Who Has Built an Ecksbot? It looks CLEAN

Check out this nice looking Mendel/Prusa/Sells derivative:

Ecksbot on Thingiverse

Ecks Bot B.O.M and Build Guide



She looks nice and polished. A very familiar look to her. The parts are curvaceous and sleek. It's neat to see the parts embossed with the site name too.

This looks like a clean, simple build and even has full-color instructions... Wow.

She has been out for about 3 months now; I saw her before, but she slipped my mind.

I might have to throw this onto my growing pile of projects.

Anyone here make one of these yet and have anything to say about it?

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FabberForge - Printing Happiness

[www.fabberforge.com]

Besides the printed bed plate (which I experimented with and abandoned as unworkable with a HPB ), how is this any different than a prusa v1 with some of parts upgraded to better versions that are on Thingiverse?

Edited 1 time(s). Last edit at 10/03/2012 10:28AM by crispy1.

Dunno from first had experience; their blog talks about various improvements though.

The fact that they addressed the X belt alignment was enough to get my attention. And the Y belt path appears to induce substantially less arbitrary friction than the Prusa i2 design. In fact, the whole design seems to be a fully realized, functionally sound design, compared to the standard Prusa i2. In that light, I wonder how long it will be before the Prusa i3 gets evolved into a truly sound design.

I think that one of the weaknesses of the Prusa i2 which still remains in the Ecksbot is having the z motors on the top instead of on the bottom. This makes the z threaded rods susceptible to downward movement if the coupling to the motor becomes loose. With the motor in the bottom as I did here, this problem doesn't exist.

Edited 1 time(s). Last edit at 10/03/2012 07:33PM by brnrd.

Think you can build/design an ecksbot with the z-motor on the bottom?

I think you hit the mail on the head.

I think an ecksbot with bottom mounted z-motors could be an idealized, fully realized, simple RepRap design.

Edited 1 time(s). Last edit at 10/03/2012 11:16PM by Idolcrasher.

If you look at my photo, mounting the motors in the bottom doesn't require any newly designed parts. It required the z smooth rod clamps from the original Mendel and an additional horizontal threaded bar and some 8 mm nuts and washers. I mounted the standard z smooth rod clamps from the original Mendel in place of the Prusa z motor mounts. The additional horizontal threaded bar was added to support the motors in the bottom and they were mounted using the bar clamps that were used to support the z smooth rods.

Of course, one can redesign the Mendel z smooth rod clamps to make it match the clean look of the Ecksbot.

Edited 1 time(s). Last edit at 10/04/2012 01:10AM by brnrd.

And what holds the smooth rod on the top? Your photo doesn't show that.

alagi Wrote:
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> And what holds the smooth rod on the top? Your
> photo doesn't show that.


I'm sorry. You can see it in this video. Those are the upper z smooth rod clamps from the Sells Mendel.

I see now, thanks.

I don't think having the z motors on top is so bad. Let me tell you why:
Getting rid of the z wobble is easiest by using a small threaded rod instead of M8. I'm using M5. It doesn't matter how bent that is, the smooth rod is stronger than the M5 threaded rod, so it will keep straight. Now if you put the motors on the bottom, the M5 might buckle out if the X axis is too heavy (I have no idea how much force you need for that, maybe this is a non-issue, one should check ). Having the z on top this can not happen. Making sure that the coupling does not come loose is much easier than getting rid of z-wobble with M8 threaded rods, isn't it?

Getting rid of z wobble due to bent threaded rods is actually not that complicated. There just need to be freedom for the threaded rods to move in the x-y direction. Currently, my Prusa i2 does this automatically because the nut traps in the x ends for the z nuts are oversized. This, of course, results in z backlash but it's not a big deal since I don't use the z lift feature in slic3r so that my z axis only moves upwards while printing. The backlash probably affects the 1st layer depending on how the z axis homing is performed by the firmware but I haven't looked closely at the fw yet. To get rid of backlash, you can use DaleDunn's Z screw isolator.

Also, the Prusa i3 already uses M5 threaded rods with the motors in the bottom so there might not be buckling a problem.

Edited 1 time(s). Last edit at 10/04/2012 08:23AM by brnrd.

These are also good ideas which I did not know about, thanks for bringing them to my attention.

One last thing you did not respond to: why is it hard to couple the threaded rod to the motor without comeing loose?

The z coupler need to reduce wobble by allowing some flex. The Prusa i2 and the eksbot use Nophead's z coupler design which requires a somewhat flexible plastic tubing between the motor shaft and coupler. Others may have succeded in preventing the threaded rod from sliding off but I wanted to avoid dealing with that. I also didn't like the printer to be top heavy.

I ended up gluing my coupler/motor/rods together on my Huxley Pro.

Evers since then, I have wanted a Huxley pro with bottom mounted motors

The things that make the Mendel Prusa and variants good is that they are simple and use cheap parts to keep the cost down, and this variation is the same basic design with a couple of nice mods but still the simple and cheap design. When you can afford a better machine you buy a one of the more expensive varieties which have sturdier frames, bottom mounted motors and use high quality 10mm rod and lead screws. As an entry level machine the Prusa works and if you buy a kit it will go together and print quickly and easily. If you are able to, build it your self as you will learn how it all works and be more able to calibrate if not, buy one ready made and enjoy it anyway.

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Richmond, New Zealand
Thingiverse ~ YouTube

Mounting the z motors in the bottom is just as simple and easy as mounting it on top.

True, can't think why they did it that way in the first place. I like the way you mounted your motors, is it the same part just upside-down? and what did you do at the top? Ok watched your video now, might try this.

Edited 1 time(s). Last edit at 10/06/2012 06:32AM by Wired1.

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Richmond, New Zealand
Thingiverse ~ YouTube

Brnrd used the same method I did to put the motors at the bottom. However, I still suffered from Z wobble, using M8 rod as the leadscrew. I fixed this by adding z-isolators like [www.thingiverse.com] though I designed my own. This decouples the wobble of the z leadscrew from the X axis, and I recommend them to everyone. Using smaller M5 leadscrew is also a good idea, especially as the coupler can just be PVC tubing as the leadscrew is the same diameter as the motor shaft, when the motors are at the bottom - may slip off when at the motors are at the top.

Yes. I actually copied droftart's method: [forums.reprap.org]. I was going to use two sets of motor mounts and clamps until I saw his photos in that thread.

On the scond machine I built I bought some M8 stainless threaded rod which is machined to a higher standard than el cheapo zinc plated rod and it is perfectly straight to the naked eye. I'm also using Z-stabilisers at the bottom, which I know some frown on, but the combination gives virtually no Z-wobble. I'm going to use Acme lead screws on the Mendel Max I'm building and these will be free-floating so I'll see how that goes, hopefully won't need any additional end support.

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Richmond, New Zealand
Thingiverse ~ YouTube

This is by far the best designed Mendel/Prusa out there, IMHO.
I updated my prusa v1 X axis and upper motor mounts to the ecksbot parts, If i were ambitious I would print an entire machine out because everything is just better. The belt is centered above the x axis rod instead of levered off the back like most of the other designs.

Quote
Gulf
The belt is centered above the x axis rod instead of levered off the back like most of the other designs.

I did the same with the standard Pruse i2 parts with new design x carriage belt clamps: [www.thingiverse.com]

Sadly it doesn't fix the most serious flaw, which is that the frame is stiff exactly in the direction it doesn't need to be (Y) and flexible in the direction it needs to be stiff (X)...

Let's see now, the Y carriage won't work with a heated plate build....? It's just a Prusa 1 with some other peoples upgrades from Thingiverse (like Brnrds X carriage idler). If the Z motor couplers come loose the X carriage can fall right off. It's top heavy. It's prone to the old RepRap Z wobble, and sadly it doesn't fix that most serious flaw in the Mendel design, wobbly in the X.
What a picture you paint: It's just another crappy old RepRap with a pretty face modified with ideas pilfered from Thingiverse.

Not sure just how I should respond to all these complaints and address the allegations so I guess I should just start at the top and work my way down.

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Crispy1
Besides the printed bed plate (which I experimented with and abandoned as unworkable with a HPB ),

Sorry to hear your experiment failed, but the failure was one of your making not the ecksbot design. There are videos on the Internet showing ecksbots printing ABS on heated beds, it works just fine. Had you taken the time to ask for help on our forum or emailed directly before blindly dismissing it as unusable I would have gladly showed you where you were going wrong.

"X Idler mount is the same as Brnrds": Brnrd it's apples and oranges. Just because two things look similar at a glance doesn't mean they are the same. Yes our belt track ended up looking the same as yours from a downward view but you missed the whole point of the modification or what it even is.

The reason for the modification was to eliminate the pulley deflection caused by the stub shaft levering against the printed mounting area of the idler block and distorting the plastic when the belt is tightened. This is the reason for the belt tracking issues noted on this forum from time to time, the tighter the belt the worse it gets.

Our modification: We replaced the stub shaft with a straight axle which holds the bearing straight and true no matter how tight the belt. In order to accomplish this we had to create a second mounting surface to attach the opposite end of the shaft. In order to do that we had to turn the bearing inward on the idler bracket and that's why the resemblance. We also replaced the threaded rod and washers with a 4mm bolt and printed flanged hubs to eliminate the problem of the washers rubbing on the dust seals of the bearing.

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brnrd
I think that one of the weaknesses of the Prusa i2 which still remains in the Ecksbot is having the z motors on the top instead of on the bottom. This makes the z threaded rods susceptible to downward movement if the coupling to the motor becomes loose.

Actually the whole of any RepRap machine is susceptible to wobbling around and falling apart if the components are not properly installed in the first place. Blaming the design of the machine for poor assembly techniques is really not fair to the designer. From our own personal experience: We have been running the original ecksbot daily for over four months now and the clamps haven't moved a tick.

While on the topic, I have a question about Z motors placement. Comparing the Prusa to the Sells Mendel, what is the main noticeable difference between the two?...... (apart from the Y carriage drive on the ecksbot which we have already derived from the Sells Mendel). In my eyes it is motors on the top vs motor on the bottom. So if we move the ecksbot motors to the bottom does it remain to be seen as a Prusa derivative with a little Sells mixed in, or does it now become a first generation Sells derivative with a little Prusa mixed in? People have done such a “brilliant” job of slandering the Sells name to a point where most people consider it to be an old failed overcomplicated design of the past, that should stay in the past. Would the machine be black balled right off the bat as a direct derivative of Sells?

On wobble caused by the rods themselves

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Wired1
On the scond machine I built I bought some M8 stainless threaded rod which is machined to a higher standard than el cheapo zinc plated rod and it is perfectly straight to the naked eye.

While I agree that higher quality threaded rod generally has a more consistent thread pattern. In either case running the rods through a dye will provide a dramatic improvement.

Quote
ttsalo
Sadly it doesn't fix the most serious flaw, which is that the frame is stiff exactly in the direction it doesn't need to be (Y) and flexible in the direction it needs to be stiff (X)...

If you are having problems assembling an ecksbot so that it doesn't wobble. You should have registered on our forum or sent an email and asked for help. Since the advent of acceleration in the firmware frame wobble is a bit of a non issue. Even a modest amount of acceleration should allow even a wobbly machine like yours to print at reasonable speeds without noticeable effect on the printed object.

Other ecksbot owners have found that there prints come out A-OK



When it comes to the point where you have to use a magnifying glass to detect Z wobble I think that's pretty good for a hobby printer.

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[www.eckertech.com]
[blog.eckertech.com]
[forum.eckertech.com]

Eckertech on the scene COOL

I saw some folks here saying that they don't use the "lift" feature in Slic3r... RUN! (don't walk); change your settings and start using the Lift feature!

If your machine can't handle the feature... BUILD A NEW MACHINE

Just one man's humble opinion

Do what you like; for me, lift is extremely useful

eckertech - I think most people's criticisms are about the fundamental design, not your version specifically. Regarding frame wobble, yes, it's a design flaw, but it isn't actually as much of an issue as it used to be. Why not? Because most reprap firmware now has acceleration, which damps out the wobble in most cases. And the condition that sets off the wobble is usually tight infill, where the problem doesn't matter; perimeters don't set up a resonance. Besides, there are solutions if people are REALLY concerned about it, like the cross-bracing vertices I made: [www.thingiverse.com] This does cut a small amount out of the build area, but it's not significant.

The other argument is about Z wobble, which has already been discussed above - I use z-isolators. The main reason that the z wobbles on Prusa machines is because of a mistake in the design files that, I believe, STILL hasn't be rectified: the spacing between the z leadscrew and z smooth rod is different on the X end (30mm) compared to the z motor mount (29.5mm - and you can't adjust the motor in the mount because of the design), see [github.com] . So the motor is always trying to move the rod eccentrically. Coupled with potentially non-straight leadscrews, and the pre-Nophead-style z-coupling (which tended to put the leadscrew off-centre with the motor shaft) and you get wobbly layers, and they may not even be consistently wobbly, so it's difficult to diagnose. However, you look to have engineered out these issues, and all credit to you.

The thing people forget about with the Mendel and Prusa is the materials it's built from - printed parts and metal rod. Solutions that are properly stabilised in each axis, like the Ultimaker or Makerbot and more recently Mendel90 and upcoming Prusa 3, all use larger wood parts to constrain axes, that generally need to be accurately cut on larger laser cutters or CNC routers, and, when bought as kits, cost more. It's just not within the scope of your redesign to change or fix this; perhaps others think that the Mendel/Prusa design has run it's course, and everyone should be using the newer designs? I don't; I think it still has it's place. Some commercial companies still sell kits based on the complex Sells Mendel.

I think you have done a fantastic job updating the Prusa design; it enrichens the reprap universe. You have thought about every part and sought to improve it. The X and Y axis improvements are particularly commendable. The TVRRUG.org Round 2 build (which I am involved with) has gone for a similar Y axis setup (you also get to lower the bed around 2cm as the bearing on the top rail is removed, improving Z height), but we have laser cut acrylic lower beds. I'm not entirely convinced by a printed y-carriage (is it ABS?), but I'm not going to dispute it with you if you say it is successful printing ABS.

The only criticism (and it is only a small gripe so please don't take offence) I can think to level at you has nothing to do with the design itself; it's your choice of software for your design - Solidworks - and that this makes it harder for people to adapt your design to their needs - for example, if their printer was was not accurate printing holes and hex nut traps, the tolerances might need to be a bit looser, or perhaps need to adapt the extruder for a different hot end. Adrian Bowyer has talked about closed source development leading to dead ends, and part of that is using closed source tools. However, you have released stl files, and the solidworks source files, for which I once again applaud you. And I appreciate designing parts in a professional package is so much easier than the weaker open-source options - I do it myself! It does mean, however, that people are less likely to submit their changes/improvements back to you, too!

Overall, very well done, I give you 9 out of 10!

@idolcrasher: lift works fine for me too, but can sometimes lead to a bit more blobbing, so unless I'm printing lots of small things that could get knocked off, I don't use it.

eckertech Wrote:
-------------------------------------------------------
> Let's see now, the Y carriage won't work with a
> heated plate build....? It's just a Prusa 1 with
> some other peoples upgrades from Thingiverse (like
> Brnrds X carriage idler). If the Z motor couplers
> come loose the X carriage can fall right off. It's
> top heavy. It's prone to the old RepRap Z wobble,
> and sadly it doesn't fix that most serious flaw in
> the Mendel design, wobbly in the X.
> What a picture you paint: It's just another crappy
> old RepRap with a pretty face modified with ideas
> pilfered from Thingiverse.
>
> ...

I think you've misunderstood most of what has been posted here. As droftarts suggested, these are things that we thought would have also been good to add to your tweaks to make an even better printer.

As far as the x-carriage modifications, there was no suggestion that you copied my modifications. I merely pointed out that I also moved the belts right above one of the smooth rods as you did using standard Prusa i2 parts with the addition of a belt clamp. You can call it a hack. Not as pretty as your redesign, but it works for me.

On the location of the z motors, I don't think you should worry about whether people would confuse the printer with a Sells Mendel instead of a Prusa. Along with simplifying the x-axis and reducing the printed parts, the other main difference is the use of two z motors to drive the two threaded rods versus using one motor with belts and gears. Locating the motor in the top or bottom is minor. As far as which way is better, even Prusa has designed the i3 to have the motors in the bottom along with Nophead's Mendel90.

On the rigidity of the Prusa frame, I think this is well accepted in the community, so there's no point in discussing further. Others, including Prusa, have moved on to address the issue. I don't think that acceleration in the firmware fixes this if you really want to go as fast as possible. Even though you can pretty much eliminate frame vibration with the right acceleration parameters, there are still issues with the extruder not being able to keep up with the x and y axes. Printing at high speeds with acceleration results in thicker threads near the ends and thinner threads in the middle as a result.

Lastly, if showing a high quality print from a printer proves how good the design is, then you didn't need to tweak the Prusa i2. Prusa and many others has plenty of examples of excellent prints from their i2.

EcksBot Build in Progress:

1000 big thanks to ecker tech for sending me a Y-Carriage

I decided to hold off on the QU-BD extruder on this build. The "eckstruder" is a thing of beauty any way

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FabberForge - Printing Happiness

[www.fabberforge.com]