer head. But you can simply add a line to the end gcode in Cura to make the hotend retract back to your desired position. I've added it to a list of improvements. Thanks!

I'm wiring the motors and was wondering if you keep the wires at full length ot if you cut them down to specific lengths. If so, what lengths?

Hi! I'm looking into building myself one of these, and was wondering a few things...
What resolution does it print at, at it's smallest? Also, what's the estimated cost of the whole build? I did a bit of research and found a pretty good price for all of it, but was curious as to how much all of you guys spent.

I have printed at 0.1mm layer height with no problems at all. Other users are trying below that and I think it is possible too.

i printed a few pieces at 0.055 and it seemed perfect.

With all the things I missed and have to reorder I lost track of the actual cost. I'd estimate that I'm at about 200 Euros at the end. A little more due to my own stupidity.

Hi all,

I have an Ultimaker 2 at the office and I'm hooked. I want to build my own for home so I can print more stuff. What are your thoughts on M Prime printer? Will I like it and can it print a variety of sizes and complexity. I know it's a budget printer, but just want some advice before purchasing parts.


I cannot answer this impartially ;-)

But I'll say that objectively it's a simple and economical printer, and that if you are prepared to deal with a RepRap printer (assembling the printer, adjusting some parameters, resolving some technical problems...) it's an option that you can consider.

It will be helpful to hear experiences from other users.

could you send me one?

If you refer to the printer, send us an email to [email protected] and we can give you a quote with shipping to your country.

I figured it out. My PLA is shrinking alot. I printing it in ABS and all is good.

I should say where you have to tighten a 3mm screw/nut to squeeze the plastic to hold the smooth 8mms rods

The x axis ends or any where where the smooth 8mm rod attaches. not the bearings.

HI everyone. I am having a problem with tightening the parts down onto the smooth rods x and y axis. When I tighten the PLA part down to the smooth rod it never really gets tight enough to hold the rod. I tried to just keep tightening but then the part will warp or crack? Seems like holes for the rods are a little to big or something? I printed the parts in PLA at 25% infill also tried it at 50% infill. Ideas? I am using good 8mm rods from a old printer.

Can you identify which parts specifically? I do not have this issue. If you mean the LM8UU bearings, there is a specific way the zip ties have to go in order for the bearings to not move.


It is a problem that has already been reported by 2 users, because depending on the printer, calibration, material... the dimension of the holes may vary. Others have fixed the issue by shimming the rod using some kind of tape. Or you may adapt the files to make the holes smaller.

Hope this helps.

Hey Diego, what is this problem exactly? In my build I was able to get the bearings to sit just fine and to tighten them down just fine too. Now, granted if you/me redid these with built-in bearing housings you wouldn't be caring about getting the bearings to sit right, but I just wanted to know exactly what the issue is so that I can look for it.

SkyRider, the problem is not about the bearing seats but the smooth rod holes, those that are tightened with bolts. We have treated the issue in the Google Plus community, in this post that you can read (info at the comments) if you need detailed information: https://plus.google.com/u/0/109084808114644504190/posts/QGVhFVdXDCu.

Basically the problem is that the smooth rod holes are designed to be bigger than the actual rods, because of the distortion that holes suffer in the FDM printing technology (mainly due to printer calibration and material shrinkage, more details here: http://manual.slic3r.org/troubleshooting/dimension-errors) and that typically make them smaller.

In some cases this design choice may result in the holes being too big and cracking of the parts when the screws are tightened. But it is a problem hard to control from our side, since the parts are meant to be printed in many different printers and the variability is too high.

Ok, well I have (maybe, big maybe) a solution for that. I designed an 8mm rod clamp I have used in my all metal SmartRap which worked very well, perhaps too well. It held down my rods to my Y and X-ends very very well. Printed in ABS on several printers. After you mount on the rod, you then slide into the end and then drill 2 small holes to secure the clamp. Maybe that will help. I published the clamp here: http://www.thingiverse.com/thing:1280841

8mm Rod Clamp

When will parts be able to be shipped to the US? If ever? I want to do this but would like to order the parts off of your site but it currently is only Spain shipment... will that change? Or am I missing something?

Hi I could print you the parts Justin. Just email me thanks

I have a 3D printer, just cannot afford the other parts. I was going to start my friend on printing.

Justin, thanks for the deference of contacting with me and considering my offer, I know you and SkyRider appreciate the fact that this is an open source project and have expressed your interest in sourcing the parts from me. The shipping costs to the US make it hard to offer a very competitive price, but viewing the Amazon prices I think that the difference is not much and we can put together something that fits in a tight budget. There aren't many more open source printers designed to be so simple and economical. I'll send you an email and we'll see if we can make you a part of the community ;)

That's just awesome Diego! I ordered a P3 Steel frame from Spain and managed to get the shipping addressed, and of course I ordered parts from Serge at SmartFriendz. Even though you made this open source, the only reason I didn't order from you was that you were out of stock at the time I wanted to get underway. I think it's important that we support people like you, by buying from you, to incentivise you to continue to grow and improve your design. Thanks for this design. It really is fun and so easy to build.

You can order the parts by sending an email at [email protected] We will give you a quote with the shipping costs if you include your ZIP code.


I am building 2 of these over here in the US and I am sure if you wanted to get these done locally, you could. Try any local MakerSpace or just send them off to 3D Hubs. I printed my own and it was fairly reasonable. You can go to my Hub here : https://www.3dhubs.com/washington/hubs/samer and upload your parts and I will print them for you. But, you should also try a hub nearer to you. I also sourced all my parts locally (US), or from eBay/China/Amazon. Motors from eBay, rods from eBay and Amazon, same for the bearings (or you can have a hub print nylon ones for you). Screws and nuts from Amazon, RAMPS board from eBay or Amazon, you can get your V6 hotend just about anywhere online. Stuff like the pulleys and gear wheel can be acquired from anywhere as well as the belts. The shipping from Spain may be prohibitive so be careful what you ask for. If you are in a hurry, put together your list on Amazon and choose items that are delivered with Amazon Prime so that you can get 2 day shipping. If I print these for you, I highly recommend PLA. The parts are more solid and work very well, although mine have been using some ABS parts. I believe I posed a Make of my own here.

I am going to 3D print all of the parts I can as I have a 3D printer, I am comparing the cost of this and a kit on Amazon.com for $200. Whichever is more cost effective. Message me with the sources for the parts you got @SkyRider.

Nevermind... I don't think it will be cost-effective. Would have been a cool project but its unfortunately out of budget for me...

That's too bad. It really is a nice system and very much doable if you do some scrounging.

I may be able to get the parts like the rods and frame... But what about a power supply? I would rather not work with a PC one.

I got the frame from Polulu. I had them cut one for me out 6mm acrylic. Cost me $35. I also used a run of the mill power supply from eBay ($20) and on the second one, I used an old XBox 360 power supply -- works great. Rods from Amazon.

Awesome! So other than the parts like motors and an extruder, this is like a replicating printer! Cool!

Pretty much. i am using various printers to illustrate the point, At some point, this will print its own upgrades.

thanks for this...
but whats frame thickness?

I am using 6mm acrylic. Works fine.

8 to 10mm is OK.

Ordered my frame cut my Ponoko out of 6mm acrylic. Going to retire my 2 SmartRaps and move the parts into this!

Then publish it when you do it, I want to see the result. Good luck with the project!

Ok I need some information please. What magnets are you using and what inductive sensor are you recommending?

My magnets have the equivalent to 6kg in force. The inductive sensor is the typical reprap sensor, LJ12A3-4-Z/BY. It has to be packed in a M12 threaded body so it fits in the holder, if you use a larger sensor you'll need to redesign the holder.

Oh and one more thing...the ones I find on Amazon are 6V sensors. Does your lashup need a 5V or will a 6V do?

Ok thanks. NPN or PNP NO for the sensor?

PNP, NPN, NO or NC is irrelevant because it can be configured via firmware. Sensors are usually 6-36V (mine is), so the supply voltage is 12V (the power supply voltage) and the board has to be protected with a diode from the 12V sensor signal (more info here, in Spanish: http://mprime.io/es/pregunta/conexion-inductivo/).

Thank you. The frame parts are printed now and as soon as the threaded rod arrives tomorrow we can begin.

You got it. Polulu (not Ponoko) shipped the frame and Amazon shipped the threaded rod. I will probably do this over the weekend. Question: Are the settings in the RAMPS board the same as the SmartRap or do you have the Marlin collection you can upload somewhere (or is it on GitHub, forgive me, I didn't look and I didn't see it on your site)? I plan to use a metal heated bed and mount a glass plate on it. I will probably mount my LCD right to the frame as well. After that, I'll likely enclose the whole thing in an acrylic box to keep the heat in. I have some excellent leadscrews (the sort that would do better than ordinary threaded rod) but for this, I'll stick to the plan as you have it and have it make its own upgrades. It will join my other printers in my farm....

Now I am excited to see how you build your M Prime One! =) You can download the firmware from the github repository: https://github.com/M-Prime/M_Prime_One/tree/master/firmware/Marlin.

Me too. I have been printing some parts in PLA and others in ABS just based in what printer is free. I am doing 2 copies, one for me and one for a family friend. Frame isn't here yet but just about everything else is. Thanks for the link. I will do the load last. After that I will look at dual extrusion. At one point I made an all metal SmartRap (well almost all metal). That I will retire and put the parts into the second MPrime1. Many thanks for your efforts.

This printer design is very similar to the SmartRap printer from SmartFriendz in France except yours has a support frame. Nicely done!

Yes, it's inspired by the Smartrap. Thanks for the support!

i've managed to build one (mostly) and ive come across one problem, the x carriage is able to lozenge, by that i mean that there is nothing keeping it square or stopping it from twisting, i think that it needs a cross brace to stop this from happening, else the bed could pop off mid way through a print. ive also increased the print area to 200x200x200mm, other than that i like how simple this is, but im yet to print with it so there may be other suggestions coming in the future.

Hello kaighn80, you could solve the problem y axis twist? you could share the changes you made to print 200x200x200?

the twist in the y axis isn't that much of an issue, there isn't anywhere near enough force to be concerned with it twisting, the only thing you need to do to increase the build area is to increase the size of the components that make them up, i.e. the smooth rods and threaded rod and belts, everything else stays the same, but bear in mind that if you increase the size of the build area you have more mass flying backwards and forwards when the x axis is moving so you may need to slow the prints down to compensate. the x axis becomes a lot more solid when theres a build platform bolted to it, just waiting on a new filament tube to arrive and its all systems go. the only other issue I've had has been with the ramps side of things, more actually to do with the power supply, please make sure your 500w pc power supply is actually putting out 500w, because most wont be, not when you consider that that power output is divided between +12v -12v 5v and 3.3v, three of those voltages you wont be using, buy a dedicated 12v supply and you'll have no end of joy!

Comments deleted.

Thanks for your feedback. We are aware of the relative flexibility of the Y axis, but being a very light axis and not a very long one, it's something that haven't caused us problems. May be your problems are due to the increased Y length, we haven't experienced those problems (yet?).

Anyway, good luck with your printer and thank you very much for sharing your experience.

Is it possible to modify the z-axis to be driven by lead-screw instead?

You would have to modify the yz carriage part to accommodate the new "nut", because currently there is just room for a M5 nut.

the parts in the image are very similar to PrinterBot pieces.

The printer resembles the Printrbot Junior and Simple, but apart from that, I don't understand what you refer to.

dont suppose you have a layout for the frame so i can make it by hand?

As damauk says, the frame files are in the online repository, more specifically in the directory https://github.com/M-Prime/M_Prime_One/tree/master/3D_model/frame. There you can find the dxf files, that you can open with LibreCAD, and the FreeCAD files to edit the design or obtain the exact dimensions the frame has been designed with.

what program are you using to view the dxf file? i intend on printing it out full size and then cutting from alluminium sheet, thats why i wanted a layout.

I recommend trying LibreCAD for viewing/editing the DXF files. here is the link to there website http://librecad.org/cms/home.html Its cross platform and open source. And here is the link to the github page with files for anyone that hasn't found them yet.


hi, what's the "sav" holder? oh and also how you move your z axis? I mean I can not see the any holder nut or something on your threaded rod?.. Thanks.

The SAV holder is an electronics holder designed for the SAV Mk1 board (http://reprap.org/wiki/SAV_MKI). And the Z axis moves thanks to a nut that is locked in a pocket in the lower surface of the YZ carriage.

Awesome design I love the frame and magnetic build plate. What thickness is the frame?

I downloaded the FreeCAD file from your github and I see that the frame is 8mm thick. Do you think layering several pieces to achieve that thickness would work? I have access to a laser cutter but the maximum it can cut is only 6mm. If the multiple layers won't work what do you think about adding supports like in the sgraber i3 frame?

You can do it. I did the same thing, gluing two wooden boards and the result was very good. You won't have any problems.

If I were to cut and drill the frame by hand, would that work? Or ist precission too important for that part and it should be lasered or milled?

It can be done by hand, but be careful to position the drills so the Z axis bars are parallel with each other and perpendicular to the "floor".

Thank you very much. I did not see it there yesterday.


how about posting the DXF file for the frame. Would like to make this printer, but would need to make the frame.


You already have the .dxf frame uploaded! =)

Very interresting but what about vibrations?

It is a design that has compromised rigidity for simplicity and low cost, but it has proven capable to print great quality items. I'll upload some photos so you can see yourself what can it print.

Do you have a video of it printing and photo of prints made with it ?

Now you have another video of my personal M Prime One printing: https://www.youtube.com/watch?v=BJROiZyinXQ

The photos are already uploaded and you can find them in the main slider, including a 3Dbenchy. You can wathc videos of the prototype printing in these links: https://www.youtube.com/watch?v=Ym673d5m_v4, https://www.youtube.com/watch?v=jsdfbjJOcaI. Sorry about the video quality and surroundings, they aren't very professional and that's why I didn't include them in the main page.