Dollo 3D Printable 3D Printer

[spegelius]

Racks (i.e. the rails) for Y and X are done. Took a bit more time than expected, had some problems with the models and had to do some ad hoc improvements.

Again, forum doesn't seem to work so only links available:
https://www.dropbox.com/s/noadqwl7ey...32.40.jpg?dl=0

Models to print:
- 6 x rack_5.stl (or 3 x rack_4 if not enough print area): https://github.com/spegelius/Dollo/b...STL/rack_5.stl
- 6 or 12 x rack_dove_pin.stl (optional): https://github.com/spegelius/Dollo/b...k_dove_pin.stl

Material: PETG. Can be printed in PLA, but I prefer having the racks = PETG and motor mounts = PLA, seems to be a good combination regards wear. PLA vs. PLA seems to wear down faster and PETG vs. PETG sticks too much.

Print settings:
- perimeter first
- brim if needed
- 3x perimeter
- 3-5 bottom/top layers
- 20% infill
- no supports. There's some bridging, but shouldn't be hard to get good results. Using supports with PETG is challenging to remove
- 0.2mm layers. Haven't tried higher, 0.3mm might work fine too

Assembly:
- for the frame size of this build, more than one rack part is needed. To connect the rack parts together, dovetails are used:
https://www.dropbox.com/s/0udrz5jtza...02.28.jpg?dl=0
https://www.dropbox.com/s/aukv4h7wtz...03.05.jpg?dl=0

The parts should be tight but still fit together. Use file/knife to remove material if needed, but be careful not to remove too much.
For proper positioning, the herringbone rack on both of the parts should be level. Also the grooves on the sides should also be on same level.

If the parts seem to be too loose, they can be locked together using the rack dove pins. I used small hammer to force the pins in the slots in the dovetail parts:
https://www.dropbox.com/s/hzhvbcoo1s...14.22.jpg?dl=0
https://www.dropbox.com/s/a4q55ou5nl...17.43.jpg?dl=0

The default size should be very tight, but use slicer scaling if they seem too loose.
Alternatively, soldering iron can be used to weld the parts together, but that's more permanent solution.

After the rack parts are connected, the side grooves need to be sanded so the motor mount will slide properly. Especially where to rack parts are joined needs cleanup. Use something like 180 grit sandpaper wrapped around a rectangular piece and work along the groove with long strokes until the whole length is smooth. There will be a small gap at the junction of the rack parts, but that's ok as long as there's no protrusions along the way.

Next, mounting the racks to the frame (Y axis)

Edit: forgot to mention the experimental rack alignment parts I designed for making sure that the racks are in proper distance from each other. No real need for these as the current dovetail joint seems to be working as it should.
https://github.com/spegelius/Dollo/b...gbone_base.stl
https://github.com/spegelius/Dollo/b..._tool_clip.stl

https://www.dropbox.com/s/tke90sz67g...45.21.jpg?dl=0
https://www.dropbox.com/s/c6a5smx43f...45.57.jpg?dl=0