Fly Cutters?

[ZipSnipe]

Hey Brenda if ya can afford it get a cutter like Dickeybird linked to. They work fantastic !! They not only face metal but if your mill is strong enough can take chunks off steel.

[InspirationTool]

Fly cutters are great!

Get a cheap set of them from Enco, get some HSS bits, grind some relief on the side and bottom, grind some rake into the face, radius the corner a bit, and have at it. Keep the cuts shallow and the rpms fairly low, and take it from there.

[BobWarfield]

I'm not sure why I would want a set of fly cutters so similar in size. I have a larger (2 or 3"? I forget) one similar to the ones you've pictured. I use brazed carbide bits in it. I've had no chipping problems with them despite the interrupted cut nature of fly cutting. Surface finish is great on both aluminum and steel. You will find out if your mill is trammed properly first time! For what little wear the carbide gets, I just touch it up sometimes with a stone by hand. Keeps the surface finish mirror like.

I picked up a Lovejoy facemill off eBay brand new (Lovejoy sells there) for slightly more than the facemill pictured on Grizzly's site. It works really nicely and is positive rake for low cutting forces on smaller mills:



My experience with carbide is that having the right positive rake inserts in your tooling makes all the difference on these hobby class machines.

Getting back to size of fly cutters, I view my fly cutter as being mostly useful for achieving the best finish now that I have the face mill. BTW, finish is only slightly better--the face mill does a real nice job. I prefer the face mill for most operations and just run the fly cutter last if I need a fine finish. For the best finish, you'd like to cut the whole surface in one pass. I guess you can see why I don't care much for those sets of flycutters that are so close in size--why bother, just run the biggest one?

Now I did recently purchase a really big fly cutter off eBay--6" diameter. I had watched the Widgitmaster using a flycutter of his own design that was big (plans are in one of his threads) to get a nice finish on a big plate, so I wanted a bigger fly cutter for cutting wider plate. I haven't had a chance to try it yet, but will soon.

I will also experiment with an HSS cutter, as a lot of folks swear you can get an even finer finish. They're not hard to grind, just need to find the time.

Best,

BW

[Mcgyver]

Originally Posted by BobWarfield For the best finish, you'd like to cut the whole surface in one pass. I guess you can see why I don't care much for those sets of flycutters that are so close in size--why bother, just run the biggest one?

hey Bob,

cutting the whole surface in one pass is the idea, if the mill's trammed properly you get a nice cross hatch and no line that you might if doing it in two passes. So far as the the sizes to, you want to pick a size close to the width and then adjust to tool to be just larger than it. If the tool is about the dia as the work, it enters the cut gently, as in a tangent to a circle. if its a lot larger than the work, its going to smack into side of the cut by the amount of the feed (per rpm in the case of cutters) larger dia cutters, ie flycutters, have a lot of leverage so that smacking is tough on tooling, esp carbide. Also, the smaller you keep the cutteri dia, the quicker you can run

an advantage of carbide for flycutters is when running a large dia cutter as most vertical mills don't go below 100 rpm or so. other than that i find the grind is wrong and doesn't meet my objective of being incredible frugal in the shop

[Zumba]

One thing to note about carbide insert facemills is that they are meant to be run FAST, because carbide inserts (finishing type) are meant to be run fast.

Let's say you've got a 4" diameter face mill... kind of a standard size for smaller VMCs. Diameter at the cutting edge is 12.56" = 1 foot roughly, which makes for an easy conversion to SFM (RPM will roughly equal SFM).

If you look at the carbide grade charts for all the insert manufacturers, the recommended SFM for aluminum materials is at the minimum 1000 and as high as 8000. So the RPM should be at the minimum 1000. The last guy I talked to about face milling has a Fadal VMC and spins the face mill at 5000RPM.

[BobWarfield]

Originally Posted by Zumba One thing to note about carbide insert facemills is that they are meant to be run FAST, because carbide inserts (finishing type) are meant to be run fast. Let's say you've got a 4" diameter face mill... kind of a standard size for smaller VMCs. Diameter at the cutting edge is 12.56" = 1 foot roughly, which makes for an easy conversion to SFM (RPM will roughly equal SFM). If you look at the carbide grade charts for all the insert manufacturers, the recommended SFM for aluminum materials is at the minimum 1000 and as high as 8000. So the RPM should be at the minimum 1000. The last guy I talked to about face milling has a Fadal VMC and spins the face mill at 5000RPM.

There's never enough rpms for aluminum in the home shop it seems. With that said, these face mills will run fine at 1000-1500 rpm. At least mine does. I find I can run it flat out on the mill at much faster feed rates than the flycutters when I am squaring blocks. That's my primary application for it. It's also a heck of a lot quieter than the darned flycutter.

McGyver, I see your point on flycutter diameter, but it seems to me one of degree. I do have 2 flycutters, one at the larger end of the set size and one really large. I still can't see the point of buying the set with 3 that are almost the same size. I think its a come on--spend more for 3 flycutters when 1 (in that size range) would do.

BTW, the big flycutter came from eBay seller "craigj09". He has one listed now (looks like he has a little business making them), ebay auction #
170086723247.

Best,

BW

[longhair51]

I agree with the shock issue on carbide, however necessity being the mother of invention, I used my homemade flycutter( shown in above post) to machine this 3/4" 304ss piece at approx 2400 rpm. The flat and curved part were both done w/the tool at .015 per pass. It's not finished yet so it looks pretty rough.

A coated TPG 222 insert was used

Don

[ZipSnipe]

Like Bob Warfield said the carbide cutter is the way to go, the finish is sweet. I made a two flute carbide cutter with a negative rake(negative by mistake) and it still cuts deep and sweet. On my small mill I was able to take way more off than when I was using the fly cutter.