Flycutter Balance Problem / Question

Bill, are both bars contacting the work or is the second one just for balance.

I have tried it both ways and found it to work the same. But I can usually get a bit faster feed with both contacting.

Use a tool with a large corner radius, increase table feed, and keep the same slow spindle speed. Might make work go quicker without balancing

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Trying to be helpful, but apologize as sometimes I can't make the tone come out correctly. I like the idea of attaching weight to the off-end of the assembly to balance it. I wonder if the math would be excessively involved to figure out how much weight, positioned at x-distance from center it would take to balance the assembly before attempting it. Lead weights sounds scary, but a stronger material could have the same effect without being likely to fragment. If one could figure out how much material is needed, then verify that it works, then one could know how much is needed for other settings (different radii) and apply them as needed based upon the needed working conditions. I look forward to the solution so that I can apply it in the future as well!

Randall Marx said:

Trying to be helpful, but apologize as sometimes I can't make the tone come out correctly. I like the idea of attaching weight to the off-end of the assembly to balance it. I wonder if the math would be excessively involved to figure out how much weight, positioned at x-distance from center it would take to balance the assembly before attempting it. Lead weights sounds scary, but a stronger material could have the same effect without being likely to fragment. If one could figure out how much material is needed, then verify that it works, then one could know how much is needed for other settings (different radii) and apply them as needed based upon the needed working conditions. I look forward to the solution so that I can apply it in the future as well!

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Thanks for commenting Randall Marx , and the tone is just fine ! Yes I could have calculated it out like that. Back to math 101 ... D1xW1=D2xW2 , where D are the stick out's on each side and W would be the weights of each side . I'd have to know the mass of the steel that Suburban used , the insert and on the other side; the weight of the weight I used, the bolt and then calculate for the round overs on the bar .....looking at all that I figured i'd just try something that I could add or take away from, basically I guesstimated it . I had a brass bar that I cut off, machined down, drilled a hole, bored the start of the hole larger so the allen head would be counter sunk. It ended up very close to balanced. The vibration was mostly gone so I decided to move cutting end out a little and if I had less or more vibration then I knew what to do.
Turns out I had to move the cutting end out about 1/8" from it's smallest radius ...and that gave me almost no vibration. This means I just need to mill a little off the end off my brass weight, it's a bit too heavy. Probably take about 0.050" at a time . When I find out what works then i'd know what I need to do to make another weight for a larger radius .
With that said, I really don't forsee myself doing any facing wider that the smallest that this fly cutter will do, so the one weight should be good for now.

I'll try to post a few pics later. The drilling, tapping went pretty easy. I used a 5/16x18 stainless allen bolt I had . I've run it a while with makeshift guards in place, the bolt has not moved yet but I may try and drill a side hole, use a small grub screw to prevent the allen bolt from ever vibrating loose .

On the left is making the balancer. Pic on the right is it done. Not seen is a small slot I milled
with a ball nose, so that the brass seats into the rounded back of the bar .

Coaxial indicating the hole ...bottom pic is a round over slot im milled into it where the brass weight meets the bar.

Looking good!

Thanks guys ! These are my first projects , and my first mill. Alot to learn, but it's a start .