The Talking Machine Forum — For All Antique Phonographs & Recordings

Here are two short pieces from the Nov 1923 Popular Mechanics Magazine. It indicates just how popular bamboo needles were by this point. Unfortunately the image is so retouched that it's impossible to see much of how the mechanism works. The cactus garden should give all you folks in the southwest a reason to go into cultivation.

Jim

I wouldn't mind getting my hands on one of those machines.
I'd probably consider using bamboo exclusively if I could turn out 180 needles per minute.

It looks like the machine if fairly straight forward. The operator appears to be feeding a long pre-cut bamboo length into the machine. At 180 needles per minute (or 3 per sec), the machine probably cuts 2 needles at a time, giving the operator time to feed the chute in for the next cut.

What is interesting to me is the statement that the needles are chemically treated to harden them, and polished in sawdust and wax.

What is the chemical process? What "hardness" is desired? What is the characteristics of the wax?

Knowing the answers to these questions are probably key to being able to manufacture these today as cutting the needles would be a very simple machine tool operation.

Apparently a solution of gum arabic and potassium dichromate was used to dope the needles, but I'm not sure how easy it would be to get potassium dichromate these days, and it's extremely hazardous stuff to use anyway. The needles were soaked for a number of weeks to allow the solution to penetrate the bamboo fibres, and then they were sun dried. The chemicals were added to 50% water.
I'd never heard of a reference to the wax & sawdust polishing before now, but obviously it was part of the final process.
I think the same solution was used for cactus needles too, but I'm not sure if cactus would require quite as long in the solution to penetrate properly?
I came across the chemicals used on a website some time ago & jotted it down in my little black book, but I forgot to include a reference to the site I found the information on

I'm thinking the formula and process was outlined on the infamous defunct phono board.
In my experience making bamboo needles I've found that there are all sorts of levels of hardness in bamboo samples. Of course, the harder the fiber, the better the needle, in most cases.
I've had pretty good success trimming and sharpening thorn needles off the barrel cactus.
One new source of I've found, of all things, are the clothespins made in China!
I noted with some irritation that the last package I bought was from there, not from any north American hardwood factory, until I looked closer and saw they were bamboo.
I used a wood chisel to split the length of each side into several pieces, each having a harder finished side to it, which became part of the needle point, just like the old originals. They're a bit more difficult to fashion than from bamboo skewers, but they're much harder and will play several unworn record sides before needing repointing.
Bob

I need one of those machines. I have a nice stand of bamboo in my yard.

Jim