Rek O Kut Turntable Platter Wobble

[jesusfwrl]

Hello Trolls,
Can any Rek O Kut turntable owner give me some exact numbers of how much run-out they can measure on their platter?

If you are using it with a Rek O Kut overhead, for cutting/embossing, what's the maximum run-out you can have before you start having problems with uneven depth?

Does the overhead sitting on the spindle help keep it more stable?

Are there any reliable sources for replacement centre bearings for Rek o Kut turntables?

[studiorp]

Hi, I am not an owner of a Rek o Kut ( unfortunately ), but I can say that the wobbling problem has caused by platter not exactly so precise. The only solution that isn't cheap but very good for solve the problem, is re-create another platter more precise, with an error of one or two cent. of millimeter max.

[Fela Borbone]

I solved cheaply my runout just with this tape used in packing, a dial gauge and some patience.I place the blank just on top of it

[Fela Borbone]

Pic...

[EpicenterBryan]

I solved cheaply my runout just with this tape used in packing, a dial gauge and some patience.I place the blank just on top of it

Once again, Fela comes up with an inexpensive work around.
Good work there!

[jesusfwrl]

So, the problem of wobble is not originating at the bearing on yours?

I had the impression that the centre bearing tends to wear out from the pressure of the rim drive rollers, after years of use, causing the platter to rock around. But from you r comments I am getting the impression that the surface flatness or the lack of it is more significant than any wear on the centre bearing.
Thanks for the info.

[Fela Borbone]

Hi, my platter dont seem to have any excesive play,just a little bent.Hope you can solve some how...A transplant or alike? Good luck!!

[grooveguy]

I've owned a number of "Wrench-Or-Cut" turntables over the years, and fortunately have never had a runout problem. Actually, I'm not sure if runout is the proper term, but we're talking about vertical, once-around wobble, right? The Rek-O-Kut tables featured pretty massive shafts, but other manufacturers were not so well built. My first lathe, an RCA, had a very heavy 16-inch iron platter with a 3/8-inch shaft. About 1/16-inch wobble; that is, ±1/32.

The late Tom Aye was a Presto salesman in the S.F. bay area, and I got to know him as a kid when I first began experimenting with disc recording in the 1950s. I'd sent away to Presto for a catalog, and Tom rang the front doorbell about two weeks later. Nice guy, and a friendship that lasted many years.
Tom was not really electronic- or mechanical-minded, but knew the Presto line well. He was always welcomed into radio stations and recording studios, just to say "hi" if nothing else. One "service" he provided, without the sanction of Presto, by the way, was to 'fix' wobbly turntables. He'd wait until the engineer was called out of the room, then would simply find the apex of the wobble and smack the turntable with his fist. Tom must have practiced this, and must have become intimate with different makes and models. He reported that, usually, the first smack did the job, but sometimes his fist was either too light or too heavy, and he'd have to make a second attempt. All of this was by eyeball and the seat of his pants, and he seldom said anything afterward. The engineer usually hadn't complained about the wobble, but it bothered Tom, whether the turntable was a Presto or another.

I would not recommend this, except, perhaps, with a General Industries or Recordio type of platter, or maybe a playback turntable that's not built like a battleship. The Rek-O-Kut and most other recording turntables have shafts of at least 1/2" diameter, with that entire diameter pressed into a hole machined into the platter. Bending a hunk of iron like that is not easy, and you might actually crack the platter itself, or break or bend the baseplate, which would be bad news. One sanitary fix would be to have a machinist chuck-up the shaft in a lathe and re-face the platter. This requires a lathe with a big swing, however. Fela's solution is a good and nondestructive one.

[jesusfwrl]

Wow, thanks for sharing this, grooveguy.

I love reading stories about how things were done back in the day! Also very interesting insight into the various turntable manufacturers of the time and their design concepts. I doubt I will ever resort to the fist technique myself, but gives some pointers...

[Gus]

My Rek-O-Kut LP 743 run out is + / - 0.05

DSC_0069.JPG

[jesusfwrl]

Hi Gus, do you think this is contributed mostly by the bearing, or by the platter surface? You can try measuring at the spindle itself to see if this is wobbeling or if it is standing still.

[Gus]

Hi Gus, do you think this is contributed mostly by the bearing, or by the platter surface? You can try measuring at the spindle itself to see if this is wobbeling or if it is standing still.

Hi Jesus,i have measured the spindle and did not noticed any wobble.
But i've noticed a very strange phenomenon, if for example the runout @ 45 rpm is +/- 0.5 @ 78 rpm is +/- 0,3

[Bahndahn]

Hi Gus, do you think this is contributed mostly by the bearing, or by the platter surface? You can try measuring at the spindle itself to see if this is wobbeling or if it is standing still.

Hi Jesus,i have measured the spindle and did not noticed any wobble.
But i've noticed a very strange phenomenon, if for example the runout @ 45 rpm is +/- 0.5 @ 78 rpm is +/- 0,3

Now that's a little mysterious! Two possibilities come to mind:

1. Centrifugal force is keeping the platter from settling into its resting position. This would mean that the runout is caused by a slightly mis-fitted coupling between bearing spindle/shaft and the platter, and could be tested by applying force to various places on the platter while reading the indicator.

2. The indicator is slightly delayed due to gummy lubricant or a near-sealed air pocket inside the indicator slowing the plunger movement to the maximum air-passage rate. This could be tested by using a different indicator, perhaps a dial test indicator with a lever type mechanism.

Just guesses here, but they could be the cause.

[Gus]

I had the impression that the centre bearing tends to wear out from the pressure of the rim drive rollers,

That is true but for motor bearings vs pulley vs idler, i didn't heard in the past that the centre bearing tends to wear out from the pressure of the rim drive rollers.

[Gus]

Hi Gus, do you think this is contributed mostly by the bearing, or by the platter surface? You can try measuring at the spindle itself to see if this is wobbeling or if it is standing still.

Hi Jesus,i have measured the spindle and did not noticed any wobble.
But i've noticed a very strange phenomenon, if for example the runout @ 45 rpm is +/- 0.5 @ 78 rpm is +/- 0,3

Now that's a little mysterious! Two possibilities come to mind:

1. Centrifugal force is keeping the platter from settling into its resting position. This would mean that the runout is caused by a slightly mis-fitted coupling between bearing spindle/shaft and the platter, and could be tested by applying force to various places on the platter while reading the indicator.

2. The indicator is slightly delayed due to gummy lubricant or a near-sealed air pocket inside the indicator slowing the plunger movement to the maximum air-passage rate. This could be tested by using a different indicator, perhaps a dial test indicator with a lever type mechanism.

Just guesses here, but they could be the cause.

Hi Bahndah, i think the No 1. is very possible to happen.

[jesusfwrl]

A perfectly balanced platter will tend to balance itself while spinning, and higher speeds up to a certain limit will assist in this process.

However, the RekoKut also has the pressure of a wheel against the rim of the platter which will most likely negate any balancing effect. Considering this, it is more likely that the difference is due to the fact that a different roller wheel is used for the different speeds. It is highly unlikely that the pressure applied by each roller would be equal, especially considering the different diameters, hence different torque and traction coefficient.

You cannot measure bearing play accurately by resting a dial indicator on the platter and pushing against the platter with your hand. This would only work in an ideal world where such metallic structures would exhibit infinite rigidity. Since they don't, apart from bearing play you are also measuring the lack of rigidity of the shaft and platter, which would be of no particular use as a measurement.

[Bahndahn]

You cannot measure bearing play accurately by resting a dial indicator on the platter and pushing against the platter with your hand. This would only work in an ideal world where such metallic structures would exhibit infinite rigidity. Since they don't, apart from bearing play you are also measuring the lack of rigidity of the shaft and platter, which would be of no particular use as a measurement.

Hmm good point!