Polishing a pitted flywheel

I'm restoring an old tape recorder. The capstan flywheel is very lightly pitted. I'd like to polish this out.
What would be a suitable polish? Or if it's likely to be too hard for a polish, could it perhaps be sanded first?
It will need to be the very finest abrasive paper, because it needs to have an extremely smooth surface.
Daniele
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D.M. Procida wrote:

It doesnt have to be THAT smooth.
However the trouble is, that anything you take off it will slow the tape down.
Th 'pro' approah wuld be to get the spindle off and make a new one, or turn it down and fit a machined sleeve to it.
But for non critical applications, go to Halfords and get some wet and dry of the finest grade - about 600 grit, cut strips and simply wind round the capstan while running.
You can use jewellers rouge or valve grinding compound or even T-cut for a final polish.
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Wet and Dry goes to 1200......and on to "Flour Paper". *Then* it might be worth using rouge etc
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Speed it up, not slow it down.
However, I'd bet that it would make an unmeasurable difference. The pitting's very, very light.

It's not the capstan, it's the flywheel, that needs attention.
Daniele
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D.M. Procida wrote:

It would help if you properly described what bit you are actually talking about. Do you mean the peripheral surface of the part the tape wraps round, against which it is held by a pinch wheel and thus pulled past the recording heads?
If so then I'd leave it alone unless the pits have sharp edges which might damage the tape. The capstan surface should be almost mirror smooth. Some of the advice you've been given such as 180 grit it bleedin' absurd. 180 grit is rough as a dog's arse. 1000 grit is what you'd call a fine grit but even that, or in fact any grade of abrasive paper will destroy the original finish. You get surfaces that smooth by fine polishing with things like high speed felt mops containing very mild abrasives in a slurry form.
If you remove material and decrease the capstan's diameter then the tape speed will slow down NOT speed up. This is hardly rocket surgery. Smaller diameter = lower peripheral speed for a given diameter not the reverse. It's the capstan that drives the tape not vice versa!
If you remove the pits then the tape will no longer run at the right speed which is fairly pointless. You'll also never remove them without machining even if they're only a few thou deep. You can't polish off large amounts of metal like that by hand and have any hope of keeping the capstan truly circular. I've spent half a lifetime polishing crankshaft journals in race engines so I know what it takes to remove a given amount of metal and what surface finish you end up with. Half a thou is a shed load to remove by any sort of polishing even when you're rotating the part on a lathe. You're normally only talking about the odd tenth of a thou or even fractions of a tenth for the final polishing operation.
The most I'd do just to make sure the pits didn't have sharp edges is go over the surface very lightly with a fine metal polish, or even toothpaste, and a cloth. Try on an old capstan first to make sure that even this doesn't just lead to scratches.
--
Dave Baker



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He did. He said it's the flywheel. You then spend the rest of your post ranting about the capstan. Perhaps you could spend slightly less time being angry and slightly more time reading?
If he reduces the diameter of the flywheel and the flywheel is driven by a belt then reducing the diameter of the flywheel will speed the tape up.
Piddling about with the flywheel and flatting it in an attempt to remove pits (which is just about inevitable if one does it by hand) will introduce "wow". It depends if the aim is to have a working tape recorder or a pretty one that doesn't function properly.
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Steve Firth wrote:

If something is driven by a belt then it's a pulley not a flywheel! It might well be a pulley that's attached to a flywheel but it clearly isn't the same thing. So you clearly don't know for sure which bit he/she is talking about either. Until he/she makes clear which bit is being discussed, what it's made of, whether it's functional or decorative, whether it contacts the tape or a belt or not we're all pissing in the wind here.
--
Dave Baker



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It's the flywheel. You obviously know fuck-all about tape recorders.

No, it's a belt drive to the edge of the flywheel.

I know exactly what he's talking about. But then unlike you I know what the inside of a tape recorder looks like.

No, you're flaming away with unrighteous anger because you don't know what you're talking about.
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%steve%@malloc.co.uk (Steve Firth) wrote:

Excellent. Profanity *and* personal abuse.
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When were you elected the language policeman for the newsgroup, fucknuts?
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(Steve Firth) wrote:

I think this is one of your saddest moments. In the past I've always respected you posts but in this case you've hit rock bottom. I have no intention to go into the semantics of flywheels, belts and pulley. You're both grasping on so little information it's unbelievable. We still don't have a clue whether it's significant the flywheel has pits or if it's made smaller will alter the speed of the tape. You're both pissing in the wind upstream. I prefer downstream myself, then it less likely to come back and haunt me.
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There are so many variations in the way the various drives work I doubt anyone knows them all.
--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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All no. But in context it's easy to work out which type Danielle was talking about. And it's easy to tell that LoudMouth didn't have a clue.
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Steve Firth wrote:

You are a rude and churlish person who I have no interest in squabbling with A) because it's Xmas and B) because I gave up doing that many years ago on Usenet after realising it was pointless and there's always someone new who wants to troll or bicker. If you don't mind I'll just pop you in the killfile instead and talk to the grownups, some of whom are no doubt familiar with the extent of my engineering background.
--
Dave Baker



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You proved that you didn't know what you were rattling on about. Like most LoudMouths, you assumed instead of thinking. And if your skills with a kill-file match your other talents you'll be reading this.
Heck, you're too dumb to realise that Outhouse Excess doesn't have a kill file.
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Perhaps you should check out Dave's site - his engineering expertise isn't in question. And well engineered tape recorders don't use rubber band drives anyway. That's reserved for the bottom of the market.
--
*Depression is merely anger without enthusiasm *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Steve Firth wrote:

It's Daniele not Danielle. Maybe you should spend more time reading and less time shouting angrily at other people :) The missing L is significant.
--
Dave Baker



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oooh reduced to sniping at typos, you must be desperate.
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On 27 Dec, 17:23, % snipped-for-privacy@malloc.co.uk (Steve Firth) wrote:

Hey Rick, that "he" is a "she" anyway, if you want to start nit- picking,
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How stupid do you feel?
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