Super Totally Awesome Flycutter Bit Grind

jgedde

Active User
Registered
Joined
Jun 23, 2011
Messages
787
I was at work when I noticed one of the machinists flycutting a piece of aluminum on one of the Bridgeports. The surface finish he was getting was amazing. I stopped and asked him how he ground the cutter. Not only did he show me, he was kind enough to grind one for me.

I brought it home, put it in my fly cutter and got terrific results.

So, I thought I'd share his grind with you guys. Rather than try to explain it, I took closeup pictures. This bit started life as a brazed carbide AL (left hand) bit. I don't see any reason this couldn't be duplicated in HSS.

Here are the pictures... Note the slight radius appiled to the cuitting edge...

John

fly cutter front.jpgfly cutter side.jpgfly cutter top.jpg

fly cutter front.jpg fly cutter side.jpg fly cutter top.jpg
 

nicky

Active User
Registered
Joined
Apr 5, 2011
Messages
118
That is a mighty fine grind. What kind of wheel did he have? Diamond? I don't think you could get that with a green wheel. It would end up too mushie I would think.
 

jgedde

Active User
Registered
Joined
Jun 23, 2011
Messages
787
That is a mighty fine grind. What kind of wheel did he have? Diamond? I don't think you could get that with a green wheel. It would end up too mushie I would think.
Yep, It was one of those $300 diamond wheels. I take my carbides to work to sharpen.

John
 

HSS

Active User
Registered
Joined
Nov 28, 2010
Messages
466
I have never had any luck grinding a fly cutter bit. I guess I'll have to stick to a face mill. LOL

Pat
 

Highpower

Active Member
Registered
Joined
Mar 22, 2011
Messages
450
I tried grinding one of those in HSS. It cut extremely well, like a hot knife through butter - notice the long spaghetti strands...
But the surface finish was horrible. Tried all kinds of speeds and feeds and it didn't get much better. :(

Then I switched to a plain old brazed carbide bit and got an almost mirror finish right off the bat. :nuts:

P7280085-1.jpg

P7280085-1.jpg

P7280085-1.jpg
 

george wilson

Global Moderator
Staff member
H-M Supporter - Gold Member ($25)
Joined
Jul 26, 2011
Messages
3,494
I had one of those octagonal milling cutters at work. It cut aluminum like crazy.
 

bret4

Newbie
Registered
Joined
Jun 19, 2011
Messages
7
That is the same way I grind my fly cutter tool bits. Only difference is I just leave the face flat. Nice work man!
 

AR1911

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 5, 2010
Messages
867
Paddy, I am working on a friend to improve his surface finish on aluminum pieces like that.
Can you tell me exactly what tooling and inserts you are using?

EDIT: I did find your other thread where you listed the numbers (as shown on the pic)

Gotta find me one of those
 

Buffalo Bob

Active User
Registered
Joined
Sep 28, 2013
Messages
40
I was at work when I noticed one of the machinists flycutting a piece of aluminum on one of the Bridgeports. The surface finish he was getting was amazing. I stopped and asked him how he ground the cutter. Not only did he show me, he was kind enough to grind one for me.
I brought it home, put it in my fly cutter and got terrific results.
So, I thought I'd share his grind with you guys. Rather than try to explain it, I took closeup pictures. This bit started life as a brazed carbide AL (left hand) bit. I don't see any reason this couldn't be duplicated in HSS.
Here are the pictures... Note the slight radius appiled to the cuitting edge...
John

View attachment 29336View attachment 29337View attachment 29338
jgedde thank you for the great pix. This is what I was looking for. Gives me a lesson in tool grinding as well as flycutting. Nothing beats a good picture in my book. Except maybe a video. Thanks again... :)
BB
 

DMS

Active User
Registered
Joined
Aug 5, 2011
Messages
1,567
Ox Tool (Youtube) just did a video series on flycutter grinding. The grind he used looks a lot like the one JGedde posted.

[video=youtube;tCrJVYF95aE]http://www.youtube.com/watch?v=tCrJVYF95aE&feature=share&list=UUZC9LGZLfyjrKT4OZne-JNw[/video]

The really cool thing is he takes test cuts after each stage of the grind, to show what effect it has on the finish.
 

george wilson

Global Moderator
Staff member
H-M Supporter - Gold Member ($25)
Joined
Jul 26, 2011
Messages
3,494
Aluminum cutters generally have a cutting edge similar to the one shown. It is indeed a chip breaker grind because it twists chips so much they break into little curled,short chips. This is exactly what must be had for use in lathes like CNC,where large amounts of chips are made,and must be small so they will be carried away on the built in belt that removes chips. Long,curled chips are not desirable in modern machining. Indeed,in the late 19th. C.,it was thought that lathes had reached their maximum practical cutting rates because the volume of long,stringy chips would become unmanageable if the lathes ran much faster. Then,someone invented this simple,practical chip breaker cutting tool. It works in steel,too.

I had an "Octo Mill"(I think that's what it was called) at work. It had octagonal inserts with cutting edges like the chip breaker bit shown. It was for aluminum,and cut like crazy,leaving a very smooth,polished surface(not a MIRROR surface,mind you),on aluminum. The inserts were Titanium nitride coated,too.
 

Bill C.

Active User
Registered
Joined
Mar 11, 2013
Messages
1,390
That is a mighty fine grind. What kind of wheel did he have? Diamond? I don't think you could get that with a green wheel. It would end up too mushie I would think.
I agree I don't think a green wheel could do a nice grind like it. I am impressed, nice tool bit.
 

epanzella

Active User
Registered
Joined
Apr 8, 2013
Messages
1,065
At what angle do you present that to the work? It looks like it will be fairly flat with the angle of the fly cutter.
 

tech610

Newbie
Registered
Joined
Nov 29, 2018
Messages
18
I have never had any luck grinding a fly cutter bit. I guess I'll have to stick to a face mill. LOL

Pat
HSS left hand bits that I grind myself is what I use and it works. Just basic textbook angles ground on a Sears gray wheel.
 
Top