Does this fly cutter look right?

D.sebens said:
Trying to figure out why my cut is poor with this fly cutter. I ground the tool myself and honed the edge. The finish improved with more radius added to the nose of the tool but you can still feel the ridges even if you feed really slow.

My questions are about which direction the tool is supposed to be and if my grind looks okay.

On the direction, seems like I need to grind a LH tool for it as it lines up more center to the tool but then wouldn’t the set screws be on the wrong side for that?

On the grind question I’m going to guess it’s been 1/16-1/32”. I haven’t measured it. The blank is 1/2”. I honed it after grinding to get it nice and sharp. I’m using a 15 degree rake and about 8-10 degree reliefs.

Since you can’t feel the picture, those ridges are pretty pronounced. They are probably just enough to catch a fingernail but it’s really translated in to roughness when dragging a finger down the surface.
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From pictures 1 and 2 it looks like your honing has introduced negative rake at the edge-pretty easy to do and will definitely affect finish
 
pacifica said:
From pictures 1 and 2 it looks like your honing has introduced negative rake at the edge-pretty easy to do and will definitely affect finish
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It might. I’ll check. It was ground on a bench grinder and honed afterwards. That’s why it’s honed on the ends. I will definitely check it out though.
 
All of my Fly cutters have the cutting load against the set screws. Even all of the ones I look at online have the cutting force against the screws. For some reason I can not figure out that is how almost everyone does it.
I have to run all of my fly cutters in reverse.

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Flyinfool said:
All of my Fly cutters have the cutting load against the set screws. Even all of the ones I look at online have the cutting force against the screws. For some reason I can not figure out that is how almost everyone does it.
I have to run all of my fly cutters in reverse.

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That’s interesting. Am I wrong but the drawing you posted would have the load on the solid wall right, not the set screws?
 
Both drawings show the cutting edge on the side of the slot that is on center to the shank. The pics look like you have yours the opposite way.
 
Flyinfool said:
Both drawings show the cutting edge on the side of the slot that is on center to the shank. The pics look like you have yours the opposite way.
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I agree with that. If I flip mine around the set screws are on the side with the load. Seems like rigidity would be decreased? Maybe I’m overthinking it. I’ll just grind a LH tool and flip it around and try it
 
Grinding a left hand tool is exactly what you need to do. All flycutters that use a lathe tool as a cutter require a LH tool.
 
I feel like a detail is being overlooked. I am running the cutter the correct direction for the but that’s in it. This requires using the reverse direction. I’m not spinning the tool backwards. The question is if I should reverse the grind and run in forwards. I’m going to try a new grind and running the other way.
 
D.sebens said:
I feel like a detail is being overlooked. I am running the cutter the correct direction for the but that’s in it. This requires using the reverse direction. I’m not spinning the tool backwards. The question is if I should reverse the grind and run in forwards. I’m going to try a new grind and running the other way.
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Try running this cutter in clockwise rotation, but rotate it 90 degrees.

Granted, I can't see much of the geometry from the pics. You should be cutting with the same edge and faces as would be used on the lathe.

I think your cutter holder will work fine in conventional rotation. The fixed index is (should be) the centerline, who cares if the clamp bolts support the cutter on the load side or not. The cutter is overkill for the job at 3/8".
 
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