Grinder Balancing again

During last year there were a number of interesting posts regarding the subject. Among the suggestions was a comment that it could be
worth trying to CD-balancing scheme with a number of loose balls in within a rim. I was intrigued and a week or two ago somewhat bored one afternoon so I made one. The result is brilliant, for so simple a device, I'll always put one on a ginder in future it saves a lot of fast footwork catching the things that now no longer vibrate off the shelf and adjacent bench.
I used a 2" ish diameter 5/16" deep cup with barely 1/16" walls and a suitable lid with a boss so as not to crush the thing when used as a thick 'washer' against the side of the stone. The biggest I could manage to fit within teh grinder end cover. I bunged in an arbitray half dozen 3/16 steel balls loose to fly about as they will. It whizzes up to speed and stabilises within a second or so and more noticably, when switched off, if free wheels on and on and on and ..... whereas it used previously to get to 1/4 speed or so and just about leap off the bench ina rapid dieing shudder.
I presume anyone reading this will well enough be able to deduce a design suitable for their own grinder, but if you want I'll do a pdf of what I did and post it somewhere.
Cheers all, Richard
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Richard Shute heeft ons zojuist aangekondigd :

Would like to read that pdf..!
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Richard Shute was zeer hard aan het denken :

Thank you..!
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Richard Shute explained on 30/03/2010 :

Thanks,
The 'in towards the centre' lip on the RH part looks like the only difficult part to machine and I don't really see a need for it, providing the two parts are made to fit such that the balls cannot escape.
Does this work with a grinder fitted with a wheel at either end of the motor shaft? I would expect one to be needed for each wheel.
--
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Harry (M1BYT) (L)
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I'm trying replying via Google Groups as I'm sick of the 3hrs-ish a day only access to NG's from my ISP, so this may appear differently from my previous post
Harry, I agree with you. The lip started as a mild replication of a ball bearing track which seemed a good idea initially when I thought I might not be able to fit a lid, but after putting the lid on it becomes superfluous and the lid is definitely needed or the balls will probably fall out when it's stationary and it would also fill up with grit and crap which would be no good. It's not difficult, I just used a grooving tool, but I could have saved some axial length had I omitted it - or used larger balls, if I had them :-)
As I said at the start, it was an entirely empirical undertaking which evolved as each bit of swarf got removed, no plans, no measurements, no 'design', just lob it in the lathe and make some swarf till it fitted - not my usual approach, but sometimes it happens.
It is fitted to a grinder with a wheel at each end. I was very aware that one wheel (Chinese cheapy) was much more badly balanced than the other (Norton) so in the first instance I made only the one balancer and put it on the 'bad end' just to see. Certainly at some point I will make a second, but the better wheel is not badly worn and at present the overall balance is pretty good so it is well down the list....
Richard
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Richard wrote:

Try setting up an account with freenews.netfront.net.
No password required and it lets you post as well as read. I resorted to it when my normal usenet service was down for maintenance. It covers all my usual groups, fast access and no time constraints or posting limits.
--
Dave Baker



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writes

That's useful to know in case my ISP ever decides to cut the news feed, thanks Dave. (Mind you, that might just tip me into changing ISP instead!)
David
--
David Littlewood

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Richard Shute wrote:

Thanks for that - it seems most counter-intuitive, does anyone know how it works?
-- Peter Fairbrother
82 microns, and falling
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Gosh! that looks simple. I take it that the balls are not crowded and automatically take up a position that resolves any imbalance. Wow!! I look forward to hearing the theory if any body knows it; not that it really matters 'cos it apparently works.
Thanks for the info. Andy Cawley
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On Wed, 31 Mar 2010 02:12:08 -0700 (PDT), Anzaniste

Hello Andy, Yes you are correct, the crucially important feature is that the balls are NOT crowded, indeed I'd say something less than 30% is about right so they can move and bunch as best suits the instant.
I haven't bothered to do any theoretical analysis on this, but for a 1st yr student it should be an amusing diversion to see the most efficient filling and other dynamics of it all. Richard
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Hello Peter, It's actually blindingly obvious once you draw out a sketch of the situation. I have put one here: http://www.4shared.com/file/253476830/aaff5fce/BalanceHow.html
We want the whole system to rotate about the bearing centre as indicated by the centre cross mark. But, the 'system' will try to rotate about the CoG as marked.
This then means that the balls are flung to the far side of their circular track and in doing so move in a manner such as to counteract the imbalance about the bearing centre. The whole lot thrashes about for a bit until it stabilises, and the only stable situation is 'balanced', providing the mass of balls available is adequate.
Richard
PS Thanks Dave for the NG pointer, but I'm already using them. It is the ISP who somehow prevents access for much of the day, 'though perversely and uniquely, I did have access yesterday afternoon.
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Ah sorry. I'd only looked at the Google post and not noticed your others were already from Freenews.
It's unusual for an ISP to block Usenet. P2p yes, mine does that for a few hours every day but I can't see why Usenet would be a problem to anyone or even how they'd block it.
--
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Dave Baker wrote:

Not at all. ISP's block/throttle usenet to stop/limit binary downloads. Downloading pron/DVDs/TV programmes/CD ISOs from a binary newsgroup provider uses mega bandwidth.
ISP's that block/throttle typically don't discriminate between binary and text-only newsgroups or indeed binary and text-only servers.
AFAIK the ISPs maintain a list of newsgroup servers and throttle/block at IP level.
Sometimes, the ISP will provide an in-house text-only service and block third-party services.
HTH.
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Dave Osborne was thinking very hard :

They tend to block the port number rather than the IP. You can easily get around it by using a newsreader and news server which allows use of a none standard port number.
--
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Harry (M1BYT) (L)
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On Sat, 10 Apr 2010 12:54:11 +0100, Harry Bloomfield

That's interesting, are there any specific ports to use as normal-non-standard or is it completely free/random?
Richard
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Richard Shute laid this down on his screen :

You can only successfully connect to a news server on one of its valid port numbers. Some NS's only use the default port number, but others accept connections via alternate port numbers. To be able to use them, you also need a news reader which allows you to specify the port to be used and the type of connection.
For instance I use a free NS called news.eternal-september.org and a free news reader called Mesnews. With that combination I can connect via port 563 without interference from Tiscali (Talk Talk as it is now).
There is nothing to prevent you from setting up something similar to the above and running it for a while in parallel with your current news reader, to see how it goes.
--
Regards,
Harry (M1BYT) (L)
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Harry Bloomfield wrote:

Have you had any internet browsing issues since Tiscali was taking over?. A mate is with Tiscali, now talktalk, and the quality of his internet service seems to have gone down the pan since the take over. Not sure where the problem is at the moment but a usual example is you might be using google, ebay, etc and be going through some items then it just continually comes up with an internet connection problem page for some period, sometimes the pages display malformed without the intended formatting. If left for awhile it may come back when refreshed but it is highly annoying and only seems to have happened since the changeover.
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David Billington formulated on Sunday :

Not even the slightest of problems. We get around 7Mb on an 8Mb connection - it has always been fast and stable. We have had a rare hiccup with email in the past and lots of newsgroup issues, entirely resolved by changing ports.
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Harry (M1BYT) (L)
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I'm in the same boat, but in my case it's nowhere near as good as 'down the pan' it has some way to improve to get to atrocious.

Yes, I get that. On other occasions it can take several minutes to connect (to BrdBnd) and on others you are casually surfing away and get an 404 page not found and after a bit of checking find you have been disconnected.
I would really like to change, but the inertia of changing emails all over the place and having to re-arrange the phone line is quite large :-|
Richard
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