Crank balancing

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As Scott apparently is no longer balancing cranks. Does anybody have a suggestion who they would recommend balance a CMB VAC 45? Scott did my original and it is awesome.
 
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Really Dave? That's a large company that works on large rotating equipment. Have you had them do work for you on RC motors? I sent them an email will see what happens.
 
As Scott apparently is no longer balancing cranks. Does anybody have a suggestion who they would recommend balance a CMB VAC 45? Scott did my original and it is awesome.

Just curious, what size slug(s) did he use? Did you check the amount of weight the crank would offset after it was slugged?

I checked and the crank would balance about 5.15 g or 26% of the total recip. weight. (CMB 21 shown)

Picture_005.jpg


https://www.intlwaters.com/gallery/albums/userpics/10068/2012_CMB_VAC_45.xls
 
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Terry, great question. I did not check yet. As Scott had done so many that worked I just had him take care of it. Now that he is no longer doing it I will have to measure the difference between the one he did and my stock crank I need done. I only have jeweled balancer at this time. Ill let you know after I come up with a way to check it. After I find that out how the heck do you drill a hardened crank and not damage it?
 
Terry, great question. I did not check yet. As Scott had done so many that worked I just had him take care of it. Now that he is no longer doing it I will have to measure the difference between the one he did and my stock crank I need done. I only have jeweled balancer at this time. Ill let you know after I come up with a way to check it. After I find that out how the heck do you drill a hardened crank and not damage it?
Carbide drill and reamer.
 
Terry, great question. I did not check yet. As Scott had done so many that worked I just had him take care of it. Now that he is no longer doing it I will have to measure the difference between the one he did and my stock crank I need done. I only have jeweled balancer at this time. Ill let you know after I come up with a way to check it. After I find that out how the heck do you drill a hardened crank and not damage it?
Carbide drill and reamer.

Yup, I was using a G carbide "Hi roc" drill followed by an H sized carbide reamer. These were the size slugs I harvested from the old K&B 7.5 cranks. I later discovered Mi-Tech metals from Henry Nelson.

But in all honesty I haven't slugged a crank in 20 years or more, just haven't seen the need for it with our rubber mounts these days...
 
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Thanks Terry. I know that I preferred the VAC after I had it slugged by Scott. I have a second one now I wanted to perform the same and after contacting Scott found out he is no longer doing that kind of work. Thanks for the info on Mi-Tech looks like my first task will be to find out what weight I need to use.
 
As Scott apparently is no longer balancing cranks. Does anybody have a suggestion who they would recommend balance a CMB VAC 45? Scott did my original and it is awesome.

Just curious, what size slug(s) did he use? Did you check the amount of weight the crank would offset after it was slugged?

I checked and the crank would balance about 5.15 g or 26% of the total recip. weight. (CMB 21 shown)

Picture_005.jpg


https://www.intlwaters.com/gallery/albums/userpics/10068/2012_CMB_VAC_45.xls
The best counter weight for the 45's is a two slug add. Slugs are .200" to .205" in diameter. This balances motor to 51.2% and is very good.

Stu
 
Not sure where I got this years ago, but your welcome to give it a try. Just needs some cleaning. Been collecting dust for a while now.

20180403_171342.jpg
 
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DIng, the light goes on. Those were the days. Turn right. throttle up.....turn left throttle down.....LOL You and Russ with Russel riggers
 
Speaking of balancing, here is an original 1980's generation Picco P80 Marine crankshaft (Part No. 3016). It was aquired from someone else. Looking closely, you can see that the forward-facing distal surface of the flywheel, on the opposing-side of the crankpin, has been grinded to a smooth radius. Also, from the face view (crankpin side), the circular perimeter shape has been grinded, or altered, from crankpin TDC position, 50 degrees or so equally both directions into a smooth upside-down parabolic shape. Is this done to provide some rotational balancing? Or to reduce turbulence?

One image shows the modded P80 crankshaft positioned next to an equal stock part for comparison.

Picco_P80_Crankshaft_PartNo.3016_ModdedVsStock_April2018_06.jpg

Picco_P80_Crankshaft_PartNo.3016_ModdedVsStock_April2018_08.jpg

Picco_P80_Crankshaft_PartNo.3016_ModdedVsStock_April2018_09.jpg

Picco_P80_Crankshaft_PartNo.3016_ModdedVsStock_April2018_10.jpg
 
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