printable bearing

Hi out there!

This is another design of a printable bearing. But only the cage is printable - the balls you have to get yourselves!
I got the balls from a toy of my daughter, which should be used to make the sound of rain. It contains hundreds of little steel balls.



I got the permission to open it and she gave me some of the balls for testing my design. The radius is about 1.5 to 1.7 mm - almost perfect.



...almost: So I created a "filter" for these balls with holes in different diameters and let my daughter test, which diameter
would be the best to print the bearing.



This filter showed, that my skeinforge settings are far away from perfect: balls having a real diameter of exactly 3 mm should
get holes with a diameter of 3.6 mm in my 3D model to fit. With that filter I selected the balls fitting to the holes anyway - so no further problem.

I designed these bearings because I tried 3 versions from thingiverse, printed them myselves - adopted to my ball size - and not any of
them did fit properly. That's surely because of the size of my bearing balls and has nothing to do with the thingiverse designs - they are all very good!
So I tried to change the size a little bit, to make if fit, but this ended in a wobbly bearing construction :-(

Then I loaded openSCAD, made a little object where I can change every part independently and printed it.
I had to change the size of the inner cylinders for the bearings a few times until it was fitting perfect, but this depends
on the size of the balls and the accuracy you need to fit to the rod inside the bearing.

Using a lot of bearing lubricant the 3. try slided perfectly - especially, when you put weight on it :-)



The only problem is that you have to load the balls when the bearing is printed and put a plug into the hole.

This part surely is not comparable to steel bearings - neither in perdurability nor in the ease of sliding, but it can carry a lot
and runs easy enough to be a usable substitute for the linear bearings made of steel.

...so if you have any kind of little balls - insert the size, choose a height and print a bearing :-)

You can download the openSCAD file and an example file for a bearing 608 at thingiverse : here

Greetings

BonsaiBrain



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LED Controller

My brother works as a technician in a theater and needed some LEDs for lightning effects. As i know a bit about electronics, i looked into my parts bin and found a TLC5940 chip, which is a LED drivrer for up to 16 LEDs with PWM control. This chip is really easy to connect, it talks over serial with a microcontoller and only needs one current limiting resistor for all those LEDs.

So i made a small board for it, with the neccessary connections and pins to put it as a shield on a Arduino. You can see a few pictures of that here:

The big black chip is the LED driver, the plugable resistor controls the maximum current through the LEDs, and the pin headers connect to the Arduino board. I was missing connectors for all those LED-cables so i soldered them directly to the board, and to make it more durable, i printed a strain-relief for those cables.

The Arduino and the additional shield also got a nice printed case, which you can see here:

This box is closed off, with a nice cover with the name of my brother on it. Its very nice to have a 3D printer, no need for those ugly project boxes anymore :-)

A little program on the Arduino can now control the state and intensity of all those LEDs. This got even easier as i thought, because there is already a Arduino library for this TLC5940 chip. So i only needed to include the correct header, call the init function and send LED values to the driver. A little example:

#include "Tlc5940.h"
void setup()
{
   // Init LED driver
   Tlc.init();

   //set some LEDs
   Tlc.set(0, 4000); // LED 1 is (nearly) full on
   Tlc.set(1, 2000); // LED 2 is half on
   Tlc.set(2, 0);    //LED 3 is off
   Tlc.update();
}
void loop()
{
}

So now i hope my brother likes this and it gets some nice use in the theater.

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