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Thoren drum disassembly.

Posted: Tue Aug 14, 2018 4:50 pm
by Groundhog74
Anybody know how to get thes drums open? I need to inspect the springs.

Re: Thoren drum disassembly.

Posted: Tue Aug 14, 2018 5:33 pm
by Curt A
You need to disassemble the motor by removing the four screws in the posts that hold the two motor plates together like a sandwich. You might also need to remove the two screws that hold the small plate which holds the motor shaft in.

Re: Thoren drum disassembly.

Posted: Tue Aug 14, 2018 5:47 pm
by Groundhog74
I have had the motor apart and back together. The springs in the drums are disconnected from the "hooks" on the shaft that goes up through them. I cannot get them to re connect. I suspect either broken springs or petrified grease. I need to open the drums to inspect/degrease. I am hoping someone would know if the gears are threaded on, pressed or what? Thanks for the help.

Re: Thoren drum disassembly.

Posted: Wed Aug 15, 2018 5:41 am
by coyote
To clear up a bit of confusion, what I think Groundhog is asking is how to open the spring barrels after they are removed from the pillar-and-plate assembly. Are the gears attached to the spring barrels press-fit, i.e. the "cookie tin" type, or do these open another way?

Re: Thoren drum disassembly.

Posted: Wed Aug 15, 2018 9:15 am
by Groundhog74
Yes. If pressed, after reassembly, is there a need to re-tighten the open mouth of the barrel? Similar to crimping the case in ammunition reloading? Thanks again. First time digging in this far.

Re: Thoren drum disassembly.

Posted: Wed Aug 15, 2018 10:25 am
by Curt A
If you don't see screws or rivets holding the spring barrels together, then they are most likely press fit. Obviously, if they were assembled originally they can be disassembled somehow. The question is how to get them apart and I can't help with that answer... You might try an automotive gear puller. I used one to work on one of my machines, but I had to modify it by grinding the puller jaws to fit the application. Good luck...

Re: Thoren drum disassembly.

Posted: Wed Aug 15, 2018 1:11 pm
by Groundhog74
Well, I got them open. Put them in a vise, heated up the “can” with a torch until I could see the grease in the seam bubble a bit then tapped on the notch in the lid with a small hammer and brass punch. They popped right out after a couple good taps with the hammer. Here’s the situation, bottom drum has a broken spring. Top drum appears ok. So.... do I try to drill a new hole in the bottom spring? Or send the drums in and have new springs installed? Also, the springs are wound in opposite directions. Not sure I understand the concept of how that works.

Re: Thoren drum disassembly.

Posted: Wed Aug 15, 2018 4:35 pm
by Curt A
It would be a good idea to replace both springs, now that you have the barrels opened up. Even if one spring appears to be good, it has probably been weakened with age and replacing the pair is the optimum choice. If you aren't comfortable with doing them, send them to Ron Sitko.

Make sure you mark the winding direction of each spring... use an awl or a sharp scribe to permanently mark the barrel top with an arrow showing the direction each spring is wound. Also, make note of the top spring barrel and the bottom one, so you can put them back in the same order.

Re: Thoren drum disassembly.

Posted: Sat Aug 18, 2018 8:18 pm
by Groundhog74
Since this (and my other 3 machines) will get played about twice a year, I decided to try and repair the broken spring. After removal and degreasing, I clamped the spring in a vise between a scrap piece of 2x4 and a piece of composite fence I had laying around. I had drilled a 1 ½” hole in the composite fence piece to pull the center coil through. I “trapped” the pulled through end in place with a piece of flat steel. Then on the back side I stuffed a wet shop rag into the coils to reduce the spread of the heat. I heated the broken end until red and let it cool. Then I found the correct drill bit sizes by testing the bit shafts against the large and small ends of the pear shaped hole in the good end of the spring until I found a perfect fit. Drilled 2 small pilot holes first, then the full size holes. Cut out the Center with a Dremel and filed the rough edges. Then I coiled the annealed end of the spring for a good fit around the center arbor. Installed the spring in the barrel (twice, backwards the first time) re greased everything as well as I had some good quality graphite grease on hand. Works good so far and it will play a full record with no problem. I only remembered to take 2 photos when I had the center pulled out right after heating. Hope this will help someone else with a broken spring on the inner coil. If it does not last, then I’ll order new springs. They are an odd length and I was quoted a little over $50 each for them. Worth a shot.

Re: Thoren drum disassembly.

Posted: Sat Aug 18, 2018 9:58 pm
by Curt A
Great... fixing it yourself is the best way and it worked out fine...