MECCANO SPRING CORD- Three factors
1. The rule of thumb which I generally
use as a starting point is to cut the cord length to the same length as
the axle shaft centres.
2. Spring Cord lengths should be determined to prevent slipping so that the cord must be sufficiently ‘loaded’ when applied to the pulleys.
3. Another major point to consider is that spring cord is mainly suited to permanent applications, therefore if possible determine some average lengths which will be needed for intended models and make them permanent parts.
Everyone I encounter who has had difficulty in joining spring cord used blunt side cutting pliers to cut the cord and consequently cannot get the worm to start. Whatever the cutting method it must be sharp to ensure an efficient and professional looking joint.
Pedigree "Holey" worms are expensive (IF YOU CAN GET THEM) and other replicas I have seen are not very suitable either. Here is my simple method of joining Meccano Spring Cord which will not burn holes in your pockets.
I use 10 B.A. threaded rod or screws (Available at Model shops and model engineering suppliers) cut down into 1/8" or 5/32" lengths dependent on the diameter of the pulleys it is intended for.
Rule of thumb - For all smaller diameters
where the drive pulley is 1/2" I use the short one. If the drive
pulley is 1" or larger then the longer one will work.
1. Fit the worm to one end using Thread lock or other suitable non permanent engineering adhesive to no more than halway.
2. Wind the opposite end of the cord anticlockwise and let it go on the exposed end of the ‘worm’ -
Do not use super glue.