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


by nophead, published

Mendel90 by nophead Feb 19, 2012


RepRap Mendel variant using two sheets at right angles for the frame.

Recent Comments

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As always, your skills at designing amaze me.

If the rod is bent and you constrain the top then for the carriage not to be displaced the coupling at the bottom would need to be able to displace radially rather than just bend. If the top end is free to wobble it has no effect on the carriage so preventing it from wobbling is detrimental not beneficial.

Your design is very good, but I am looking for solution wich is more simple regarding assembly process and have less dependencies (motor, coupler with flexible insert). In case of hanging Z, you have only put bearings and connect any flexible coupler - commertial one made of alloy, printed or just made from flexible tube.

All true with assumption that you have quite solid coupler at the bottom. My concept is base on "floating" threaded rod - as flexible coupler as possible, rood with some clearance between the ball bearing internal hole. At the end you have no wobbling, and adventages I have mentioned before.

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Mendel90 by nophead is licensed under the GNU - GPL license.

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See hydraraptor.blogspot.com/2011/12/mendel90.html

This is the 8mm rod version with NEMA17 motors, T5 belts
and an acrylic frame.

The source files and STLs for other sizes are on Github here: github.com/nophead/Mendel90. There are also bills of materials for each sub assembly, so you can see which parts go where.

Detailed instructions will be on the RepRap wiki soon.

I have built this version, but not run it yet. The "Sturdy" version has been running for three Months.

The base sheet is designed to be 10mm acrylic and the rest of the frame 6mm.


10 fixing-block.stl
2 z-screw_pointer.stl
4 z-coupling.stl
2 pulley.stl

and one of all the other STL files.

Vitamins.txt lists all the other mechanical parts.

File Name




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digitalw00t on Jan 27, 2014 said:

As always, your skills at designing amaze me.

SwimmingNaked on Dec 1, 2013 said:

I'm planning on building the Sturdy over the next few months. Do you know of a good source for a vitamins complete package? I live in a rural area in Canada and it's difficult to source here. Thanks!

3dmakers on Dec 1, 2013 said:

Hi nophead,

I am looking on latest x_idler_bracket and x_motor_bracket from Github and wonder why nut hole is much biger than M8 nut. How you would like to mount NUT for Z axis ?

nophead on Dec 1, 2013 said:

See the X ends section of this post: http://hydraraptor.blogspot.co...

3dmakers on Nov 25, 2013 said:

Had anybody problems with z axis stability ?

If yes, I have made and tested "hanging" screws there http://www.thingiverse.com/thi...

Karabas on Dec 6, 2012 said:

BTW you can use motocycle lamp 6v 50W as PSU 5v load. It will be light source too.

Anden86 on Oct 26, 2013 said:

or just some 12v Leds :)

nophead on Nov 27, 2012 said:

I only use a top limit switch. The bottom one can be turned on by changing the config file.

Karabas on Nov 27, 2012 said:

I see z-limit-switch disappeared from latest git ?

mohag on Oct 14, 2012 said:

What is the difference between the versions? Especially sturdy and mendel. (Looking at the ones on github)

nophead on Oct 14, 2012 said:

Mendel90 is acrylic with 8mm rods, so pretty much equivalent to a Mendel. The sturdy version uses 12mm MDF and 10mm rods and has a slightly bigger build area.

Telemah on Sep 3, 2012 said:

fan mount for mendel90 http://www.thingiverse.com/thi... thanks for richgain

webtek on Aug 13, 2012 said:

Hi nophead, could you recommend anywhere we can buy the electronics required to build this? (UK)

nophead on Aug 13, 2012 said:

Think3dPrint3d sell Sanguinololus: http://www.emakershop.com/brow...

but it will work with any reprap electronics.

Telemah on Jul 3, 2012 said:

have anyone add fan mount to the x-carriage? )

fest on Jul 9, 2012 said:

I tried, but I failed :-[

Here's my attempt https://lh3.googleusercontent....

(the side of fan duct closer to carriage is actually vertical, picture is shot from weird angle).

The problem with this design is that airflow is too low/exit is too far from nozzle. I get better results with 120mm fan blowing across the whole heated bed. Attached to carriage is 60mm fan.

fest on Jun 22, 2012 said:

I'm now building one from my previous Prusa Mendel's parts. I got fed up with bed leveling issues and difficulties getting axes perpendicular. I also had a verusion with PLA bushings and was unable to tension X axis belt properly- because when tensioned enough, PLA bushings popped out of Z bars.

I do have a couple of comments regarding Mendel90:
* I do not find X axis belt tensioner (plastic half-circle) strong enough to tension belt- it split open for me. I replaced it with nyloc nut and it seems to work better.
* I have dual shaft steppers, and the second shaft is in the way of ribbon c
able for X axis. The only option for dual shaft motors is to mount X axis ribbon cable perpendicular to gantry frame, to the side of motor. I will probably try to do it once I get the printer working. Back to wiring :)

nophead on Jun 22, 2012 said:

Odd the tensioner split, I have no problems with 3 I printed in ABS and PLA should be harder if anything. Did it de-laminate? If so perhaps the hole was a bit tight. It could also be printed lying down which would make it stronger.

I started with just a nyloc but the belt stopped it turning so the screw went through it and cut into the belt.

Yes I can see duel shaft could be a problem. Maybe the gantry should move back a bit.

sicarius on Apr 26, 2012 said:

Thanks again, here's a movie of it working: http://www.youtube.com/watch?v...

Going to go for the ribbon cable next, phone wire works, but it looks really ghetto :(

bifi5590 on Apr 21, 2012 said:

Looks great. Parts are printing now. I post results when I run into problems or it is finished :)

andrei_socivoi on Apr 18, 2012 said:

i will like to get my hands on a set of acrillyc cut parts... can eny one help me? were i can go to get them? thank you :))

north90ty on Apr 12, 2012 said:

Finished building and first testing of a Mendel90. It is a great design Nophead!

I had just one problem: the x-bar clamps don't clamp the rods tight enough, so if i tighten the x-belt the rods move. Maybe you can increase the gap a little so it is possible to secure the rods a little more. I know that my printer was printing a littlebit to little plastic and therefore the hole
s are a bit large. But i think it would be an easy improvement.

Personally i really prefer a vertical x-axis and i am working on one compatible with this printer.

Thanks for your great work!

idolcrasher on Apr 6, 2012 said:

Not that it would be practical, but if you printed the two support sheets (like a series of puzzle pieces), this printer would be over 80% printable ;)

nophead on Mar 22, 2012 said:

22/3/12 Improved Wades extruder:

Front moved back to allow for deeper hobbed bolts.

Added upper support web and reduced the lower one to one layer.

Added composite STL.

richgain on Mar 15, 2012 said:

I've started gathering parts to begin building the Mendel90. I got the python scripts to run OK using your instructions, and have been able to view the plans in OpenSCAD.

One thing that puzzled me was the polypropylene strips. I can't see them in the model or find any reference to them in the blog.

Where do they go and what are they for?


nophead on Mar 15, 2012 said:

Those are the purple strips that you can see in the model. They are mentioned here: http://hydraraptor.blogspot.co... under the Cables heading.

Anonymous on Mar 8, 2012 said:

Woo! Printing this now! Thanks for posting the design. I am going to laser cut the sheets at school. I will let you know how the build goes/contribute where I can. Thanks again.

Telemah on Mar 6, 2012 said:

it seems for me that z-coupling and x-idler-bracket models mave problems with though holes. It`s a bug or a feature?

nophead on Mar 6, 2012 said:

They have a support layer because they have a smaller hole on top of bigger one. That would mean printing the smaller one in mid air.

They are one layer thick and easily removed with a drill or a penknife.

sicarius on Mar 4, 2012 said:

Thank you for this great design, i would love to build one, but i have one question (if its been asked already, i'm sorry)

Is there a way to easily convert a prusa into a mendel90. without having to replace a lot of parts?

It seems like the X-carriage and vertical parts could be the same exact parts..

Also: Will this appear on reprap.org once you feel the design is "finished" ?

One more: Could you compress these into a few "plates" like the prusa design?

nophead on Mar 4, 2012 said:

Sorry, none of the printed parts are compatible with the Prusa. I swapped the smooth rods and lead screws at the X-ends, the spacing is different and so is the x-bar spacing.

I will put the instructions on reprap.org. Whether it appears on the front page is up to Dr Bowyer.

It is easy to combine parts onto build plates with openscad. The problem is Skienforge only has one infill direction per layer, so bridging does not work properly. When one parts needs a bridge lay
er they all get it. If two parts need a bridge in opposite directions on the same layer one is not right.

I also print some pulleys at a different layer height and some parts with 100% infill.

Anonymous on Feb 28, 2012 said:

I'm working on building one...it's really hard without documentation. I got a few questions.

Should the templates work for MDF? The numbers are for the sizes of holes in mm, right? What are the 2 8mm holes on the base?
Are the microswitches in the BoM the endstops? Why only 3? In this picture, I can see 4, 2 on the Z axis, 1 on X and 1 on Y. Shouldn't you use 2 on each axis?
Where do the
ball bearings go? I can only think of 3 places, the extruder pinch wheel, X idler, and Y idler. They are also known as 624 and 608 bearings, you should put that into the BoM.
Why so many kinds of screws? Can you try to consolidate them?
What would the screws be in SAE?

nophead on Feb 28, 2012 said:

I will do the documentation as fast as I can but it takes time and I have other things to do. Some of these questions are answered on my blog.

The two 8mm holes are in case the motor has two shafts.

The templates will work for MDF but I use 12mm so the gantry would end up 6mm further back. I also use No6 wood screws which have smaller pilot holes . Best to wait for me to publish the source as that can generate any permutation.

The ext
ruder uses 3 608 bearings, one 624 on the X idler and 2 on the Y. The BOM is generated automatically from the ball bearing dimensions. I will have to add another field to get the type in there.

Yes the microswitches are the endstops. You only need one on Z. I use the top and everybody else uses the
bottom. I am going to redesign the bottom limit to be simpler and will probably change that to a full size microswitch because lower force ones are available. A high force one may lift the x end.

The screws have to be the right length in most cases. For example they can stick through the base and
would look ugly sticking through the frame. There is one that is far too long on the y-idler to avoid yet another type.

I don't know anything about SAE screws and find them impossible to Google, unlike metric where I can just do "M4 nut size".

With the source files you could put in the size of SAE
you want to use and everything would change, the plastic parts and the sheet pilot holes, etc.

nophead on Feb 26, 2012 said:

The latest Prusa just uses friction fit for the bars. I haven't had a problem with one screw one prototype.

Yes the y-idler was missing, thanks for spotting it, I have added it.

tiagofumo on Feb 25, 2012 said:

why didn't you use greg's hinged instead of wade's?

nophead on Feb 26, 2012 said:

I don't think Greg's idler bracket is strong enough when printed with ABS, Greg only uses PLA.

I don't need to raise the motor because the bolts have captive heads, so I have no need to get under it, and I prefer to keep the centre of gravity low.

I have no reason to open the idler and prefer to keep it in place once the spring tension has been set. It doesn't close fully like the original
Wade's so it is easy to load filament, just push it in and turn the wheel.

If I need to clean the hobbed bolt I take the nut off with my fingers and remove the bolt and big gear.

The mounting holes are still on 50mm centres, so you should be able to fit Greg's if you want.

More details here: htt

owais on Feb 25, 2012 said:

What is your estimated cost of the unprinted parts?

nophead on Feb 26, 2012 said:

The cost depends a lot on where and how you buy the parts but is should be about the same as an LM8UU Prusa. Same motors, electronics, and bearings. The rods and belts are slightly shorter in total I think. The frame is cheap if you use MDF and probably similar to the Prusa studding. The fasteners are more numerous but smaller ones, and don't cost much anyway.

hudbrog on Feb 25, 2012 said:

nophead, from dxf file frame base is almost 1.2mx1.1m in dimensions. Is it really that big?

nophead on Feb 25, 2012 said:

No the sizes are as stated in vitamins.txt. I have just loaded the base into Rhino and that is correct at 468 wide It looks like whatever you are viewing it with is taking the units as inches instead of mm. Are DXFs dimensionless like STLs? I have never used them before.

ScribbleJ on Feb 25, 2012 said:

Check again. I measure it at much closer to 450mm... using Qcad to measure.

ScribbleJ on Feb 24, 2012 said:

This looks fantastic - I'm excited to build one, with a few slight modifications. When will the .scad files be available?

Two questions -

1) The bolts in the base dont' appear to have nuts on the bottom side, are they supposed to be threaded in the MDF/acrylic?

2) I can't see in the smooth rod holders how they are adjustable to make sure the rods are parallel. I know you have mentioned this feature - is it just mi
ssing from these renderings, or am I missing it?

nophead on Feb 25, 2012 said:

The scad files will be up when I have finished the build scripts and sussed out git. Hopefully this weekend, but I have to make two new hot ends first.

1) Yes they are M4 tapped for acrylic and No6 wood screws in a pilot hole for MDF. You can also tap MDF M4 and it works very well.

2) If you look at the bar-clamps.stl you will see the screw holes in the base are actually slots with 2mm of movement side to side.

jamesmoe on Feb 24, 2012 said:

Are these printed parts the same as for the MDF version?

nophead on Feb 24, 2012 said:

More or less. The hole sizes might be slightly different as the screws go from M4 to No 6 wood screws. However you can actually tap MDF M4. The sheet drawings will change as the sheets are thicker, which moves the gantry back a few mm, and the pilot holes get smaller. Also the BOM changes of course.

Note that the MDF version shown on my blog is slightly bigger and uses 10mm rods and bearings.

If you wait a couple of days I will publish the source with scripts to make all the STL and DXF files and the BOM. You specify the build volume, sheet materials, motors and rods, etc, and it makes custo
mised versions of all the parts.

nophead on Feb 23, 2012 said:

Added a bill of materials.

nophead on Feb 22, 2012 said:

I added the sheet drawings in DXF and PDF.

ipblythe on Feb 22, 2012 said:

Hi Nop head, it's like my happy day to see this! Will you also be providing one for

M6 rods/NEMA14s as originally forecast as NEMA14s are a lot cheaper than NEMA17s.

I know, some people are never happy! Sorry about that.

Are you also going to provide the dimensions for the acrylic/MDF? are they different for the M6 version vs the M8 version. I was going to get some M6 threaded rods from Screwfix this week as well!

nophead on Feb 22, 2012 said:

Where can you get NEMA14's cheaper than NEMA17, I have always found them more expensive?

With the source files you can chose any combination you want but all the sheets and plastic parts will change. As one of the predefined configurations I have a Huxley sized machine with M6 rods and NEMA14. It needs a small extruder designing as it looks a bit silly with a full sized Wade's and the
re is no justification for using the smaller motor on X unless the extruder is lighter.

I am currently working on scripts to build all the files automatically as it takes a long time to export everything by hand.

I will add the files for the acrylic M8 version to this thing.

Anonymous on Feb 21, 2012 said:

Where's the .scad files?

nophead on Feb 21, 2012 said:

As stated I will publish them soon. Probably as a link to github.

nophead on Feb 20, 2012 said:

I wonder why there are no printable 3D printers in the Thingiverse Features Things O:-)

nophead on Feb 23, 2012 said:

The other difference with Printrbot is the vertical carriage / x-axis. That gives smaller printed parts but I prefer to have the carriage horizontal with a low centre of gravity.

nophead on Feb 23, 2012 said:

The unique thing about a Printrbot is that it is a Mendel style machine with no frame and the Z and Y axes are unsupported.

If you add a frame you would end up with a machine like this. You don't need the chunky Z motor brackets and the studding connecting them. You wouldn't use the Y-axis where the rods move and the bearings are stationary because that makes the Y carriage (and hence the depth of the machine) bigger a
nd heavier.

Anonymous on Feb 23, 2012 said:

I did a quick search using the tag system and of the 63 things that were tagged "3d printer" the following printers have been previously featured. the maker bot cupcake, the makerbot thing-o-matic, the ultimaker, and the CUBE(printable). did some more poking beyond that and found the reprap wallace(printable), the prusa air2, and the 3D printed full size makerbot(printable).

there is probably more but the prusa and reprap tags are used so liberally(basically any thing that can be printed with a prusa seems to have a prusa or reprap tag) that wading through and finding the original upload is beyond my attention span.

p.s. have you considered making a version of the me
ndel90 that bolts a mendel90 frame to a wallace or printrbot?

sgraber on Feb 20, 2012 said:

Awesome! Definitely looking forward to seeing the other sizes, BOM, etc. Keep up the great work! :D

Anonymous on Feb 20, 2012 said:

Awesome! Definitely looking forward to seeing the other sizes, BOM, etc. Keep up the great work! :D

triffid_hunter on Feb 20, 2012 said:

congrats on the release! looks really well thought out like everything else you've given this community :D

Spacexula on Feb 20, 2012 said:

Thanks nophead