Hi man, first, my name is pronounced "proosha". As you said, its old model, no reason to bitch about it in 2013 you are three years too late ;-) It is still built as there are thousands of ppl who can help you with it. Hanging Z axis was made because it transfers less wobble to the print, now with tube couplings, its not needed. Your coupling slid out of the shafts either because they were oversized or you didnt tighten them. Sanding the motor shafts helps a lot too. Your cables broke as you didn't bolt them to the Y carriage or used poor cables. Two motor Z axis is much easier to maintain then the original mendel one, if you would built original mendel, you would know. That thing sucked to calibrate. The x axis wobble is true, but during prints it wasn't affecting the quality too much. ... Anyway, keep up the good work.

10 years later and I would still want to build an i2 just for the nostalgia.

Never knew there was so much upkeep on the Mendel, thx for sharing your experience and being honest about it! :)

I am with you in that Prusa Mendel It 2 had some flaws (one of the reasons it evolved, as it is natural), still, you went over the line with the "it sucks" part. I find it disrespectful and pretencious. If you don't like the design, and want to be useful you might (and should) make a new, better one rather than post a video criticizing it.

i have one and i NEVER experienced one of the problems you mentioned. my x-axis is verry stable and i never had a cabel that broke - this is mainly a fact of choosing the correct wire and fixing the cables so you dont stress the solder joints... i never had to replace a part but this point is verry valid! on the other hand i've seen printers where you have to order all the spare parts and replacing them is even more stressing

OK, what are your solutions?

Intersting video... Truth is, I have my printer for three years now and I had _none_ of the problems you mentioned. My machine is based on the Pusa but modified to work with unipolar stepper motors I had lying around. I never had a single broken wire, I never needed over an hour to repair the machine and I never hat problems with the precision of the X-axis... Anyways, I still find your list very valid - which is why I'm constructing a new printer at the moment...

Thanks you for your advices. I will look the Mendel90 model.

Attaching the mic to my chair keeps it at the same distance to my mouth as I rotate the chair, which is important since condenser mics are very sensitive to distance changes.

How did you hook up your microphone to the chair. Love it.

Cool shirt man... had to really strain my eyes to read it all. Is that a rock collection in the background? Geologist here... I have more rocks around my desk than in my landscaping. As for the printer, thanks for the review. I am pre-purchase researching now and its vids like yours that help me make decisions about my selection. I too will expect the machine to be a fun learning experience during the build phase, but then I want the build phase to end and the printer to work. Your English is great and your accent is cool. Keep up the good work. Thanks a lot.

Thank you very informative. What machines would you recomend?

Its good to know about the common prusa issues.

I have a reprappro mendel and this has solved some of the problems you mention. Also, I think it is possible to turn both Z-axis motors simultaneously, but I take your point, it isn't easy.

this is the same reason why when I wanted to build a home brew CNC machine, I opted to just design it myself from the ground up, the result was a machine that has not had hardly 8 hours of maintenance over the last 8 years.

Thanks for this video. I downloaded some files to build one, and now I am going to take the time to make some of the side frame pieces better so as to triangulate with the cross pieces, making the side shake a non issue and design a single, bottom mount for the z-axis. I also will redesign the major components so they can be removed without disassembly of the unit. The plan is to get a cheap makibox for Christmas and I will make a bigger printer on that, and useits parts to complete it.

You really have your points, thanks for raising these issues for those who can tackle them, and to improve and evolve into better machines like prusa i3

thanks a lot for this precise informations. This would help me by looking forward to my 3d printer.

what do you think about prusa i3? is it better than prusa mendel?

the reason the z motor is upside down is that it is always aligned, if it was in the right direction the tip would draw a circle. I don't like double z axis because in my model it always have to be re calibrated.

You could solve the wobble problem by welding a cross to the back side, to artificially make a triangle (or even 4) out of the square.

did you ever add the Fixes at startup mine is not Standard I fixed all the Bugs and it works fine. I also put Braced the top and put the Ramps on the left Bottom. and the Bed Cables are running with the Bed. I solved the Z Axes by putting Neopreen tubing on the Motors.

were did u get the parts just wondering i made one but my dog got to it and i lost the plans and part list/website name so if u dont mind plz tell me or give me a basic idea thanks for the help

Yes, but what about the olympic arenas? aka What should I buy? For my first printer that is..

You might also want to check out the "form1" made by formlabs. It's based on stereolithography and has a z-axis-resolution of 25microns.

what would you choose? Mendel90 or Prusa i3

what do you think about the i3 version of this printer

I want to say a lot of your input on why this printer sucks was fixed in the I3

Nice shelf, but why the rocks?

How far they came!

Of course there are all kinds of ways you can solve all of these issues. The problem is not that the issues are unsolvable but that people continue to use an out-of-date printer when all these problems have been fixed in recent designs like the mendel90.

Most of the issues You'd noted have been remedied. The Prusa Mendel was designed so that ANYONE could build one. 5.: There are X axis braces to fix the wobble. 4.: It's really pretty easy to maintain compared to much higher cost machines. The Y holder has been redesigned. 3.: Wire strain, putting loops in your wires is easy. 2.: 2 motors are simpler/cheaper than extra belts. the Z poulo overdrive is never an issue. 1.:There are improved Z couplers and mods to move the motors to the bottom.

The temperature sensor one surprises me. I have a Tronxy I'm working on that I got as a basket case and it has some really marginal connectors. If I have a pin pull on the temp sensor it instantly tells me it's unhappy. If you put wires on with zero strain relief you'll have issues. You have to be honest when you look at the Mendel especially now. There were things that were revolutionary about this generation but it's quite certain we're still in the infancy of printing even now. There's a lot to come.

Good logic well expressed.

Live in Norway, where to buy it online?

what I don't understand is the comments that says this guy sucks and similar yet not a single correction that I saw that explains why any of these points are wrong. He isn't saying it's not fixable in the video, that isn't the point of what's being said.

Well connecting steppers in series is the solution. Same amps an due to the small resistance the voltage is more than enough. Also same steppercurrent on each motor. In parallel it would not be the same due to different resistance.

I bought all the parts to build a prusa mendel on my own, today. than I saw your video. Thank you very much, i will now build a prusa i3.

So why hasn't the machines parts been made better to take into account the x axis wobble, my first thought would have been that it needed a cross brace and this could have been incorporated into the top motor mount and the apex of the A frame, those 2 parts could be as one, and the same for the bottom of the A frame with the mounts for the slider bars for the platform, less nuts as well. But that's just my opinion.

Good video, you point out the major weaknesses on the prusa, the reason why its so popular still is because of the massive community backing it, even if its obsolete design now. More and more people are moving on to better designs, as the mendel 90 and the prusa i3. but really, the prusa mendel was just a bump in the road on the way to better designs, but the community have learned a lot from the kinks and flaws of the mendel. Many new and effective designs are on the way, rostock, wally.

Exactly my experiences as well. 10x more maintenance than print time. Constant issues, constant expenses on upgrading 1 part at a time. Judging from this video - you had it easy as well!

1. The wobble can be easily solved by printing a set of stabilizing brackets. They take all of ten minutes to install and eliminate the problem. 2. Hard to replace parts? That one I agree with. 3. Wire strain - not a huge issue if you run the cabling correctly but it's not ideal.4. Dual motors on Z? My drivers run these easily - both motors are smaller than the X, Y and E motors. 5. Hanging Z axis - you have an old design there. The new ones do not hang.

Which model would you recommend? Prusa i3? Man, I am sad for this people pissed at you. This video is very useful and only I landed here because I own a Prusa Mendel and I started seeing this very same problems, after one year. This post made me review parts of my Mendel that would have never though about.

I've been working with one for about 3 months now and al it did is printing imperfect prints.. Switching to a aluminum prusa i3 now see if that works..

Yea Madmaxx, you forget to mention what are the other open source 3d printers that ar better than the Prusa mendel. . no value on your revue if you just complain about it, as other people said, the model you are reviewing is old, and these is the open source version, maybe what you should have chosen a commercial model.

I'm confident anyone with even a modicum of mechanical knowhow could address all of the problems you highlighted. At the price point of this printer or any others at the same price point there are bound to be some issues. Not all people can afford to spend more. A very informative video, I have seen these printers do amazing things.

Have you tried the i3?

Nice video man, in another video, i see you cooking on this machine.... hahahaha. I found here in Brasil, a reinforced Prusa I3 version, and i buy one and i loved it.

Just to tell how badly it is without detailed solution is that what the most people like to do

Good that you're critical about this but I think there are a lot of solutions to your frustrations. 1. Z-axis slipping + wobble: main thing I see you're doing wrong is using bearings on the threaded rodds. What happens is you try to clamp these rods and they're not perfectly straight meaning all the stresses end up on your motor and coupling making it wear and come loose. Solution: use some aquarium tubing around your stepper motor shaft and then clamp the threaded rods and use no extra bearings

Thank you so much you saved me a lot of crapp!!!!

Summed that design issue up nicely. I've seen the models perform nicely,,, for a few prints, then it needs an adjustment somewhere. All five of those 3D friends bailed on that concept and either quit the hobby or followed my lead and went open source Replicator or a rep1 clone. Sure, I've done mods on my rep1, but once done it's done and now my bots are 'press go, come back later' machines and have been for 1000's of hours with maybe a tweak every two months. I've got 12k+ hours on my rep1 and 5k on a FF. Just slice, insert card, press go, do invoice paperwork, sleep, remove print, ship, repeat..

Prusa himself has realized all the problems with his printer, hence why the i3 solves the majority of them (sheet material, standing z-axis). The nature of the opensource 3D community like every opensource community, is that everyone can point out and work on flaws. DIY 3D printing is still in its infancy, hence why an early machine like the prusa 1 has plenty of issues. Some of which are just designflaws, like the hanging z-axis and the way you join all the threaded rods.

You can add braces to eliminate X axis wobble. And your Z axis is wrong. The bearings go on the bottom of the threaded rod and you use a couple of nuts locked together to ride on top of the bearing supporting the Z axis - So no hanging Z axis. For your heated bed wires, I drilled holes in my heated bed to thread the wires through. This takes all the stress of the bending wires - never get any breaks.

This is all open hardware. If you find problems, fix it and publish for everyone. That's how it works. And as Josef said, there are newer and improved versions of the RepRap now.

The two Z axis motors is not really the issue, the issue is the lack of support for absolute encoders on the controller (the fact that they are not independently controlled does not help either). However In the terms of functionality two motors is not required it just serves to overcomplicate the task (Murphy's law). A single motor with a screw drive could easily preform the task.

I should add that I don't like the dual Z axis motors. They should be driven by one motor driving two pulleys one continuous belt - no more alignment issues.

What can I possibly respond to such a well thought-out comment.

Part of the this whole Open Source thing is to not get upset when people have trouble with your designs and rather work to improve them.

Just clamped it to a plate and it will reduce the wobbling

I agree with most of what you say, except the 3rd and 4th points. I regularly do move my Z axis by hand, you can move the motors together very easily with the motors wired together. Z is also my coolest stepper driver by far, you never need much power on this axis. But yes, Prusa Mendel 1/2 needs to be EOL'd I want to replace mine with a max style printer. Did you know that we exceed the thrust allowed on the Z stepper motors?

if i had to do it again i would buy a printrbot and put a heated bed on it or try another design. maintenance is a huge pita..documentation is horrible. im planning on designing a more standard cnc version (x/y on bottom and the z simply raises and lowers) and use a nema23 stepper on the z or the dual 17's. ifi were doing the same thing again i would get the taurino board instead of ramps (higher amperage) and use nema23 motors with 100-200oz/in holding power. oh and the bed is a nightmare

I'm really impressed, your arguments are well thought out and really hit the nail on the head. I just go by my gut feeling but I can tell something is really wrong with the current design of 3D home built printers. There is no beauty in them. It seems they are complex just for the sake of being complex so you have something to print....repair parts. We have to let go of the idea of self replication and just do what is best for the machine. My own design is nothing like this...and it is pretty.

You say there are equally-priced better alternatives. Which are? I'm honestly asking because I don't know.

The i3 looks ok, though I never used it. The Mendel90 is really good as well, very sturdy and easy to build. Most likely also cheaper when you already own a prusa.

I have a Prusa Mendel I2 and other than changing the bluetape on the bed and feeding it new filament, I have done absolutely zero maintenance on my machine in the last 6 months........ I lied, I did oil the rods...... twice.

uh, maybe very useful information, that polulu steps out for "milliseconds"...I never would have recognized that on my own. thanks lot! For me, worst thing is the instability of x, but slightly different models have quite same problems. The outcoming solution could be nothing different than a one-arm-roboter, like they are used in industrial production for many years...even if those wobble on axis as well ;) anyway, there aren´t any solutions much better right now, so at least pricing seems fair

Five good points. I looked at the rep rap designs and decided to design and build my own for most of the reasons you raise. Unfortunately the whole construct is, from an engineers point of view, unsound. BUT! The whole idea is to get 3D printers out into the world and into the hands of non engineer builders, as easily and cheaply as possible and from that point of view it works just fine.

More importantly, the nature of the Open Source movement means that Madplays is free to take his criticisms, and design and build a better machine. He speaks of 'getting to the point of a 3D printer in every home'... Does he think that it was like 10 years from the Wright brothers' first flight to the Space Shuttle? No, there were a metric crapton of less-than-perfect-but-still-useful machines in a very long path between those two points.

yeah.. just noticed after posting the comment.. didn't want to write another comment just for that.

that's all about, finding problems and of course sharing them to the community and help each other to find a solution. ( that means open source).

it's a free project. feel encouraged to improve it.

dear sir I think the I2 is a good idee i build several and still think its cool to work with yes you have to be handy butt he ,its a big difference if you buying one that does it all perfect coust easy 4 times more and ever sinds autobedleveling things got real different

it's like he didn't even watch the video XD

the printrbot which is a kit is lacking alot maybe even more than the prusa mendel

1-5: get the mendel 90. uses ribbon cables, is sturdier, cheaper, easier to build, standing z axis.

Hehe, das sind die Gründe dafür das ich nach kurzer zeit den MendelMax gebaut habe, die 2 Z Motoren mit durchgehender Achse habe und die mit einem Riemen synchronisiert sind, ich Alu Kupplungen auf der Z Achse habe, und ich den Extruder nicht auf die X Achse gebaut habe sonder einen Bowden Extruder habe;)

Sounds to me like the only problem with this mendle Prusa is the user.

This project definitely got the open source community working on the concepts and that in itself was a good accomplishment. I agree with you though, that a machine could be made that, once built, could maintain dimensional stability and rigidity. The problem in my mind is that people that design these machines do not borrow ideas from machine tool design...there is no rigidity or load bearing members used in these designs. Milling machines use ways and rigid bases and frames, and I think it would be beneficial to look at these old word techniques to improve an open source design. Why could we not print out an I beam and use the beams to make the frame...surely this has to be more rigid than a threaded rod? The geometry of the machine could be changed...maybe a moving table is not the way to go if it's heated? I wish I had more time from my normal work as I would love to make a model of a more rigid machine that has more printed parts in it than the RepRap. I have a Replicator 2 on my desk at work and the thing just works...there are many ideas in this unit that could be borrowed (like the one motor for Z axis) that makes sense to me.

The i3 version (box) pretty much rectifies all the problems you mentioned in this vid. Why are you bashing a pretty old version of the mendel??? >_>

A triangle is a stable shape... A triangular prism, isn't... The more stable 3d shape would be a tetrihedron... or a pyramid. A tetrihedron I don't think would make a good 3d printer shape... So... either a pyramid or a cube of some sort? Wouldn't a cube also wobble, except it would wobble in both directions... right?

Talking about printers, you can talk about your XIX Century Epson.

I think pretty much everything he said was down to user error.

huh. thank you for making this video... I'm looking to buy a 3d printer, and I'm trying to make sure I get one I won't hate... I mean, while building and calibrating I'll probably hate them all... but I want one which isn't a brazilian dollars ;D and also can be improved a lot.... Now time to watch the video :D

The dual Z axis motor design is very poor. There's no good reason for it. They should have used one larger motor and a timing belt for the other side.

i don't even know why you bought it in the first place :P normal printer to mainstream? ;D How about fixing the wobble by jamming it between 2 stable objectives?

necessity is the mother of invention. If you h ave a problem with this and that thing and list it and modify the parts so they are better. Like the plastic chain.

Yes I have fixed that Y axe wobbling problem by adding diagonal steel rods on the base and all rectangular imaginary surface created by the steel rods. Clamps for rods are on : www.thingiverse.com/thing:1920151 purse I3 I think douse not have these problems. Got more stiff and heavy.

Its open source, that's why its so cheap and why it has small problems that are solved by the customers. I think you thought you was buying a fully tested and revised 3d printer when you purchased it.

Unfortunatly what you say about the Prusa is true. It does have some issues. There are some really good fixes that are not hard to do at all, and most of the ones you mentioned were not prusa's fault he simply made Darwin easier and cheaper. You should consider using locktight, and going to metal z couplers, a gear and belt system between the two z motors. The Prusa is designed to be the cheapest way to start 3d printing that is simple to build and has a really good manual.

Two Z axis? That's normal. Other adjustments should be in software, never hardware

well, thats the case with all self build 3d printers. software configuration is always the worst part.

2. Mount your electronics on the side not on top :indeed mounting on top is not the right place. 3. The cable wear/tear. Well pretty much every 3d printer has this issue. Then again I've yet to have 1 cable breaking and I've 3d printed over 6 complete new printers using a similar model to yours. Also just give the cables of your heatbed more slack so they don't get streched. The part you mention print this removable one: thing:86288

completly agree with You. I'm building CNC machine by years and this is exactly what a cnc machine never shold be. wrong materials, wrong architecture, wrong setup. very exspensive to mantain. people follow the legend of 3d printer as self replicating machine: it doesn't replicate a F**K, only plastic parts. so do you want reliable machine using plastic mechanical parts? Please study a bit on books and pass by the youtube this time

Your point about the two z-axis motors is wrong ! Those pololu stepper drivers are current limited. So you do not get more current running through the stepper driver, when you connect more then one motor. Instead both motors get half the power. If your stepper driver gets too hot, you opened the power controlling screw on the driver too much.

I think you miss the entire idea of this reprap. It is a beginner and budget model. It is designed to be a very cheap project, i have managed to build one for just over £200 which i think you will agree is an extraordinarily low price for such a machine. This is the lowest 3d printer of the reprap range. If you dont like it spend more on a higher version. However this printer doe not suck, I have seen plenty of these work perfectly, if anything problems come in a lack of ability and experience in the user. Also a lot of the problems you state can be corrected with upgrades, so upgrade it so it 'sucks' less

I studied geoscience.

friend of mine has got a "japica" model which is kind of a cube...to make long story short: despite the lack of support from japica, it was badly built (boughjt assembled already!) and has all the problems mentioned above, if not in a harder version...it´s very disappointing but luckily none o my money is involved. Maybe it would have been better to wait with order, otherwise we wouldn´t be experienced now and also could become betrayed as well. 1st day I said, i´d prefer it made of steel ;)

If you don't know why it's more desirable from an engineering standpoint to have the Z-axis in tension than under compression, why are you complaining about it? Not hating on you, just saying, it's pretty basic first-year engineering stuff. One major b**ch I have on the Mendel is how it's a PITA to adjust Y-belt tension... you gotta remove the whole printbed for what should be a simple adjustment. That bugs me way more than some of your (valid) points.

Big thanks for 3d printer critics, thats good when it isnt too much. It wasnt too much in here)) So why so 234 likes against 234 dislikes)))