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Old 26th October 2012, 03:16 PM   #111
johnm is offline johnm  United Kingdom
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User510 - I'm doing a full strip-down of my SP-10, spurred on by your own work with the Technics (so thanks for rekindling my enthusiasm ).

I have the deck in pieces now, also have removed the end cap exposing the ball bearing in the bearing shaft. As you said, fairly easy to unscrew after a few seconds with a heat gun on full.

Is the ball bearing captive, or can it be removed? I'd like to clean it and expose a 'fresh face' to the bottom of the turntable spindle. I don't want to force anything though so thought I'd best ask first. It seems pretty solidly held in place.

Cheers,

- John
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Old 27th October 2012, 02:05 PM   #112
sklimek is offline sklimek  United States
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Originally Posted by sklimek View Post
I have a SP-10 Mk2 mounting template from soundfountain that was never used and is free for anyone that could use it. Just pm me and we'll figure out how to get it to you. I am in Pittsburgh.
The template just found its new home - good luck w/ the build...
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Old 27th October 2012, 05:09 PM   #113
abone is offline abone  Canada
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Originally Posted by sklimek View Post
The template just found its new home - good luck w/ the build...
Thanks Stan!
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Old 27th October 2012, 05:33 PM   #114
abone is offline abone  Canada
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I'm beginning a similar project in baltic birch and wondering if adding in MDF, either as alternating layers or top and bottom layers, has acoustic benefits? Anyone have any experience with this?
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Old 27th October 2012, 10:44 PM   #115
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Quote:
Originally Posted by johnm View Post
User510 - I'm doing a full strip-down of my SP-10, spurred on by your own work with the Technics (so thanks for rekindling my enthusiasm ).

I have the deck in pieces now, also have removed the end cap exposing the ball bearing in the bearing shaft. As you said, fairly easy to unscrew after a few seconds with a heat gun on full.

Is the ball bearing captive, or can it be removed? I'd like to clean it and expose a 'fresh face' to the bottom of the turntable spindle. I don't want to force anything though so thought I'd best ask first. It seems pretty solidly held in place.

Cheers,

- John
Click the image to open in full size.

What I have discovered is that bearing ball size.....

Click the image to open in full size.


Click the image to open in full size.
Click the image to open in full size.

.........and bore size at the thrust end are the same. This indicates the intent. The ball fits with a light press inside the walls of the bore and in this way has no choice but to find exact center of the bore for the thrust pad on the spindle to stand on.

In practice I found that a small piece of wood doweling can be used to lightly tap the bearing ball out the end of the spindle bushing.

Not much force required. Just be ready to catch the ball.

Fwiw I also checked the rest of the bushing interior for size. It is a straight through bushing with no relief or stepped areas. All the same size.
7.143 mm in dia
The spindle shaft measures:
Click the image to open in full size.

7.123. That leaves .020 mm of running clearance between shaft and bushing. Or .010mm per side. Let's convert that to inches for those of us who think that way:
.020mm = .0008 inches (clearance shaft to bushing wall)
7.143mm = .2812 inches
7.123mm = .2804 inches

Prior to taking these measurements I had taken the following photo:
Click the image to open in full size.

Back lit like it is, one can make out the cross-hatch marks produced by the hone operation during manufacture of this part. Just below that it can be seen that the cross-hatch marks have been worn away by the spindle shaft. I had feared that this might be evidence of severe wear. But measurements in these two regions indicate no measurable differences in size. I'd probably need an air gage to get a size difference between the two areas. I am somewhat relieved. Now to decide if I need to replace the bushing with a new piece or not. I'm leaning toward "not". But I will look at these parts closer on a different day and consider again.

-Steve
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Old 27th October 2012, 11:08 PM   #116
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Quote:
Originally Posted by abone View Post
I'm beginning a similar project in baltic birch and wondering if adding in MDF, either as alternating layers or top and bottom layers, has acoustic benefits? Anyone have any experience with this?
I suspect that the amount of spindle bushing and spindle thrust wear on these 30 year old players will tend to confuse the issue when considering " how much plinth" is needed to achieve the quietest possible background noise levels. (rumble)

But I suppose you could take a plan out of the Lenco modifiers playbook and go high mass baltic birch with a couple of mdf layers. And also a piece of 3/16 inch thick aluminum plate just to enhance rigidity.

Check earlier posts to this thread for some interesting comments.

For myself I intend to experiment with the isophthalic resin/kitty litter as a casting project. I really like the idea of "casting" a plinth as opposed to building one up out of several pieces of wood.

-Steve
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Old 28th October 2012, 12:55 AM   #117
Rush is offline Rush  United States
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Originally Posted by abone View Post
I'm beginning a similar project in baltic birch and wondering if adding in MDF, either as alternating layers or top and bottom layers, has acoustic benefits? Anyone have any experience with this?
Abone,

Go to Audio Qualia's site and look at the damping factors for different layers of different materials. You need to know the damping before you build the plinth.
Home - Audio qualia
There is so much more to this than you would think.
I read every page before I decided what to use.
I'll bet Porterhouse spent a lot of money and time working up to his end plinth design.

Rush
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Old 28th October 2012, 04:39 AM   #118
jlsem is offline jlsem  United States
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I'll bet Porterhouse spent a lot of money and time working up to his end plinth design.
And now I'm doing a substantial re-design with a few improvements because of unscrupulous copycats.

John
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Old 28th October 2012, 04:46 AM   #119
abone is offline abone  Canada
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Quote:
Originally Posted by Rush View Post
Abone,

Go to Audio Qualia's site and look at the damping factors for different layers of different materials. You need to know the damping before you build the plinth.
Home - Audio qualia
There is so much more to this than you would think.
I read every page before I decided what to use.
I'll bet Porterhouse spent a lot of money and time working up to his end plinth design.

Rush
Thanks Rush,

I'll have to read through this a few times before I fully grasp all that it entails. From my first read however it appears getting my hands on a sheet of panzerholz would be a good bet. Not easy to obtain however though there is a supplier in eastern Canada.
As this will be my first attempt I am thinking building the perfect plinth initially may not be necessary. Woodsong Audio in Idaho builds a wonderful product in Panzerholz at what seems a very reasonable price considering the workmanship. After experimenting with my own, I may end up going that way, if only for the aesthetics.

What did you end up doing?

Andy
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Old 28th October 2012, 10:21 AM   #120
johnm is offline johnm  United Kingdom
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Quote:
Originally Posted by user510 View Post

What I have discovered is that bearing ball size and bore size at the thrust end are the same. This indicates the intent. The ball fits with a light press inside the walls of the bore and in this way has no choice but to find exact center of the bore for the thrust pad on the spindle to stand on.

In practice I found that a small piece of wood doweling can be used to lightly tap the bearing ball out the end of the spindle bushing.

Not much force required. Just be ready to catch the ball.

Fwiw I also checked the rest of the bushing interior for size. It is a straight through bushing with no relief or stepped areas. All the same size.
7.143 mm in dia
The spindle shaft measures:

7.123. That leaves .020 mm of running clearance between shaft and bushing. Or .010mm per side. Let's convert that to inches for those of us who think that way:
.020mm = .0008 inches (clearance shaft to bushing wall)
7.143mm = .2812 inches
7.123mm = .2804 inches

Back lit like it is, one can make out the cross-hatch marks produced by the hone operation during manufacture of this part. Just below that it can be seen that the cross-hatch marks have been worn away by the spindle shaft. I had feared that this might be evidence of severe wear. But measurements in these two regions indicate no measurable differences in size. I'd probably need an air gage to get a size difference between the two areas. I am somewhat relieved. Now to decide if I need to replace the bushing with a new piece or not. I'm leaning toward "not". But I will look at these parts closer on a different day and consider again.

-Steve
Thanks so much for that information Steve - really helpful. Great pictures too! Wondering whether I should leave the bearing where it is, or push it out now. Pushing it out might lightly score the sides of the ball bearing?

Did you find a flat spot or evidence of wear on the ball bearing from where the spindle had rested upon it all these years? I imagine the 'plastic' (Teflon?) button at the bottom of the spindle is designed to be softer than the ball bearing though. If there was no flat spot or mark on yours, I guess there'd be no point in removing mine.

John.
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