91 cmb vac bearings

dwilfong said:

I use the set up that Scott Bouchie explained to me.

I made a setup with two razor blades attached to a machined aluminum block. the blades are just CA attached to the block.

I set the block on a flat surface so the blades are level with each other when you attach them.

The make sure the surface you put this setup on is level.

The crank will roll on this setup and find the heavy spot pointing down.

Now I take all the rotating parts crank , wrist pin , clips , rod and rod bearings and weigh them on a gunpowder scale.

This is the bob weight. now take 52% of this weight ( Greg Settel turned me on to this) and make a small brass piece that fits on the crank pin.

To find out how much it is off I CA a small screw on the bottom side of the crank as it sits in the setup jig with the bob weight on it.

Then start to add thing to the screw till the crank rolls even and dose not stop at the same place.

Now remove the screw and all the pieces you added to get it balanced.

Weigh this and that is how much you need to add to the crank.

Figuring what to remove and add is a pain......you need to calculate how much weight is removed when you drill the hole for the slug of tungsten.

Then how much the tungsten weights.

Volume of a cylinder works for the amount you take out with the drill and add with the slug and the weights by volume are posted in a few places.

McMaster Carr sells the tungsten and has the weight show for volume.

Drill the hole using a 2 flute carbide drill slow and dry then press the slug in. just don't get to close to the edge or the crank will crack.....ask me how I know......LOL

About .001/.002 press fit will work I have found.

Not to hard just takes time to get it all figured out............ or just send it to Scott he has it down to a system...........

Click to expand...

Charles Perdue said:

dwilfong said:

I use the set up that Scott Bouchie explained to me.

I made a setup with two razor blades attached to a machined aluminum block. the blades are just CA attached to the block.

I set the block on a flat surface so the blades are level with each other when you attach them.

The make sure the surface you put this setup on is level.

The crank will roll on this setup and find the heavy spot pointing down.

Now I take all the rotating parts crank , wrist pin , clips , rod and rod bearings and weigh them on a gunpowder scale.

This is the bob weight. now take 52% of this weight ( Greg Settel turned me on to this) and make a small brass piece that fits on the crank pin.

To find out how much it is off I CA a small screw on the bottom side of the crank as it sits in the setup jig with the bob weight on it.

Then start to add thing to the screw till the crank rolls even and dose not stop at the same place.

Now remove the screw and all the pieces you added to get it balanced.

Weigh this and that is how much you need to add to the crank.

Figuring what to remove and add is a pain......you need to calculate how much weight is removed when you drill the hole for the slug of tungsten.

Then how much the tungsten weights.

Volume of a cylinder works for the amount you take out with the drill and add with the slug and the weights by volume are posted in a few places.

McMaster Carr sells the tungsten and has the weight show for volume.

Drill the hole using a 2 flute carbide drill slow and dry then press the slug in. just don't get to close to the edge or the crank will crack.....ask me how I know......LOL

About .001/.002 press fit will work I have found.

Not to hard just takes time to get it all figured out............ or just send it to Scott he has it down to a system...........

Click to expand...

David, where do you think that Scott got his information???????

Three guesses and the first two do not count.....

Try Jack O'Donnell. He was just messing with your head

He has forgotten more than most people will ever know on our toy motors.

One other thing, when you attach your screw, or whatever you fasten your bob weight to on the crankshaft counterbalance, if it is not in the SAME EXACT POSITION as where the tungsten weight will be going, your entire process will be off. I learned from the master.

Charles

Click to expand...

Tim van Schyndel said:

Charles Perdue said:

dwilfong said:

I use the set up that Scott Bouchie explained to me.

I made a setup with two razor blades attached to a machined aluminum block. the blades are just CA attached to the block.

I set the block on a flat surface so the blades are level with each other when you attach them.

The make sure the surface you put this setup on is level.

The crank will roll on this setup and find the heavy spot pointing down.

Now I take all the rotating parts crank , wrist pin , clips , rod and rod bearings and weigh them on a gunpowder scale.

This is the bob weight. now take 52% of this weight ( Greg Settel turned me on to this) and make a small brass piece that fits on the crank pin.

To find out how much it is off I CA a small screw on the bottom side of the crank as it sits in the setup jig with the bob weight on it.

Then start to add thing to the screw till the crank rolls even and dose not stop at the same place.

Now remove the screw and all the pieces you added to get it balanced.

Weigh this and that is how much you need to add to the crank.

Figuring what to remove and add is a pain......you need to calculate how much weight is removed when you drill the hole for the slug of tungsten.

Then how much the tungsten weights.

Volume of a cylinder works for the amount you take out with the drill and add with the slug and the weights by volume are posted in a few places.

McMaster Carr sells the tungsten and has the weight show for volume.

Drill the hole using a 2 flute carbide drill slow and dry then press the slug in. just don't get to close to the edge or the crank will crack.....ask me how I know......LOL

About .001/.002 press fit will work I have found.

Not to hard just takes time to get it all figured out............ or just send it to Scott he has it down to a system...........

Click to expand...

David, where do you think that Scott got his information???????

Three guesses and the first two do not count.....

Try Jack O'Donnell. He was just messing with your head

He has forgotten more than most people will ever know on our toy motors.

One other thing, when you attach your screw, or whatever you fasten your bob weight to on the crankshaft counterbalance, if it is not in the SAME EXACT POSITION as where the tungsten weight will be going, your entire process will be off. I learned from the master.

Charles

Click to expand...

Does the 52% magic number apply to all sizes 21, 45, 67 etc.

Cheers

Tim

Click to expand...

Charles Perdue said:

Tim van Schyndel said:

Charles Perdue said:

dwilfong said:

I use the set up that Scott Bouchie explained to me.

I made a setup with two razor blades attached to a machined aluminum block. the blades are just CA attached to the block.

I set the block on a flat surface so the blades are level with each other when you attach them.

The make sure the surface you put this setup on is level.

The crank will roll on this setup and find the heavy spot pointing down.

Now I take all the rotating parts crank , wrist pin , clips , rod and rod bearings and weigh them on a gunpowder scale.

This is the bob weight. now take 52% of this weight ( Greg Settel turned me on to this) and make a small brass piece that fits on the crank pin.

To find out how much it is off I CA a small screw on the bottom side of the crank as it sits in the setup jig with the bob weight on it.

Then start to add thing to the screw till the crank rolls even and dose not stop at the same place.

Now remove the screw and all the pieces you added to get it balanced.

Weigh this and that is how much you need to add to the crank.

Figuring what to remove and add is a pain......you need to calculate how much weight is removed when you drill the hole for the slug of tungsten.

Then how much the tungsten weights.

Volume of a cylinder works for the amount you take out with the drill and add with the slug and the weights by volume are posted in a few places.

McMaster Carr sells the tungsten and has the weight show for volume.

Drill the hole using a 2 flute carbide drill slow and dry then press the slug in. just don't get to close to the edge or the crank will crack.....ask me how I know......LOL

About .001/.002 press fit will work I have found.

Not to hard just takes time to get it all figured out............ or just send it to Scott he has it down to a system...........

Click to expand...

David, where do you think that Scott got his information???????

Three guesses and the first two do not count.....

Try Jack O'Donnell. He was just messing with your head

He has forgotten more than most people will ever know on our toy motors.

One other thing, when you attach your screw, or whatever you fasten your bob weight to on the crankshaft counterbalance, if it is not in the SAME EXACT POSITION as where the tungsten weight will be going, your entire process will be off. I learned from the master.

Charles

Click to expand...

Does the 52% magic number apply to all sizes 21, 45, 67 etc.

Cheers

Tim

Click to expand...

Yes

Click to expand...