Generator vibration and torque pulses

[hotater]

jens---   If you have trouble with Mr.X method, go to any machine shop and ask the machinist to show you how he roughly 'indicates' a piece in a four jaw chuck......rest a pencil and run it in until it touches.  Where the mark is is HIGH....adjust and re-try.  Its' exactly the same thing.

BTW-- It'd be best to NOT put a belt on that engine until you get the movement sorted out.  Under load vibration can become the Energizer Bunny on speed.   I notice that you still have the same problem that you did on page one.....and still haven't addressed the solutions suggested then!
  Are you just being stubborn??!   

[BruceM]

The Sculpy plastic modeling clay I used was useable at 650 rpm on a 24" rim, so your mileage may vary.
Rather than build something elaborate, I'd suggest just go buy some clay or plan on wasting some stickon lead mag wheel weghts. A search for "plastic modeling clay" shows lots of 1 lb boxes for under $2.  If you use some carpet tape and the wheel weights upside down, then you can save the "good side" for your permanent attachment.

[hotater]

jens---

I refer specifically to the bracing comments.   ROUND pipe bracing, not square.  The whole assembly is not rigid enough to absorb the energy it's being fed.

You don't make a house of cards stronger by adding more cards....you use TAPE......bracing.

For weights you can use 3M mounting tape temporarily.  Solvents will eventually result in failure of the tape but it's good for hours on a milling machine or surface grinder.
   For permanant application, form a lead strip of the proper weight and epoxy it to the inner rim so centrpedal force holds it there.  Spread the weight OUTward....DON'T put a heavy lump in one spot.

[sailawayrb]

sailawayrb - your picture did not post, could you try again please ?

I tried to post photos, but haven't had any luck.  When I click the Insert Image icon, it just puts following into post:



In other bulletin board websites I use, you get an opportunity to browse to the location of photo on your PC and then upload it onto the bulletin board.  Anyhow, if someone can walk me through the process, I would be happy to modifiy my previous post to include the photos of my stand.

[hotater]

Bob---  THis forum has to have the address of the photo hosting site between the url brackets.   Look up 'free photo hosting' for a LONG list of sites you upload your photos to and then use their url to point this forum's sofware to look for it.

[sailawayrb]

Bob---  THis forum has to have the address of the photo hosting site between the url brackets.   Look up 'free photo hosting' for a LONG list of sites you upload your photos to and then use their url to point this forum's sofware to look for it.

Wow, that's pretty draconian, but I will give this a try.  Thanks!

[mike90045]

you could try welding a rectangular plate to both sides, if you don't have a large U channel,  but it may start flexing sideways, where a U channel would prevent that.

 Plate should be tall enough to cover all of the square tube ends, down to the ground, full length and well welded.

I suspect the next weak area will start to flex then.   Whats the phrase ?  Polishing a  t _ _ d  ?

[hotater]

jens---

The best you can do is set up a 'protocol' and analyze what works and what doesn't.

Start with a pound at the same position on both flywheels and keep a hand on the throttle bar to see how it acts....then change the position with the same weights and see how that reacts.  Once you know *where* it goes start adjusting how *much* it needs.
Then by laying a sensitive finger on the engine's two sides, determine which one needs to be different.

One thing to remember-- It'll NEVER be perfect...ESPECIALLY if the mount is flimsy....   

<the Devil made me say it.>

[ronmar]

The way I look at the situation, especially with the generator disconnected, if the engine stops shaking the generator will stop shaking.
Jens

Jens
  You are still missing the point. THE ENGINE WILL NEVER STOP SHAKING!  Even if it is absolutely perfectly balanced...  For every action there is an equal and opposite re-action(Don't blame me, blame Newton).  Every time the engine rolls around on compression, the wheels and crankshaft  decelerate Since the piston is providing a braking force, the case tries to rotate in the same direction as the crankshaft(like a motorcycle doing a stoppie). As soon as the cylinder fires on the power stroke, the crank and wheels are trying to accelerate.  This force being provided by the case means the case tries to rotate in the opposite direction.  Watch this video closely.  As soon as the engine fires, the rack being wide open and trying to accelerate the flywheels to the set RPM(high torque), the case wheelies on each power stroke.    http://video.google.com/videoplay?docid=-2472879285322243628  Unless you never plan on running this really expensive boat anchor, that is the force your frame must withstand. 

Ron 

[BruceM]

Jens,
You should start by putting the weight opposite the line you marked on the flywheel, adding increments of 4oz.  Restart, remark, add some more as indicated.  Slightly leading the indicated placement (say 4" ahead in the direction of rotation on a 24" wheel) may help.

Start with either wheel, switch to the other after you've made some improvement on the first.

Starting a twin has got to be quite a challenge compared to the singles.  If you don't have a starter of some sort maybe Ron's motorized approach is a better bet for you.

[vwbeamer]

Ya'll make an easy subject hard.

[hotater]

Jens---

Back in history on this thread I suggested a 'box' of eight inch channel poured full of concrete.  I think it would be nearly as effective to floor it and stack in sand bags.

Use  PIPE for cross bracing!!  Gusset all the corners in all directions.

[dieseldave]

   I just talked to a millwright and he said that conveyor belting is the thing to use. Rubber by itself will absorb shock but bounce back,

    Mounts for the base could also be fashioned out of coveyor belting as well. It might be labour intensive,but well worth it.

[peterako]

Jens.
Sand under vibration is like a liquid/gel it is not the same as concrete but at the same time maybe it is enough to remove the energy.

I have big heavy concrete block and for the second time i have broken fixing bolts.

and i am still trying to solve the problem maybe a sand filled sub frame will be a solution for me.

Greetings from Greece 

[dieseldave]

   How about a base made entirely from conveyer belting.If one could obtain it cheap enough, a plant closure or a revamp of equipment at a plant.

   Obtain about 50 feet of conveyer belting 36 inches wide or so and for example 3/8 inch thick. Next, cut it into 4 foot long lengths.
   I know this would be time consuming!  Obtain a good degreaser to clean the belting and get down to clean rubber. Buy 1 gallon of contact cement. Glue the 4 foot strips together so that you have 11 pieces making up a thickness of a little over 4 inches. This would then be sandwiched in between channel iron.

   For mounting the engine and generator, 4 pieces of 4"channel,4 feet long with the hollow pointing down,top and bottom. 6"x 3/4" bolts every 12" or so. Distance apart would be determined by Listeroid mounting hole dimensions.

   4 pieces of 6" channel ,5 feet long would be used on the outside for mounting onto the floor. Hollow pointing up at the top and hollow pointing down at the bottom.

    Getting back to the 4" channel,it might be better to have the top pieces pointing up,and then weld pieces in for mounting the engine and whatever your driving.

This would be one huge vibration dampener. I can imagine 1 foot of 36 inch, 3/8 thick belting would probably 5lbs or more!