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EddyCurr
04-17-2010, 03:36 AM
Are the following tool bit angles correctly located on the fly cutter
shown in the images below?

Side cutting edge angle
End cutting edge angle
End relief (clearance) angle
Side relief (clearance) angle
Side rake angle

http://www.slalom4me.com/imaged_a01/jpg/other/tools/mills/tooling/Flycutter_01a.jpg
http://www.slalom4me.com/imaged_a01/jpg/other/tools/mills/tooling/Flycutter_02a.jpg
http://www.slalom4me.com/imaged_a01/jpg/other/tools/mills/tooling/Flycutter_03a.jpg

Davo J
04-17-2010, 04:20 AM
A rounded edge is needed for a good finish.
Have a look here, it is quite a good right up
http://madmodder.net/index.php?topic=850.msg6442#msg6442
Dave
Edit
Here is another
http://www.thewarfields.com/cnccookbook/MTMillSurfaceFinish.htm

Scishopguy
04-17-2010, 12:42 PM
When you sharpen a tool bit for a fly cutter, think of it as if it was a turning tool for the lathe. Really, there is no difference other than it is going in a circular pattern instead of straight. The result is the same. You have to sharpen the bit with the material you are cutting in mind and adjust the clearance angles and rake accordingly. The angles are not black and white but many shades of grey, if you know what I mean.

Paul Alciatore
04-17-2010, 01:12 PM
First photo, the angles labeled "cutting angle". I don't usually worry too much about the one you labeled "end cutting" as it really is not a "cutting" angle. Fly cutters are usually used in a sideways motion to produce a flat surface so only the tip will actually cut on the "end". But if you are cutting to a shoulder, the one you labeled "side cutting angle" will produce that shoulder and if you want a square shoulder, you will need to modify that angle on this cutter.

You have the other three angles correctly labeled. There would also be an "end rake" angle but it is of less importance as a fly cutter would not be used for a plunging cut so 0 degrees would be just fine.

The side relief angle must be large enough to allow clearance for the radius of the cut. One good way to do this is to use the angle you want for the primary clearance here and add a secondary clearance facet that ends a bit behind the cutting edge at a larger angle.

As Davo said, do round the tip a bit for a better finish unless you just must have a square corner in a shoulder.

BadDog
04-17-2010, 01:52 PM
The surface/edge you have labeled "side cutting edge angle" is actually THE cutting edge. That is what you want to worry about getting a nice edge on (stoning), or at least the bottom 0.100 or so (depending on desired DOC). If you want/need "rake", it will be back from this edge. Also remember that the end is sweeping a radius, so you need more clearance "under" (behind) the cutting edge than normal. You need to clear the inscribed circle PLUS a bit to allow for in-feed clearance.

Also as stated, you may want a small radius at the bottom contact point in order to get a good finish. And your "side cutting edge angle" varies depending on what you are doing. As shown, it will give you a nice cut without as much drama/hammering, but you can't get close to a wall, and you sure can't get under an overhang (I have ground them to cleanup a dovetail).

Most of the other angles should be established by the fly-cutter body, though clearance is easily if needed.

So it works somewhat like a cheap boring bar using replaceable HSS bits, but the cutting edge shifted 90*.

lynnl
04-17-2010, 02:05 PM
Guys, I think that's just an unground, new tool bit he's using for illustration purposes.

dp
04-17-2010, 02:57 PM
I think if you ignore the labels which I doubt many would agree on, the angles are the right ones.

Here's an image I edited from one on Wikepedia:

http://metalworkingathome.com/images/flycuttergeometry.jpg

It is essentially a left-hand lathe cutter, rather common geometry and which should slip right into your flycutter holder. The surface labeled side view becomes the advancing surface in your holder.

and here's the original from Wikepedia - a right hand version of the same thing:

http://en.wikipedia.org/wiki/File:Tool_Bit_Geometry.JPG

Edit: I edited the surface names in the image to make it more appropriate for a flycutter.

Mcgyver
04-17-2010, 04:07 PM
your last photo correctly shows where the rake and clearance are...not many seem to get this for a fly cutter. The right tool to use is NOT a lathe knife tool, a knife tool has the cutting edge on the side of the bit, whereas a fly cutter cuts on the end of the bit

The links dp put up are imo misleading in the sense that the give the location of the angles for a knife tool. The identity of the angle isn't determined by their orientation to the tool bit, but by where the cutting action is taking place, which i think you've nailed. For a flycutter as you presented the cutting is at the end as you've shown, not on the side as it is for a left hand knife tool.

The nicest fly cutter tools imo, and the nicest lathe facing tools, are those with the cutting edge on the end with positive rake formed by grinding a chip breaker

Dennis i know thinks himself pragmatic for not knowing or caring where the cutting edge is and me a nanny for paying attention to it :D....but I think you're on the right track; if you can't actually identify where the cutting edge is, how the heck are you going to grind things properly? Fundamental I say.

http://i20.photobucket.com/albums/b201/michael0100/DSC_3151-large.jpg

Spin Doctor
04-17-2010, 04:10 PM
First off, I really dislike fly cutters. IMO they are hard on milling machines. Especially the light duty mills seen in home shops (I am including BP's in this). Think of it this way. While the tool geometry is similar to a lathe tool it is also like taking an interrupted cut on the lathe. Every revolution you are putting a load on the bearings and drive system and then unloading them. Just think of the strain the keys are being subjected to in the pulleys. That said there ways to limit the shock load on the machine. 1)Try to make the tool entry as easy as possible. That means finding a cutting path that upon entry intt the work the amount of material being cut is as thin as possible and the cut gets progressively thicker as the tool rotates. Think of it as conventional vs climb milling. 2) Grind the tool so it has more shear angle on the top rake. Better 10D than 5D. Keep the tool nose radius to a minimum if possible. The longer the radius the more material being sliced off each pass. Side rake has to be enough that the tool does not drag against the back side of the cut if the feed rate per revolution is high. 7D is about right IMO. 5D for the front clearance should work . Go to a web site like Sandvik or Valenite http://www2.coromant.sandvik.com/coromant/downloads/catalogue/US/MC_USA_klick_D.pdf and look at the insert geometry for and how they are mounted in the cutter for the light cut and low HP face mills. Granted they pound when only one insert at a time is in the cut but once one insert is in the cut all the time the load on the machine is much smoother and puts less of a strain on it. another analogy to this is if you ever have to order a Woodruff Keyseat Cutter spend the extra couple of bucks and get the stagger tooth type versus the straight tooth version. The difference in cutting performance is really noticable.

dp
04-17-2010, 04:25 PM
Dennis i know thinks himself pragmatic for not knowing or caring where the cutting edge is and me a nanny for paying attention to it :D....but I think you're on the right track; if you can't actually identify where the cutting edge is, how the heck are you going to grind things properly? Fundamental I say.


I actually didn't care for the poor orientation in the original lathe cutter view as applied to a flycutter so I rotated the end view and labeled the surfaces for a flycutter orientation. Never attribute to pragmatism that which can be explained by pure laziness :)

Mark K
04-17-2010, 06:18 PM
Hope this is not redundant comment, haven't read every word in this thread.

To help visualize fly cutter tool angles, grind a left hand lathe facing tool (for turning the left, or headstock, face) and install this in the fly cutter.

Mark

EddyCurr
04-19-2010, 07:59 PM
Thank you to everyone for the replies - I apologize for the lengthy delay
in replying.


Your last photo correctly shows where the rake and clearance are...
not many seem to get this for a fly cutter. The right tool to use is NOT
a lathe knife tool, a knife tool has the cutting edge on the side of the bit,
whereas a fly cutter cuts on the end of the bitThank you.


http://metalworkingathome.com/images/flycuttergeometry.jpg

The links dp put up are imo misleading in the sense that they give the
location of the angles for a [left hand] knife tool. The identity of the
angle isn't determined by their orientation to the tool bit, but by where
the cutting action is taking place, which I think you've nailed [in the OP].
For a flycutter as you presented the cutting is at the end as you've shown,
not on the side as it is for a left hand knife tool.If a Right Hand turning bit was positioned vertically as shown in the revised
image below, then I believe that the respective angles and clearances
would be correctly located for a fly cutting operation. However, just
mounting a Right (or Left) Hand bit in the illustrated fly cutting tool
would not position the bit optimally for cutting.

http://www.slalom4me.com/imaged_a01/jpg/other/tools/mills/tooling/Flycutter_01b.jpg


The nicest fly cutter tools imo, and the nicest lathe facing
tools, are those with the cutting edge on the end with positive rake formed
by grinding a chip breaker.

http://i20.photobucket.com/albums/b201/michael0100/DSC_3151-large.jpgThank you for this picture, it validates the suppositions made in the OP.

Would you be able to provide another image showing the type of finish
this bit produces and post about feeds/speeds (along with a bit of
background about the class & HP of machine: drill/mill, BP or other)?

.

Edit: Changed 'suitably' to 'optimally'

Carld
04-19-2010, 11:47 PM
This is my collection of flycutters and cutters I use in them. I run the flycutters at 1000+ rpm and take up to .050" on most metals. It helps to have a 30 to 45 deg leading angle on the cutter to cut smoothly and I don't use a radius on the cutter except for special cuts. A radius will make the cutter hammer and the larger the radius the more it hammers.

http://i82.photobucket.com/albums/j276/yeathatshim/flycutters.jpg

PixMan
04-20-2010, 12:19 AM
I haven't used a fly cutter in years because I don't much care for the hammering on the spindle of the Bridgeport. I suppose I'd use one if I needed to get a single full-width finish on a piece of aluminum, but for everything else I've been satisfied with the results I get with a 2-1/2" 45-lead 4-insert Widia face mill I have.

As long as the spindle is trammed-in right, the finish has been outstanding and no steps. It runs 4x the feed rate of a fly cutter, and much more if the fly cutter has HSS bits. Smooth as butter, light loads on the 1HP motor and the high shear angle imparts no hammering. I think I've rotated the 4-sided inserts once in 2 years of infrequent use, though if I needed more inserts the SEHN43's available from a wide variety of sources, in milling-specific grades and coatings.

dp
04-20-2010, 12:21 AM
This image shows the flycutter as installed in the tool. These cutters do not advance into the work as your arrow shows - they cut a sweeping spiral as seen from above like stretching a Slinky (tm) sideways into a flattened series of spirals.

The specific relief angle shown on the work facing surface is not correct for this service (zero degrees is fine, in fact, as shown in McGyver's photo) and further demonstrates that all cutter angles are ground to satisfy a specific need. If you see specific angles shown for a cutter then there should also be a description of how it is expected to be used or at least be obvious.

http://metalworkingathome.com/images/flycutteroverlay.jpg

Mcgyver
04-20-2010, 12:34 AM
If a Right Hand turning bit was positioned vertically as shown in the revised
image below, then I believe that the respective angles and clearances
would be correctly located for a fly cutting operation. However, just
mounting a Right (or Left) Hand bit in the illustrated fly cutting tool
would not position the bit suitably for cutting.


Eddy, on the above I 100% agree with your description of angles and orientation, but we have to be a little careful about categorizing it as 'not suitable for cutting'. My response was the subject of the thread being where and what are the various angles on a flycutter...i think you've got them right and i proffer that you will produce a better flycutter this way however the lathe knife tool approach will work; it'll remove material. ....sometimes i'll grab a brazed carbide bit and have at it..Lots of guys do it all the time as do I sometimes...its just not optimal.

It would be like taking a right hand knife tool and plunging a facing cut with it - it'll work. If it works, why do we care what's optimal? Because putting the right grind on reduces the cutting force and hopefully gets a better finish. There are times when things matter more than others, ie, the left hand lathe tool will work to a degree, but once one gets onto thinking in terms of where the cutting edge is and the ensuing angles, its not more effort to grind the bit right than fudge it.

my mill is an XLO, which is a beefy bridgeport style. imo the lighter the mill, the more you have to think about reducing cutting force. Speed is based on diam, material and cutter material and feed is based on DOC when roughing (what the machine can handle) and slow for finishing. I don't have a pic handy of the finish, but a good cross hatch pattern says things are working well.

I may be misinterpreting Dennis's diagram but it looks like a left hand lathe tool put in a flycutter which wouldn't be ideal - unless plunging down. flycutters to most of the work along the yellow line whereas the lathe knife tool is ground to cut along the red

EddyCurr
04-20-2010, 12:49 AM
This is my collection of flycutters and cutters I use in them.

I run the flycutters at 1000+ rpm and take up to .050" on most metals.
It helps to have a 30 to 45 deg leading angle on the cutter to cut smoothly
and I don't use a radius on the cutter except for special cuts. A radius will
make the cutter hammer and the larger the radius the more it hammers.

I have edited a copy of your image by adding identifying icons to
assist discussion. If this is unsatisfactory, I will remove the image.

http://www.slalom4me.com/imaged_a01/jpg/other/tools/mills/tooling/Flycutters_Carld_01b.jpg
The cutters appear to be left hand turning tool bits.

For the bits denoted by blue triangles, which of the edges on the face
do you observe to be acting as the cutting (chip-forming) edge - the
one with the yellow circle or the one with the red circle?

Do the blue triangle bits cut the same as the the orange square bits?

What is the diameter of the largest fly cutter tool and how far out does
the cutting edge of the insert extend from the circumference of the FC?

Thanks,

.

dp
04-20-2010, 01:09 AM
My personal favorite flycutters are shop made. They use round hss such as broken drills or centering drills and even round hss stock can be used (the centering drill shown for demonstration purposes). The cutter on the larger tool is parallel to the arbor, perpendicular to the bottom face.

http://metalworkingathome.com/images/flycutterExamples.jpg

The larger one was used to square and size this bar:

http://metalworkingathome.com/images/BoringBarHolder.jpg

EddyCurr
04-20-2010, 01:11 AM
This image shows the flycutter as installed in the tool. These cutters
do not advance into the work as your arrow shows - they cut a sweeping
spiral as seen from above like stretching a Slinky (tm) sideways into a
flattened series of spirals.

http://metalworkingathome.com/images/flycutteroverlay.jpgI need help understanding.

Isn't a fly cutter predominently used by setting it to a fixed Z-height and
then moved horizontally into and then across a surface?

In such a scenario, as the cutter reaches full engagement, isn't it cutting
using the edge denoted by the yellow angle for a maximum of 180 each
revolution? Isn't the edge denoted by the red angle sweeping the just-cut
new horizontal plane determined by the DOC?

.

dp
04-20-2010, 01:16 AM
Look at the swirls in the picture above - the stock was centered under the spindle and the cutter spiral-cut across the piece. The exit point was slightly further down the part than the entry point because of the table advance, but not by much. At 300 RPM and 3"/minute table feed the swirls are nearly circular. Note too that the swirls are made on the leading and trailing pass indicating the tram was pretty decent and the surface is not dished.

In the overlay image the tool I've pasted in has too much angle on the lower face. Zero angle is fine and adding a bit of angle with a rounded nose will produce a glassy surface on aluminum. A very sharp edge will leave cutter marks.

And I should add that I have a very small bench top mill. A larger mill will be able to leave swirls that have more diagonal sweep to them as they can feed faster.

Frank Ford made a similar cutter but his uses two dissimilar cutters:

http://www.frets.com/HomeShopTech/Projects/FlyCutter/flycutter.html

And here's a youtube vid of a carbide cutter going at 6061 aluminum:

http://www.youtube.com/watch?v=koYGLVGkRsI

And the pdf file with cutter geometry:

http://www.tormach.com/MfgDatabase/20103_surf_6061.pdf

EddyCurr
04-20-2010, 01:58 AM
Eddy, on the above I 100% agree with your description of angles and
orientation, but we have to be a little careful about categorizing it as
'not suitable for cutting'.I edited my remark in post #12 to change the wording from 'suitable' to 'optimal'.


My mill is an XLO, which is a beefy bridgeport style. imo the lighter the
mill, the more you have to think about reducing cutting force. Speed is
based on diam, material and cutter material and feed is based on DOC when
roughing (what the machine can handle) and slow for finishing. I don't have
a pic handy of the finish, but a good cross hatch pattern says things are
working well.I am working with a mill/drill similar to Grizzly's 2 HP G1007 (http://www.grizzly.com/products/Mill-Drill-w-Variable-Speed-Power-Feed/G1007) (although in the
Canadian market, the equivalent B1977 from Busy Bee (http://busybeetools.ca/cgi-bin/picture10?NTITEM=B1977) is rated at 1-1/2 HP.)

While it may be relatively more powerful and rigid than some other mills out
there, it is no bruiser.


http://cdn1.grizzly.com/pics/jpeg288/g/g1007.jpg

I am familiar with cutting speed approximations for combinations of cutting
tool and work piece materials, along with a few of the exceptions to made
in certain situations when turning, facing, boring and drilling for instance.

However, I have not come across recommendations yet for fly cutting
operations and am grateful for any guidance folks can offer along the lines
of "try starting out at 75% of the SFM recommended for turning when
using HSS on plain carbon ..."


... but for everything else I've been satisfied with the results I get with a
2-1/2" 45-lead 4-insert Widia face mill I have.

It runs 4x the feed rate of a fly cutter, and much more if the fly cutter has
HSS bits. Smooth as butter, light loads on the 1HP motor and the high shear
angle imparts no hammering.I started down the path toward using fly cutters with single point HSS bits in
order to address the perception that a face mill fitted with multiple carbide
inserts is not optimal for my machine in some instances.

Am I chasing my tail for no good reason ?

.

Edit: changed 'will appreciate' to 'am grateful for'

BadDog
04-20-2010, 03:34 AM
For reference, I just recently made a 10" fly cutter (capable of 10.250 diameter pass without over extend) and it works fine in my Bridgeport cutting steel. It is very carefully made to be both concentric and true as well as (near) perfectly balanced. It works beautifully in steel with no evidence of "hammering" or chatter when cutting using slow feed, 0.001 to 0.005 DOC (all tested so far), and about 300 rpm (about 800 SFPM using Kennametal bronze brazed bits - 350s?). Makes depending on speed/feed, nice curls or longer spring like chips.

I've heard the argument about "hammering" since I first got my mill. The only time I get troublesome hammering is when I have screwed up (or situation forces less than ideal config). Perhaps the bit is dull (or sharpened wrong), or the cut is configured wrong (use shallow entry, like standard milling, not climb milling), or feed/speed/doc combo isn't working with other variables. On my recent big plate facing with the 10" cutter, it started off noisy/hammering, but adjusting only rpm and and feed I quickly had it producing near perfect chips and sounding as smooth as any face mill, but with finish far better (though slower). In this case, roughed out the bulk of the 1/2" deep total drop (approx 10" x 9" leaving ledge for subsequent dovetail) using a 2.5" 6 insert face mill. 6 inserts means 6 times the feed rate! Then finished with 2 passes (first didn't fully cleanup) using the bit fly cutter. Very happy...

BadDog
04-20-2010, 03:54 AM
You know, I always think "I need to take some pictures of that stuff one of these days, and never do. So what the heck, I went out and got one. Here is the 10" fly cutter I made, along with it's scrap box stand to protect the edge of the bits.

http://img4.pixa.us/366/18809964_th.jpg (http://baddog.pixa.us/images/18809964/)
Click for larger image. Then click that image for full size.

EddyCurr
04-20-2010, 12:12 PM
Thank you for the observations on the subject of fly cutters and
"hammering".


For reference, I just recently made a 10" fly cutter (capable of
10.250 diameter pass without over extend) and it works fine in my
Bridgeport cutting steel. It works beautifully in steel with no
evidence of "hammering" or chatter when cutting using slow feed,
0.001 to 0.005 DOC (all tested so far), and about 300 rpm (about
800 SFPM using Kennametal bronze brazed bits - 350s?).

http://img4.pixa.us/366/18809964.jpg
That is an attractive piece of tooling. It sounds like it works
very well in use and the inclusion of operating parameters is a
benefit.

I have some questions about the geometry of the edges.

Are the Kennametal bits in this application Left or Right Handed?
What is the approximate angle of the vertical cutting edge at the
outer circumference, relative to the vertical axis of the tool holder?

.

EddyCurr
04-20-2010, 12:44 PM
My personal favorite flycutters are shop made. They use
round hss such as broken drills or centering drills and even round hss
stock can be used (the centering drill shown for demonstration purposes).
The cutter on the larger tool is parallel to the arbor, perpendicular to the
bottom face.

http://metalworkingathome.com/images/flycutterExamples.jpg

The larger one was used to square and size this bar:

http://metalworkingathome.com/images/BoringBarHolder.jpgI can see the benefit of a holder that permits recycling/repurposing of
objects. Also, the vertical orientation and round shape of the 'bits' seems
like it would simplify the cutter geometry required on the working end of
the bit.

Then there is the option of adding a second complementary bit at 180
from the first one as shown in the link provided to Frank Ford's Fly Cutter
page (http://www.frets.com/HomeShopTech/Projects/FlyCutter/flycutter.html) at Frets.com must assist tool balance at higher speeds.
Positioning the cutters in the holder on different radii and setting heights
to different depths, too.

I bought a commercial fly cutter to get started, but I'm looking forward to
building cutters like your's and Mr Ford's to try in the future.

Thanks.

.

EddyCurr
04-20-2010, 12:45 PM
A rounded edge is needed for a good finish.
Have a look here, it is quite a good right up
http://madmodder.net/index.php?topic=850.msg6442#msg6442
Dave
Edit
Here is another
http://www.thewarfields.com/cnccookbook/MTMillSurfaceFinish.htmSomehow, I overlooked thanking you for these links earlier.

They are very helpful. The second link contributed to my initial
images in this thread - it left some questions, hence this thread.

.

Paul Alciatore
04-20-2010, 03:33 PM
Here's a fly cutter I made for milling in the lathe. It fits my SB-9 spindle thread.

http://img.photobucket.com/albums/v55/EPAIII/FlyCutter4In.jpg

It has two cutting tools so it is more balanced. This means less vibration. Two cutting edges can produce a better finish.

And the tools can be ground almost exactly the same way that you would grind a lathe tool. Only difference is the side clearance necessary due to the circular cutting path. See my first post above.

johnhurd
04-20-2010, 04:45 PM
First off, I really dislike fly cutters. IMO they are hard on milling machines. Especially the light duty mills seen in home shops (I am including BP's in this). Think of it this way. While the tool geometry is similar to a lathe tool it is also like taking an interrupted cut on the lathe. Every revolution you are putting a load on the bearings and drive system and then unloading them.

Doesn't a 2-4-6 flute EM do the same thing only at a much faster rate?

BadDog
04-20-2010, 04:59 PM
Are the Kennametal bits in this application Left or Right Handed?
What is the approximate angle of the vertical cutting edge at the
outer circumference, relative to the vertical axis of the tool holder?.
They are left-hand bits modified as stated earlier. Just clearance for the swept diameter, and add a point radius to suit. The slots are (IIRC?) at 40*. When used with the L bits pictured, the stock end angle is about right to make a smooth cut at very low DOC when not cutting to wall or other feature. As I said, I've used it for 0.001 to 0.005 so far, but I suspect about 0.010 to 0.020 it's going to start having trouble due to excessive leverage. Then again, it was not meant for that. If I need to remove material, I can either increase feed a bit (and sacrifice finish). If I want still faster removal, I'll switch to my small face mill to plow on through, then switch to the fly cutter to handle the finish with slow single pass cut over the entire area.

BadDog
04-20-2010, 05:12 PM
Doesn't a 2-4-6 flute EM do the same thing only at a much faster rate?
The problem comes in with the cutting edge completely leaving the cut/material, then reentering. A multi flute cutter (depending on width of cut, number of flutes, and helix angle) generally keeps at least one edge cutting all the time. So the load doesn't constantly slam back and forth from "0" to "N". But this can be marginalized in a fly cutter by proper selection of swept diameter and in-feed position. For instance, you basically never "climb mill" with a fly cutter. With a 50% WOC, that's basically the worst case scenario. So I'll assume "standard milling". Ideally you want only a little overhang on the side approaching the cut. This causes the cut to start with a fairly small/thin chip, increasing as it goes (including in-feed), and then maybe (or not) decreasing out the back side if you are over 50% WOC.

I think the main problem comes in when folks make one or more of a few mistakes (or are forced into this by requirements/limitations). One is an improper ground bit. If you don't (or can't) have that lead angle, it gets quite a bit rougher, and much harder to get it to settle down. Or, if you don't have a suitably sized fly cutter while also dealing with an obstruction, you may have to (effectively) enter like you were climb milling. Combine the two and now you have real troubles. You also don't want to get too aggressive with DOC, particularly in harder/tougher materials (i.e. steel) with a larger diameter cutter. But if you can avoid these situations, and have a rigid cutter body, playing with the feed/speed will generally make it settle to a nice smooth cut.

One other thing to consider is that you don't want the cutter overhang on the entry side to be TOO small. If you do, you'll get a horrendous bur (particularly soft steel). So experiment. Sometimes things stack up against you and you have to make do, but fly cutters don't have to hammer or otherwise risk damaging your machine to work.

johnhurd
04-20-2010, 05:30 PM
I am not even close to knowing what I am doing but when I saw the centering tool in the shop made tools thread I had to have one
http://img.photobucket.com/albums/v338/johnhurd/MVC-006S.jpg

the first one I just milled stock and welded it to the bearing bar this one was a poser as I had no dove tail cutter so I just ground a bit and put it in my fly cutter. I realize it is not NASA bound but works for me.....

Carld
04-20-2010, 09:19 PM
Eddy asked:

For the bits denoted by blue triangles, which of the edges on the face
do you observe to be acting as the cutting (chip-forming) edge - the
one with the yellow circle or the one with the red circle?

Do the blue triangle bits cut the same as the the orange square bits?

What is the diameter of the largest fly cutter tool and how far out does
the cutting edge of the insert extend from the circumference of the FC?


Answers:


On a flycutter the edge that leads into the cut is the cutting surface. That means the edge on the circumference does the cutting as it leads across the surface of the work.

The cutters marked with blue triangles cut a square shoulder and hammer when they cut. I only used them to square a shoulder, not to cut the full surface of the work. You have to use a 30 to 45 deg leading angle to cut smooth. If the leading edge is perpendicular to or angled away from perpendicular they will hammer like hell.

The smallest is 3/4" dia and the largest is 3". The smaller flycutters were made for special jobs. The various cutters were for special jobs and for normal flycutting a surface I only use cutters with a leading angle and most the time I use the two largest flycutters.

It's hard to believe how fast of rpm and feed rate I can run them at. I get excellent surface finish with them. A very small radius, about 1/64", on the cutter works best.

dp
04-21-2010, 01:31 AM
Here is another interesting idea for fly cutting. By rotating the insert slightly this goes from being a boring tool to an adjustable fly cutter.

http://www.mesatool.com/index.php?main_page=product_info&cPath=2&products_id=9