Dollo 3D Printable 3D Printer

[Chris_Hinson]

Hey, wow, glad to see someone actually made a dollo and got it working. I found the dollo through the reprap wiki a few months ago and was initially disappointing at the lack of available information on it. Despite this, I'm still fascinated by the design and would like to move forward in making one this summer. Any advice on doing so? Should I even bother with the unique z-axis design or try for the normal threaded rod initially? Any advice on 3d printing services to print the parts rather than printing them on the school's printer? What motors would be best to use? I hope someone can help me out here. . .

[spegelius]

Hey, wow, glad to see someone actually made a dollo and got it working. I found the dollo through the reprap wiki a few months ago and was initially disappointing at the lack of available information on it. Despite this, I'm still fascinated by the design and would like to move forward in making one this summer. Any advice on doing so? Should I even bother with the unique z-axis design or try for the normal threaded rod initially? Any advice on 3d printing services to print the parts rather than printing them on the school's printer? What motors would be best to use? I hope someone can help me out here. . .

Alright, you make 3rd active, or at least interested, person regarding Dollo . Ok so I'll try to give some information about how to go on about building one:

• If you are going to print the parts yourself, make sure you have well calibrated machine. Print only few different parts and see how well they fit together. If they are too loose or too tight, you can use scaling option in your Slicer to slightly change the size of the parts. Do this for all the ties and extensions. Also the X and Y rails and motor mounts are good to check.
• Also if using multiple printers, this goes double of course
• About printing services I know nothing, I haven't used them. But I'd expect them to have good quality if they do it professionally
• Material: I used PLA for most of the parts. It's quite rigid and seems to work well. For some of the long ties and bow ties I switched to PETG, mostly because it's bit more flexible and can be used with parts that vary in dimensions (see first bullet, I have too much variation and it's PITA on some parts). PETG might also be better for X and Y axis racks, might slide better
• PLA needs lubricant to make the axes move. The problem with friction is heat; PLA heats up fast to 60+ degrees and softens -> it jams. What I'm using successfully is http://www.wurth.fi/site/media/pdf/t...LIKONRASVA.pdf. Sorry it's Finnish, but basically silicon grease, quite thick but works like charm. Longest print on Dollo was over 11h, no problems. I tried a quite runny generic oil but this caused random missed steps and it was evident that it's doesn't work as well when by moving the axes by hand the axes did stick more.
• Assembly: if the parts fit well, it's quite easy. If needed, sandpaper and file tools are good to have around (along with hammer, heat gun, sharp knife etc. ). I used sandpaper for X and Y racks to make them smoother, so those can be actually printed to be quite tight and sanded for best fit.
• Z axis: if you want a printer that produces decent prints, go with the traditional lead screw setup. The original Dollo Z-axis needs work to make it viable. It works, but not well. Tackling it is on my very long to do list
• Motors: it shouldn't need that powerful steppers, I have these http://www.omc-stepperonline.com/09d...04s-p-122.html for Z-leadscrews and http://www.omc-stepperonline.com/3d-...004s-p-18.html for X and Y. Both types are 2A motors, but I'm not running them at even half of that. This of course how easily the axes move.
• Electronics: shouldn't really matter as long as it can drive 4 axes (X,Y,Z,E) and few with multiple motors. I think all boards should be capable. However, I've only used chinese RAMPS 1.4 with Dollo. Getting a better board is advisable if you are concerned about how reliable and stable such board is. But since this is kind of a budget endeavor, RAMPS is not a bad deal, even with full graphics display.

I'm still using and upgrading my build. Been tied on other project lately, got a Prometheus system a while back and been tinkering with it.
But this is what I'm working on currently:

https://www.dropbox.com/s/v4k8wru43q...44.43.jpg?dl=0
https://www.dropbox.com/s/jl3k48oa7r...44.50.jpg?dl=0
https://www.dropbox.com/s/zgalspijm7...44.57.jpg?dl=0

A part cooling fan for printing PLA. I've had to redesign couple of X coupler parts to make room under the X-axis, there's not much of it. Will post more pics when I get it finished.

Future ideas: as I saw https://www.bcn3dtechnologies.com/en...r/bcn3d-sigma/ with dual X-carriages, I thought that Dollo could have such setup quite easily: just print another motor mount, gear, hotend mount and extruder, add stepper extender to RAMPS, tune firmware and off you go. Well might need something more than that , but entirely doable.

Edit: again it seems that Dropbox links might not be working. I need to find something better to serve the pics. For now, here's the link to all of the pics: https://www.dropbox.com/sh/g2z5027vm...vJxo-6MXa?dl=0 (hopefully working...)

[Chris_Hinson]

Thanks for the response. The dopbox full of pictures is very useful in helping me visualize the task ahead. Right now I'm trying to assemble a BOM and approximate cost. Anything you can tell me on that front? On a related note, how long did it take to print all the printed parts? I tried putting a single corner and extention into my schools 3d printer and it estimated ~30 hours to finish

[spegelius]

Thanks for the response. The dopbox full of pictures is very useful in helping me visualize the task ahead. Right now I'm trying to assemble a BOM and approximate cost. Anything you can tell me on that front? On a related note, how long did it take to print all the printed parts? I tried putting a single corner and extention into my schools 3d printer and it estimated ~30 hours to finish

Hmm,if I remember correctly, the non-printed parts cost about 170 eur. I had most of the crews already, but buying those isn't a big cost. I didn't try to find the cheapest parts, because getting el cheapo chinese E3Dv6 hotend hascaused way too much trouble. Also wanted to make sure that the motors are powerful enough, just in case.

For the initial build, I think I used around 2 1kg rolls of PLA. Granted, I didn't have the settings tuned for least amount of filament use and I had to reprint some of the stuff after finding out they don't fit. Initial printing took about 2 weeks, with a slow af modded Cube2. Which also made all parts slightly too small. I didn't count the smaller parts as I thought that once I start to build the thing, I'll just print them as I go. Which I did, printing the missing bow ties etc. took few days.

Of course the current models on my github have changed quite a lot so the original BOM isn't valid anymore. Practically all the Z-axis stuff using lead screws is my design and should be documented. Also the racks and motor gears have gone through few iterations. And hotend mount. And other random bits and pieces. I'll see if I can get and updated BOM done soon.

Update on the fan duct: got it installed and working. It's not working 100% yet, the airflow should be directed more to the nozzle. As can be seen on the Benchy pictures below, the chimney hasn't cooled properly. Otherwise the quality is quite good. Well, apart from the retraction jams on the cabin, E3Dv6 clone again... have to do some cooling modifications on it.

https://www.dropbox.com/s/owqvuk6hg9...55.44.jpg?dl=0
https://www.dropbox.com/s/009jbg36zl...56.13.jpg?dl=0
https://www.dropbox.com/s/5haierfr3t...44.12.jpg?dl=0
https://www.dropbox.com/s/yieg0og7pd...44.36.jpg?dl=0