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Worn out TWG bearings

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  • Worn out TWG bearings

    Some time ago I got service call from my client who has early 70's A100 (yes, they were still manufactured in Europe in 70's under license) with couple of dead and some badly fluttering tones. He told me that previous owner had kept it in warehouse unused for over a decade, so I expected it was just about gummed oil. New owner already had oiled it couple of times and been waiting for months to oil moving to bearings. As there were no effect he finally called me.

    The organ made so bad screaming when started that I right away ended up remove the generator to oil all the bearings manually. What I found out was three badly worn out bearing sleeves on the other end of three tonewheel shafts. Those shafts had finally fluttered so bad that also their bakellite gear teeth were worn almost away and that's why they didn't even spin any more.

    The cause of these damages had surely been lack of oil, but weird thing is that there are only these three bearing sleeves which had worn out. All other bearing were in good condition, even those neighbouring sleeves which have had oil from same oil wick with damaged ones. All oil wicks were ok and after the new owner had oiled it recently multiple times, oil was clearly seen in all bearings.

    I was just wondering could last batch organs have had problems with uneven build quality, as some poorly machined parts. As said, this organ is pretty young one compared to many other Hammonds still running, and with pretty tight keyboard guide felts it also seems not to be even played much.

    Click image for larger version

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  • #2
    Wow. That looks like nothing I've ever seen before!

    Yes, the last tonewheelers were of dubious quality compared to the earlier ones, but this... has to be down to someting else.
    Current organs: AV, M-3, A-100
    Current Leslies: 22H, 122, 770


    • #3
      Some updating as I'm finally getting this TG back alive... There were total of six bearings that needed new sleeves, all of those were located in first seven compartments at run motor end. Fortunately, only two bakelite gears needed to be renewed.

      I ended up making new inner sleeves to worn bearings, which was the easiest part of project. Making new bakelite gears wasn't as easy though, but it can be done too.

      Attached Files


      • #4
        That is masterful work...I`ll bet that with your skills,you could come up with a practical rehab for worn-out buss bars.


        • #5
          It is amazing workmanship, but I would imagine it also has to be staggeringly expensive to undertake that level of disassembly and parts fabrication.
          I'm David. 'Dave' is someone else's name.


          • #6
            Looks like you have used a small hobby lathe with a tape measure attached to the chuck to produce the gears and replacement bushes, hopefully this will work out.


            • #7
              It should work just fine for this.

              Very nice work! It's very refreshing to see someone not resort to alternate materials or 3D printing.


              • #8
                Originally posted by KC9UDX View Post
                It's very refreshing to see someone not resort to alternate materials or 3D printing.
                I actually made a 3D printed gear too for test. It's way faster to do but as I wasn't sure how PLA material would withstand wear compared to bakelite, so I preferred the old-school method. Anyway, there are lot of other places where 3D modeling and printing has its benefits.

                Those pinions seen in the previous picture are still preformed blanks, as I didn't have suitable bit for a correct tooth profile. They were shaped and matched to final form by hand file and I bet any experienced watchmaker would have done it faster and better than I did.

                And yes, dismantling TG even partially is a time consuming job (and assembling it will take even more time...), but it can be done and after all it's not more complicated than rebuilding any other mechanical device. It actually is designed so clever that to dismantle it you won't need to break anything, no weldings nor rivets etc.


                • #9
                  3D modeling is very beneficial in most cases. 3D printing is great for prototyping, as it was used long before it was called 3D printing. It has some practical uses otherwise, but most things that people use it for could be better done other ways. It's "quick and dirty".


                  • #10
                    Yes gear cutting is a very precise business requiring special workshop equipment, very difficult to do accurately using the methods you have shown.

                    However congratulations on having a go and thinking outside the box, because this is what it will take save and maintain TWG hammonds further down the track.


                    • #11
                      Valotus, may I ask what copper alloy you used for the replacement bearings? My understanding is that these Hammonds employ a bronze alloy commonly called 'Oilite.' Yours look much shinier (and without the sintered/porous appearance).


                      • #12
                        Turned Oilite can look that way. It's called "smearing" and defeats the oil capacity feature of Oilite.


                        • #13
                          Originally posted by drg View Post
                          Valotus, may I ask what copper alloy you used for the replacement bearings? My understanding is that these Hammonds employ a bronze alloy commonly called 'Oilite.' Yours look much shinier (and without the sintered/porous appearance).
                          At least in this era Hammond bearing bushes have sintered look, but I wouldn't be sure if they are real "Oilite", which originally were meant to work without additional lubrication by having oil impregnated inside pores during manufacturing process.

                          Anyway, Hammond does have active oil supply for bearings as far as wicks are unbroken and saturated with oil, so material could be any suitable alloy that stands wearing and rotational forces. Mostly used are different bronze (Cu/Sn/...) or brass (Cu/Zn/...) alloys, there are virtually dozens of them, plus manufacturing process (sintered/cast). I machined sleeves from some common bronze cast I already had in my workshop.


                          • #14
                            Just curious, but as long as you've got it disassembled this far, why not just turn some teflon-impregnated nylon bearings and be done with it?

                            Yes, bronze is romantic and has a wonderful shop-appeal, but for the simple tribology involved, there are much better materials available these days. Not a HDPE, but a silicon-nylon-teflon kind of thing. There are thousands of formulations, but even the common ones will far outperform bronze in these kinds of no-load applications.

                            For that matter, replace them all and never oil again. Instead of wearing out in 50 years, they'll last another 300 years or more.

                            Just throwing out some ideas, is all. Your generator. Not my bizness.


                            • #15
                              Has anything with those materials been round 300 years? This reminds me of the fifty year life expectancy of Edison base LEDs.