Dynamic Balance SQ4 Crankshafts?

[Syd.Kallechy]

I agree to be perfect the knife edges might be best choice, as there was some friction in the ball bearings I used. However it wasn't as bad as you would think. After I removed the bearing seals and used machine oil to lube the bearings...friction was pretty minimal and I could get the crank to repeat on the heavy side within 5-10 degrees. Even while checking and removing material, as the balance got closer, if I placed the crank 90 deg opposite the heavy side it would find it's way to the heavy point and repeat. Also if I gave the crank a little spin on this fixture it rotates for quite awhile after (as long as the fixtures were aligned correctly).

I wanted to build this fixture anyways for future use building and balancing wheels on the bench. In future I may have some disks machined to fit the outer race of the existing bearings to reduce friction further. (See the following links for similar rigs I can find on the internet.... http://andersonscraper.com/Anderson-Sta ... g-Ways.php and http://www.youtube.com/watch?v=HbsGGSjmpko )

But I think I may also try using the two angle irons shown in the photo (the fixture base) to check static balance with their knife edges ...just to see how much difference there is between the two methods!

[nevhunter]

You have applied commonsense to the process. Your set up is good for dialling up everything to check for true, though there, I just use fixed narrow Vee's. Nev

[Syd.Kallechy]

The V's are probably the simplest/cheapest solution. Out of curiosity I did do check balance using the V method last night. Surprisingly both cranks checked OK so perhaps the SKF ball bearings I chose are better than we thought.