Made a fly cutter

Brad

Brad

Benevolent Overlord and site owner
Staff member
Long story short, I had last week off as vacation. That included the past weekend. Went to work today and another RP showed up. Whaaaaaattttt? Hell, when I work the weekend I get the following Tuesday off and that includes weekends I take as vacation. I had today off!

Went back home and decided to make a flycutter. Found a simple set of plans online and went to work. Used a hunk of 1045 just shy of 1.5”. Plans called for 1.5” final diameter but this isn’t that critical.

Did the basic turning, did some figuring, and got it in the mill at a 20° angle. To make sure I milled the groove on the proper side I compared it to my purchased fly cutter. I don’t want a reverse cutting fly cutter!

Other than a cleanup I only need to drill and tap for set screws. I may cold blue it to prevent rust.

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Rick

Rick

Moderator
Staff member
Looks great but ya need to add a description of just what a fly cutter is and what ya do with it, besides cut flies. For us dummies don't ya know.
 
Ian

Ian

Notorious member
Hech yeah! That looks great.

If you want a more durable blue finish, get a bottle of Mark Lee express blue and hot-water blue it. Degrease, boil, flash dry, coat, boil, card, boil, flash dry, coat, boil, card, and so on about 6-8 times. All you need is a sauce pan, distilled water (or snow), the solution, and the kitchen sink. While domestic-freindly, it might best be done in the garage with a hot plate and separate rinse bath from your boiling pot. You could do a bunch of things at once on a cold winter day.
 
KeithB

KeithB

Resident Half Fast Machinist
Looking good there Brad.

A fly cutter is simply a single tooth facing cutter. It allows you to use a square shank HSS or carbide tipped lathe turning tool to cut the face of a piece of material. You can't take much off with each cut, but it is the best way to create a flat-as-you-can-get-it surface with a milling machine. By extending the tool and of course paying attention to the power and rigidity of the milling machine being used you can cut a wide surface in one pass instead of having to take multiple passes with a small end mill.

We use a large flycutter to clean up the face of the 3/4" x 3" aluminum stock we use to make one of our premium products. It guarantees we will have one flat surface to start with, cuz aluminum flat stock isn't really flat and smooth. I have a large homemade flycutter that has been used to face an 8" wide steel block in one pass.

A 4" dia flycutter cutting a 6" wide 6061 aluminum fixture base.
flycutter1.jpg
 
Brad

Brad

Benevolent Overlord and site owner
Staff member
Got the screw holes drilled and tapped. Trig isn’t a friend yet but damn is he handy. I got a free app for the phone called right angle. Made it easy to know how much offset in x for a .375 change in y.

Damn does the photo make the surface finish look like crap.
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Rick

Rick

Moderator
Staff member
Dang, a 27 minute video on fly cutters. Just needed a quick sentence what they are and what they're used for. :confused: Just cause I dunno don't ya know.
 
Brad

Brad

Benevolent Overlord and site owner
Staff member
Lots of videos on making a boring head on YouTube. Not a simple project. Dovetails, a screw to make, and a need for real precision. Abe in time.

And Rick, a flycutter is handy to have. Want me to make you one?
 
fiver

fiver

Well-Known Member
you could put it in your drill press and shove some not so flat stuff through it, making it less not so flat.
 
KeithB

KeithB

Resident Half Fast Machinist
fiver said:
you could put it in your drill press and shove some not so flat stuff through it, making it less not so flat.
Click to expand...

Yeah. or you could end up eating it or making it real crooked real quick.


For what you can get boring heads for on eBay there is no economic reason to make one. I have made several simple square slot no-moving-parts type boring heads but for $85 I'll buy a dovetail slide one.
 
Pistolero

Pistolero

Well-Known Member
Oh, come on Rick. I told you what you could do with it in post #7.

Agreed, Keith. The first time I needed to bore a hole to an accurate, non-standard
dimension, I did in on my friend's Bridgeport with a boring head. Oh, was THAT
a revelation. Nice to be able to dial in a few thousandths and get it. Esp $85 for
one with an R8 stub on it.

Bill
 
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KeithB

KeithB

Resident Half Fast Machinist
I have a 2" and a 3" boring head, very handy for boring accurate holes as we all agree. I also have a 6" boring/facing head. You can use it just to bore with, but you can also use it to face and groove. There is a fairly simple mechanism that bumps the dovetail slide out a tiny amount each revolution of the spindle as long as you hold onto a knurled collar. There are stops that can be set to control the final diameter. I have used it once to backface a bore and several times to cut internal grooves for O-rings and such. Now that I have a CNC mill that can accurately move in a circular path my need for boring heads is greatly reduced, although I have used the 2" several times in the CNC mill. But if you have a manual milling machine a good boring head adds a lot of capability.
 
JWFilips

JWFilips

Well-Known Member
Brad,
I'm enjoying this thread. I don't have any of these machines but I love learning how to make tools
 
Pistolero

Pistolero

Well-Known Member
Yeah, Kieth, that whole CNC 'mill in a circle' deal it a real game changer.
One friend who has two has shown me some cool tricks.
Single point thread milling, inside or outside is just wild!
I am guessing that Miha uses circular path milling with sub diam profile cutters to make his molds in halves. He offers the same design in diff bullet diams, no big deal, just program in a different circle diameter, same cutter.
A really big difference in CNC milling and manual milling.
 
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Ian

Ian

Notorious member
Miha does orbit the tool to control diameter. I imagine that reduces tool load somewhat as well.
 
smokeywolf

smokeywolf

Well-Known Member
Would love to put an NC retrofit on my Bridgeport, but without a job or project to justify the expense I'll stick with using a boring head or rotary table. Don't come close to doing what an NC mill can do, but that's the way the mop flops.
I never forget that I'm bloody lucky to have what I have.
 
KeithB

KeithB

Resident Half Fast Machinist
I always remember that some of the finest designed and machined products - guns, appliances, tools, etc. - were developed prior to CNC machines. Nowadays you just can't compete commercially w/o CNC, but some fine work can still be done with manual machines, a few good accessories, some knowledge of trig, and a smart guy using all of the above. You qualify on all counts, especially the last one there Smokey.

The most fun I have in the shop is when somebody else is doing the production work on the CNC machines while I make one-off tooling and fixturing on the manual mill and lathe.
 
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