Looking for thoughts on material for project

Jim F said:
Hobby guys tend to overthink things.......
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You are very likely correct, but it never hurts to ask. I kept looking at it thinking, is there a twisting or shearing load I am missing... I appreciate everyone's thoughts, I will likely use the 1045 since it is the more desirable dimension.
 
Those are alloy steels that have a lot of strength. They machine and grind better than mild steel, and are low on internal stress. It doubles the price of any project to use 41x0, etc. It would be my preference too, if it's available. But your fly cutter isn't going to need any strength beyond what the press fit and alloy body can provide. Weakest links being what they are.

Fly cutters can really get hammered overlapping cuts and interrupted cuts. The moment a fly cutter touches the work, it's a hard life of whup-whup-whup, a rhythm that is going to ripple and flex that alloy disc and amplify harmonics as the vibration chatters your work like a fat chick in a coin-op relaxo bed.

I have a fly cutter that I like an awful lot. It's like 7.625" pass width, and the base plate is 3/4" steel and uses a simple 3/4" stud for an R8 collet. It's kind of a no-brainer design. They're made by Flexbar now, and would be easier to make than the one you have planned.
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pontiac428 said:
Those are alloy steels that have a lot of strength. They machine and grind better than mild steel, and are low on internal stress. It doubles the price of any project to use 41x0, etc. It would be my preference too, if it's available. But your fly cutter isn't going to need any strength beyond what the press fit and alloy body can provide. Weakest links being what they are.

Fly cutters can really get hammered overlapping cuts and interrupted cuts. The moment a fly cutter touches the work, it's a hard life of whup-whup-whup, a rhythm that is going to ripple and flex that alloy disc and amplify harmonics as the vibration chatters your work like a fat chick in a coin-op relaxo bed.

I have a fly cutter that I like an awful lot. It's like 7.625" pass width, and the base plate is 3/4" steel and uses a simple 3/4" stud for an R8 collet. It's kind of a no-brainer design. They're made by Flexbar now, and would be easier to make than the one you have planned.
19003-19010_1800x1800.jpg
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That is interesting, are the 2 tools set at different heights and run at once or do you run the roughing tool then the finish tool? I actually have the material to make that....

Your analogy of the relaxo bed is a good one, I have a smaller fly cutter I built that doesn't quite give the finish I would like and thinking about your analogy makes me thing the tool stickout may be too far, it is likely flexing... Now I need to go to the garage and do an experiment on that one.
 
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The trick is your feed per rev should be equal to the tool tip radius. Each revolution, the rougher cuts 1/2 step ahead of the finisher. So if you set a .010 stagger (recommended) and you cut .040, the rougher does the first .030 and the finisher does a nice finishing depth of .010. It's pretty neat, and you can take some big steps with it.
 
pontiac428 said:
The trick is your feed per rev should be equal to the tool tip radius. Each revolution, the rougher cuts 1/2 step ahead of the finisher. So if you set a .010 stagger (recommended) and you cut .040, the rougher does the first .030 and the finisher does a nice finishing depth of .010. It's pretty neat, and you can take some big steps with it.
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Thanks John, I may save that aluminum for something else and build one of these, I like that design.
 
verbotenwhisky said:
I am building a large fly cutter, I will be machining it with an R8 connection for my mill and it will join the fly cutter disk (a 8.75" dia piece of 6061 Aluminum) at a pressed connection with a small 4 bolt flange. I have a piece of 4041 but it is a bit smaller in Dia than I would like and I have a piece of 1045 which in a great fit. I am curious about the thought on using the 1045 for this application as opposed to the 4041.
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Why not use an R8 shell mill arbor & connect the flycutter to it. Better still get a large face mill & take all but one of the inserts out if you aren't in a hurry.
 
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