Need Help Adjusting the Columbia BK/BKT Four-Minute Adapter

[Rexophone]

I am restoring a Columbia BK with a four-minute adapter. I really don’t plan on playing four-minute records on this machine (I don’t have the right reproducer anyway), but I was interested in making the speed adjustment functional because it looks like a very interesting little device.

My question is about the two planet gears which appear to engage with the feed screw gear when you switch the phono to four-minute operation. When I obtained the phonograph these were just dangling loose so I didn’t understand until I began reassembly that you should move the mount which holds the planetary gears until one of them engages properly, then tighten the screw that holds the intermediate gear train.

I see that one of the planet gears extends further than the other. I assume that is the one which should engage with the feed screw gear? Do you play with the mount which holds the two planet gears until you obtain the best engagement with the feed screw? Do you position this mount where it is above the feed screw gear or below it?

I have tried both ways and it seems to be a pretty finicky little mechanism. There doesn’t seem to be much room between being not quite or too tightly engaged. The planetary gears on my adapter may also be a bit worn and not doing as well as they should.

I was just wondering if this little adapter is supposed to be this finicky or if mine is just half worn out.

Steve

[Curt A]

I had a similar problem with one of mine.... The small V shaped piece with the two gears was dangling on mine and if I put in 4 minute mode, it would run backwards. As I recall, the piece mounts on top of the other gears and appeared to have some beeswax that was used to hold it in place and failed. I used a piece of automotive double sided trim tape to reposition it and it now works perfectly...

[Rexophone]

Thanks. Yes one of the small gears is supposed to engage with that intermediate gear. If you position the piece so that the feed screw connects to that one it does run backwards. I like the idea of using the double-sided tape. The screw is supposed to hold that piece tight, but that seems like a clumsy way of doing it. The tape seems like an easier way of getting things positioned right before tightening the screw. I just can't seem to get mine positions where it runs consistently. I think my gears or just a little too worn but I'm going to play with it some more.

Steve

[gsphonos]

There is a previous thread from a few years back on the same thing....I was having problems. Have 2 BK machines with the 2/4 minute adaptors, and could get NEITHER working. It seems that sometimes the V shaped piece with the 2 little gears just gets worn out. This is a very FRAGILE arrangement! Notice how thin the gears are. Had a couple of people try to get either of mine working, as well as my tries, and it I could never get them to work with the adaptor. Hopefully yours won't be worn like mine! I finally bought a BK at Union a couple of years back, and it works great! I just wanted to have a machine with the adapter that actually WORKED! They are nice little machines, with a seldom seen adapter. Good luck!

Mike Sorter
Riverside, CA

[zapper]

Hi
Try Looking at this previous post, which maybe useful as gsphonos suggests.
Columbia Cylinder machine 2/4 minute attachment HELP!!
Regards Brian

[Rexophone]

Thanks all! Your comments have been very helpful as well as the link to the earlier post about the same subject. I was encouraged to see that the problems I am having are not unique. I plan to secure my planetary gears using the two-sided tape, but looking closely I see that I also have a little bit of jiggle in the intermediate gear which goes between the mandrel and the feed screw. This causes this intermediate gear to lift up about half the time and not engage with one of the planetary gears. As you say, this is a rather fragile and finicky device.

What also worries me is the amount of wear I see on the mandrel gear. The teeth are half worn through where they contact that thin intermediate gear.

Anyway you all have given me the knowledge I need to put this thing together properly. Many thanks!

Steve