MendelMax 1.5

by kludgineer, published

MendelMax 1.5 by kludgineer Mar 30, 2012
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MendelMax 1.5 by kludgineer is licensed under the Creative Commons - Attribution license.

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An updated version of the MendelMax 3d Printer. Nearly every printed part on the bot has been updated to make the assembly easier and faster and the printer more accurate.

Major upgrades include easier to assemble lower vertexes, Lower mounted Z motor mounts, an improved Y axis belt tensioner system, and easy to align Z axis smooth rod mounts.

NOTE: While I do not consider this a work in progress, it is still not widely tested. I recommend this design even for new users, but if you prefer a rock solid well tested design you may prefer the original MendelMax.


Full instructions will be published eventually.

The Bill of Materials is available at http://goo.gl/x29Kj. Note that except for the bushings, at present it does not include the components for the X carriage or extruder. That BoM is for the kit as supplied by store.mendelmax.com, other variants may require other components.

You can also get the full recommended hardware kit or a full printer kit from http://store.mendelmax.com

You can download the full STL file set in the first zip file. It is current as of 3/30/2012, but be sure to download any later files separate from the zip file.

To see the full model in 3d, download the MendelMax 1.5 PDF file and open with Adobe Acrobat (most 3rd party PDF viewers do not suppport 3d PDF files).

The source files are available in the MendelMax 1.5 Alibre files.zip file, and are editable with Alibre CAD.

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Started to collect and print parts for this.. noticed that x-carriage and Y-motor/rail parts are missing? Which X-carriage and Y-parts are (prefer 10mm round rails) recommended for this? What about extrurder (Greg's)? I will be using E3D v6 hotend.



Sooo, where do I find the other files? Is there another site with the complete downloadable list?

I don't think you ever come around here, but just wanted to let you know I finished my MendelMax ;) Thanks!

Ofcourse, it's never really finished, I will improve many parts, but the machine is working as it is now :)

What I changed: X-axes are above eachother instead of next to eachother, X-ends re-designed from Prusa i3, 10mm rods are all 8mm chromed rods (also changed all the printed parts to accept 8mm rods), self-designed Y-bed and Y-clamps on the frame, PTFE-lined bushings in the whole machine instead of LM8UU linear bearings and finally it's a bowden type extruder that I've designed the hotend part all myself.

Thanks for giving a good starting point on the machine, it really helped. Now I'm ready to make my own design completely ;)

Hmm.. I have my mendel max kit on my desk. I go to send the person running the lab the files I need printed.. but .. uhm.. the BOM provided here does not match what's provided?

I see many of the missing files are hidden in the zip files (so I had to download them to even see them..) but they aren't in a .stl format, so I can't look at them to see if they are right. I don't even know what on earth these files are. I'm not a mech engineer, I don't use anything that isn't free.

The plan, google, get the part list, get the stls, email, done 10 minutes, reality waste about an hour. I have to get it right, as it takes more than a week to request 3d printer time....... Perhaps it would be a good idea to match your BOM with STLs in the main directory, and provide platter prints.. That way people who don't know what you know can easily get these printed :D

Can you provide the whole Alibre assembly file for this or 1.5+? Would save tons of time for me.

Meanwhile, you're pretty silent, BUT, it's ok, I have started building your MendelMax! :)

Currently finishing the last few printed parts and by the end of the week I will be receiving most of my vitamins! Exciting stuff.

I have decided on using all 8mm rods since I have a stash of them and they are hardened and precisely ground down smooth rods and I also have a set of 12 bronze self-lubricating bushes in 8mm already.

It is great you have added the 8mm printable parts in the STL's for the motor mount, and the Z-vertex so I don't even have to change the STL's myself. Thanks for that.

Will incorporate the Prusa i3 vertical X-axis into the Mendelmax, because I am very impressed by how very efficient it is. Adding to that I am going to put in a Bowden extruder system. I really hope this Bowden extruder will make it a bit faster/less shaky and it will have even lower wear on the smooth rods.

Are you still happy with your MendelMax? And what are the improvements you made to your machine? Did you change the design that we see in here? Or did you already continue with a different machine?

Hope to hear from you!

  • Marinus

This looks good! I am currently improving my Reprap Air 2 XL but to be honest, I am finding the Air very limiting in it's design. The acrylic parts are too much 'boxing' the machine already and also make the machine slightly wobbly. To be honest, you don't really notice the wobbling much in the prints that come out, but some parts on the machine are heavily under stress. This is also due to the parts that I bought not being entirely the same sizes. The seller has sold me some parts that are pretty warped and shrunken in comparison to their counterparts which makes the spacing between the smooth rods a little off, causing the LM8UU bearings to dig into the smooth rod at some points.

I am really anxious to start a 2nd project for a 3D printer for which I won't buy the materials as a kit, but buy raw materials and compose my own kit to create a printer.

The aluminium extruded beams really make me feel excited and I think that this machine you have here might be the next one I will be building.

Only doubt for now is between the Rostock Delta and Mendelmax 1.5 but for the Mendelmax I see more users using it so probably more experience available online.

Are there any other machines you can recommend me besides the Mendelmax for a newbie, but who has grown over the simplicity of the Reprap Air?

Do you happen to know where to find files related to the MendelMax 2.0? I'm coming up empty here.

where can I found end stop mountings?

Any chance you could save the source files in Solidworks format? I dl'd the trial version of Alibre but I cannot convert them myself without buying an additional license. The geometry in some of the .stp files isn't right, and SW can't convert most of them back to parametric form.

Sorry, the best I can do is provide the STEP files already available in the downloads section.

I answered my own question , so removed

I answered my own question, so removed

                        Y-Idler-tensioner.stl the hole is closed ? Left Side hole on the picture. 

Are there MendelMax 1.5 source files available anywhere? STL files are a software artifact for distribution, and are not source-code. They are generated from source code, analogous to EXE files. In order to be considered open-source, a project must distribute source code under an open-source license, of which there are many. Software that is provided for free but does not provide the source-code files is commonly called freeware. Is the MendelMax 1.5 freeware, or open-source?

Read the instructions above please. ;-) Source files were posted the day the design was released. In addition to the native Alibre files, I have two different STP file versions that are compatible with the majority of CAD programs.

Like every other Thing on Thingiverse, the license is listed at the bottom of the column to the left.

What kind of couplings do you suggest for minimal backlash? Are flexible beam couplings okay, or should I avoid those?

cant print the y rod mount 2 on a makerbot thingomatic is there any other parts that cant print thanks anyone know were i can buy them individualy

hola todos estoy entrando al mundo de las 3d y escogi la mendelmax para empezar

que opinan? :)

Brand new here :)

Can someone tell me what the dimensions are of the largest part in this set is? Cheers

It prints on a Mosaic w/ 5x5x8 print area, but does not need the height. My prusa can print it w/ ~4" of Z can print it

Is there a place to download the files for the laser cut Y carriage? Or a template for the build plate?

Thanks again - My MM 1.5 looks awesome :-D

Can you confirm how the leads screw nut is clamped on the the new X-ends you've produced that are included in the .zip? I assume it's the disks that are detailed in the PDF but as far as I can tell they aren't a printed part and I've not come across anything that looks like this in the BOM.... Sorry if this is a dumb question.

I could not find the x-ends, can you point me where are they? My acme lead screw uses an standard sized M8 nut, would it work?

Scratch that, I've worked out that it's just a different flavour of leadscrew nut I wasn't aware of. I'll design an adaptor part to accommodate for acme lead screw nuts.

Cross-posting this question on my 8mm derivative:

I printed these out (they were just what I was looking for) but I can't determine what to use for the retention nuts. Standard M5s do not fit, nor do t slot M5s that are used in 20mm extrusions."

The slots for the nuts are sized 8.5x3mm and indeed fit neither a M4 nor M5 nut (ISO 4032),
while a M3 nut will be too loose to tighten down. They would fit slim M5 nuts (8x2,7mm, ISO 4035/4036). What size were they intended for?

The parts were originally designed to use M5 thin nuts, which are what I recommend. many of the parts allow the use of either nut type, but there are still some that require thin nuts. I will try to reqork the remaining parts to allow the use of standard M5 soon.

FWIW, the reason I recommend using M5 thin nuts is that they can be used in a pinch as post-insert t-slot nuts (in other words they can be inserted into the slot from the top of the slot instead of the end) so they are a bit more flexible, unfortunately they are harder to find.

Thanks, I guess I need to place another McMaster order!! :-D

I think the Z rods are out by 5mm at the top? unless the top Aluminium bars have changed since V1?

On the bottom motor mount I get 65mm to bar centre and at the top mount I get 60mm.

The top z shaft mount is now adjustable. Move them as needed to make the shafts parellel and square. In theory the old version is easier, but it unless your printer is perfectly calibrated it required shimming to adjust the spacing of the Z shafts. The new design allows the shaft mounts to be adjusted as needed.

Thanks, got it, It makes sense to be able to nudge it a little.

I spotted the 'normal' position on the PDF, it's all fitting nice now.



The source files are from Alibre CAD.

Another printer smartley moves its Z-Motors to the bottom of the bot. Well played :) I am also a fan of driving the Z axis with a single motor, using a belt system to turn both rods at once.

The SeeMeCNC H-1 printer does this, and it seems to work like gang busters. I am not sure if their design is open source or not though.

A single Z motor adds significant extra complexity (mounting the pulleys ie easy enough, but you also need to design a belt tensioner), and it really doesn't save much cost. By the time you buy three pulleys and a belt you are over $15, so compared to a stepper motor at $20 it is not really compelling.

It's not about cost or the complexity of assembly, it's more of a long-term benefit. I've built both a Sells and a Prusa (and now a Max), and the Sells had the only fire-and-forget solution for the Z rods. With two motors, i had to re-synchronize the rods countless times (mostly after trying out higher speeds and having just one motor skip), where the Sells' belt kept everything synchronized.

Not only do you have to re-sync them occasionally during normal operation; the belt-driven z-axis fails gracefully, whereas two z-axis motors fail miserably. The belt-driven z-axis has proven to be much more reliable than two motors on the z-axis on every machine we've employed it. It's more efficient, the leadscrews are synced, and it runs faster. The key is...machine alignment. Without that - you should just run two motors...

I do see the benefits, but I also see the complexities. I am not saying I will never look at such a design, but for now it is low on my list of priorities.

if your z motors are out of sync, connect them in series instead of parallel. It is easy to make a simple cable adapter that does it and it greatly increases the reliability of them. When in parallel the current won't be evenly split between them unless they have exactly the same resistance which isn't going to happen. By connecting the motors in series the exact same amount of current has to go through both motors coils.

I have built many MendelMax 1.5's, and I always wire them in series. But, in my experience, if there is binding on one of the motors, they can still get out of sync. I fix the binding issue, so they usually don't get out of sync. Still, its easy for some idiot to grab one of my z-axis motors and turn one of them while the printer is off, un-syncing them..

I have not tried parallel wiring the z-motors.

I turn my motors a little here a little there on every single print WHILE the printer is going. It doesn't hurt it at all, and it helps me get the first layer down perfectly every time. I just make my adjustments while it's printing the circle around the print. I use the printerboard with marlin firmware, and when the motors are not actually turning they are powered off, so it feels easy and loose to adjust. once it is going I never see a problem.

I had started my MendelMax 1 before you posted this, so I have 8mm rods and have invested in LM8UUs. Any chance that you will be able to release stls for X and Z axis items that accomodate 8mm rods and LM8UU bearings?

No, I am not a fan of lm8uu's so I doubt I will ever make the effort to convert the parts, though others may do so or you can always mix and match parts with LM8uu poieces from thingiverse (the X ends, X carriage, and Y axis are all compatible with Prusa-compatible parts).

This topic seems to be coming up more and more lately, not sure why. I recommend at least starting with the recommended bronze bushings. Unlike LM8UUs, bronze bushings are completely maintenance free. They are smoother, quieter, cheaper and lower maintenance.

LM8UU's are beneficial when you are m
oving a very heavy load. Sliding resistance vs. rolling resistance becomes more of an issue if you are moving a large weight. For the loads we are moving, there is no benefit and a significant number of disadvantages.

Okay, straightforward enough. I do like your Z top and bottom vertices but notice that that they (and the clamps) only accommodate 10mm smooth rods. Curious, have you found a performance difference between 8mm and 10mm on the z rods?

Yes, 10mm has about ~60% more material than 8mm, so it is considerably more rigid. Because the X axis moves on the Z axis, and because of the high speeds possible on the MendelMax, beefing up the z axis is worthwhile. The difference is small, but the cost difference is negligible.

There is a way to measure and calculate stiffness: http://en.wikipedia.org/wiki/Second_moment_of_areahttp://en.wikipedia.org/wiki/S...

For a 8mm rod and the type of load we have, it calculates to 201mm^4. For a 10mm rod, you get 490mm^4, so it's 144% stiffer and therefore will bend only 40% as much as 8mm ones.

By the way, i do like LM8UUs, as they are cheap, practically wear-free and require about the same amount of lubing as bushings while gliding along smoothly at any speed and load.

"ii do like LM8UUs, as they are cheap, practically wear-free and require about the same amount of lubing as bushings"

Heh, well, no. Self lubricating bronze bushings require ZERO lubrication. While there are certainly variables, lm8uu's will require lubrication sooner or later, and cheap ones will probably be sooner. As for usable life, bronze bushings will last pretty much forever. How often do you need to repl
ace or lubricate the bushings on your inkjet printer?

Don't get me wrong, if you really prefer LM8uu's, go for them. I just don't feel like spending time design for parts that I feel are inferior for our application. The design is open source, I highly encourage you to improve it in any way you se
e fit.

"How often do you need to replace or lubricate the bushings on your inkjet printer? "

Never - it doesn't even have any rod-based bearing. All the printhead is sliding on is a fold of the sheet metal frame, it was already well lubed when i got it. It's a 180
€ Canon printer, and still working well after 10000+ pages.

What type of bronze bushing do you mean? Since there is no BOM available yet, i'm assuming those are non-self-aligning bushings, and i've had a horrible experience with those. I had tried to build a small CNC mill and used bronze bushing
s, but they were binding (as in "blocking any movement") as soon as they were even slightly misaligned. For use with printed parts, i'd suggest at least self-aligning ones (like the ones MBI uses) or, for short-term use, IGUS-style polymer bushings.

For linear ball bearings, i shall re-design the m
ounting parts for the Z and Y rods and post them here. :)

They are self-aligning. That said, it can still be a challenge to get them all aligned right since they're so tight.

This is looking like I might get into (Another) hobby. I really like your design. Any idea when the store will have pictures and be ready for shipping?

Soon! We are shipping kits daily and working to get caught up. We hope to be fully caught up within a few weeks.

So you are shipping version 1.5 now?

Yes, orders placed now will receive MM 1.5

These are great. One issue I've run into so far: There are two nasty unsupported holes in the middle of a bridge in the Z_lower_motor_mount_10mm_2_copies.

BTW, you can rotate it and print it with the top (top in the final piece, that is) down. I prefer to print it vertically since the top will be visible, and if you print it down it will not look as good.

Ther are no unsupported overhjangs that I can see... The bridge is definitely a bit extreme, but it is printable. The bridged part is completely hidden on the final assembly, so it does not need to be perfect.

I added 0.6mm (2 layers) more solid infill at the start of the bridge and they come out perfect, no sag and not a single strand out of place now.

I printed them flat, no problems.

I tried vertically and they were ok, just a little bit of sag. I just modified the model to add a bit more support for the next print, should be perfect then.

It looks like they will not be so strong printed flat, the layers will not be in compression with the top M5 bolts into the frame.

I was just about to print those, I'm thinking about printing it flat instead of vertically.

Did you print it upright or flat?

I printed it upright, but I'm gonna try flat for my next attempt.

Very nice, I like the motors at the bottom and it looks like there is a lot more room under the Y carriage now - space for Powersupply and electronics.

I think my next one will be a mash-up of V1 and V1.5.


Also, what x-ends and lead screw setup are you using in the render? The motor side looks similar to AlephObjects' one, but the idler side looks different. How are the rodes held in on the idler side?

The X ends and leadscrews are custom also. The leadscrews will be available in my shop in about 2 weeks. The X ends are included in the Zip file but will be listed as a separate item on Thingiverse as soon as I get a chance to add it.

Note that these new X ends are designed to reduce Z axis binding, so they require 4 extra bronze bushings on one of the X ends.

Will recent orders (i.e. mine) be getting these new leadscrews? Soooo excited.

Aww, I just recently printed off a set of MendelMax parts and assembled my frame :/

I like the lower z-mount. I may have to replace that on mine.

So did i...

Btw, is the 1.5 x-axis still Sells / Prusa Mendel compatible?

Yes, the X shaft spacing is the same.

Ordered a hardware kit too, can't wait builing my mendel max :)

Woot! I just ordered a hardware kit minutes ago. Anybody want a makerbot TOM? I've projected mine will fall out of use.

Oh, it will. Mine did!