6/1 Balance Vs Design issues .

[guest22972]

I'm reading many comments where people are saying that the single Cylinder engines cannot run particularly steady and smooth due to their design and the forces at play in the engine.
From what is being said, it seems that the consensus of some is these engines have to be bolted down or run on anti vibration mounts in order to stop going for a leisurley stroll down the road.

This conflicts with what I am seeing in Vids of these engines running where they are on light trolleys or otherwise unsecured and appear to run very smoothly and stay put with no trouble.
Here are some examples:

http://www.youtube.com/watch?v=Ih4eY1WzHqo

http://www.youtube.com/watch?v=a7Kz7uFOm84

http://www.youtube.com/watch?v=5mjQJq0a4nI

http://www.youtube.com/watch?v=qVlAROfAfko

http://www.youtube.com/watch?v=NCPhcpRT1BI

http://www.youtube.com/watch?v=WqxvqwMDQPA


Now from what I can see in these clips, none of these 6/1 types appear to need to be bolted to 14 tons of concrete OR vibration mounts designed for high rises in earthquake zones.  They appear to run very steadily and don't walk around on their trolleys or jump up and down off the concrete they are resting on.

If these engines can run so smooth, why can't they all if they are balanced properly?
The forces in these engines would be the same as in any other of the design so this leads me to question the notion of smooth running without securing the things to Bedrock is not possible.

There are also many other brands of single cylinder vertical Diesels and all of them appear to run smooth as silk with no danger of destroying pavement or shaking buildings off their foundations.
Again this leads me to ask what is really stopping SOME listeroids ( mainly) from being balanced well enough to sit on light frames and trolleys as most of these engines in the Vids do without problem?

[Tom]

Every video there shows an engine with the heavy flywheels, except for the 3.5/1 with the standard 6 spoke wheels. When you double the weight of the flywheels it really does smooth out the power pulses. The 3.5 would have effectively double the flywheel mass to HP of the standard 6/1. You can tell this by how slowly it spins up.

[bschwartz]

".......Again this leads me to ask what is really stopping SOME listeroids ( mainly) from being balanced well enough to sit on light frames........."

Two words....      Quality Control.


If the parts of a listeroid were made to any kind of standard (shape, size, weight) it wouldn't be as big of an issue.
The reality is that the flywheels on many listeroids are cast so poorly that they are unbalanced.  Add to that keyways that are cut in the wrong spot.  Hmmm maybe throw in a connecting rod bored slightly out of line etc........

Yes, SOME listeroids can be balanced reasonably well, but others....... well lets just say that they can be real jumpers.

[BruceM]

All the cast parts will vary widely in materials, density, and finished (machined) weight.  I had two connecting rods with well over a pound of difference between them, I'm sure the cast iron pistons vary considerably also.  The flywheels probably vary most just because they're so large.

I also agree that the SOM (heavy) flywheel would help in both smoothness and voltage stability (Listerflicker) for those engines used as generators.

I think that if you are willing to take the time, you can optimize the balance for a given typical load and operating rpm.  

[38ac]

I really don't want to sound off like the know it all because I am not. What you guys have said here is all correct in my opinion. Heavy 'wheels that are correctly balanced are going to help out everything. That is not to say the spokes cant be made to run decent because they can.  Balance doesn't know Dursley from India, its all math, geometry and weights.  It is also true that your not going to get one of these engines to settle down at all RPMS. It is also true but not talked about on here that an engine can be pretty bad out of balance yet run half decent at some given RPM. However when the engine balance is actually right, the range it will run decent is pretty broad.  Once you think you are getting good at balance you will also get your pride handed back to you when you put the engine on some wheels. The things I have learned in balancing (about 10 now) Listeroids is they can be worked to a decent balance by what everyone here calls Dr X method. Its one heck of a lot quicker and easier to get the wheels to an equal condition first then use DrX method to get things as good as you can.

Here is my Metro w spoke wheels sitting on cast iron wheels on a concrete floor , about every evil you can have. As I remember this is 635 RPM. I can run this engine up to 700 or back down to around 500 and it sits just like it is now.  It can be done, but short cuts are actual long cuts in the process most of the time.
[youtube]p2YwtlfAVfc[/youtube]

[xyzer]

38,
100% smooth! Did you balance it and can you post a picture of where the weights were added? Does it have a cast iron piston?

[BruceM]

Glort- yes, external balancing of flywheels will compensate for variances in weights of components.
The Mr X method worked well for my 6/1 which was a shed shaker, but as 38ac says, you're best off starting with matched flywheels.

[ronmar]

Glort, like mentioned, it is a long way from Dursley to Rakjot:) If you have seen any vids of how these are cast and assembled, you would fully understand why each listeroid is unique...  Mine runs about like 38's, AFTER I balanced it. Before balance, it would slowly creep across the floor and spin in a circle.  After balance, with It set on 3/4" pipe rollers on the garage floor will only move around 15 thousandths of an inch back and forth, even with 3KW of load on the generator.  It has spoked flywheels, that were actually intended for a internally balanced engine(no cast in weight).  SInce I was planning on balancing anyway, it was no big deal. I think I added 17oz of lead on each wheel.

Another thing that muddies the waters a little is that each of these unique listeroids gets a custom designed and fabricated base(most put together by us non-engineers).  The overall movement is the sum of ALL the forces applied.  Theser engines have a massive power stroke, and a resulting massive torque input to the frame from their base.  Any spring or flex in the frame, can absorb, store and release this torque energy unpredictably.  This torque energy applied to an uneven floor/frame interface can easilly translate to a rocking motion, and next thing you know you got a walker that appears to be jumping all over the place...  On a reasonably balanced engine, a little bit of freedome can actually make them appear to run smoother as these forces don't get anything to push off of and are absorbed by the mass of engine, frame and generator head which is well over 1000# on a 6/1-ST5 combo.  
As an example, I bought a chinese single with a 10KW generator head. this sucker is easilly heavier than the 6/1 generator.  Bare frame setting on the concrete, and it walks across the floor and visibly vibrates.  Add a little block of 2" thick ethefoam under each corner(squishes nearly flat), to provide a little isolation and set it on 4 points, and it sets rock steady with no visible movement even under load...

Yes it can be done, but getting your brain around all your particular variables can be quite a learning experience...

[38ac]

The Metro is one of the odd-ball DI engines with an aluminum piston with a cavity in it. I can get some pictures but it may be just a bit as we are getting our 12/14 Petter ready for the spring event at Coolsprings Pa.  The Metro was my very first Listeroid and was balanced 100% by the Mr X Method, or is it Dr X?  anyway I probably have 4 12 hours days in getting it to the condition you see. As we have discussed previously the problem with the ??X method is once you get close you end up chasing your tail. What I mean by that is the  imbalance in one wheel shows up on the opposite side of the other one and if you get the weight on the right one is pure luck, no way to know for sure without some equipment besides chaulk. When you have it close but the weight on the wrong side of the wrong wheel things get spooky acting and the engine wants to spin around in circles.  Thinking this is a crock I went about a better way which was to check the wheels first and what you find will amaze you. I have written this all up previously so I wont bore you with it but the end result of having two matched wheels is you only have two places to put weight on each wheel. In line with the throw or directly opposite and in equal amounts for both wheels. You chances of being right go fro one in thousand to damn near a sucker bet. Another video here is the first engine I did with pre balance and matched wheels. I started and stopped this engine exactly 4 times to get it to this condition and dont think that is because it was close from India.  It is because the guessing game has been reduced by 98% I was pretty proud of this one, Look close and you see a bit of shake, but then look under it. Sitting on a tiny cart with rubber tired casters and about 3 minutes run time and still stiff. The power pulses smooth out considerably after just 10 15 minutes run time. This engine is a Dursey 6/1 copy. cast iron, bushing mains etc, one of Gary's DES badged units. I posted this before and one of the sharpies here said good gawd Butch, slow that thing down its running 800 RPM!!  I had set the RPMs by ear,, told ya I aint the brightest, LOL

[youtube]8r32P1I62Mc[/youtube]



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[xyzer]

Aluminum piston! That really makes a big difference in the math! A cast iron piston will add a considerable amount of mass to the reciprocating part of the equation. A castiron vs aluminum piston are two different animals.

[BruceM]

If I was starting over I'd do as Butch, Carl and others have suggested- pull and match the flywheels, making sure that the counterbalance weight is actually the heaviest point.  It makes sense to me that if the wheels are grossly mismatched, it will be very difficult to get a good balance by Mr X, dial gauge and by sight/feel (in that order), as I did.

I think I just got lucky that my flywheels weren't too far mismatched.  I did alternate between the two wheels, applying only half the indicated clay each time, but others I respect greatly with far better mechanical skills than I have had no luck with that approach.

So it seems best to treat the flywheels on any new Listeroid as suspect, pull them and match them up. Perhaps someone could provide a link or summary for a good method.  The tricky part would just be the hub balance support.

[38ac]

Bruce, here is a link to my thread from a couple years ago and dealing with getting the wheels matched up.

http://listerengine.com/smf/index.php?topic=6158.0

[ronmar]

You know, even with NO cast-in counterweights on my flywheels, it didn't run all that bad...

Glort, do you have any pics of your base/frame?

[DirtMerchant]

 This might be a silly question, but when matching flywheels I assume you mean to get both flywheels to "rest" exactly the same with the counter weights down opposing the crankshaft counterweight which I intend to do myself. However in thinking about this, does it make sense to weigh each flywheel and when adding weight make sure that the flywheels are not only equal from a rest position perspective but also equal in overall weight to each other?

[38ac]

This might be a silly question, but when matching flywheels I assume you mean to get both flywheels to "rest" exactly the same with the counter weights down opposing the crankshaft counterweight which I intend to do myself. However in thinking about this, does it make sense to weigh each flywheel and when adding weight make sure that the flywheels are not only equal from a rest position perspective but also equal in overall weight to each other?

Click the link two posts up and it is all covered in my thread on the subject.

Two things are very important.
1, That the heaviest part of the flywheel is in the correct relationship to the keyway
2. That the off set weight is the same for both.
 
In a perfect world you would match them for total weight but I haven't found it to be necessary.  You must weigh and check both flywheels ( 1 and 2 above) and then sit down and think about what you are doing, otherwise you end up being redundant in your work.