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printingSome

D-Bot Core_XY gone Linear (was: in Threes)

by printingSome Feb 8, 2017
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Looks like you've made some modifications to the X carriage. The top of the carriage doesn't seem the same as the link you've posted. It was your remix? Is it a good upgrade? Do you have the STL's?

I see what you mean, I am a bit sloppy with updating my pictures here. Also because the whole thing is not always photogenic when I am working on some part. For instance: I now have another electronics box in place. That is documented in the link to that thing, but at that moment the top of the printer was in disarray, still is..
Let's say this is more about the big picture and in the link "3-wheeled Modular X-carriage (D-Bot Core-XY 3D Printer) by printingSome", http://www.thingiverse.com/thing:2206664, you'll find everything about the details of the developments of the carriage, which are still very much in motion.
Anyway all stl's are the latest of what I have and want published. And I mention in my edits why I do things and also when things don't work out.

I tend to think that my updates are improvements, but I disappoint myself regularly.
For instance: I have a bit of a problem to saying goodbye to my Direct Drives Mount, but I simply cannot get it working the way I want, so I will withdraw it in the near future and will replace it with something with the Zesty Nimbles. So I already told that in advance. (I see that I mention it here, instead of in the other place..., so I'll correct that too ;-) )

Please let me know if there is something I miss in your question.

3-wheeled or Linear Railed Modular X-carriage (D-Bot Core_XY 3D Printer)

Thaks for your answer. One more question... How is the motion with the 3 wheels on this extruder carriage? Any improvement from the original D-Bot 4 Wheel design? Or is this design only to save wheels? I have an original D Bot design in place (so, I already spent the money on the weels), but I'm making some improvements right now, and I wish to know if it worth the trouble of changing the original carriage for this one.

It is a difficult question to answer because I don't have any measurements to offer so I can't quantify differences.

I find it a good thing that as soon as I feel unwanted movement or have doubts I can do something about it with the little bolt beneath.
I couldn't do that before, when there was always some wheel a bit more loose than another. Not any more.

Now and then I ask myself whether there could be better torsion-independence when you have 4 wheels, i.e. when you have fast X-movements. But then I console myself with the thought that in such cases the fourth wheel, either the right or the left one, only gets to work after the distance the looseness involves has been crossed. After that movement, which would always mean some distortion, that fourth wheel has more support to offer then my poor lonely 3rd wheel in the middle. But again, how much difference that gives in practice, I don't know.

Remains the fact that I find 3 wheels much more elegant. That is why I immediately fell for NickRimmer's 3-wheel-solutions for the Y- and Z-axis and replaced the working 4 wheel-things from the original. And I still am happy with all of that.

Despite the fact that I am not satisfied with the end results I am getting with double-direct-drives and such.
Which is why I am very near to replace those direct drives with Zesty nimbles.
I would be very disappointed if that would not solve those problems.
And even then I wouldn't doubt the 3-wheel solution, compared to the 4, but I would think of going for the linear guide solution, you know, MGN12 and such.
In short: I did find it rewarding to go for the 3 wheels on all axes, also in my case because that led to different dimensions of the plates, which again offered easier ways to mount the chimera/cyclops etc., still viable when you want to use bowden tubes.

Far from me to advise anyone to switch or not. I can only offer a glimpse of my experiences and my considerations.
Then again, it's really not that much work etc. And after that you know the answer for yourself, which is always worth a lot.

Edit (11/2/17): I began to doubt the 3-wheel-solution for the Z-axis, and only for this axis because the load is always in one direction. And lo and behold, discovered yesterday that indeed only 2 wheels are used, up as well as down, The upper back one and the front middle one.
In which case the 3-wheel solution is worse then the original, because the distance between those 2 wheels is smaller then with the original, so I am now considering whether to use the original with only 2 wheels, or to use all 4, not because they ever have any work-related function but only to protect the leadscrews from when I accidentally lift the bed, in which case those wheel want to come free form the rails. I don't see any reason to want to have an adjustment for the wheels either, exactly because the 2 actor-wheels are pressed to the rails by the load of the bed, also when I am going up.
I was looking around today and found that somebody else had similar findings, in the comments of the D-Box, but wanted to make a quick note of it here too, just in case somebody is considering that solution. ;-)
Note: I am still a defender of the 3-wheel solution for the other axes for when one would want to use wheels, but am also going for a linear guide for the X-carriage.

I see what you mean. I see that until now you have no regrets.
Now that I have the hood open, I'll give it a try and then I will give my opinion. I've ordered a titan extruder with volcano and I'm planning on make a mount to fit your 3 wheel carriage design. Then, If it works, I'll post my experience and share my remix. If you already have a titan extruder mount for your carriage, please share it, otherwise I'll waste my time...
Best regards

Right. ;-)
Great. Looking forward to your remix and experiences.
No, I don't have a titan extruder mount.
Success!

Where can I get that electronics box files?

As stated:
Ramps 1.4 Enclosure for Vslot, a bit bigger by printingSome
http://www.thingiverse.com/thing:2053035

Ramps 1.4 and Rumba Enclosures for V-slot

Anyone know of any designs for enclosing the D-Bot?
I.e. brackets/standoffs that attach to the V-Slot, that sides and a lid can be fixed to?

Have seen a redesign of the C-Bot/D-Bot that moves the motors and rollers inside the frame.
But wondering about enclosures for the D-Bot as is.

Found D-Bot Panel stand-offs and 20x20 T-Slot extrusion spool holder
http://www.thingiverse.com/thing:1789575

D-Bot Panel stand-offs and 20x20 T-Slot extrusion spool holder.

Not me. Nice idea, though. ;-)
In the beginning I was sure I would want to enclose it, but I don't feel the need for it any more. I avoid ABS like, well, I hope that the one spool I have will last longer then me. So far PLA, PETG and PVA served me well and they don't stink (too much).

How did you wire all 3 z motors to the ramps board? There's only 2 pin rows for 2 Z motors.

I did give an extensive answer, but it got flagged for moderation, I don't know why. So let's wait patiently. ;-)

Appreciate the clear explanation!

I read on forums that syncing issues occur when different drivers are used. So, in your case, it would be the driver with the 2 z-motors and the E1 driver with the 3rd z-motor. But it seems like that's false, right?

Also, do you notice any power reduction to the 2 z-motors (sharing current from 1 driver) as opposed to the 3rd z-motor (current from 1 driver all to itself)?

I use the same drivers (DRV8825) on the Ramps and the CNC-shield, but I don't know whether that was the problem or not.
And now in fantasy mode: I wondered about that 2nd issue too and I then reassured myself by fantasizing that in the case of 2 motors the total resistance is halved, so the current must be doubled to get the same voltage, say 400mV, you are calibrating.
As long I don't have problems I stick to it. ;-)

I use the E1 pins for that. You can easily configure the software to that purpose with repetier-firmware, see my Configuration.h file.
I used the development version 1 of it, changed the file since then, but it clearly shows how it handles it:
"mirrorZ": "1",
"mirrorZMotor": {
"name": "Extruder 1",
"step": "ORIG_E1_STEP_PIN",
"dir": "ORIG_E1_DIR_PIN",
"enable": "ORIG_E1_ENABLE_PIN"
}
I mention it here just to check. Let the repetier website https://www.repetier.com/firmware/v092/ do that for you.

And before you ask: I am working on a configuration with 2 extruders and those same 3 Z-motors and for that I changed the Extruder E1 pins back to its originally intended use and used the CNC-shield for the 3rd Z-motor.
That worked well, when I used the CNC-shield for a 3rd extruder (with the diamond hot end), but this time it failed for unknown reasons.
It looked like the 3 motors were badly synchronized/mirrored, so the bed tilted and the whole thing got stuck.
This problem was solved, when I connected the 3rd Z-motor again to the E1-pins and the 2nd Extruder to the CNC-shield.

And, talking about that CNC-shield, for the setup see: http://www.reprap.org/wiki/Adding_more_extruders, but for the connections see: http://www.reprap.org/wiki/Repetier_Color_Mixing. I made a mount for it in my (remixed) electronics box, see there.
The change in pins.h for that is:
Add at the relevant place for ramps1.3:
define ORIG_E2_STEP_PIN 64
define ORIG_E2_DIR_PIN 59
define ORIG_E2_ENABLE_PIN 44
and a bit further on:
-define E2_PINS ORIG_E2_STEP_PIN,ORIG_E2_DIR_PIN,ORIG_E2_ENABLE_PIN,
(comma included)

When I use the CNC-shield for the 2nd extruder, the Configuration.h file shows:
"stepper": {
"name": "Extruder 2",
"step": "ORIG_E2_STEP_PIN",
"dir": "ORIG_E2_DIR_PIN",
"enable": "ORIG_E2_ENABLE_PIN"
},
But again, let the repetier website do the work, then change the pins.h file manually as above.

Edit: left out the hash signs before "define", because these produced enormous fonts. ;-)
Edit: problem solved, comment adapted.

Is this a drop in addon for a standard D Bot? Also do you see any issues with doing this with a 300x300 print bed?

What you see is a 300x300 print bed. I do not understand "drop in addon", please could you explain in other terms what you mean?
I did describe rather extensively how i came to this build, but feel free to specify your question. ;-)

What if make not only one but both sides of bed carriage go along the vertical rails (like in J-bot) and also implement this:
http://www.thingiverse.com/thing:2185911
What's you opinion?

Three lead screws and one nema 17 motor remix for C/D/J-bot
by oeyhaga

I do not see the advantage of supporting both sides when you already have 3 lead screws for support.
I started off with the J-Bot solution, because it looked beautiful to me. But when I saw the sea-sawing, I fled to the 3-lead-screw solution. Keeping the support at both sides when using 3 lead screws could even be counterproductive: too many support points.
As for the solution with one motor: it would be ideal, but for some reason or another 2 motors weren't not enough for my printer.
I still cannot fathom why and I still hope to find the reason, the more so because others seem to succeed with one, but for now I have 3 motors working. In harmony. ;-)

Nice build, What firmware are you using?

Thanks. ;-)
Repetier.

No problem! I have been slowly working on mine and now I'm on to the firmware. Z-Axis homing is behaving strangely on my Repetier Firmware, I was able to get Marlin configured and working but Repetier just doesn't like me. Would you mind sharing a copy of your configuration.h?

You are welcome, but be careful with what you are wishing for! ;-)

  • I use different endstop switches here and there, min and max, and I use the front as starting point for Y.
  • My prints are not nice to see at the moment, for whatever reason, so it is very much in need of optimizing.
    Perhaps my filament is partly to blame, but at the moment I am more interested in things like finishing my modular variation of my 3-wheeled X-carriage etc.
    It works flawlessly with my system though. Just don't copy this to your system, because you will have problems.
    It just shows how I do it.

I really appreciate it! I am just using it as a reference. I haven't even began a test print... Just making sure the mechanics are in order.