This version has been made on the LASER cutting machine at the Vigyan Ashram Fablab. Here is how it looks as made in SolidWorks.
A small video of this is here:
The materials used are:
- 12 mm Acrylic sheets
- 4 mm acrylic sheets
- Some motorcycle wheel spokes (3.5 mm diameter)
- A 3 inch PVC pipe section.
- Fevi-Quick or some other fast action glue.
- Washers.
- Rubber bands.
How it works:
The way cotton passes through this machine is as follows:
The raw cotton is made into a small string that can pass through the main hole in blue in the following image.The string should be meshed and passed through the twister assembly and out through the other end.
The twister assembly cross section is as shown here:
Once through, the string must be passed through the thread guide which does a back and forth motion on a 3″ PVC pipe cut in the form of a cam.
This cam action lets the thread wind onto the spool which rotates with the speed of the crank handle. A proper video of the working will be made soon.
ISSUES: The issues with this version are:
- Lase cutting the acrylic was not proper and resulted in rough gear teeth. This results in a lot of friction.
- The large friction makes the spinning handle slip at the main rod, thus making the rotation of all the wheels very erratic.
- The lack of a proper tube for conducting the cotton through the machine forced the fabrication of this tube out of stacking various disks of 12mm thickness cut from the acrylic sheet. The LASER bed was not uniform so this resulted in a badly shaped tube, causing further friction and noise.
- The current PVC cam has been cut simply and the profile will cause the threads to cluster at the edges where the thread guide will have a slower motion. Ideally the cam profile should be such that the thread guide follows a simple harmonic motion.
Files
Meanwhile the files for LASER cutting (in DXF format) and the original SolidWorks parts and assembly files can be downloaded from here.
Vigyan Ashram DIC 