Balancing a large cast iron flat pulley

[projectnut]

The Magna-Matic magnet has a 120 lb. Pull it can hold an object up to 50 lbs. the cone can handle an object with a center hole from 3/8” to 1 1/2”. It will balance as close as 2 grams

If you Google “Magna-Matic blade balancer” there are several videos showing how it works, and what it can be use for. I bought mine around 1964 and they haven’t changed much since then except for the price. I think I paid less than $25.00 at the time.

 

[Jake M]

Looking for suggestions on balancing a 20” diameter cast iron pulley. I trued up these two pulleys and when they are mounted to. The shaft and bearing, it will always turn to the same position.
What is the Mandrel on the fence method?
Short of drilling holes, can I epoxy some lead to the opposite side?
Also is there a way to tell how much to heavy it is on the unbalanced side?
Thanks
Martin

You've got to find some way to let it roll absolutely freely...

One option for adding weight- And of course if you can duct tape any old chunk of crap in place, you can baseline some starting point to estimate just how much weight this is going to take, and if you're looking at ounces or pounds, so you can get the package size and weight denomination in some appropriate range. And these can stack over top of themselves... Instead of a row of fifteen weights, you can very legitamately stack a row of five weights, three deep.

https://www.amazon.com/Accretion-Adhesive-Backed-Wheel-Weights/dp/B07RWDDHHP?th=1

If you can't get it to roll absolutely freely, use whatever you've got that's allowing it to return to it's position, and add weight slowly, just tape it at first, until you can get it to "almost" roll properly. Add weight slowly so that you can guarantee that you're on the "low side" of the correct weight.
Once you hit that spot where you're "almost there" and the balance is just percievable as being not quite enough, make that weight permanent. and leave it alone. Then start temporarily taping on more new weights, again, slowly and incrementally.... Bring it to the point where it has exactly the same, just barely percievable amount of "over balance". however much weight you added to go from "under balanced" to "over balanced", take half of that, and that's obviously not "perfect", but it'll get you pretty darned close. Probably more than close enough. And if it's not... These can be very easily adjusted in place.

 

[Just for fun]

Here is how I ballanced my 4-jaw chuck. Maybe you can do something like that.

Chuck Balancer

Made a unit to check the balance of my 4-jaw chuck. I bought a bicycle exerciser unit at a secondhand store for $5 bucks a while back. I disassembled it and turned a couple of bearing holders and a shaft to go between them. It seems to work, the best I can tell it's a little over a half ounce...

www.hobby-machinist.com

 

[FOMOGO]

I've always done it like Cadillac described using a motorcycle truing stand I made years ago, but the 120 deg method sounds like it may have merit. What is the 20" wheel going on? Mike

 

[Martin W]

I've always done it like Cadillac described using a motorcycle truing stand I made years ago, but the 120 deg method sounds like it may have merit. What is the 20" wheel going on? Mike

It's for a sawmill. One pulley is an IH, which I suppose is off an old threshing machine. The other one is from a line shaft. They are the same diameter now and width. The International pulley machined really nice. The other one was hard as heck. And very dirty to turn.

Thanks for everyone's input. I have magnets on them right now and they spin beautifully. I did like Daryl suggested spanning to V's on the lathe Just waiting to complete more fab work, in case I need to do more machine work on them.
Cheers
Martin

 

[Uglydog]

Here is what the instructions said to balance tires on an old Snap-on manual balancer.

Place weights 120 degrees apart opposite heavy end. If possible split those weights between both sides of the rim.

Using this info, may give you other thoughts on how to best balance your pulley.

View attachment 471551


Sent from my iPhone using Tapatalk

Toprecyler,
This is especially interesting thanks.
Daryl
MN