401 platter 'dinged'- can it be skimmed?!

301, 401, plinths and assorted idler stuff
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Mike H
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Post by Mike H » Thu Sep 02, 2010 6:53 pm

Yes here we're probably talking fractions of a mm



 
 
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pre65
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Post by pre65 » Thu Sep 02, 2010 6:56 pm

Mike H wrote:Yes here we're probably talking fractions of a mm



 
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Dave the bass
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Post by Dave the bass » Thu Sep 02, 2010 7:20 pm

thomas wrote:Well I'm over to Sidcup machine shop tomorrow so we'll see how it goes....!
Sidcup :shock: Don't let it out of yer sight....!

You could pick up a bag-load of those rubbish ol' Lowther screecher-speakers while you're over that neck of the woods :)

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thomas
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Post by thomas » Thu Sep 02, 2010 7:53 pm

Nah been there done that. :D The phrase 'pet free and smoke free home' didn't apply.... :lol:

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Ali Tait
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Post by Ali Tait » Thu Sep 02, 2010 7:57 pm

Nick wrote:I am sure you are right Phil, I am happy to defer to your experience on this matter. I was just thinking out loud that the requirements of a disk drum skim would be similar to the platter in that it would need to be centred.

In the past I am sure there wound be loads of local machine shops who could do it, or someone who was a machinist who could have done it in his lunch break for a pint.

Its much the same problem as me and Ali are having finding someone to make a chassis for the static amps.
Speaking of which Nick,I'm informed that I should be able to speak to Nigel tomorrow,so hopefully they'll be able to do it.Any word from Nick L?

Does anyone know anywhere where we could have the chassis made? I'd like to get a few quotes if possible.I'm looking for them to be made of copper,or copper plated ali if it would be cheaper.

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Post by Greg » Thu Sep 02, 2010 8:46 pm

Hi Ali,

Your main problem will be that you are looking for a 'one off' job. Even a pair will be expensive if you are building mono's. Most quality chassis makers now use CAD so what you want will need to be transposed. It's the set up that takes the time and where the cost is involved.

Those of us a while back who built clone WAD 300B PP used the following company. They are flexible and will meet your specific need including working with Copper. At the time which was several years ago, a one off steel chassis was more than £200. An order for five brought the item cost down to £70. Give Martin Reeves a call and see what he can offer. The phone may get answered by his wife and secretary, Sandra. I collected our order from the plant and can confirm that his business is a pukka pressing, folding and welding company. I think WAD used them for a while and so did Neal Gibbons on his 2A3 PP venture.

MJR Fabrications
Unit B, Cranborne Ind. Est.
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Nick
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Post by Nick » Thu Sep 02, 2010 8:54 pm

Cool thanks Greg. Yep, what we need is a pair of chassis, similar ti the WD ones, but as Ali said maybe different material. I can supply the layout in DXF form so hopefully that would help a little.
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Ali Tait
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Post by Ali Tait » Thu Sep 02, 2010 8:54 pm

That's great Greg,thanks for that.

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Post by Greg » Thu Sep 02, 2010 9:11 pm

Hi Thomas,

Sorry for the hi-jack. Just answering Ali's question.

What Phil says is what I would say. Your problem is that the sort of hobby people who would happily make adaptations to lathe mountings to do your job will generally not possess a lathe that has the throw to accommodate a 12" platter. Clearly centralised mounting is critical and I'm doubtful a brake hub skimmer could do that with any accuracy, particularly with the centre hole being tapered with the narrowest end close to the lathe mounting point.

As you say, if it can't be done, the platter is scrap, however, if the brake skimmer can't help (or you don't trust him......be tentative here), I'd be inclined to come away and try a bit of work at home to sort it yourself. Do some geometory to work out how much metal needs to be removed and then consider a 'hand job' (behave Philip :wink: ) with abrassive wheels/papers etc.

As for the balancing aspect, I wouldn't worry too much. Certainly the platters are statically balanced but I am well aware of owners (Will et al)who have stuck all sorts of guff to the underside of the platter for damping purposes and this doesn't appear to have any affect on speed consistancy.

Regards,

Greg

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Ali Tait
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Post by Ali Tait » Thu Sep 02, 2010 9:30 pm

Nick wrote:Cool thanks Greg. Yep, what we need is a pair of chassis, similar ti the WD ones, but as Ali said maybe different material. I can supply the layout in DXF form so hopefully that would help a little.
Could you mail me that Nick,in case I need to send it?

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Ali Tait
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Post by Ali Tait » Thu Sep 02, 2010 9:30 pm

P.S. sorry for nicking your thread Thomas. :oops:

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pre65
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Post by pre65 » Thu Sep 02, 2010 9:39 pm

Having a quick search on the net it seems aluminium can be anodized to give a durable copper finish.

How much that would cost is another matter, but I would guess it was cheaper than using "proper" copper for the chassis.
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Ali Tait
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Post by Ali Tait » Thu Sep 02, 2010 9:43 pm

Yes,that was Nick's thought.We'll see what they come up with.

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thomas
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Post by thomas » Thu Sep 02, 2010 9:58 pm

What Phil says is what I would say. Your problem is that the sort of hobby people who would happily make adaptations to lathe mountings to do your job will generally not possess a lathe that has the throw to accommodate a 12" platter. Clearly centralised mounting is critical and I'm doubtful a brake hub skimmer could do that with any accuracy, particularly with the centre hole being tapered with the narrowest end close to the lathe mounting point.

As you say, if it can't be done, the platter is scrap, however, if the brake skimmer can't help (or you don't trust him......be tentative here), I'd be inclined to come away and try a bit of work at home to sort it yourself. Do some geometory to work out how much metal needs to be removed and then consider a 'hand job' (behave Philip Wink ) with abrassive wheels/papers etc.

As for the balancing aspect, I wouldn't worry too much. Certainly the platters are statically balanced but I am well aware of owners (Will et al)who have stuck all sorts of guff to the underside of the platter for damping purposes and this doesn't appear to have any affect on speed consistancy.

Good points I think I understand....
I'll see what Mr Brake skimmer says before I let him loose. Unfortunately I don't think there's any way I could have a go myself...!
Cheers
Thomas

P.S. sorry for nicking your thread Thomas. Embarassed

Thats OK :)

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pre65
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Re: 401 platter 'dinged'- can it be skimmed?!

Post by pre65 » Thu Sep 02, 2010 10:17 pm

thomas wrote: ps hoping to get to Egg- currently doing my first ever 'breadboard' (D3a, Tx, 2A3)!
Why not put some details in the "Projects" section, I'm sure there will be more than just me interested in the what and how ! :wink:
Life is what happens to you while you're busy making other plans. John Lennon

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