Making pulleys with a 3D printer

[Astrofriend]

Now I have come so far that I can start with making 3D CAD drawings for the pulleys I want to 3D print.

This is something new and I do a lot of mistakes, but still I have my first 3D printed puley and it looks to be usable.

First part of my documentation:
http://www.astrofriend.eu/3d-printing/camera-lens-focus-gears/01-camera-lens-focus-gears.html

This is an sub part of my new setup for a 300 mm camera lens.

3D printing is amazing !

/Lars

[Ilmenite]

Lars,
Thingiverse has several different parametric pulley designs into which you enter the desired properties (teeth, teeth profile GT2 etc, centre hole size etc) and out will pop a pretty good file which can be directly imported into a slicer for printing. This allows very large teeth count pulleys to be made, if your printer is large enough.
I have been experimenting with such things to motorise an alt-az mount but have to divide them up into multiple segments as my printer isn't too big. To save plastic, I use a very large centre hole and pin the segments to MDF for actual use.
Good luck.
Nick

[Astrofriend]

Hi Nick,
If I download a STL format file, can I import it to my CAD software and add more of my own details on it ?

Do you have an example of your favorite pulley design tool ?

I have printed my first GT2 pulley now and it looks pretty good. Did some mistake when setting up the slicer software, but no other problems.

Added some more pages:
http://www.astrofriend.eu/3d-printing/camera-lens-focus-gears/01-camera-lens-focus-gears.html

/Lars

[Pepper]

I found 3D printed pulleys were fine for light duty work like focuser motors and such, but when the going gets tough, your pushing a chain...

[BKruger]

G'day Lars

I am using this (https://www.thingiverse.com/thing:16627)parametric model available on Thingiverse. It allows design of 12 different tooth profiles but I have only designed GT2 pulleys on it.

In my case I use OpenSCAD to design the pulley, export the STL file, edit it in Sketchup (I know it is not the best but I know it well and don't have other CAD software), generate a new STL file in Sketchup and export it to the 3D printer software.

I have printed various pulleys for a 16" scope and for a Nexstar 11" mount (both ONSTEP conversions) and the pulleys are strong enough to handle the balanced loads. Slewing speeds up to 4 degrees per second. I have also printed pulleys for focusers and a rotator/de-rotator (light duty applications).

My biggest challange was to allow for shrinkage (tooth meshing on the outside) and to get the inner diameters to fit accurately on different shafts because it is almost impossible to accurately drill out the 3D printed pulley (pulley either wobble or the hole is off centre or you can't drill when using a D shaft). I also found that 24T GT2 pulleys is about my smallest pulley I can print with the ABS I am using. I have tried smaller but it didn't work with my setup.

On the heavy load pulleys I am using M4 grub screws where necessary (tap my own thread into a pre-printed hole). Usually 2 grub screws for a round shaft and one for a D shaft.

Bert

[Ilmenite]

Lars,
I have used the same Thingiverse parametric file as Bert and imported it into Fusion 360 for further work. So far, I have managed to print as low as 12 tooth GT2 pulleys, but they weren't overly successful as the teeth tended to be uneven.
I have used grub screws into tapped holes but prefer using a clamping arrangement with two nut-bolt pairs on a shaft as this avoids relying on tapped holes which are easy to strip the threads off wheen tightening. However, this arrangement takes a lot more space to use than grub screws.
Regards
Nick

[Astrofriend]

Hi,
What a lot of tips and information, thanks a lot !

I'm printing my 144 teeth pulley now, 11.5 hours. After that I shall try to print 12 and 15 teeth pulleys, GT1 standard all of them:

http://www.astrofriend.eu/3d-printing/camera-lens-focus-gears/01-camera-lens-focus-gears.html

Now I'm doing the CAD work pretty well, with that I mean I can handle the basic.

/Lars