Michael Karas wrote:
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An added comment.
In most applications it would not even be necessary to use pulleys for the fixed points on the mechanism that I pictured. One could just replace the fixed points with two hard steel pins. The thread on a sewing machine for example traverses through numerous holes, eyes and metal guides.

Michael Karas


I am assuming that 400 or more threads of different colors and sizes
are being positioned in some form of "weaving machine"
1- You need to bring the threads from diverse and separate thread spools to a common processing point.
This must be a system that is easily set up and will not damage the threads.
I believe that glass "lab type" thin tubing be heat bent and one end made into a small funnel this is easily done with a little practice with a propane torch and a tapered metal pointed pick, so the threads can easily be started to be "threaded" into the glass tubes.
This assembly will need to be mounted in a frame securely.
The other sides of the glass tubing is mounted so that 400 of these tubes are next to each other in a 1 by 400 matrix "400 wide by 1 deep"
This is terminated in a metal box. A vacuum pump "an old refrigerator compressor works well" so that the started threads are puled by the vacuum into the tubes with enough forces to feed them form the spools.
this will deliver all the thread to the 400 threads ends inside of the small vacuum chamber. Install a filter at the vacuum outlet there will be some dust from all these threads, which you don't want getting into the vacuum pump.
Also in this vacuum box is a set of rubber rollers the length of the 400
glass tubes. This is driven by a gear motor and the friction of the rollers pick up the thread and deliver them out of the vacuum box. Care must be taken to arrange the rollers close to the ends of the glass tubes and they must be so arrange that minimum if vacuum leakage is present!a speed control "DC" motor is used the microprocess can set the speed that the threads are delivered.
As all 400 may not always be used, or one or two may the forgotten to be included, or some thread spools may run out, or one or more threads broken. You need to monitor this problem.
Thread security:
in the microprocess a list if the threads that are used and the order is stored. This will be for each set up. as a file.
A stepper motor is programed to move a reflective send/recive optical sensor past the exiting threads held in a transparent channel after leaving the roller unit. This is on a reversing transverse gear arrangement so that any missing thread is detected at least ones a second by the stored list and the system identifies the missing thread and stops the system till it is corrected. An alarm and halt procedure.
I believe this is the simplest and most reliable way of handling an otherwise difficult problem.
If you need more detailes Emale me at LanceHenruiqies@AOL.COM