ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I recently acquired a BG5500 for restoration and found that the carriage drive string and its spring were both missing, mostly likely because the post H was broken off. I fitted a small screw, washer and nut to create a new anchor post as recommended many times in the forum.
After searching for a while, I was unable to find a replacement string so decided to try making one. This post is offered to help others who may have the same problem.
Luckily, I also have a BG3300 so removed the string from that to use as a template for a simple jig. The string measured 618mm end to end with the knot positioned 215mm from the left end. I used a length of wood with nails 618mm apart (to their outside edges) and marked the 215mm position for the knot.
I investigated suitable replacement wire and settled on jewellery wire. This is available as 49 strand, ultra flexible stainless steel wire and nylon coated in white with a diameter of 0.45mm. It looks very like the B&O original. I also sourced 2mm x 2mm tubular crimp ferrules and crimping pliers that produce a nice smooth and secure spherical crimp.
The method is as follows.
1. Cut an oversize length of wire approximately 700mm.
2. Tie a simple overhand knot in roughly in the correct position and pull tight (otherwise the knot will be too large to fit in the wire pulley notch.
3. hold the knot firmly on the 215mm mark and pull the wire taut around the left nail. Mark the wire at the outside centre of the nail. Repeat for the right side nail.
4. The marks show the crown of the eye at each end of the wire. At the mark, fold the wire back on itself to form the eye and crimp 10mm from the end. Repeat for the other eye.
5. Fold the excess wire in the opposite direction and trim close to the crimp.
Follow the wire fitting instruction in the manual and adjust the eccentrics for the 17cm and 30cm set down positions if required.
If your spring is also missing, I found an extension spring of length 15mm, diameter 3.8mm and wire diameter of 0.32mm to be a good fit.
In my case, the new drive string worked perfectly and no adjustments were necessary. It was good to see this lovely machine working again.
See photo below: