by kludgineer, published

MendelMax by kludgineer Oct 17, 2011
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MendelMax by kludgineer is licensed under the GNU - GPL license.

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UPDATE: A New updated version of MendelMax is available at http://www.thingiverse.com/thing:20355. It is recommended for all new builds.

MendelMax is a new RepRap 3d printer designed by Maxbots. It is a true reprap, using printed brackets, but instead of using threaded rod for the structural elements it uses inexpensive aluminum extrusions. This gives a huge increase in rigidity for a minimal extra cost (Self sourcing will cost about $50 more than a standard Prusa when purchased from the recommended suppliers). The required extrusions are available world wide from a variety of suppliers.

In addition to greatly increased rigidity, this design is faster to assemble (probably 4 hours for most users), easier to print, has a larger build volume (~215x235x190 if built at the standard dimensions), and is easier to hack on.

Update 2/7/2012: MendelMax full kits and hardware only kits are now available from Maxbots (aka Kludgineer on Thingiverse) @ http://store.mendelmax.com!


For full assembly instructions and parts lists, see http://www.mendelmax.com.

The X & Y axes are standard Prusa parts, so any design can be used.

UPDATE I finally got an STP file uploaded. Please let me know if you have any issues with that file. Update: The SCAD conversion is mostly complete and available at https://github.com/maxbots/MendelMax To learn how to execute scripts in FreeCAD, read the tutorial at: http://mendelmax.com/tikiwiki/tiki-index.php?page=Getting+Started+with+FreeCAD+scripting Note there may be minor incompatibilities between SCAD generated parts and the parts here on Thingiverse. It should not be an issue intermixing to some extent, but parts that directly connect to another (for example the Y & Z rod mounts & clasps) should always come from the same source. Also note that the SCAD parts are untested at this point so I recommend only using them if you already have a working printer to reprint any parts that may need tweaking. Update 1/15/2012: Y motor mount & Y Idler mount replaced with much more robust designs. These should fix any flexing issues you might have. The part "Lower Vertex Cupcake" is a replacement for the standard Lower Vertex, but is reduced in height slightly to allow printing on the Cupcake and other small-format printers. Either part will work, but you only need to print one or the other, don't print both. Update 2/7/2012: New, improved Lower Vertex pieces uploaded. These parts should be easier to print, easier to assemble, and better looking, though that comes at the expense of being somewhat slower to print. The new parts need to be printed in mirrored pairs, so the the included STLs include one of each part. Print two copies of each of the parts (lower vertex lower and lower vertex upper). You will end up with 8 parts total. If you prefer, you can get the individual STLs for each of the four different parts in the individual lower vertex zip file. One important not about these new parts: WHile they are just as rigid as the old parts, they are not as storng as the old ones. They are amply strong to use the MendelMax as a printer, but DO NOT STAND ON IT! The original parts are still here if you prefer them.

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Hi there, first of all amazing looking design! So i am relatively new to 3d printing but find i learn best by tackling big projects and problem solving my way through them. I am currently running a Pursa i3 from MakerFarm, which i assembled myself. Very interested in getting a second printer going, would you recommend this design for some one who is still getting into 3D printing or go for a more basic design?

Also having a look through the printed parts and Bill of materials, i see some pieces fall under Laser Cut. Is it not possible to print these parts? Would i have to buy those from your store?

Cheers for the help :)

="thingiverse-11d867796d85db8cad5280ac44cec7c1:disqus" href="http://disqus.com/thingiverse-11d867796d85db8cad5280ac44cec7c1/kludgineer tnxx for all the good work, it looks realy nice and I'll start tomorrow at a fablab in The Netherlands to reproduce some of the parts. So far so good...but I have a lot of Bosch/Rexroth materials based on 30 and 45mm extrusions. The 30mm type is what I want to use for the project. For that reason, I'll need to resize some of the parts. From this point, the question:

In your opinion, which parts will give me the most difficulty? I'll use M6 bolts and wingnuts. Tnxx.

I do not recommend you try to use 30mm extrusions. You will need to completely redesign everything if you do, all the hole spacings are designed for 20mm extrusions. That is true for both the 1.0 and 1.5.

Ok, thanks. That's a pity:-( The extrusion is relatively cheap, but in my case very expensive because it has to be orderered especially. The nuts, bolts, wingnuts and T-bolts are the biggest cost and these I have in large quantity's on hand......for the 30x30.

I'll have to think some more about the redrawingtime against the expenses....

You'll hear from me.

Can someone tell me what settings to use in replicatorG when converting the STL to gcode and printing with a Makerbot Replicator.  For example what infill  % should I use?  Should use a raft?

I typically print at a 35% fill, and that should be fine for most parts. A bit more is fine. You should not need a raft, but that is entirely dependent on the printer, so you may need one on the Replicator.

Hi i was wondering if you still had your original solidworks part files. I need to split the parts up because of the size makerbot we have.

The model was not designed in Solidworks, so I don't have Solidworks files. In the comments below someone links to a SW port of the design, though.

Very nice! Can I suggest that you upload it here as a derivative?

If I knew how I would. I just converted this for whoever needs or wants it.


Just click the "I made a deriviative" button in the left column of this page.

If you have trouble, I can add one for you and give you credit in the text if you want. Unfortunately, it will still show up as my creation. You should get full credit for your work!

Hi, I am trying to open the step file (MendelMax.stp) with SolidWorks but I can't :'(

Could anyone post the MendelMax in SolidWorks format? Thank you.

You can go to http://www.techdesignandcad.com/mendelmax/mendelmax.ziphttp://www.techdesignandcad.co... to download in SolidWorks format.

Only what is seen here on Thingiverse is included and the files are converted from the stp file that is available.

Have Fun

Thank you very much!!! It's perfect!!! :) :) :)

Sorry, it was designed in Alibre, and it is not that easy to go from one CAD program to another. I know the latest solidworks with all updates can open the STP file.

I'm not seeing the SCAD conversion on your github.

BTW, I've ordered everything I need except for the aluminum extrusion, aluminum plates, and power supply. Should have this up and running soon!

Sorry, I should have been more specific. It was converted to FreeCAD, not OpenSCAD. Both are Scripted CAD, but I personally think FreeCAD is a nicer language (though it is not quite as simple to use in a purely scripted manner).

Ah, my mistake. I assumed OpenSCAD where you stated SCAD. I am building a slightly oversized MendelMax with 10 mm rods for all axes, so slight modifications are necessary.

FreeCAD will let you make all those changes just like OpenSCAD will. It is a bit more complicated getting started with FreeCAD, but once you get over the initial hump, I think the language itself is quite a bit nicer, and it is certainly more powerful.

Looking at pictures an the parts I printed I can't seem to figure out what the 70mm Jig is used for, was it meant for one of the old versions of the parts?

The two 420mm have holes drilled 70mm from each end that are used to create a blind joint with the diagonal uprights. That jog is used to make it super easy to position the hole when you drill them.

Has anyone tried building a MendelMax using printed beams like this http://www.thingiverse.com/thing:10261?http://www.thingiverse.com/thi...

20mm Plastic T-Slot

I'm about to build a MendelMax, since nophead doesn't seem to be releasing the files for his Mendel90 anytime soon.

I have a question about the MendelMax's frame design, though: does the extruder collide with the frame triangle like it does on the Sells or Prusa Mendel? On my Prusa, i simply built X 150mm longer and added a large heatbed, will i need to oversize the Max as well?

It depends on how you mount it. If you rotate the extruder 90 degrees, then yes, at extreme Z heights it limits your movement a bit, but not until you are greater than ~100mm above the table. Even then the build volume is bigger than a Prusa.

Awesome design! I have a working Prusa and was planning to build a larger bot and the rigidity of the extruded aluminum used for the MendelMax makes this possible. You instructions recommend the GT2 belts (T5/XL is definitely the worst choice for linear motion.) I just thought I'd let you know about this synchromesh cable as another possibility:


It works great on my standard-sized Prusa so I plan on using it for my double-size MendelMax. Also, I'm currently modifying your parts to use 12mm rods instead of 8mm for building scaled up versions (I will post the modified parts once I've got everything w
orking)--I only have the frame built currently, but it's very study even with all dimensions doubled!


Synchromesh Cable Idler Pulley for 608 bearings
by granz

Technically, Synchromesh does not appear to be an anti-backlash design. At least there is no mention of the benefit on the Synchromesh product page at:


That said, it will almost certainly have a lower backlash amount then T* belts. The big benefit of Snychromesh is that it can be used in multiple planes, since the "teeth" wrap all the way around the cable. That allows you to use a single belt to drive pulleys that can be mounted at odd angles to
one another easily, somthing that would be difficult or impossible with a traditional belt.

I recommend 2mm GT2 because it is the most cost effective anti-backlash design that I have found. There are several other suitable design, such at HTD, AT* and more, but they are typically more expensive.

Yeah, I suppose it doesn't say "no backlash" exactly, but these cables are designed for exactly what we do. As Sanjay replied to my post, here's another link about the cable that I didn't find on my own:

(I case you didn't stumble upon that document)

The GT2 belts work great as well and I've had zero backlash with them also. The very small pitch means that printing a pulley for a GT2 belt is nearly impossible though, and I've found that I can print p
ulleys for the Synchromesh cable and still get zero backlash and this makes the cable a cheaper option :) (I will be posting the printable pulley soon.) The rounded plastic which is attached to the cable and the self-centering nature of a cable makes it possible to print an imperfect pulley and st
ill get no slop.

Anyhow, I'm just about finished with my scaled up printer (thanks for the link on scaling up on http://mendelmax.commendelmax.com, BTW) so I guess I'll see how well the cable works on that.

You may be right, I did some reading today and I cannot tell one way or the other whether these are designed to minimize backlash. There are a variety of ways to eliminate backlash in a system, so the fact that they are designed for linear motion does not inherently mean they are designed to minimize backlash. It seems to me that if that were a design feature, ther would say so, but you never know for sure. I have a call in to SDP's engineering department, so hopefully they can confirm one way or the other.

All that said, these are definitely cool, one way or the other. The ability to route the belt in 3 dimensions is an incredibly powerful option, and if we can reliably print pulleys that would be even better.


Just to let you know that after applying the latest service pack Inventor 2012 Imported the stp files perfectly

Great, glad to hear you were able to resolve your problem.

Umm... Wrong angles relative to what?

As to your second question, some lengths can be adjusted a bit, others cannot. This is both a feature and a bug, depending on how you look at it.

When I designed the MendelMax, it was deisgned to take advantage of Misumi's extremely accurate cutting. Their standard cuts are +/- .5mm, but in prac
tice they are almost alwatys dead on. Their cuts are plenty accurate for our needs. As I note in the FAQ, I do not recommend you cut these parts yourself because of the high level of accuracy that is required.

That required accuracy, though, has a big benefit. Because I am relying on the accuracy
of the parts, the assembly process is relatively trivial, and almost all of the fiddling that a Prusa requires to square everything up is eliminated.

All that said, the required lengths are actually quite forgiving. It does not matter so much if your extrusions are a mm or two longer or shorter th
an the specified lengths, all that matters is that they are consistent within the length... So it is ok if your 300mm extrusions are really 302mm, and your 340mm are only 338mm, so long as each length is the same length. The only exception to that is that two of your 420mm extrusions need to be th
e same over/under as the 300mm (I am open to hearing suggestions to fix this). In practice, this is not an issue if you get your extrusions from the recommended source or another source with accurate cutting capabilities.

gt; (I am open to hearing suggestions to fix this)

Drop the triangular shape, and stick to the boxy form.
The extrusion profiles are designed to squares for a reason.

At least this is my conclusion after a week debugging.


gt; At least this is my conclusion after a week debugging.

Lol, you should have emailed me a week ago, I could have saved you plenty of time. If your model is wrong, any data you get from it will also be wrong.

BTW, if you want to look at a CAD model, why not use the STP file on this page, or the FreeCAD model in the Github? https://github.com/maxbots/Mhttps://github.com/maxbots/M

gt; Drop the triangular shape, and stick to the boxy form.

Every issue you brought up would also apply to a cube or similar "boxy" design. And building a boxy design would sacrifice the benefits on the triangular design and would cost more. Cubes have their own benefits, so I'm not saying a boxy design is without merit, but they are not inherently better
or inherently more suited to being built with extrusions.

gt; Umm... Wrong angles relative to what?



In that triangle there is no play allowed at all.

So if the extrusion is 338mm instead of 340mm (lets assume the models are not wrong), then the angles of both z_motor_m
ount and lower_vertex_middle and top_vertex_y needs to be adjusted. To be accurate.

At least if you care, the machine is flat at the bottom, or on a table it waggles.

I was quite surprised, that when I put everything in CAD, the two leg of the triangle is almost touching each other at the top (5
mm gap between them).
(I was also equally surprised that when I fastened the bolts, the machines started waggle on a table)


gt; I was quite surprised, that when I put everything in CAD, the two leg of the
gt; triangle is almost touching each other at the top (5mm gap between them).

Your CAD is wrong. You left out the 300mm extrusions that are before and after the 420mm extrusions. That adds 40mm, so the gap between the tops of the extrusions is ~45mm. The stepper motor sits between them.

If you build the machine as the instruction say, it will sit flat on the table. The as
sembly order was specifically chosen to guarantee that it does. The worst that would happen if your 420mm extrusions were not a consistent length would be a gap on one or more corners where the extrusion make the right angle. That sounds bad, but the structure is designed with that in mind, so it ha
s no effect on the overall strength. If you are not comfortable with that, you could always add shims, but personally, I wouldn't bother, once you tighetn the screws holding the 420mm extrusions, they won't move even if there is a mm or two gap..

mea culpa. You are right. 460mm is the total length at the bottom of the triangle.

I indeed assembled in the correct order. Pic:


Just I forgot the 20mm from each side of 420mm extrusion in qcad.

So Im out of ideas what is wrong. The bottom is flat until I start tighten the bolts of z_motor_mount. So something is wrong.

I suspected the z_motor_mount, because on one of you picture you have a slightly different version, pic:


But right now Im clueless, why it waggles, once the bolts are tightened

I was just about to drop that here after I saw someone made it. :-P

To reduce the parts list why not run rollers on the extruded aluminum for they Y-axis? I know this will not be as effective as the Makerslide, but for a scaled up version it should be better than 8mm rods.

My first bot did exactly that. Trust me, it increases the part count, not decreases it.


A group of us built MendelMax' using Makerslide, and honestly for our purposes it was not a good choice. It is more expensive, more complicated, and higher maintenance than linear rods,
and there is nothing really gained to justify it. For a laser cutter or other projects with a long moving axis it is beneficial, but for a printer you are better off sticking with linear rods.

For anybody who is having trouble printing the Y Rod Mount on a ToM or Cupcake due to its immense size, kludgineer has pointed me towards a ToM/Cupcake friendly version.


This smaller Y Rod Mount printed perfectly on my ToM. Thanks kludgineer!

I see kludgineer already gave this link in an earlier comment. Doh.

I would love to see a scaled up parts list

Other than the extrusions, the parts are the same if you scale it up, and the extrusions lengths are documented in the scaling document at http://mendelmax.com/tikiwiki/tiki-index.php?page=Scalinghttp://mendelmax.com/tikiwiki/... so basically there already is a "scaled up parts list".

Note, large scale printers are not recommended for beginners, and are not really supported. Unless you know what you are doing, I would not recommend you make a printer much larger than the stock size.

What the total cost of parts come out to? Assuming you are using all the distributors on the http://mendelmax.commendelmax.com website.

The BoM online gives you a good idea, but you should understand that it is for a fairly premium build, with careful shopping and cutting some reasonable corners (printed bushings instead of commercial ones, Sanguinololu instead of RAMPS, etc) you should be able to make a MM for at least $100 less than the total posted there.

It's mostly those T-slot Nuts that cost a fortune. But thankfully there are alternatives: http://www.thingiverse.com/thing:13626http://www.thingiverse.com/thi...


Have look at the BoM and its suppliers list: http://reprap.org/wiki/MendelMaxhttp://reprap.org/wiki/MendelM...
Add if anything is missing! Thanks.

Dual Printable T-Slot nut for MendelMax
by RichRap
Printable T-Slot nut for Misumi Extrusions

How does Mendelmax's greater rigidity translate to vibration? Does vibration propagate from the extruder moving around to the frame?

The frame itself does not seem to conduct vibrations badly. Since the extrusions are connected together by plastic, the vibrations tend to be deadened, and the extruder is mounted on the same rods and X ends as on the Prusa, so not a lot of vibration is transmitted to the frame itself.

The one area where I am currently having noise issues is on my table. Currently I am using a sheet of 1/8" aluminum with blue tape, and that acts as a speaker and amplifies the sound of the vibratiions. That should be solved once I install the silicone heat bed and the fiberglass insulation which
together should dampen much of the vibration.

For the table vibration, you might consider mounting some rubber (via adhesive) to the underside of the table.

Look at compound bows for an example. they sell little mushroom-looking dampeners that you peel/stick to the limbs of a compound bow to dampen noise and it really works well.

As a machinist, machining long aluminum tubes (think 5" dia x 6' long) we would wrap a sheet of rubber around the tube wi
th rubber bunji cords (like hold truck tarps down) and the rubber sheets cut the vibration and "singing" down to almost nothing.

You are a creative guy, try taking some rubber limb dampeners, cut in half or quarters, to a shape that can still vibrate and fasten to the bottom corners of the table.

Doing the same on the frame behind the x axis and that should cancel any vibration that does get to the frame from the x slide.

That is basically exactly what the silicone heater is. Add to that the layer of insulation below it and the vibration-deadening wooden frame in my kits and there is very little remaining vibration in the table

Brilliant design again. Just looking at it the printable pieces.... are they printable on a Cupcake?

A cupcake-printable Y Rod Mount is now available in out GitHib repository at https://github.com/maxbots/MendelMax/blob/master/build/YRodMount.stlhttps://github.com/maxbots/Men...

I am no longer recommending the Y Top Vertex for normal use because the printer is plenty rigid without it, so it seems to be superfluous. Because of that I will not be releasing a Cupcake-printable version of that part, if you really want one, you can always print it after you get your MendelMax

Most pieces are easily printable on a Cupcake, but a few are not. Currently the Top_Vertex_X and Y_Rod_Mount parts are larger than the build area of the Cupcake. You could probably get by without the Top_Vertex piece long enough to print them on the MendelMax (the motor mounts serve the same purpose, these just add rigidity). It would be easy enough to make a smaller version of the Y Rod Mounts that could be printed on the Cupcake, but that would make the rods closer together, so you would lose some rigidity, but again, this should work fine long enough to print the correct part on the MendelMax. I will try to put up a Cupcake printable version of that part sometime in the next few days.

How does this printer compare to the Thing-O-Matic?

MendelMax will cost about 1/2 as much for a fully loaded system when self-sourced (see http://MendelMax.comMendelMax.com for a full BoM), is faster to assemble, gives you about 4x the printable volume, will print faster, and will be more easy to hack on if you are so inclined. I'm sure ToM is better in some way, but I can't think of any.

I guess strictly speaking, ToM has a larger installed base, but since MendelMax is basically just a Prusa Mendel on Steroids, that benefit doesn't really get you much.

To make this worthwhile, it could do with a further redesign to replace the M8 smooth rods with those same extruded beams in all axes.

Specialised X/Y carriages would then be needed, probably using skate bearings instead of linear bearings, but without that you're not really gaining rigidity where it counts most, and so can't scale the machine up by a significant amount.

After that, +1 for the first maker to replace their T5 belts with bicycle chains. 8-)

Oh, and regarding scaling, I already address your concerns about scalability here: http://mendelmax.com/tikiwiki/tiki-index.php?page=Scalinghttp://mendelmax.com/tikiwiki/...

My interest would be to scale it to support dual StepStruderMK7s . Seems like a pretty simple mod to add a little length to the rods and cross beams but keep the same table and other dimensions to allow full printing with either extruder.

Yeah, need thicker rods, which are expensive, but that makerslide option looks pretty cool, I hope they can be made efficiently. :)

We had a group build for 6 MM with Makerslide tonight. We didn't finish, so we won't be testing the bots until next weekend, but initial impressions were quite good. I will post updated files for building with Makerslide once they are tested.

Very excited to see result and cost difference. I am thinking of going down the MendelMax path and want to start with those slick looking slides :)

Trust me, it is quite worthwhile as is. ;-)

As noted on http://MendelMax.comMendelMax.com, I plan on releasing an X
amp; Y deisgn using Makerslide as soon as it starts shipping to the general public (http://makerslide.com/)http://makerslide.com/).

My first RepStrap design used the aluminum extrusions as the linear rods, and while it worked very well, the parts required to properly constrain the carriages were considerably more complicated. It is much simpler to stick with the current designs and use linear bearings (or better yet, linear bu
shings) until a proper linear motion system such as Makerslide is available.

Bike chain would work, but would have the same problem that T5 does only much worse-- they are designed for rotary motion, not linear motion, so they make no attempt to eliminate backlash. I suspect you would have backlas
h of 1-2mm or possibly much more with bike chain. To get the best quality prints, you really need to switch to a belt design that is intended for linear motion, such as GT2. See my Choosing Pulleys FAQ for more information: http://mendelmax.com/tikiwiki/tiki-index.php?page=Choosing+Belts+and+Pulleyhttp://mendelmax.com/tikiwiki/...

So whose going to be the first who will test this?

At least a few people have parts on order, I expect you will see a few copies soon.

My prototype is actually working now, here is a print of it printing at 150mm/sec:


It is currently only working ok at those speeds, but the problems are software ones, not hardware. I also need to rebuild my Y axis to make it more rigid, but that is an
assembly problem, not a design one. I should have that done before the end of the weekend time allowing, and I will post an updated video then.

Is your platform heated in that video?

No, still have not installed a HBP on the MM yet. I mostly print PLA, so on most prints I don't need one. That video was peeling a bit, but wiping down the blue tape with Isopropyl alcohol occasionally helps a lot.

Outstanding! What a mean and cool looking machine. I want one! 8-)

Outstanding work...

I will have to add this to my to-do-list.
8-) 8-) 8-) 8-) 8-)

Looks great! Can you please post videos of it printing as well as detailed pictures of non-trivial objects printed by it, so that we can get an idea as to the print quality?

It's not printing yet, but I will certainly post pics once it is. Print quality should be at least as good as a Prusa since it is a Prusa, just with a stronger frame.

looks great. which x carriage do you plan on using? which hottip?

The design is flexible, so you can use whichever X axis parts your prefer.

I am using the Makergear X ends and my own X carriage design. I will be switching to the Felt branch X carriage as soon as I get some Igus bushings. I use the Makergear hot end and extruder, but you can use a Wade's or whatever you prefer.

I'd like to use MG parts for X too, (I have a Mosaic and love the extruder/hotend, and people seem to love the X axis designs) but as a semi inexperienced builder, could you help out by showing deviations from the full BoM so that I can understand which need to be ordered through MakerGear? I may start ordering piecemeal bits and printing parts to give my daughter the chance to help build our second printer :)

Really nice Idea. The only thing I would change is the Z axis - i would go for a belt / one motor design. But this is just my opinion... ;)

A single motor/belt design would add complication with little savings. The extra motor costs $20, two pulleys and a belt would cost near that much, quite possibly more (unless you print your pulleys, which I do not recommend for best print quality).

A single motor design would also increase both the printed part count and the vitamin count since you would need to design a tensioner mechanism.

Personally I prefer the current design, but since the design is (or at least will be) Open Source, I look forward to seeing the new ideas other people
put forward. I fully intend this design to change rapidly as other people submit designs.

Forgot to ask, what software did you use to design the bot?

It is currently designed in Alibre. I will be porting the design to FreeCAD in the near future.

Can't wait to see that freecad. You mention in the comments here that you haven't printed yet... based on your website can I assume that's no longer the case?

Do you think the MendelMax has the rigidity to push the resolution like the Ultimakers? http://www.hive76.org/wp-content/uploads/2011/09/LowerMag_WithFingerAndScaleBar_162pixelsPerMillimeter.jpghttp://www.hive76.org/wp-conte...

Yes, I am now printing, and it is working wonderfully. In fact I am printing a set of MendelMax parts on it right now, and just this weekend we had the first two MendelMaxes in the wild start printing.

There's a link in a comment above to a short video of it printing at 150mm/sec, and photos of several prints in the pictures at https://picasaweb.google.com/111347501166295022626/MendelMax?authkey=Gv1sRgCLOd7NeZhJuTjgEhttps://picasaweb.google.com/1....

For print quality, I see no reason at all why this can't do just as good as
the Ultimaker. Honestly, I am not sure we can compete with the Ultimaker on raw speed, since the MendelMax has much heavier axes than the Ultimaker's. but I fully expect to see it pushing the limits of what the reprap is capable of once it is in the hands of some more capable people than me (I am mu
ch better at designing printers than I am at printing with them).

Thanks for bringing this to the Seattle Makerbot night at StudentRND! Awesome work!

Why not give more vertical clearance for the extruder by moving the vertical frame all the way to the outside and making the bottom horizontal frame sections the same length as the top ones? This is a problem with the Mendel frames that limits the vertical build height to well below the 140 mm spec unless you use the original extruder and hot end design.

I am not 100% certain exactly what you mean, but this design nearly doubles the usable Z axis to about 200mm including the extruder (compared to ~100mm including the extruder on a Prusa, final usable clearance TBD).

Making the bottom cross-wise (X axis) extrusions longer would not give you any additional build area in any axis. The limiting factor is the ends of your X carriage. By moving them outside of the main frame you lower the build cost slightly, and reduce the overall footprint of the machine.

I was referring to the triangular frame sections. In the Mendel (both Sells and Prusa), either the extruder motor or gear hits them well below the 140 mm spec. You can move them outside and keep the z smooth and threaded rods in the same location so that the x axis doesn't change.

Is your frame larger than the original and Prusa Mendel?

BTW, http://mendelmax.com/tikiwiki/tiki-index.php?page=Scalinghttp://mendelmax.com/tikiwiki/... has details on scaling the MendelMax design, so if you really need more Z axis it is easy to add it.

I finally have the printer fully assembled and printing, and on my prototype, I have just about 170mm of Z. I changed things around just a bit on the final that should increase that by 10-20mm more.

Sorry for the slow response. This is actually not a bad idea, though I don't think I will roll it into the official design. It would add to the cost, and only be beneficial in a few edge cases. This design already gives roughly double the Z and greater Y, so for most prints if you are really pushing the limits you can just rotate it so the long part is in the Y axis.

That said, it should be trivial to modify your own printer to do this if you want. Instead of using 300mm extrusions for the front and back horizontal extrusions, make them 420mm instead. That will push the diagonal rods to the outside. As far as I can see, no other modifications should be needed.
If you decide to build it this way, let me know if it worked for you.

FWIW, I solved that problem on my Prusa by simply rotating the extruder 90 degrees.


Is this a Mendel made with Makerbeams? That's awesome

No, Makerbeams are a 10mm profile, which would not really be rigid enough for a full sized Mendel (though at least one person has already told me of plans to take my design and build a Huxley scale bot with Makerbeam).

This design uses Misumi or any other 20mm profile aluminum extrusion. 20mm Profile extrusions are available from a number of global suppliers and are very in expensive ($5.20/meter from Misumi).

Oh, and a list of suppliers is available at the link above.

there are various printable makerbeam pieces on this site.... While I doubt there's really any way to print at the rigidity required I find myself wanting to try....

Ok, so scaling to half size has.. unfortunate side effects. Too bad it's not that simple. BUT! I think some of the pieces of this could be printed INTO the makerbeam stuff that's here. Will keep you posted.

If you want to make a printable printer, you would probably be much better off starting from scratch. These extrusions are so nice because of the natural rigidity of the aluminum. switching to plastic extrusions-- even if they were actually extruded in the proper shape and not printed-- would lose most of that benefit. You can certainly print segments that may be useful for accessories and such, but it is doubtful that you will ever be satisfied with the extrusions as the main structural components.