Wobbly turntables...

[snallast]

Another question while I´m at it... it must happen to almost everyone?

When the turntable moves up and down a bit when it spins - what can one do? When I was a kid my father told me to press the opposite side until it was even, I´ve done that a lot over the years and not broken any spindles. But in 1966 a machine from 1926 was 40 yrs old... now it´s 90. I feel more hesitant about doing it this way these days - especially with an unusual and valuable machine. A lot of them are wobbly!

Any tips...?

Snal

[Jerry B.]

I suspect many were wobbly when new and people never suspected a problem. I don't think you'll ever damage a spindle when you attempt to correct a wobble on a sheet metal turntable but I'd be more careful with a cast turntable. Jerry Blais

[De Soto Frank]

Best to start by removing the platter, and observing the spindle rotating by itself... if the tip of the spindle wobbles back and forth, the issue is with the spindle, not the platter. Pressing on the "high side" of the platter might bend the platter at the hub, which may even things out, until the the platter is removed for some reason and doesn't go back in exactly the same orientation.

[CarlosV]

Be careful when pressing the turntable, remember that the whole turntable and motor are screwed to a wood board, and exerting pressure may crack the wood.

[need4art]

Here's what I have done 3 times and it has always worked. Rotate the turntable by hand and using a black felt marker mark the beginning and the end of the high point. Clamp the turntable face down on a solid work bench or table. Go to your auto tools and find a ½" socket that fits as close as possible to the turntable nub that sticks up-put an extension rod into the socket and push it in the opposite direction of the high point. In my case this takes 4 or 5 tries going slowly to flex the turntable to level. The last one started with nearly a ⅜" up its now just 1/16 of an inch. Go slow and add pressure gradually-its worked really well for me!
Abe

[Henry]

This thread is reminding me of the saw shop at Bethlehem Steel. There, they made the huge (6-ft. diameter) circular saw blades for the hot and cold saws used in the structural mill to cut off ends of steel beams. In the shop, the way they trued up the blades and made them perfectly flat was that ten or so guys with small sledge hammers stood around the perimeter and pounded the blade; every once in a while, the flatness was checked with a straight edge (surface level), the high spot(s) marked with chalk, and the pounding continued until the entire surface was perfectly flat. Of course, those guys had it easy: there was no spindle to contend with!

[VintageTechnologies]

I would be cautious trying to bend a spindle shaft, you don't know what kind of metal you are dealing with.

Once, I tried to straighten a wobbly mandrel shaft on an Edison Standard. I removed the mandrel and shaft, then pulled the mandrel off the shaft. I had a polished block of granite that machinists use to check flatness of parts. Yep, the shaft had a bow in it. I gingerly tapped on the raised center while supporting the ends on blocks. The cursed thing snapped like a pretzel! The language I used was just shameful! The metal was very brittle as if it was cast iron, and it had a similar granular appearance on the surface of the breaks. I had wrongly assumed the metal was rolled steel, not cast.

I worked as a machinist in those days and had the lathe and other tooling to make another identical shaft. After the machine's owner saw the mandrel running true, I confessed what I had done.

[need4art]

Thats why you do the turntable not the shaft!

[Oceangoer1]

On my Credenza, I fixed the wobble by switching which slot was resting on the single turntable shaft pin. There are two slots on the underside of the turntable, and one of mine makes it wobbly and the other makes it non-wobbly! Might be something to check into on certain disc machines.

Also, dirt, rust, or filth could cause the slot to rest unevenly on that little pin. So cleaning the area might make a difference too'

[startgroove]

Desoto Frank and need4art gave good tips, which I can confirm work well. I can give more details as follows:

First, I make sure the shaft on the machine is not bent according to what Desoto Frank suggests. If it is the shaft on the machine that is bent, then you will have to remove the shaft to straighten it (or replace it all together). I straighten them by using a modified version of vintagetechnologies' roll test. I roll the shaft on a flat surface. You could use a piece of ¼ inch plate steel (or ⅜ inch aluminum plate) about 10 inches square. Roll it so the pin hangs off the edge. As you roll, if the shaft is bent, a high spot will show up along the shaft as a gap between the plate and the shaft. Orient the shaft so the bend is at its highest point and mark the very top with a marker. Next, place the shaft centered on the plate with the pin end hanging off the edge. Then, find some brass shim stock (in a pinch a section of a tin can will work). Cut up several one inch square pieces of shim stock and put one under one end of the shaft with the previously marked high spot facing straight up. Use some duct tape to hold down one end of the shaft to the plate, and to keep the shaft from rolling. Take a 6 to 8 inch piece of 5/16 or ½ inch aluminum or brass dowel and place one end directly over the mark on the tt shaft, oriented vertically. With a smaller hammer, tap on the other end of the punch and observe the results. If the gap does not change, add another shim and/or hit the punch a little harder or use a heavier hammer. After observing that the gap has closed some, perform another roll test. Repeat the procedure as necessary until you are satisfied with the straightness. Occasionally, both the shaft and the turntable are bent, so you'll have to perform both procedures.

Once I confirm that the shaft is straight, I do the need4art trick on the tt with the marking pen. I have several spare Victola shafts which I've used as an aid to straighten the turntable. I place an old shaft in a vice deep enough so the tt sits on the vice jaws, and also so the tt seats normally on the shaft. I then press at the edge of the tt on the high side, and then put the tt back on the machine and check the results by doing the marking pen test again. If there is no change, I perform the routine again and press harder this time. If I bent it too far, I do the routine again, except on the opposite side and use less pressure. Most of the time it indicates that I didn't press hard enough. It is a good idea to mount a ruler beside the edge of the turntable so you can tell each time how far you have pressed the edge down, and hence how much more you should press the next time if it didn't straighten out enough. (It's surprising how much pressure it takes to bend a turntable this way.) Repeat the procedure until you are satisfied with the results.

Cheers, Russie