View Full Version : Flycutting on "smaller" mills

Mike P
04-15-2008, 10:48 AM
Hi All,

I have an M head Bridgeport and was wondering, based on the recent thread about flycutting if I'd be able to use a 2" to 3" flycutter?? Everything I've read says rigidity is the key, making every other process more successful, as well.

Is the M head rigid enough to run a flycutter with success? Do I want to limit the size to something under 3" or even 2"?


04-15-2008, 11:50 AM
Depending on how aggressive you are, those sizes should be no problem. give it a whirl!


04-15-2008, 01:29 PM
I've run 3" on an m-head. Just take small bites! 2" feels safer to me, like i'm not going to tear up the machine ... but 3" is ok imho.

04-15-2008, 01:54 PM
I run a 2 1/2" Iscar face mill on a horror fright 40939, which is puny compared to your Bridgeport. The key is having positive cutting angles, and sharp bits.

04-15-2008, 02:17 PM
I have been successfully using a 3" cutter on my Smithy G1324.

04-15-2008, 02:36 PM
ive been using a 3" on my round column mill/drill without problems...

04-15-2008, 06:29 PM
I just planed some steel stock with a small flycutter. It uses a 5/16" bit, and has a 1 1/8" body, the bit was set to almost 3 1/2" diameter, so plenty of bit overhang, on my Shoptask. I used one of the lowest spindle speeds to get the cutting speed right, and ran the power feed at 3/4" per minute for an .008" chip per tooth. Beautiful finish. I love flycutters. And my tool grind is so goofy I don't even want to show you! I just put some angles on the bit and try it out. By the book I have way too much clearance angles, so theoretically not much support for the cutting edge.

Be sure the mill is well trammed to minimize cutting on the back swing. Even then it is best to make a pass in each direction and see which way produces the best cut. Take light passes to avoid deflection.


04-15-2008, 07:02 PM
All of these other machines have much thicker spindles than the M head. M heads are mostly 2 MT, some 7 B&S, a very few B-3. All hold 1/2" dia tools max.

04-15-2008, 07:53 PM
All of these other machines have much thicker spindles than the M head. M heads are mostly 2 MT, some 7 B&S, a very few B-3. All hold 1/2" dia tools max.

I didn't realize the taper was that small. Still, you can get 3/4" end mill holders for 2 MT. And even a small Bridgeport weighs a heck of a lot more than a Shoptask, Smithy or mill/drill, and is much stiffer, I would think.


Mike P
04-16-2008, 01:38 PM
Oh yeah, I forgot to mention the tiny #2 Morse spindle on the M head. I didn't realize the newer little mills had bigger spindles.

I'll start out conservative on diameter, feed and cutting depth and see how it goes.


04-16-2008, 02:25 PM
Yes, they have smaller tapers, but I would agree that they are much stiffer than smithy's. I own the small smithy they make it shakes all over the place when the quill is all the way out. Its not even the spindle thats moving, its the quill that the spindle and spindle bearings ride in. Of course, that was when I was working on cutting those forged steel hitches to a larger diameter.