Here is an epic story, i will try to keep it short
I am referring here to my spare Elmo ST1200HD Magnetic only model. I bought his machine some years ago off ebay, it was in very good shape but all rubber turned to goo (as advertised). I fixed it all, replaced as standard the second sprocket guide, got it all going with a new exchange shutter with matching lower pulley to correct the speed, but needed to get it off to Bill for a professional sorting. All done. For a few more years i was never all that happy as it always produced this annoying vibration through the whole body, almost a heavy droning after around 400ft of film but it still ran fine, anyway after years of trying various things i noticed that the shutter supplied had forward /backward wobble, i have put this vibration down to this annoying wobble. Never noticed it for years.
Well, all i could do is speak with the supplier of the shutter but as it was years since i purchased it i had no choice but to pay for another pair, shutter and wheel, i got it all fitted, and have to say, unlike the previous lower pulley, this one was abysmal.
It was chunky, rough looking with a belt pitch rounded and twice the size it should be, but hey ho, i fitted it anyway, and guess what, wrong speed & in reverse/rewind the belt jumped about like a jack in the box, by far, too small, but so chunky when it was fitted it only just cleared the flywheel and shutter, you could hardly get a feeler gauge it the gaps, IMAGE 1.


I tried to explain it all to the supplier who asked, "have you fitted it correctly? er, YES, "Is the motor faulty"? errr NO, "is there another fault with the projector perhaps"? NO. In fact there was No speed issue before i fitted the shutter and lower pulley. I was lucky enough to speak with Bill on it, (BTW this was a few months ago now), who said "",i wonder if the shutter is from a 1200 and not a HD, so to prove a point Bill managed, via another person, to loan me a lower pulley form a NON HD 1200, i fitted it, but it ran too fast, it was too big, My point proven to a tee, and Bill was right as always.
I explained everything to the shutter supplier, with Bill measuring the 1200 pulley width it was 33.6mm so i guess with the other crappy ones being 29 that i needed one at 31/31.5mm to get the speed corrected.
I asked the shutter supplier to have a word with his pulley maker to get one made with a width of said measurement. He sent four to me ranging from 21mm to 29.2 max, all too small resulting in all too slow, i only tried the 29mm to prove a point, it was becoming a pain in the ass. I am really not too sure what they didn't understand about 31/31.5 mm.
In the end i thought bollocks i am getting nowhere. I went to my own trusty precision engineers here in Plymouth, PEG engineering, I took one of my own pulleys to him and said can you knock up one of these with a width of 31/31.5mm and amazingly he still had the programme in his system used all those years ago when i had some made with the 24fps clutch wheels.
See that clumsy pulley in image one?
This is how you do it lads, no plastic 3D crap here, this is made as one piece from a light alloy block weighing almost nothing, even the pitch for the belt is as the original Elmo with the correct straight edge and pitch to take the original Elmo belt, This is how its, and £30. That from scratch by an engineering firm is pretty good, all i need to do now is fit it and report back to you all on here.
BTW, The last image shows the size difference needed from my original to match my own 24 fps clutch wheels to the larger one i now need to match the shutter.


BTW do you think image 2 above here reminds you of the Flying saucer in Earth Vs the Flying saucers???