Dollo 3D Printable 3D Printer

[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...)