# Superfly Cutter



## ddickey (Nov 29, 2017)

I made my own cutter body and bought the tool bar for SEHT Insert.
My surface finish has never been very good. Although bright and shiny there is a small amount of ripples on every cut. The back cut takes the ripples out for the most part if the mill is trammed perfectly. Anyway I noticed the wear under a new insert I put in. I'm wondering if the wear is indicative of some small amount of incorrect angle when I made it. 
Sorry the pic is not very good.


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## Wreck™Wreck (Nov 29, 2017)

Tilt the head so that the tool cuts on one side only, dragging the tool over the back side will result in more tooling marks and poor finishes.

By tilt I mean just enough to clear the following part of the tool, depending on the machine and part holding of course, this may be as little a .001" across the tool path, if the machine is a bit wobbly the chances of a nice finish when recutting on the backside with a fly cutter approach zero.


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## chips&more (Nov 29, 2017)

If you tilt the head from perpendicular. Your fly cutter will not cut a flat surface. It will be concaved. A perfectly aligned head to table with the pass of a cutter will leave cut marks leading and trailing. I find that pattern of cut very acceptable and shows a well aligned machine. Or it's time for a surface grinder...Dave


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## Chipper5783 (Nov 30, 2017)

My vote is for Wreck's method.  Kick the head very slightly out of tram (so the return cut has slight clearance).  I don't disagree with Dave, that the surface will be slightly concave.  You can set the fly cutter to cut a wider track than your work piece (example - for a 2" wide part, set a 4" wide sweep, and with a 0.001" clearance on the back side, it will only be 0.0005" concave).  This is a flycutter on a mill - that half thou out of flat is probably a smaller error than other flatness / squareness tolerances.  As Dave pointed out, if that isn't good enough then get a surface grinder.

Also, that back side cut of approximately 0.000" drags the cutting edge, causing it to dull more quickly.  If you are cutting a tough material, it can be tricky to complete a pass with the tool still being sharp.

In terms of surface finish with a fly cutter, I find that the brazed carbide bits, sharpened with a very small radius (almost to a point) and a keen edge, and the head tilted slightly out of tram, just so the back side clears - usually produces a very nice finish.


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## mikey (Nov 30, 2017)

ddickey said:


> I made my own cutter body and bought the tool bar for SEHT Insert.
> My surface finish has never been very good. Although bright and shiny there is a small amount of ripples on every cut. The back cut takes the ripples out for the most part if the mill is trammed perfectly. Anyway I noticed the wear under a new insert I put in. I'm wondering if the wear is indicative of some small amount of incorrect angle when I made it.
> Sorry the pic is not very good.
> View attachment 248377



Sorry, Duane. We cannot see the area of wear clearly, although there is a blob of light just below the flat of the insert - is that it? I just checked my insert and there is no wear in the area of your light blob.

My column is trammed within 0.0005" of dead flat, which is adequate for most work. I get a cut on the front and back with my fly cutter but the finish is adequate. I'm not sure if it is the angle of the tool in the holder or the tram of your mill that is causing the wear but I suspect the former.

Have you tried indexing the cutter to see if the pattern repeats? If the insert wears in the same place then you have a real issue.


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## spumco (Nov 30, 2017)

If you suspect the holder isn't quite perfect, then maybe what you're seeing is some rubbing behind the cutting edge.  My superfly doesn't have any of it.

Before you fiddle with the head tram, maybe try sticking a thin, narrow shim on the back of the tool bar at the top ('top' when it's in the spindle).  The shim should be no more than 1/4" the width of the toolbar and full-length of the pocket.  The idea is to rotate the tool bar in the holder a bit to take out some of the positive rake to give yourself a little more relief on the back side.  Should take about a minute with some brass shim stock, and you can snug up the tool bar good and tight.  Aluminum pop can might be even better as it's a bit more 'grabby' than brass, but it may be too thick.

Another thing to check is if the cutting edge is truly flat on the surface.  You will be adjusting the bar angle in the holder a little bit to get the cutting edge flat.  I did mine by putting a fly-cut aluminum chunk in the vise and rubbing a bunch of sharpie ink on it.  Once it's dry you can lower the head and rotate the cutter by hand until it just starts to scrape off the ink.  Adjust the tool angle until you're scraping off the full width of the cutting edge.  This helped quite a bit with surface finish on my mill.


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## ddickey (Nov 30, 2017)

Yes Mikey. Its a wear mark or rub mark. The insert is a Kennametal - SEHT43 KCPK30.
My mill is trammed in about the same as you. I get a cut on the front and back going in both directions. I think I must've screwed up the angle slightly when I made the body. Spumco is on to something as I noticed the insert was not cutting on the full face when I turned the cutter by hand and barely took a scrape. I'll try the shim the angle but I'm back to work tomorrow night so will have to wait until my next days off.


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## Billh50 (Nov 30, 2017)

Tilting the head will cause a concave surface. The wider the surface the more it will be noticed.


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## Bob Korves (Nov 30, 2017)

If the spindle is truly square to the work, the leading cut will be heavier, and with the material already having removed, the trailing cutter will be doing very little actual cutting, but will leave marks on the work.  The marks left on the finished work should be visually about the same, a light crosshatch, if the head is truly square.  I actually find that finish appealing.  If it needs to be smoother, use a surface grinder or other method.


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## spumco (Nov 30, 2017)

ddickey said:


> Yes Mikey. Its a wear mark or rub mark. The insert is a Kennametal - SEHT43 KCPK30.
> My mill is trammed in about the same as you. I get a cut on the front and back going in both directions. I think I must've screwed up the angle slightly when I made the body. Spumco is on to something as I noticed the insert was not cutting on the full face when I turned the cutter by hand and barely took a scrape. I'll try the shim the angle but I'm back to work tomorrow night so will have to wait until my next days off.



Let us know how it works out.  I think you'll find improvement with just setting the cutting edge flat - my cutter needed some tweaking straight from Tormach.

If it doesn't get better, I'd be interested in your material & feed/speed WOC and DOC.  My superfly can really rip chunks off, but surface finish suffers unless I keep it down to 0.01" and moderate feed on aluminum.


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## ddickey (Dec 4, 2017)

Tried some shimming. Nothing helped.insert is cutting flat as it appears on a scratch test.


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## ddickey (Dec 4, 2017)

This photo I stopped halfways through the back cut.


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## spumco (Dec 4, 2017)

Depending on your feeds/speeds and DOC/WOC, I think you're getting some vibration.  I suspect the head is bouncing up and down, or the column is flexing - the marks that appear as a radial pattern in the upper part of the second photo look like the cutter is doing a 'bite-skip-bite-skip' routine.  The fly cutter may simply be too much of a shock load for your mill frame.

The other thing is you didn't mention - or I missed it - what you're using for lubricant or coolant.  The second photo appears to have some galling/smearing that could be an indicator of chips sticking to the cutter or the cutter getting hot.

About the only thing I can suggest - short of seriously reinforcing the column with triangulated braces - is to take another light cut after tightening everything up.  Set the cutter to cut about 0.005-0.010 deep and tighten the Z-gibs until it won't move.  Tighten the Y-gibs same way.  Take a cut in X using plenty of lube (WD40 or kerosene if you're not running flood) and see if it's any better.

Do you have a big bullnose endmill?  say, about 1/2"?  If that surfaces better than the fly cutter (ignore pattern - just the surface finish/scratches) then I think I'm right about the frame simply being too floppy.  What RPM and IPM for those cuts?


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## Dan_S (Dec 4, 2017)

@ddickey

I'm with @spumco 

It looks like you have chatter on the leading cut, what rpm, feed, doc, and cutting diameter are you using? also do you have the quill locked?


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## ddickey (Dec 4, 2017)

Makes sense guys. 
No coolant. 1400 rpm. I tried a slow medium and fast feed (manual). Quill locked. I just adjusted the gibs but will try locking everything down. The diameter is set to the smallest. I think it is 2". I do have a bullnose endmill. 
I wonder if the body has anything to do with it. I believe I made it out of 12l14.


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## ddickey (Dec 4, 2017)

delete


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## ddickey (Dec 4, 2017)

deleted


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## ddickey (Dec 5, 2017)

Horrid finish. First is carbide @1400 RPM. Next was hss @ 490 RPM.


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## spumco (Dec 5, 2017)

ddickey said:


> Makes sense guys.
> No coolant. 1400 rpm. I tried a slow medium and fast feed (manual). Quill locked. I just adjusted the gibs but will try locking everything down. The diameter is set to the smallest. I think it is 2". I do have a bullnose endmill.
> I wonder if the body has anything to do with it. I believe I made it out of 12l14.



For aluminum, try 2500RPM and 15ipm at 0.01" DOC (superfly).  Spray liberally with WD40 while cutting, at least for this round of testing.

If there's flex, the tool body is probably the last thing.  You've got head movement, table movement, column flex, and so forth before you need to worry about the tool body.  Maybe I missed it earlier, but what brand/model is the mill?


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## spumco (Dec 5, 2017)

ddickey said:


> Horrid finish. First is carbide @1400 RPM. Next was hss @ 490 RPM.


That looks like when I tried to mill with a drill press and a Chinese X/Y table.  Yuck.


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## spumco (Dec 5, 2017)

Here's another test:
Put a dial indicator on the head or quill and bring it in to contact with the top of a parallel in the vise.

Now... push back hard on the head.  Is the indicator moving?  Do the same thing on the table.  Push on the long axis.  Pull it, push it, twist it, move the head side to side.

If the needle is moving much with a good shove, there's the primary reason for the surface finish issue.


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## Dan_S (Dec 5, 2017)

@ddickey what make/model mill are you using?


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## ddickey (Dec 5, 2017)

Spumco. I will try tomorrow and post back. I should've mentioned this was a scrap piece of 4140. I will try aluminum tomorrow. 
Dan, it is a 2000 Grizzly g1004.


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## spumco (Dec 5, 2017)

4140, that explains it.  The insert you showed at the beginning post is for aluminum, not steel.  The steel inserts are TiN coated and have a honed edge with a bit of a radius.

And the appropriate - theoretically - F&S for steel is about 800RPM, 3.5IPM for a 0.020" DOC and 2" WOC.  Gives about 470SFM.  At 1400RPM you're at 750SFM - way above the recommended speed.

Having said that, I have a larger, heavier, stiffer mill than you do (about like a Tormach 1100), and I can't get the superfly to cut well in steel.  It chatters and looks like your surface.

I've moved to a 5-flute insert mill and it works much better - less bouncing around.  Yes, it's probably less efficient, in theory, than the superfly (according to Tormach), but leave a glass surface.  I've reserved the superfly for aluminum only on my machine.


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## Billh50 (Dec 5, 2017)

Some un-coated inserts are for steels. It all depends on the grade and style.


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## ddickey (Dec 5, 2017)

I may try again in a different material today. 
The insert is coated. It is  Kenametal with a KCPK30 coating. Supposed to be used dry so I don't think that was the problem. It also has a T-Land edge. I tried another that had a honed T-Land edge with no difference. The radius is .039". I did try 900 rpm, appeared to be no difference. I agree I think it is a rigidity issue.

*KCPK30*
A multilayered TiN-TiCN-Al2O3-CVD-coated carbide grade with advanced Beyond™ post-coat treatment and a very tough substrate. KCPK30 has a wide application area in general and rough milling of steels and cast irons. It performs best dry but can also be used we


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## ddickey (Dec 5, 2017)

Billh50 said:


> Some un-coated inserts are for steels. It all depends on the grade and style.


One of the grades I have is a k68, x83, x45 and the KCPK 30. They must be manufacturer specific. I could spend all day researching but then I'd never get anything done.


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## Dan_S (Dec 5, 2017)

ddickey said:


> One of the grades I have is a k68, x83, x45 and the KCPK 30. They must be manufacturer specific. I could spend all day researching but then I'd never get anything done.


 Grades are brand specific.

Take a picture of the back of the pack and post it.


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## ddickey (Dec 5, 2017)

I have no box as I buy one at a time. 
This one I bought from MSC.
The others from Maritool & Little Machine Shop.
https://www.mscdirect.com/product/details/03270998


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## Dan_S (Dec 5, 2017)

ugh, kennametal's website is a steaming pile of crap, it never works, and they never provide clear material or cutting parameters.

from the picture it looks like it has either a blunt edge or a wide land. both require a powerful and rigid machine to get a nice finish.

Do you have any like this? This is the type your machine would need for alluminum.
https://www.maritool.com/Indexable-...110/p17209/SEHT1204AFFN-X83/product_info.html

Thats what I'm using here to make this cut in 7075-t6


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## ddickey (Dec 5, 2017)

Yes I do, and the K68 grade also in an SEHT.  
Blunt edge? Why would an insert have a blunt edge?


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## Dan_S (Dec 5, 2017)

ddickey said:


> Blunt edge? Why would an insert have a blunt edge?



A land makes the inserts last longer. If you are hogging off material, a razor sharp edge isn't needed and is a liability as it's delicate and will break easily.


This image shows what i mean even though they are referencing turning inserts.




For a machine like yours, you want high positive finishing style inserts, as they will require less rigidity and power.


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## Dan_S (Dec 5, 2017)

Mount the alluminum insert, run at your machine's maximum rprm, feed fast, at take about .01" off. If you can lube the cut with wd40 and post your results.


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## spumco (Dec 5, 2017)

ddickey said:


> I may try again in a different material today.
> The insert is coated. It is  Kenametal with a KCPK30 coating. Supposed to be used dry so I don't think that was the problem. It also has a T-Land edge. I tried another that had a honed T-Land edge with no difference. The radius is .039". I did try 900 rpm, appeared to be no difference. I agree I think it is a rigidity issue.
> 
> *KCPK30*
> A multilayered TiN-TiCN-Al2O3-CVD-coated carbide grade with advanced Beyond™ post-coat treatment and a very tough substrate. KCPK30 has a wide application area in general and rough milling of steels and cast irons. It performs best dry but can also be used we


Yea, I needed to look at that insert again.  It looked at first like the super-sharp aluminum insert, but a closer look shows the radius.  You clearly know what insert you're using - sorry for the assumption.

If you have, or can get, an insert with a smaller tip radius you may be able to get a better finish with the shallow cuts your mill can handle.  Positive rake, sharp edge, small tip radius, light cuts - everything for an under-powered, floppy mill.

SO...  we're back to rigidity.  About the only other thing I can suggest - given my staggeringly inadequate machining experience - is to suggest bracing the column.  There's an older youtube video of a guy who bolted big A-frame struts at the top and bottom of his mill column to a concrete wall and he indicated it stiffened things up significantly.  When I was considering a G0704 or PM940, I half-way designed a mill table that incorporated a triangulated brace from the column top to the table bottom with the apex tied to the mill base.  It would have stuck out another foot from the back of the mill, but would have reduced the mill base to column joint acting like a hinge.  Would have done nothing for the table or base twisting, but probably would have helped a bit.  I bought a different mill, so the design didn't make it off the napkin...


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## ddickey (Dec 5, 2017)

Here are some pics of aluminum. The back cut was only cutting in one direction so looks like I'll gave to tram the head tonight.


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## Dan_S (Dec 5, 2017)

The other thing you want to do is make sure you are never climb cutting.


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## mikey (Dec 5, 2017)

Duane, is the cutting edge of your insert flush with the work? These inserts have a rather broad cutting edge that needs to sit square to the work. If is doesn't then you will have finish issues. I suspect the angle of your tool is off.


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## ddickey (Dec 5, 2017)

That's what I suspected from the beginning but could be a combination of things.


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## mikey (Dec 5, 2017)

I'm sure you can correct the bedding angle in your tool holder. Maybe give it a try. This is not a head movement or flexing issue.


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## Dan_S (Dec 5, 2017)

@ddickey   If the angle isn't 45 degrees as referenced in this image adjust the cutter in the fly cutter body so that the angle is less than 45 degrees. Two or threes degrees less is fine,  a few degrees greater could cause the chattering you have shown in previous photos.





You don't need to worry about getting it perfect. Unless your running a cnc mill it will be next to impossible for you to really take advantage of the wipper. At 2" and 2000 rpm (what you need to get a good sfpm), you would need to be cranking the handle at 80+ rpm just to reach the minimum chipload for the insert.


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## ddickey (Dec 5, 2017)

I must've forgotten to mention I shimmed the holder. After seeing no change I doubled the shim. Still nothing to I shimmed the opposite side and still I could not detect and noticeable change. I could try again tomorrow. The shim was a piece if tin foil. .0008"


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