Author Topic: Are my flywheels typical?  (Read 11916 times)

mike90045

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Re: Are my flywheels typical?
« Reply #15 on: January 30, 2017, 03:56:45 PM »
Wow  :o  Those are really loaded up with that white bondo putty the indians are so fond of  ;)

38ac

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Re: Are my flywheels typical?
« Reply #16 on: January 30, 2017, 04:47:40 PM »
Looking good!   Make sure those weights are securely attached before the engine is operated. The exit velocity of flying weights would be rim circumference X RPM !! or LOTS.

Cujet is of course correct in that a person with the right equipment and experience can balance the engine no matter what problems exist in the flywheels but few of us have either of those at our disposal. It is also correct that a  person with neither experience nor equipment can skip all the prep work and come to a reasonable balance by marking flywheels with chalk and adding weights at various locations until he has the right amount in the right place but it doesn't come easy that way.

  I have done it both ways and what I found was that simply marking running flywheels with chalk has issues that dont meet the untrained eye. One of which is the movement due to problems with one wheel does not stay on that side of the engine,  indeed it transfers to to the other side as as movement in more or less the opposite direction and there is no way for a person without instruments to know exactly where the problem lies so he is left to guess.  Power pulses also play havoc with the chalk mark method. For me it is easier to remove the wheels, correct them and have only two places to add or remove weight. This removes 95% of the variables we are handed with poorly manufactured 'wheels and 95% of the guess work as to wear to attach or remove weight.
« Last Edit: January 31, 2017, 12:57:20 PM by 38ac »
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Barenburg

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Re: Are my flywheels typical?
« Reply #17 on: January 30, 2017, 08:32:15 PM »
Wow  :o  Those are really loaded up with that white bondo putty the indians are so fond of  ;)

Not really Mike.  I stripped them down to the bare metal, ground all the flash and lumps away..... What you are seeing is "almond" one part epoxy paint with just a bit of 3M Bondo here and there.

cujet

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Re: Are my flywheels typical?
« Reply #18 on: January 31, 2017, 01:01:25 PM »
I neglected to add that balancing equipment is not needed. Believe it or not, just pressing your index finger tip, hard, against a surface will register vibration.

While I am experienced balancing all sorts of things, the "finger test" is valid and quite accurate.

For example of the 10 shaft bearings, how do I know which one is vibrating? I can put my hand on each and they feel the same. But, push my finger tip on the bearing, and vibrations are directly transmitted into the bones and nerves. Within seconds, it's obvious which one is bad.

As crazy as it sounds, I can balance a lister this way.

Too much vertical vibes = not enough counterweight.
Too much horizontal vibes = too much counterweight.

Another thing. The weight is always opposed to the crank pin. Plus or minus a few degrees adjustment for other imbalances.
People who count on their fingers should maintain a discreet silence

38ac

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Re: Are my flywheels typical?
« Reply #19 on: January 31, 2017, 02:42:35 PM »
Gort I am intrigued by the phone app deal, please keep us posted.

Cujet, A story I think you can appreciate.
One of my neighbors, now sadly deceased was an engineer for Rolls Royce. He specialized in balancing problems on their big turbine powered gas compressors and was sent all over the world to work at his specialty.  He was also the biggest cheap skate I have ever known in my life. One day he hit a bumper jack with his push mower and bent the crankshaft on the B&S engine. Since I had a big vise on the back of my service truck he brought the mover over and asked if he could use my vise. We removed the engine and knocked the crankshaft around a bit and before it was perfectly straight he pronounced it good enough. I said it will vibrate like the dickens! And he just nodded his head. He got a piece of paper out and did some calculations and said he needed to borrow my grinder to trim one end of the blade. When he installed the blade he timed it to the way the crank was bent and said he said "That engine was designed to operate at 3600 RPM, now IF I have calculated correctly it is going to vibrate like heck at idle and will also vibrate like heck when wide open, but if I throttle it back about 200 RPM (he quoted an exact RPM)  it will be as smooth as it ever was."

I have to admit that I thought the old coot was F.OS. but he fired that mower up and it worked EXACTLY as he predicted. He could tell I was impressed and said Sonny, I am after all an engineer who specializes in vibration,,, and he went and cut his grass. 

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Barenburg

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Re: Are my flywheels typical?
« Reply #20 on: March 02, 2017, 01:22:00 PM »
With the flywheels weighted so that the counterweight rests squarely at the bottom, how to "match" them. 

Since I had nearly an 1/8th inch difference in diameter the string and bucket method would give errors based on force and distance.  How to get the force x distance thing as close as possible???  My solution is to mount them on the same shaft 180` out, so that the counterweights are opposite each other.
  I machined the shaft with two key seats 180 degrees apart, and installed the flywheels using the gib keys.
A little bit more stick-on lead, and now these guys will stay at any position I choose.

The rest of the engine is coming a long. It wont be long before we see first smoke :-)  If anyone is interested in buying / borrowing the balance (matching) shaft let me know.

vdubnut62

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Re: Are my flywheels typical?
« Reply #21 on: March 04, 2017, 05:29:03 AM »
I'm afraid that you have just matched the flywheels. You still do not know if you have underbalanced or overbalanced flywheels. And you don't know if the keyways are where they are supposed to be, and that placement dictates where the counterbalances are in relationship to the crankpin. I don't mean to criticize, I'm just puzzled.
  And if I have missed a major part of this whole thing just overlook me please.
Ron
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Barenburg

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Re: Are my flywheels typical?
« Reply #22 on: March 04, 2017, 01:48:45 PM »
Ron, You are correct I don't know if I'm over or under balanced. That's easy to fix with stick on lead later. My key seat locations have been verified as correct within my ability to measure.

Since both wheels were wrong on the same side as installed, it had the same effect as the key being placed incorrectly.  It only took a couple ounces  to match them once they were adjusted for the correct bottom.
I'll know soon enough.

Barenburg

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Re: Are my flywheels typical?
« Reply #23 on: March 04, 2017, 01:50:29 PM »
Most of these, from what I read are under balanced.

Time will tell.

BruceM

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Re: Are my flywheels typical?
« Reply #24 on: March 04, 2017, 03:11:38 PM »
Overbalance by over a pound  in the aluminum piston 8/1's is also common... no telling what wheels go on which engine, apparently.  Conrod weight variation of over 1.2 lb is also something I've seen.  38ac's marvelous method solves all variations with the least fussing and time because it's only down to more (hopper) or less (fore and aft rocking) counterweight.  All engines can be smooth runners.

I had not heard of flywheel diameter variation before.  If I had it, I'd just shim half the diameter difference under the string at 3/9 o'clock when matching counterbalance weights. And maybe try a bit of extra weight on the small one.  Close counts.



Quinnf

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Re: Are my flywheels typical?
« Reply #25 on: March 04, 2017, 09:55:01 PM »
A lot of us got our engines about 10-12 years ago, and there was a flurry of posts about how best to balance these beasts on this forum around 2005-2006.  Lots of great discussions. 

After completely stripping two engines down to nuts and bolts, removing paint to bare metal and grinding, filling and painting, it was clear to me that it would be very unlikely if both the 140 lb. 6-spoke flywheels weighed the same.  I wanted to know how much difference there was between the counterweights in the two wheels.  I figured it was best to start out with two flywheels with equal counterweights.  That gets rid of the tendency of the engine to torque around the axis of the cylinder with each power and compression pulse.  Then begin balancing in earnest. 

I decided I'd build a bubble balancer.  I turned a 3" round of aluminum into the shape of a tall top hat with a deep recess drilled into it.  The hat fit inside the bore of the flywheel, and the assembly balanced on the point of a 1/4" steel rod I welded to a plate of steel.    I set a bullseye-type bubble leveler on top of the end of the top hat, and slowly added weight to the high side of the flywheel rim until the bubble was centered in the bullseye.  Then I weighed the lead.

The amount of lead needed to balance the flywheels was 35 oz. on one, and 48 oz. on the other.  So there was more than a pound of difference in the counterweights of the two flywheels.

There's been a LOT of discussion over the years about what the weight of the counterweight SHOULD BE on a 6/1.  But I don't think anyone ever reported the weight. 

Quinn
Ashwamegh 6/1, PowerSolutions 6/1 "Kit" engine, and a Changfa R175a that looks like a Yanmar I once knew

BruceM

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Re: Are my flywheels typical?
« Reply #26 on: March 05, 2017, 02:32:21 AM »
I think Quinn was the one of the first to do a good analytical approach to balancing. Some folks had engines so badly under-balanced than attempts to bolt them down led to broken bolts, and  they literally shook the ground for quite some distance.

 I miss reading about Quinn's projects- lots of good engineering to learn from and be inspired by. 

Quinnf

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Re: Are my flywheels typical?
« Reply #27 on: March 05, 2017, 04:59:27 AM »
Aw, shucks, Bruce.  Thank you.  I've been a pharmaceutical R&D chemist for 35 years, and always have felt I never embraced my true love.  I sure do love nuts and bolts! 
Ashwamegh 6/1, PowerSolutions 6/1 "Kit" engine, and a Changfa R175a that looks like a Yanmar I once knew

38ac

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Re: Are my flywheels typical?
« Reply #28 on: March 06, 2017, 01:11:50 PM »
Yessir, I read all of the achieved material on the balancing subject that I could find. Some interesting reading that's for sure and I am grateful to those who posted their work.

  As a matter of fact the entire deal that those early engine importers went through is interesting reading. High expectations that were rarely met, dealing with the problems, inventing work arounds in the engine shed.  All of it is interesting reading for me. I have probably read virtually every archived post on this site and learned much more than I have ever offered back.  Every build that goes through the shop offers a new challenge it seems, keeps life interesting.

Had a pretty good winter for sales, even sold my personal 6/1 work engine and  my oldest son has  "borrowed" ??? my KOEL 8/1 set permanently leaving me without a 'roid work engine.  Time to get another kit out of storage and build a D.E.S. 8/1 for myself.  I have also have  Z2 Bamford apart but it will have to wait until I  fix my work personal work engine problem ;)

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Barenburg

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Re: Are my flywheels typical?
« Reply #29 on: March 07, 2017, 02:29:18 PM »
A lot of us got our engines about 10-12 years ago, and there was a flurry of posts about how best to balance these beasts on this forum around 2005-2006.  Lots of great discussions. 

After completely stripping two engines down to nuts and bolts, removing paint to bare metal and grinding, filling and painting, it was clear to me that it would be very unlikely if both the 140 lb. 6-spoke flywheels weighed the same.  I wanted to know how much difference there was between the counterweights in the two wheels.  I figured it was best to start out with two flywheels with equal counterweights.  That gets rid of the tendency of the engine to torque around the axis of the cylinder with each power and compression pulse.  Then begin balancing in earnest. 

I decided I'd build a bubble balancer.  I turned a 3" round of aluminum into the shape of a tall top hat with a deep recess drilled into it.  The hat fit inside the bore of the flywheel, and the assembly balanced on the point of a 1/4" steel rod I welded to a plate of steel.    I set a bullseye-type bubble leveler on top of the end of the top hat, and slowly added weight to the high side of the flywheel rim until the bubble was centered in the bullseye.  Then I weighed the lead.

The amount of lead needed to balance the flywheels was 35 oz. on one, and 48 oz. on the other.  So there was more than a pound of difference in the counterweights of the two flywheels.

There's been a LOT of discussion over the years about what the weight of the counterweight SHOULD BE on a 6/1.  But I don't think anyone ever reported the weight. 

Quinn


BTW, I read with keen interest your posts on Utterpower.  Did you ever finish part three of the 6/1 build?

I'm learning a lot as I go here helped immensely by all that have done these things before me.  I must admit that without all of the info I might have given this Indian a resting place of the coast of St Augustine as a mooring. To one degree or another I found all the problems mentioned, a beach full of sand, poorly machined valve train, and a 14:1 compression ratio. Now with all that fixed, I'm close to smoke on my Anil 6/1.  Since I have the Indirect with a cast iron piston I expect to be under balanced, but with about a pound of lead already added, maybe it will be close.  Finger test and the phone ap will be used for fun of course......