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Guest pobox-123

Townshend Rock II & the Rock reference.

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Hi All.

New member, first post, Rock owner. Thought I'd share a few nuggets I've picked up over the years.

clamp - you can have the head of an M5 socket/allen bolt (preferably stainless) turned down to 7.1 - 7.2mm, about 6-7mm ithread length, and you now have an adapter that allows a Michell (or similar) clamp to be used. It also saves wear on the brass thread in the Rock's spindle. You can use a small drop of loctite if desired (don't over-do it, you need to able to remove it in future if the thrust ball needs to be drifted out for replacement).

Bearing lubrication. Two-man job. With the subplatter upside-down, use a precision oiler to introduce 0.6ml of your chosen oil to the very bottom of the bearing, being careful to keep the sides bone-dry.  Have an assistant hold the plinth upside-down (the shaft and bearing well also bone-dry) and slide the subplatter into place - if you've kept the sides dry it won't trap air, and will stop about 5mm short of fully home. This is the tricky part - beween the two of you, very carefully right the deck while making sure the subplatter doesn't move. Leave it to settle under the weight of platter (which won't take as long as it would if air was trapped in it). You can now be sure that the bearing is running fully bathed in oil. If a new thrust ball has been fitted I put a small dab of lithium grease on the center of the thrust face of the shaft (whether it makes any difference I don't know, but it doesn't do any harm). Of course, it's advisable to remove the trough and arm before undertaking all this.

These two procedures actually compliment (?) each other - the spindle adapter/extension creates a gas-tight seal, and in theory once the subplatter is installed using the above method, the oil-bath you've created will stay where it is indefinitely.

ETA > in case anyone wonders how the oil in the bearing is "defying gravity", think about it this way; if the oil were to drain from between the bearing shaft and sleeve, it has to be replaced with air. Where will this air come from? The only access to the outside world (assuming the spindle is now gas-tight) is the exposed surface of the oil in the 'sump' between bearing sleeve and the well/housing. To make its way into the bearing the air would have to defy gravity by moving down to the bottom of the sump before making its way up between the shaft and sleeve. To be honest I'm surprised no-one has thought of this before (not least Max himself), given the otherwise intractable problem of keeping the top of this design of bearing, the thrust face in particular, properly lubricated.

Edited by Mark_S

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1 hour ago, Mark_S said:

Hi All.

New member, first post, Rock owner. Thought I'd share a few nuggets I've picked up over the years.

clamp - you can have the head of an M5 socket/allen bolt (preferably stainless) turned down to 7.1 - 7.2mm, about 6-7mm ithread length, and you now have an adapter that allows a Michell (or similar) clamp to be used. It also saves wear on the brass thread in the Rock's spindle. You can use a small drop of loctite if desired (don't over-do it, you need to able to remove it in future if the thrust ball needs to be drifted out for replacement).

Bearing lubrication. Two-man job. With the subplatter upside-down, use a precision oiler to introduce 0.6ml of your chosen oil to the very bottom of the bearing, being careful to keep the sides bone-dry.  Have an assistant hold the plinth upside-down (the shaft and bearing well also bone-dry) and slide the subplatter into place - if you've kept the sides dry it won't trap air, and will stop about 5mm short of fully home. This is the tricky part - beween the two of you, very carefully right the deck while making sure the subplatter doesn't move. Leave it to settle under the weight of platter (which won't take as long as it would if air was trapped in it). You can now be sure that the bearing is running fully bathed in oil. If a new thrust ball has been fitted I put a small dab of lithium grease on the center of the thrust face of the shaft (whether it makes any difference I don't know, but it doesn't do any harm). Of course, it's advisable to remove the trough and arm before undertaking all this.

These two procedures actually compliment (?) each other - the spindle adapter/extension creates a gas-tight seal, and in theory once the subplatter is installed using the above method, the oil-bath you've created will stay where it is indefinitely.

ETA > in case anyone wonders how the oil in the bearing is "defying gravity", think about it this way; if the oil were to drain from between the bearing shaft and sleeve, it has to be replaced with air. Where will this air come from? The only access to the outside world (assuming the spindle is now gas-tight) is the exposed surface of the oil in the 'sump' between bearing sleeve and the well/housing. To make its way into the bearing the air would have to defy gravity by moving down to the bottom of the sump before making its way up between the shaft and sleeve. To be honest I'm surprised no-one has thought of this before (not least Max himself), given the otherwise intractable problem of keeping the top of this design of bearing, the thrust face in particular, properly lubricated.

Being about as untechnical as it's possible to be, any chance that you could post a video clip of that?

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7 hours ago, Rock'n'Roll3103 said:

Being about as untechnical as it's possible to be, any chance that you could post a video clip of that?

I'm actually in the middle of an overhaul and some mods of my Rock II, I don't have a decent video camera (at the moment anyway) but I'll take stills as it's put together. I can actually just about manage the oiling procedure single handed, but it's definitely MUCH easier with an assistant.

Another little light bulb came on - it's very difficult to keeping the bore completely dry while adding the oil (even a tiny drop on it will instantly create a film and trap air in it as it's slid onto the shaft), but a disc of plastic, slightly smaller than the bore diameter and about a cm or so from the end of the oiler tube would keep it centred and away from it.

(have to say, I'm getting a bit self-conscious having to talk so much about inserting shafts and what have you :oops:.)

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6 hours ago, Mark_S said:

Another little light bulb came on - it's very difficult to keeping the bore completely dry while adding the oil (even a tiny drop on it will instantly create a film and trap air in it as it's slid onto the shaft), but a disc of plastic, slightly smaller than the bore diameter and about a cm or so from the end of the oiler tube would keep it centred and away from it.

That's my point: bore?

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3 hours ago, Rock'n'Roll3103 said:

That's my point: bore?

You mean, what is the "bore"? The bearing surface, the sleeve of the bearing, the inside of brass part of the subplatter that runs on the shaft.

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Diagram of the Rock's subplatter and bearing (simplified and not to scale).

In red is where, ideally, we want oil, but actually it's usually no higher than the 'sump' in the bottom of the housing, just below level with the plinth, the only oil reaching the surface of the bearing above this has to migrate by 'capillary action' up the clearance in the bearing.

The thrust-ball is held in a taper in the brass housing, and is almost, but not quite air-tight, hence the idea of sealing the top of the spindle with an M5 bolt/screw-come-spindle adapter.

[ETA >> when I say "not to scale", I mean not even remotely - I drew it without even looking at the actual subplatter, so please don't use it as any kind of reference.]

rock%20subplatter%20bearing_zpstljghh7c..

Edited by Mark_S

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I've discovered that the Rock's bearing differs slightly from my assumptions.

there's actually an M5 set-screw inserted through the top of the spindle to adjust the location of the thrust-ball and hence the height the subplatter rides on the bearing shaft.

Further, this set-screw is apprently loctited (and has to be VERY carefully drilled out for thrust-ball replacement/bearing overhaul). IOW, the M5 thread in the spindle used for the clamp continues the entire depth of the the spindle, and I guess this all means that theoretically it's already air-tight, without the extension/adapter I suggested.

Edited by Mark_S

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Some words from Max.

Repair_Rock_Bearing.pdf

Edited by 2N3055

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I've got a very nice Rock II with SME V supplied by Mik. I was running it for a while without before building an out rigger and procuring some silicon. In that state it sounded pretty good. Eventually I got around to making an out rigger and paddle and got some silicon. The difference was an extended bass, more powerful presentation and more detail. For what a Rock II costs second hand, they are amazing value. 

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On ‎14‎/‎03‎/‎2017 at 04:49, 2N3055 said:

Some words from Max.

Repair_Rock_Bearing.pdf

Excellent. I have a much more blurred copy of this same document.

Max needs to realise that he must make ALL data and info necessary for the maintenance of his superb machines freely available.

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