Rek-O-Kut Micropoise S-320 - help me fix this tonearm!

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Any folks with a Rek-O-Kut tonearm here? I have S-320 micropoise tonearm which is loose at the horizontal bearing location. I'm figuring if I can service the bearings I can fix the issue. I've read that chatter in the bearings is common in these tonearms over time and they need to be serviced.

I've disassembled most of the tonearm; however, I've not been able to separate the gimbal from a steel cylinder to allow access to the bearings.

Photos below for reference

The turntable

An externally hosted image should be here but it was not working when we last tested it.


Below is location of looseness and rattle:

An externally hosted image should be here but it was not working when we last tested it.


For reference of the parts, below is a photo someone took when they disassembled their tonearm (not mine).

An externally hosted image should be here but it was not working when we last tested it.


I need to remove the cylinder from the gimbal but I'm not able to separate them. I didn't want to force it for fear of damaging it. I thought it would be better to seek advice before proceeding.

An externally hosted image should be here but it was not working when we last tested it.


I've gotten everything apart except for the two pieces that will allow access to the horizontal bearings. The tube appears to have a loose screw inside it that can't be retrieved. The black cylinder inside the lighter colored one appears to be metal. There is no apparent method to untether these parts.

Any help would be greatly appreciated!! :D

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.
 
While I won't be able to help you now, as I'm just starting on this path, I want to say I'm most appreciative of your photos. It's like stumbling upon some knowledge where I didn't think I could do anything but hack into the arm blindly. The fellow at Esoteric Sound (Esoteric Sound, Rek-O-Kut, turntables, sound restoration, noise reduction, folk music) is very knowledgeable and would be worth a call.

I'll keep watching this thread for sure.

Skip
 
While I won't be able to help you now, as I'm just starting on this path, I want to say I'm most appreciative of your photos. It's like stumbling upon some knowledge where I didn't think I could do anything but hack into the arm blindly. The fellow at Esoteric Sound (Esoteric Sound, Rek-O-Kut, turntables, sound restoration, noise reduction, folk music) is very knowledgeable and would be worth a call.

I'll keep watching this thread for sure.

Skip

Hi Skip Pack,

I reached out to Esoteric. He hasn't experienced this issue and wasn't able to provide guidance.
 
I think postimage.org is having technical issues displaying images. I've tried a different image host site below. Can you see this image?

pnp4Mwx.jpg
 
Since the post image host site I used earlier appears to be down today, I'm reposting the first post below with images on a different image hosting site. Hopefully these images will show up....Thanks!

==============

Any folks with a Rek-O-Kut tonearm here? I have S-320 micropoise tonearm which is loose at the horizontal bearing location. I'm figuring if I can service the bearings I can fix the issue. I've read that chatter in the bearings is common in these tonearms over time and they need to be serviced.

I've disassembled most of the tonearm; however, I've not been able to separate the gimbal from a steel cylinder to allow access to the bearings.

Photos below for reference

The turntable

1_IMG_2899.jpg


Below is location of looseness and rattle:

2_320move.jpg


For reference of the parts, below is a photo someone took when they disassembled their tonearm (not mine).

3_tonearm_2.jpg


I need to remove the cylinder from the gimbal but I'm not able to separate them. I didn't want to force it for fear of damaging it. I thought it would be better to seek advice before proceeding.

4_IMG_3648.jpg


I've gotten everything apart except for the two pieces that will allow access to the horizontal bearings. The tube appears to have a loose screw inside it that can't be retrieved. The black cylinder inside the lighter colored one appears to be metal. There is no apparent method to untether these parts.

Any help would be greatly appreciated!! :D

5_IMG_3654.jpg


6_IMG_3656.jpg


7_IMG_3657.jpg


pnp4Mwx.jpg
 
Removal of cylinder

I've disassembled most of the tonearm; however, I've not been able to separate the gimbal from a steel cylinder to allow access to the bearings.

I need to remove the cylinder from the gimbal but I'm not able to separate them. I didn't want to force it for fear of damaging it. I thought it would be better to seek advice before proceeding.

Hello monkboughtlunch,

I am not familiar with your tonearm. However, It appears that the short cylindrical component closest to the gimbal may be permanently assembled to the gimbal, either by orbital riveting or by soldering or even brazing. The lower elongated cylindrical component may be threaded into the permanently assembled component. If so, the small hole may be meant for the application of a spanner wrench. Not knowing how skilled you are, you could conceivably make one. If the lower cylindrical component has a standard fractional diameter, such as 3/8" or 1/2" etc., you could put it into a collet in a lathe to unscrew it. Proceed with care.

Sincerely,

Ralf
 
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Hi Monk

I saw your post last night, and as I have a B12H and Micropoise as one of my many "projects in waiting" on the shelf of my audio closet, I decided to go down and pull the tonearm out and take a look. My interest actually was self serving to a degree, as I had been brain storming on several occasions about the possibility of refitting it with a longer arm. Turns out I spent most of the evening crawling around on my knees finding a ball bearing that ran away...the rest of the evening was spent cursing over not being able to upload the image I took of it disassembled. Unfortunately, my arm appears to be different. I suppose it may be the 120 model. Here is the image of it pulled apart.




I hope that pic works.

Anyway, first I got the cone shaped base out of the way. I had to release the cable stop in order to be able to move anything. Getting the base off was tricky as there is a plastic plug in the hole under the set screw that did not want to allow the cone to come off. I had to rotate the base until the plug found a gap in a very thin snap spring that is fitted into a groove on the outside of the bearing housing toward its bottom. Even then, the snap ring popped off and I found it inside the cone shaped base afterward.

The first obvious difference from your arm was that there was another retaining ring at the base of the bearing housing with a set screw. I released it and it came right off.

Afterward the bearing housing didn't want to slide right off. I think it was hanging up on the slight deformities that the collar's set screw had left on the inner shaft.

Once I carefully slid the housing down a little the ball bearings started falling out. I managed not to lose them immediately, it was later on when I was careless while trying to take a pic that I managed that stupidity.

It turns out that the lower bearing in the housing looks like a bronze bushing, most likely sintered/oil impregnated.

The upper bearing had 13 balls (after I relocated the defector).

There is another small machined groove toward the bottom of the inner shaft that the collar retaining the bearing housing was attached to and a thin washer tucked up under the upper bearing dust cap. I don't think I lost a snap spring from the lower groove, as the retaining collar was mounted at or over that position on the inner shaft.

If you look up under the upper bearing dust shield you can see a C-clip in a groove that maintains the position of the dust shield. Perhaps this was an evolving design that was originally held by a C-clip on the bottom with another washer, but was changed to a collar to allow better adjustment of load on the upper bearing?

There is a small hole in the bearing housing like your arm, although much smaller than yours appears in the pictures you posted. Actually, if you look closely in my pic, you can see that another hole the same size was made about 1/4" away from it that appears to have been made mistakenly and then plugged with some brass/bronze wire. I have no idea what the hole is for other than a guess that perhaps it allows one to lubricate the assembly without disassembling it?

It's not exactly the kind of manufacturing we're used to these days with everything being perfectly CNC machined with sealed bearings etc.

It has gotten me thinking further about my project plans and the possibility of rebuilding it with some better high tolerance sealed ceramic bearing or similar.

I'm not to sure what to say about your situation. Perhaps the indication of different possible bearing arrangements and designs throughout the line indicates that they may have moved onto a design where better bearings were sourced and pressed into place at a later date. If so, some kind of puller would seem necessary that could engage the hole you have on the side of your bearing housing and push against the center shaft at its end in order to remove the housing and bearings. Have you checked carefully at the end of the housing to see if there might be a machined recess with a very thin snap ring seated into it?

Best of luck.

Kevin
 
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A few additional things I came across during reassembly of my arm that might be helpful to others looking for info here.

The very small holes that are in the bearing housing of my arm explained themselves. The hole that was drilled and "plugged" with brass/bronze wire was actually the part of the manufacturing that was carried out correctly. The wire that was pushed through the hole acts as a stop when it interferes with another pin that is similarly installed on the central shaft (which I didn't notice when the arm was disassembled because it was facing down toward the table) and together they prevent the gimbal from spinning any further than 360 degrees so that the wiring cannot get tangled up or damaged. The extra hole that was left open was most likely a first "missed" attempt to locate the pin in the outer bearing housing.

It also became obvious that the thin wire "snap ring" that sits in the groove at the bottom of the bearing housing is put in place AFTER the cone shaped base for the arm is slid up almost all the way to the top of the bearing housing. It is there to prevent accidentally pulling the arm completely up out of the base while adjusting the height of the arm.

Monk: I looked at the second set of pics you put up again. It appears that they did make these arms with bearings at the top and bottom based on what I see. The second close up pic of the bearing housing shows that there is a "cup" machined in the bottom of the housing end where the similar groove is machined (as on my arm) on its outside surface for the "snap ring" that prevents withdrawing the arm during height adjustment.

The picture of the gimble/shaft assembly on the scale is almost identical to mine except that it does not have a groove machined near the end of the shaft where they used the same collar as was used on mine to load and hold the bearings and housing together correctly.

In the picture of your bearing assembly that is taken from the bottom, it looks like a black donut. Is this a rubber seal of some sort? Is it in fact black? Or is it just in shadow? If it is, have you tested to see if pit is pliable like a seal or hard?

One additional note, if you do figure out how to disassemble your bearings and they are not sealed units, beware that it is VERY easy to over load the bearings with the SLIGHTEST amount of pressure from your finger while trying to reset the retaining collar that holds the housing and bearings together.

Mine seemed sloppy when I checked it before disassembly, so I obviously wanted to see if I could tighten it up. It was necessary to set the collar so it actually left a hair of space between itself and the bottom of the housing while holding it all together LIGHTLY with one finger on my other hand. I managed to cut the slop by about half of what it originally had I would guess, but it took 3 or 4 tries.
 
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I'm not to sure what to say about your situation. Perhaps the indication of different possible bearing arrangements and designs throughout the line indicates that they may have moved onto a design where better bearings were sourced and pressed into place at a later date. If so, some kind of puller would seem necessary that could engage the hole you have on the side of your bearing housing and push against the center shaft at its end in order to remove the housing and bearings. Have you checked carefully at the end of the housing to see if there might be a machined recess with a very thin snap ring seated into it?

Best of luck.

Kevin

Hi Kevin,

Many thanks! Yes, it appears mine is slightly different than yours. I believe mine was produced in the early 1970s when ROK was under CCA ownership. I've taken some better quality photos and have posted them below.

I can see glimpses of what appear to be the lower bearings on the underside, so the overall design must be similar to yours. However, I don't see any retaining clip on the bottom of the cylinder. If I shine a bright light into the tiny screw hole on the side of the silver cylinder below the gimbal there is a recessed area but even with lots of light I can't make out any screw head or trigger release within the darkness. The screw that plugs the hole in the outer cylinder is loose and rattling inside.

It appears the only way to extract this is via the hole in the side, but it's unclear what tool would be required. Any ideas on how to triangulate a solution?

rokrelease.jpg

roktopsidecloseup.jpg

rokundersidecloseup2.jpg

rokundersidecloseup.jpg
 
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Those pictures are a bit better.

My first impression is that the outer silver housing with the hole in it missing the screw that is rattling around inside slides up over the entire black inner shaft and is itself machine on its inner bottom lip to accommodate the lower bearings.

It looks like the screw that you say is lose inside is meant to engage the inner shaft and lock the outer housing in place once the bearings are loaded properly.

The mystery to me is, if the set screw is tumbling around inside, what is preventing the whole thing from falling apart?

Is there still a piece of the set screw in place engaging the inner shaft and outer housing?...or perhaps there is a piece of the set screw jammed between the two?

The bearings that we are peeking at in the bottom end do not look to be sealed, I can't make out if they are captive in a cage or not.

I am wondering if this is just a matter of that inner black colored shaft being made of some sort of steel that is prone to oxidation which may have formed on its surface where the outer aluminum housing meets up with it and it is effectively seized in place. If so, it may require some liquid wrench or similar product and some elbow grease.
 
Hi Monk

Anyway, first I got the cone shaped base out of the way. I had to release the cable stop in order to be able to move anything.

I haven't yet been able to remove the cylinder. But for posterity, I wanted to share and document the similar process I encountered removing the strain relief to allow the RCA cables to be removed. These are at the bottom of the threaded cylinder.

This process might interest folks who want to replace damaged or inferior phono cables with high quality ones. Or if you service the bearings, you'll have to disengage the strain relief to allow the RCA cables to be disconnected.

Here's a bottom view of the black plastic strain relief. You have to slide the inner part out a few millimeters and then squeeze down on the exposed sliver with a very narrow pair of pliers. This will allow you to disengage the locking mechanism and pull out the inner part of the black plastic strain relief. If you damage the parts of the strain relief, the original parts are still available for cheap on Mouser. If any part gets damaged during the extraction, it will most likely be 5-P4 which costs only 13 cents from Mouser.

Here are part numbers and links to replacements if needed:

Heyco SB-687-8 (part 2083 Mouser link )
Heyco 5-P4 (part 1147 Mouser link )


thread.jpg

sb6878.jpg

5p4.jpg
 
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On that note...

Perhaps those who may wander in looking for a glimmer of hope because the spring contacts on their rediculously hard to come by and expensive Micropoise headshell have broken may find these useful.


http://www.mouser.com/Search/ProductDetail.aspx?R=0922-0-15-20-75-14-11-0virtualkey57510000virtualkey575-922015

I happen to be in possession of such a headshell. I tore it down and figured out how to remove the remaining pins and took a bunch of measurements. The plug in the end of the headshell will require modifications, and I actually have considered just machining a replacement from some Delrin I have so that I can make it a little longer to accommodate the new pins.
 
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HI Monk...the "bushing" is what I called a "collar" in my post...it is not part of what you call the "cylinder" which I referred to as the "bearing housing".

It (the bushing/collar) is fastened with its own set screw below that "cylinder" on the smaller center shaft. The center shaft passes through the entire cylinder and sticks out past the lower solid brass/bronze bearing inside the cylinder and protrudes another 3/8" approximately. It is the cylinder's job to retain the ball bearings that are installed in a cup at its top which holds them up against the thrust washer that is also slid onto the center shaft at its very top under the dust shield located at the junction of the gimble and center shaft. If not held in place from below by the bushing/collar the "cylinder" would slide off of the center shaft spilling the ball bearings out from its upper race.

Your bearing design is obviously different. My feeling is that they enclosed the lower end of your "cylinder" and machined a cup there in order to use ball bearings at the top and bottom of it.

It looks like they eliminated the use of the collar/bushing, shortened the center shaft and integrated a set screw into the cylinder itself so that it could hold itself in place at the appropriate position on the center shaft in order to retain and load the bearings properly. On second thought...that doesn't make sense as then the set screw would prevent the center shaft and cylinder from rotating independently of one another. Now I'm really scratching my head wondering what the screw rattling around inside was for.

Hopefully this picture works and helps.

 
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