[4]

Using a Fly Cutter

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

oskar

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Nov 24, 2013
Messages
152
Likes
53
#1
What is the purpose of a fly cutter and why use it instead of an endmill?

Thank you

Nicolas
 

savarin

Active User
H-M Supporter - Gold Member ($25)
Joined
Aug 22, 2012
Messages
1,877
Likes
2,854
#2

MSD0

Registered
Registered
Joined
Apr 22, 2015
Messages
272
Likes
77
#3
It’s a surfacing tool and will give you a better surface finish than an end mill.
 

oskar

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Nov 24, 2013
Messages
152
Likes
53
#4
Thank you both. Savarin the project you did on that link is amazing and I admire your knowledge

Nicolas
 

stupoty

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 2, 2012
Messages
936
Likes
225
#5
What is the purpose of a fly cutter and why use it instead of an endmill?

Thank you

Nicolas

Fly cutters are very cheep to run if you use HSS tool, as the cutter can be easily sharpened when compared to an insert based face mill for example.

Stu
 

GrayTech

Registered
Registered
Joined
Jan 18, 2018
Messages
49
Likes
18
#6
With the right cutter and light cuts a fly cutter can also be used to enlarge holes in a pinch.

Sent from my H3123 using Tapatalk
 

MSD0

Registered
Registered
Joined
Apr 22, 2015
Messages
272
Likes
77
#7
Fly cutters are very cheep to run if you use HSS tool, as the cutter can be easily sharpened when compared to an insert based face mill for example.

Stu
You can also use a fly cutter (single point) on smaller, less powerful machines that would struggle with a face mill.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
332
Likes
178
#8
Hi Guys,

A fly cutter is a very very useful tool, they do however have some failings, vibration, due to an out of balance condition, chatter due to the toolbit not being rigid enough.

Here are some pictures of my home brew fly cutters.
Flycutter.JPG
This works OK, however it suffers from too long a shaft, and too much cutter stick out. This one was intended for deep hole work on a 50 mm bore.
Body-01.JPG
24-07-2018-001.JPG
This one was made and used to clean a forked end and machine to size. Sorry about the focus.
New_Flycutter-1.JPG New_Flycutter-2.JPG
This one was made for surfacing and getting a relatively large area machined in one go. It also has the advantage of balance, rigidity and depth of cut. I can take a 40 thou cut in steel without any chatter. This type also has the advantage of mass.

They are also very easy to make. The one above is 3" inches in diameter and 20 mm thick on a 20 mm X 50 mm shaft. The tool bit is a piece of square HSS lathe tool.
 

stupoty

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 2, 2012
Messages
936
Likes
225
#9
You can also use a fly cutter (single point) on smaller, less powerful machines that would struggle with a face mill.
Thats true too, I'm not sure if a face mill is better at when its hitting the edge or a hole in a thin part, Ive had a little chatter at edges when fly cutting, but I have a smaller mill so I tend not to get into face mills as you say HP and all that. :)
 

P. Waller

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Mar 10, 2018
Messages
404
Likes
248
#10
Use a fly cutter in a wobbly machine such as a Bridgeport R8 knee mill.
If you are knocking a good deal of material off of a flat part and have time constraints use a face mill, this will not likely produce the hobbyist finish results that you require, a fly cutter may be slow but is more likely to produce the uniform finish that you expect.
 

MSD0

Registered
Registered
Joined
Apr 22, 2015
Messages
272
Likes
77
#11
Thats true too, I'm not sure if a face mill is better at when its hitting the edge or a hole in a thin part, Ive had a little chatter at edges when fly cutting, but I have a smaller mill so I tend not to get into face mills as you say HP and all that. :)
Yeah, I was thinking more of a mini mill or something where you can run it slow enough to use a fly cutter.
 

MSD0

Registered
Registered
Joined
Apr 22, 2015
Messages
272
Likes
77
#12
Hi Guys,

A fly cutter is a very very useful tool, they do however have some failings, vibration, due to an out of balance condition, chatter due to the toolbit not being rigid enough.

Here are some pictures of my home brew fly cutters.
View attachment 274682
This works OK, however it suffers from too long a shaft, and too much cutter stick out. This one was intended for deep hole work on a 50 mm bore.
View attachment 274683
View attachment 274684
This one was made and used to clean a forked end and machine to size. Sorry about the focus.
View attachment 274685 View attachment 274686
This one was made for surfacing and getting a relatively large area machined in one go. It also has the advantage of balance, rigidity and depth of cut. I can take a 40 thou cut in steel without any chatter. This type also has the advantage of mass.

They are also very easy to make. The one above is 3" inches in diameter and 20 mm thick on a 20 mm X 50 mm shaft. The tool bit is a piece of square HSS lathe tool.
I never thought of making one like that (the second one on the bottom). Pretty cool.
 

mikey

Active User
H-M Supporter - Gold Member ($25)
Joined
Dec 20, 2012
Messages
4,117
Likes
4,448
#13
I've always thought of a fly cutter as a flattening device. I use it primarily for squaring stock in prep for milling projects. It does transfer the angle of the spindle to the work, though, so being in tram matters.

I've come to prefer inserted carbide fly cutters over those that use HSS; they last far longer in use and a sharp cutter is a minute away. Carbide allows you to run at much higher speeds and produces a pretty nice finish. They also allow for some decent stock reduction over a fairly large area in a very short amount of time so they can be used to dimension stock as well. Depending on how the insert is oriented, some fly cutters allow you to cut to a ledge/shoulder and that can be really handy at times.

On my little Sherline 5400, I use their inserted carbide flycutter. This is essentially a single-flute face mill intended for use in the Sherline mill. It will cut to a shoulder and will surface, flatten and dimension most machinable materials and it leaves a beautiful finish. It only cuts a 1-1/8" swath so that is somewhat limiting but still, this is easily one of the best tools Sherline makes; their fly cutter that uses a HSS or brazed carbide tool does not even come close. An insert seems to last forever in this tool.

On my RF-31, I use the Tormach Superfly and that one is also pretty okay, too. It will not cut to a shoulder but does allow me to fly cut a 6" work piece. It can take at least a 0.075" deep cut in aluminum at high speed without even slowing down the motor so I sort of like it. I have also adapted a Sherline flycutter for use on the RF-31 and use it to cut shoulders ... I really like this tool.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
332
Likes
178
#14
Hi Guys,

Here are some more pictures:
26-01-2018012.JPG 26-01-2018013.JPG 26-01-2018014.JPG 26-01-2018018.JPG 26-01-2018019.JPG
These pictures are of a dovetail slide that I made for tool grinding. Every surface in these pictures, including the dovetail was done using a fly cutter. The fly cutter used to cut the dovetail was ground at 45 degrees, and was similar to the one in my first picture but much shorter and more rigid. Notice the sharp corners. I had to stone them off to get a smooth travel without binding. The brass bolt in the side is to lock the slide in use.
 

oskar

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Nov 24, 2013
Messages
152
Likes
53
#15
Very informative, my thanks to all
 

007

Swarf
Registered
Joined
Apr 7, 2015
Messages
14
Likes
9
#16
At the job, sometimes the part to be machined is of such a shape that you can't clamp it well enough. Sometimes the part is thin or it's a weird shaped weldment etc. I use a face mill and remove all the inserts but one. Then with a sharp insert I take a thou or two with the rpm turned up a little more with a slow feed will reduce or omit completely the chatter on the part. It really helps to make a nice finish.
 

BaronJ

Registered
Registered
Joined
Aug 7, 2018
Messages
332
Likes
178
#17
Hi Guys,

Yes it is surprising just how versatile a fly cutter can be, not just for facing. Careful consideration of the job in hand can produce some useful solutions.

24-07-2018-001.JPG
Sorry about the slight out of focus.
24-07-2018-004.JPG
This is the job that I was doing. Squaring up and sizing the slot width.
 
[6]
[5] [7]
Top