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
This is my all-out favorite from the 1960's. Like the BM1400, all the tuning gears have disintegrated long ago, and so there is no possibility to feel that nice weighted movement when tuning.
For a long time, it has been on my mind to do something about it.
My local spare-parts warehouse has lot's of obsolete VCR gears in stock, so after some initial measurements on the BM, I went down there with my calipers, and spent about an hour browsing through his drawers of white plastic VCR gears. Nice guy - he knows me well after many years, and he's pretty good about giving me freedom of movement there.
I picked out a bunch of gears which I thought would work, and would give me spares if I screwed up, which of course I did - that's perfectly normal when experimenting!
Anyway, to cut a long story short (it was lot's of fun), the second pair of gears worked. I had to drill a 4mm axle hole in the small gear, and a 6mm axle hole in the large gear. The smaller gear is 15.9mm OD, and the larger gear is 19.7mm OD, and it gives a very nice spin.
Because the new smaller gear is much larger than the original smaller gear 8.5mm OD, I had to cut out a piece of the housing, to make it fit. It's a bit rough, but it works! I settled for less than pristine finishing on the cutout, because each adjustment required knocking out the brass axles with a die and punch, with the subsequent stress on the axle holes of the plastic gears. So, as soon as it fit, I left it alone.
You can see the black spacers, which prevent the gears moving forwards and backwards too much.
If anyone wants to do this for their BM1400 or 1600, I can get more of these gears - not expensive at all - you'll have to do a bit of work on them, but it's a pleasure afterwards.
Menahem
This is the finished product, with the weighted wheel back on.
This is a proof-of-concept, which if I have to do again (pretty likely), the fit and finish will be much more exact