Creating a Fly Cutter Bit

[Metalmann]

ok now i am getting it, it is used to true up a side correct. it isnt meant for large cuts correct?

Fly cutters are designed to make wide, flat, surfaces.
Most of the time you'll only be taking .020 max.
Finish/Cleanup passes are around .001-.005. in depth.

You can use them for cutting accurate arcs, or boring, also.

Feeding--X, Y, and Z, axes.

 

[Metalmann]

I put my fly cutting tools in the bottom drawer because I couldn't get an edge on the tool to do what it was intended to do. I could not locate anything on the web that explained how to sharpen the tool for fly cutting. I think I will dig them out of the drawer and give it another try. Thanks Rick.

Patrick

If your geometry is correct, most fly cutter problems stem from a tip radius...being too large.

That large radius tends to cause chattering, hammering, awful finish, etc.

 

[dennis98277]

well i guess i will get a set then, i just made the leap and purchased a mill last week and i would like to make some tooling for it such as a vise which a good one can cost $600 so i can make it cheaper (i hope) :rofl::rofl:

 

[pjf134]

Rick,
A fly cutter is easy to make. I made one for my Sherline mill and set the rotary table to 10 deg. and cut the opening for the tool and used my lathe to cut the dia. for inserting the tool into the holder. I made the cutter and guessed at the grinding. Pic shows the first try on some Alum. angle and I left it like that since it did a very good job. When I put the fly cutter in the mill I did not like the grinding work, but tried it out and it did very well so I left it like that. I used a course grinding wheel only and did not hone the tool as I was just trying it out.
Paul

 

[ksastronomer]

I appreciate all the great comments to the fly cutter write-up. I'll make some revisions and additions to the document, and submit it for inclusion in the articles section of the forum resources. I'm also anxious to put some of those ideas into practice, because we should always strive for improvement and I certainly do that - I've been accused of being a perfectionist on more than one occasion. But I do wish to point out that improvement doesn't have to result in a better surface finish (as in this case), it can deliver a safer process to the operator and his/her machinery. And I believe we're all good with that goal.

Rick

 

[keithmifflin]

Being a novice machinist I find myself searching high and low for useful information to help me get started. Information regarding how to create a fly cutter bit has been difficult to come by, so I created this guide to describe the cutting bit design I adopted. It also shares the results I got with this first attempt. While I'm sure there is much room for improvement, I hope this article is useful to other newbies fishing for similar information. I welcome your thoughts and comments.

Rick

I would add a couple of actual pictures of your finished ground bit to help solidify what you have ground.
Keith

 

[keithmifflin]

Flycutter tools are the same basic profile as lathe tools. You just have to take the angle of the holder into account. Just look at the profile of the tool as a right-hand lathe tool, with the cutting edge being the edge that progresses in the direction of the flycutter feed, not the rotation. Look at the direction of rotation as the top of the lathe tool. Clearance rake and top rake for the material still applies.

I agree but still think for folks that are learners from seeing rather than reading the addition of a couple picture would be very helpful. It appears that it is possible since you added the photo of the finished piece showing what was capable.

My 2 cents
Keith

 

[Dranreb]

I was about to start a new thread to ask this question, but hopefully it will add to this one which seems to be aimed at beginners.

I have had problem fly-cutting on my lathe, in that if the work is longer than the sweep of the cutter, the cutter starts to take another cut at the rear as it passes.

How can this happen, surely the first cut has made the work square with the spindle?

My thoughts are that this is due to some flex in the tool, or the carriage being set to cut ever so slightly concave when facing off, (I have read that this was a military requirement, my Atlas is 1941 ish) maybe I was taking too deep a cut, not having at the time yet sorted a micrometer carriage stop I was guessing a bit..I'm still working on that.

I was using my Atlas 10f, with an MT fly-cutter and a Myford milling slide fitted to my turret cross slide, which I would think is pretty rigid, other opinions may differ....picture added for critical appraisal....

Great thread, keep 'em coming.

Bernard

 

[Metalmann]

"I have had problem fly-cutting on my lathe, in that if the work is longer than the sweep of the cutter, the cutter starts to take another cut at the rear as it passes.

How can this happen, surely the first cut has made the work square with the spindle?"



Sounds to me that you have a pressure/alignment problem.

How much are you taking off on your finish pass?

 

[Dranreb]

Sounds to me that you have a pressure/alignment problem.

How much are you taking off on your finish pass?

Hi Metalmann, I was experimenting somewhat at the time, I have learned on here a bit since I last tried fly-cutting, I think you could be onto the crux of it, that's why I posted the pic of my setup, I wonder if even with all gibs tight it is stiff enough for flycutting at any more than a passing kiss..

I am working on a micrometer carriage stop so I can somewhat control the cut depth of cut.

Bernard