Rexoport Prismaphone Problems

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Technomaniac
Victor Jr
Posts: 9
Joined: Tue Jun 29, 2021 11:26 pm

Rexoport Prismaphone Problems

Post by Technomaniac »

Hi.
This is a portable machine I am repairing for a friend. Its history is unknown, but my immediate problem concerns the mainsprings, two in barrels which are held together on their open rims, by three metal-thread screws. The inner ends of both springs being in too large a loop to grab the arbors. And not wanting to be reshaped to smaller diameters, just springing back to the original diameter loop, even with as much force as I could exert. How could the spring loops become too large, in normal use, if I couldn't squeeze them back down and get them to remain at the smaller diameter? I heated the ends, reformed, and refitted the springs to the barrels. The arbors are HOLLOW and run on a common dead shaft. This means that the inner hooks couldn't pass through a hole to the other side, but had only the thickness of the tubular arbor to be threaded into. This allows the hooks to unscrew themselves over time. So I took it upon myself to make a modification. I turned up two bright steel sleeves which would be a springtight fit on the arbors with the loop end squeezed in between. Filed rectangular holes for the hook heads to locate in, which would prevent unscrewing, and cut away some of the sleeve to leave a C- section. I think hard and carefully before making modifications, but as I had much advice to NOT attempt to retemper the spring ends, this is the way I went. I did not know if my C-Clips would stay in place, or unclip themselves and cause a problem.
One spring barrel has parallel sides, the other has a larger diameter step on the mating edge, which slips firmly over the edge of the other barrel. Three metal-thread screws are meant to hold the two barrels together. But there is NO WAY this could work, as the outer- turn of one spring was right across the holes. The holes of the inner barrel edge may have been threaded, but the barrel being of less than a mm thickness, how could a square-ended screw possibly find the hole of the inner barrel when it had the spring FLAT against it, and the screw couldn't protrude through the hole.
That's when the penny dropped ! These were NOT the correct springs. The springs should be NARROWER, leaving the holes clear for the screws to protrude through.
At least this is my theory. Can anyone enlighten me as to the width of spring I should have in this machine? If the springs were only 20mm wide, the holes would be clear.
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Last edited by Technomaniac on Tue Dec 21, 2021 10:35 pm, edited 1 time in total.

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Marco Gilardetti
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Re: Rexoport Prismaphone Problems

Post by Marco Gilardetti »

Perhaps a pair of pictures would help...

JerryVan
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Re: Rexoport Prismaphone Problems

Post by JerryVan »

Marco Gilardetti wrote: Fri Dec 03, 2021 3:27 am Perhaps a pair of pictures would help...
Yes. More pictures.... less words ;)

GramophoneSmith
Victor Jr
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Re: Rexoport Prismaphone Problems

Post by GramophoneSmith »

This is an Australian that used swiss parts so try this group on Facebook https://www.facebook.com/groups/905140139507160

Technomaniac
Victor Jr
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Re: Rexoport Prismaphone Problems

Post by Technomaniac »

Problems were solved by sleeving the spring barrels internally, new spring hook pins were made and rivetted in, holding the sleeves in place. New holes for the screws were drilled and tapped, there was now effectively a greater thickness for the screws to thread into, and everything worked fine with the original springs, which we thought were too wide. I had to make a new (smaller) separator disc to insert between the two springs. I didn't want to cut up the original one, in case I had to go back to original format.

I tried to insert photos from files but it didn't work.

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