[BrendaEM]

Hi,
I have a few questions about the inexpensive fly cutters in such places Enco, and Grizzly, the kind that holds lathe-style carbide tipped bits:
http://www.grizzly.com/products/g5717

Do I want the bit I order to have carbide on the right or left hand side?

I have read that very shallow cuts are the way to go, such as .001"-.002" a pass. They do not seem like a bit I would want to crash/stall.

Which bit profile would be best for use with a fly cutter? Do I want a straight bit in which the carbine extends along the line of the bit without angling with a point-like minimal cutting length? Or do I want an angled bit that has larger cutting length, and a shallower cutting angle?

On a mill such as an X3, what is the largest fly cutter that's safe to use?

I've seen someone make, a fly cutter that holds carbide inserts directly--are these better or available?

(thank you)

[DICKEYBIRD]

I bought this one http://www.grizzly.com/products/g2861 for my X-3 and it's pretty sweet. I've only used it twice to square up some cast iron but so far it works great. The X-3 slows way down and has enough torque to work well with it.

The ad says it doesn't come with inserts but mine did. Looking at the way it was packaged I suspect they all do. I also ordered an extra set.

[Zumba]

The max size of fly cutter will depend on the material you're machining and how sharp the tool bit is. I'd say 3" max on aluminum on an X3 with shallow passes, 2" on steel. The tool bit should be a left hand style (not a big deal actually, with a RH bit, all you have to do is reverse the spindle rotation). I'm not sure what the angle is set at on those fly cutters you've shown, but if it's more than 15 degrees, you can use a "BL" style tool bit which has a 15 degree lead angle.

BL, 5/16", C5 carbide for steel, model #325-2537 (www.use-enco.com)


The carbide insert face mills that Dickeybird mentioned are quite a bit different. Carbide inserts are formed rather than ground, and are typically not as sharp. They require much heavier cuts to get a good finish, which rules them out for cutting steel on small machines. Cast iron and aluminum are more manageable. Choosing the correct insert can also be a royal PITA, as there are literally tens of thousands to choose from. If you want to go this route, I'd recommend a much bigger machine.

Are you familiar with cutting tool geometry? If not, you should definitely read up on it. Machinery's Handbook is a good place to start. The same basic rules apply to turning on a lathe. Learn the correct geometry as well as how to sharpen/shape tool bits with the correct geometry. Become familiar with the terms "relief", "rake", etc.

[BrendaEM]

Ohhhh. I think I found the source of my right-left confusion: they were meant for lathes, and lathes cut from underneath the stock. I was looking at them from the viewpoint of a mill, thinking if the cutter turns clockwise, the carbide should be on the right. The carbide is on the left, for a lathe, but for milling, they held upside down, putting the carbide on the right.

I appreciate your help. I just don't want to get a box of assorted ones and experiment, or find that I have the wrong one, and I have to spend $5.00 to skip 1 $3.20 part. I will get spares.

I imagine the carbide chip issue would also affect these:

This one is nice an beefy, though.
http://www.newmantools.com/specials/b52.htm

This one is homemade (translated):
http://babelfish.altavista.com/babel...furaisu-17.htm

They do look strong. I read somewhere that, fly cutters often cut on both directions--even at the same depth, suggesting that the stock the carbide is mounted on may bend.

[This reminds me of a article about wood plane tear out. I've read the reason would tears out, is because the blade bend as it cuts, and snaps/whips back--tearing out the wood.]

[S_J_H]

I have used a 3.125" flycutter in a boring head on both x2 and x3. I also use an angled flycutter such as the one Grizzly sells. I use a left hand lathe tool with those. Finish is about the same on each but the boring head flycutter allows easy angle adjustments for the tool bit and works real well even on the x2 in aluminum. I generally take .005"-.01" cuts . I use as much speed as possible. Steve

[Bowman]

The shell type multi insert carbide face mills are great but do require a bit of HP to be used well since depending on the width of cut you may have several cutting forces being applied at the same time by the multiple cutters. They make some smaller ones that are not indexable inserts but just a solid cutter with multiple cutters. There is a term that is eluding my memory right now that describes tool deflection where the tool is being deflected along the cut and has to be allowed time at the end to adjust itself and overcome the cutting forces causing the defelction to finish the cut cleanly. UGhhh its on the tip of my tongue just not coming out.

I used the 8 insert shell face mills on Bridgeports and they were nice for squaring up stock quickly. I have yet to try fly cutting on my Sherline but will give it a go soon.

Good luck,

Bo

[hoss2006]

Hi Brenda,
You could make your own 2 in. flycutter like I did.
Here's my print.
It uses a single Kennametal Carbide insert KC850.
You can get them here
http://www.jlindustrial.com/catalog/...tosearchpage=Y
Or a lot cheaper on Ebay like here,
http://cgi.ebay.com/Kennametal-Lot-o...QQcmdZViewItem
I hold the insert with an allen head screw.
Later Hoss (Dan Kemp)

[longhair51]

Here is a flycutter I made from 304 ss. I used a shell mill holder for the shank. The machining is rough, but I needed it and was in a hurry.

This was done on an x2 manual mill.

HTH

Don

[in2steam]

Ohhhh. I think I found the source of my right-left confusion: they were meant for lathes, and lathes cut from underneath the stock. I was looking at them from the viewpoint of a mill, thinking if the cutter turns clockwise, the carbide should be on the right. The carbide is on the left, for a lathe, but for milling, they held upside down, putting the carbide on the right.

I appreciate your help. I just don't want to get a box of assorted ones and experiment, or find that I have the wrong one, and I have to spend $5.00 to skip 1 $3.20 part. I will get spares.

I imagine the carbide chip issue would also affect these:

This one is nice an beefy, though.
http://www.newmantools.com/specials/b52.htm

This one is homemade (translated):
http://babelfish.altavista.com/babel...furaisu-17.htm

They do look strong. I read somewhere that, fly cutters often cut on both directions--even at the same depth, suggesting that the stock the carbide is mounted on may bend.

[This reminds me of a article about wood plane tear out. I've read the reason would tears out, is because the blade bend as it cuts, and snaps/whips back--tearing out the wood.]

Carbide is an amazing thing it will cut even when so dull that if it were anything else you would not do anything at all. Carbide will cut ,when inserted into a tool holder upside down(the first time I used a lathe) and sideways(the second time I used a lathe) and reversed in a wood saw a trick for very thin aluminum, of course I cut regularly with the saw forward if its over 1/8". The reason you get tearout normally in figured wood is two fold, typically its unsupported cutting, and angle which is two low(or in some cases too high). That is one of the reasons a high angle plane with good support like a Norris does so well in hard wood. Stanley has a large gap in there bed on the bailey style, and its taken up some in the bedrock series. I know because one of things I do with my equipment is restore older hand planes and make them very usable compared to new.
chris

[BrendaEM]

I appreciate all the feedback for such a newbie question. Thank You.

[Mcgyver]

Hi,
I have a few questions about the inexpensive fly cutters in such places Enco, and Grizzly, the kind that holds lathe-style carbide tipped bits:
http://www.grizzly.com/products/g5717
I have read that very shallow cuts are the way to go, such as .001"-.002" a pass. They do not seem like a bit I would want to crash/stall.

Which bit profile would be best for use with a fly cutter?

they look like they hold a lathe style carbide bit, but i'd disagree that that is the right tool - the front clearance on those bits is often insufficient in my experience. Those fly cutters orient the tool differently than when in a lathe, they are ground to cut in direction of the green arrow (from image in link below) not the red arrow:

http://www.cnczone.com/forums/showthread.php?t=28295

imo a flycutter needs to be ground for the job OR make a cutter that holds the bit vertically so the cutting edge is as was intended by the geometry. of that diy insert holder looks good.

i don't know the x3, but depth of cut with a fly cutter is determined by available torque. because there is so much leverage, they do need light cuts, but 10 or 15 thou should be doable. one advantage of carbide is that some mills won't run slow enough to use hss with the larger dia's a fly cutter provides when flycutting steel. If that isn't a constraint (or unless you are running a giant industrial machine) hss is the tooling of choice as it requires less cutting force than carbide - this allows a bigger depth of cut (plus is cheap cheap cheap and easily resharpened).

[roninB4]

Carbide makes a wonderful cutting tool but isn't my first choice for a fly cutter. The downfall of most carbide (insert, bit, solid) is in shock. It causes micro fracturing of the edge and this quickly leads to chipping. This doesn't present itself in a multi-insert gang cutter, solid end mill, or any other tool that has keeps the shock to a minimum. With a single insert/bit tool like a fly cutter the carbide gets slammed into the material every revolution with nothing to balance/distribute the shock load. An interrupted cut will just beat the chicken soup out of carbide. Yes you can use carbide in a fly cutter but tool life is not going to be as long as carbide is capable of. Even the rigidity of the machine can affect it. Carbide needs a rock solid machine to realize the benefits of it. HSS needs to be run slower but will take more of a beating than carbide and you can easily sharpen it yourself. Carbide when it chips will often need up to 1/32 removed from the edge to get past the fracture line. Hss just gets dull if you run the SFPM formula correctly. I prefer to save the carbide for hardened material. Even when cutting castings I'll often use HSS to bite through the "skin" and then resharpen for my final pass. HSS may not be capable of the speeds/feeds as carbide/ceramics but it still has a place as a cutting tool of choice. JMHO.

[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]

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]

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.