Flywheel balancing service

Mark,

I doubt you'll find an advert from this service in SEM anyway. What do you mean by balancing, do you mean skimming the circumference of the wheel to get rid of pitting? If that's the case, then ringing 'round some of your local precision engineering firms is probably the answer. A large lathe is required for the job.

What's the engine and/or the flywheel diameter?

Regards, Arthur G

40 miles away from and being very

Arthur,

No, the type of balancing I mean is that that we do with car wheels. I am buying some Lister CS Flywheels from India, and I expect that the crude castings will result in some un-even weight, so I would like to get it balanced using some sufficiently sophisticated technology and some metal addition/removal.

Mark

Arthur G wrote:

mean by balancing, do you mean skimming the

ringing 'round some of your local precision

40 miles away from and being very

You'll need to hunt through car mags or Google. However if they are SoM flywheels I wouldn't bother. If they are spoked then the flywheels have weights in the rim designed to achieve a rough dynamic balance. To improve on that you're going to have to go for a full dynamic balance. It wasn't cheap 30 years ago when I used to play with Minis and they only had one tiny flywheel! I can only offhand think of one firm that might handle such a large flywheel. Try

Roland

Roland,

That's one to remember.

Thank you.

Mark

Roland Craven wrote:

Roland,

If he is going to dynamic balance the flywheels then wont he need the crank as well ?

Mart> Roland,

To make any sense out of a CS crankshaft and flywheel you'd need some serious thinking about ratios of rotating and reciprocating weights.

CS generator flywheels are seriously heavy, out of all proportion to the weight of the crank and conrod/piston, basically to smooth the running of the alternator.

I hate to think how much out of balance they would actually be, but I don't think you would be able to carry out a meaningful balancing process on them.

We looked at this process for the Ruston, and will statically balance that lot with the flywheels carried on a dummy shaft on knife edges.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

For a simpified spoked "flywheel" (infinitely dense rim on a weightless disk) then dynamic balance is the same as static balance. Now this is obviously an approximation, but a simple static balance would be close enough for our purposes. If you're planning to redline your Lister D at a few thousand rpm so that true dynamic balance does become important, then you'll need to do it while attached to the crankshaft anyway.

I appreciate that it'll make some difference to the vibration factor if the flywheels/crank/rod/piston is out of balance, but the engines are - to a man - designed to be bolted down to something solid. Surely, vibration only really becomes an issue if the beasts are trollied?

That said, a dynamic balance will require flywheels, crank, rod & piston. It is something which is regularly discussed on the Vincent NG & various balance factors are recommended by different people. These are - mostly -

50o vee twins with inherently poor balance & they can be made to run extremely smoothly, but it does take specialised time & effort. It is, as Roland said, not cheap.

Me, I'd experiment with sticky lead weights as used on aluminium car wheels - the rotational speed will be about the same. Your time & effort, no stripping & rebuilding - win-win all round!

I think I'm going to have a go at doing this manually (statically). If I accurately draw diameter lines on one side of the flywheel at 10 degree intervals, I could then lay the wheel down on matchsticks (or something similar), one diameter line at a time, and mark on the wheel which way it tips, I should be able to identify where the heavy bits are. I could then select the diameter line that is perpendicular to the heavy point. Put the wheel on matchsticks (or something similar) on this line, then drill metal off the heavy end until it balances.

I'm not too confident about the accuracy though.

Mark

Kim Siddorn wrote:

(A purely theoretical question) Would a dynamic balance on a single even need the crank and piston, so long as you knew their masses ? You're not going to modify them, just adjust the crankshaft weights to match.

Kim,

If something is vibrating bolting it to some thing rigid only transfers the vibration/problem to something else. A case in point, where I served my apprenticeship we had five V twin Bellis and morcom compressors, four running one standby.They were mounted on a suspended floor and when all were running you could actually see a measurable ripple run down the concrete floor from one end of the building to the other. All had to have special concrete masses built and then stood on calculated rated springs to dampen the vibration otherwise they would have ended up downstairs in the basement.

Martin P

Bolting to something solid does not remove the excitation force that is present, whether it is due to imbalance, component resonance etc. All that happens is that the force, instead of creating movement, creates stress and something breaks.

As for balancing flywheels, if you are going to be running them at such a speed that balance is an issue I would also be concerned about the burst strength of the casting. As has been mentioned - running them up on a suitable mandrel on the machine at your local truck tyre emporium may give you an idea of how far out they actually are.

Regards

Dan

Martin Perman said - snip>>>

They were mounted on a suspended floor and when all were running you could actually see a measurable ripple run down the concrete floor from one end of the building to the other.

Yikes! I bet that drew some onlookers!

I agree, of course, that bolting an unbalanced rotating mass to something solid doesn't stop it vibrating, but it does offer a mass damper of considerable density. However, if one is so injudicious to mount that mass upstairs, one might reasonably expect movement ;o))

The big Tangye twin at IF, for instance, is probably not especially well balanced, but the massive castings, the reinforced concrete of its base and the low speed of rotation mean that it is apparently smooth in operation. However, if one were to (say) double its speed, Paul would be making for the hills - or his PLI policy!

Regards,

Kim Siddorn.

We still don't know if its an SoM or spoked. I doubt that any car wheel balancer will take the weight of the former!! ttfn Roland

Go to a truck place then... B-)

Speaking for myself, my wheel balance weight suggestion was one of those things which started out with my tongue in my cheek but has grown upon me.

I'd not thought of disassembly, more trial and error in a series of empirical trials. You'd soon notive which way things were going, I think.

Regards,

Kim Siddorn.

List,

The spoked CS flywheel already has a cast-in counterweight to try to offset the mass of the reciprocating piston and rods.

Even if one of these could be taken to a truck wheel balancing rig, it would just show that there was an extra few kg on one side.

Listers built CS engines for more than 50 years, and never chose to improve upon the static or dynamic balance, however they did give a sketch of the recommended concrete block on which to mount the engine.

In the case of the CS 5/1 ,Listers recommended a block 28" x 22" x 12", which with concrete of density 2400kg per m3, is a lump of almost equal mass (315kg) to the engine.

Ken