The triangular hole is for using bamboo fiber needles. These are split from bamboo with the outer hard "husk" forming the point when cut at an angle. They can be repointed about 4 or 5 times using a fiber needle cutter. The thicker the hard outer layer is on a piece of bamboo, the better the point and tone. Selecting bamboo for making your own needles is an art. I like bamboo about 2-3 inches in diameter to make my needles from and a thick layer of husk.
I just found a No 2 and an exhibition reproducer in an old box. They both have diamond points. Been doing a little research to see if they have any value. I was happy to find a video that had the exact two parts. I'm guessing they went to the same machine and not two different ones.
I have a US made exhibition that was made for the The Gramophone Company in the UK. I understand that in itself makes it no later than 1919, but it has a round hole also. Do you know if they used round hole ones on export models later than the US sold ones? Thanks
The triangular opening in the needlebar is not for a cactus needle but for a triangular shaped fibre needle. There was also a special cutter that would resharpen the manufactured fibre needles.
My understanding is the following. Thorn needles did use cactus thorns, generally from the Saguaro cactus. Fibre needles are made from bamboo both of which, from an engineering standpoint, play much better mounted with a set screw in a triangular-shaped hole due to their softer composition (compared to steel). So you're both right, but I'm pretty sure Dyslexic Genius has forgotten more about antique phonographs than most people will ever know.
