[Micro Milling]

Can someone tell me if there is a big difference in the finish when using a fly cutter vs a large end mill? Any other pointers between using the two?

[christinandavid]

A flycutter (or a facemill with one insert) will generally leave a better finish and put less pressure on the workpiece, having only one edge.

Using a smaller endmill/slotdrill can be a prefered option if your head is noticably out of square ie less of a mismatch on the stepover.

DP

[M250cnc]

Using a flycutter can also show any play in the spindle bearings/machine, as its an interrupted cut with a flycutter.

It will also show much more any head tramming issues if you have to take more than one cut.

It would only be suitable for soft material, so i would use a face mill, sharp inserts with a large radius on the insert.

Phil

[Monkey King]

fly cutter.
1.efective use if your spindle and table already worn so you can't use face mill.
which if you insist use face mill, than the insert will be very fast worn out.
2.speed will be reduced compare to face mill. Face mill have more insert, table feed multiply by insert number.
3.since using own cutter, cost nothing. but you must have skill to grind the cutter. or maybe use face mill holder with 1 insert.
4.I made myself the fly cutter, so I can adjust the diameter for the cutter,
bigger diameter perfect for cheap cost 1 time finishing, 0.05mm depth, table feed 35mm/min. but very slow.

[78nova]

A good fly cutter with 1 or even 4 inserts will normally leave a better finish than an end mill since a fly cutter will usually be free-er cutting than an end mill. End mills do not have as much end clearance and can leave an OK finish if it is factory ground. We have to use end mills to do a lot of our parts since we side cut and end cut at the same time while forming a profile radius along with the corner radius. These end mills we use are Fullerton SKI-CARB End Mills. We set them in Shrink-Fit holders most of the time but we also have some set up in ER Collet holders. The motion you drive the cutter and the amount of overlap affects the finish left behind. When we have to leave behind a 32 finish that is usually required within a certain diameter on the milled face, we finish off the face to depth and then we drive the cutter to the center of the required diameter and then spiral back out ccw to create this diameter. This helps to create a 32 finish. The factory grind works good but regrinds usually create more drag ( less clearance ) and the finish left on the face gets worse so we send these cutters out for resharpening. Most of the good stuff today is produced on multi-axis cnc tool grinders so it is very hard to reproduce the factory grinds on some tooling.

[Helmuth]

For many years I liked using a fly-cutter in place of an end mill. I also made my own fly-cutter. However, to get a nice finish I tended to run it at fairly high speeds and the thing was always out of balance. I learned to use brazed carbide tool bits quickly. I just got a feeling, from the sound, that it was beating the heck out of the spindle bearings. However, a couple of years back I bought my first indexable face-mill and fell in love with it. Finding an arbor for my old Gorton 2-30 was a nightmare but I finally got lucky on an e-bay deal. I probably won't go back to fly-cutters but the good face mills are really expensive. I wanted to attach a picture of a part's finish that the facemill makes but just directing you to our web page will be easier. Without being an attempt to advertize our business, the picture is in the photo gallery of www.qtfabrication.com. The face-mill is a Kennametal KSSR3CP40, cuts 3" in diameter, and uses 6 sharp trapezoidal carbide inserts. The block is a piece of 6061-T6 I was squaring up for a bearing housing. I have machined some copper parts for a customer that wanted it surface ground after machining. I think the face-mill leaves a nicer finish on non ferrous materials because grinding requires a rather coarse stone.