Another First---Flycutter use.

[Brian Rupnow]

This afternoon I used one of my flycutters for the first time. They seem to work allright. I have a cheesy little set of 3 different sizes from Busy Bee. They take a brazed carbide tool insert that may very well be a lathe cutting tool---it sets in a slot and has 2 small setscrews to hold it in place . I know that in order to use it I have to put my mill in reverse ---The rotation is exactly opposite of all my end mills, in order to cut on the face of the carbide. I am milling a peice of 3/4" square hotrolled to take it down to 0.625" thick. I seem to get good results at about 1100 RPM and a feed rate of .005" each pass. I hope this works out as a viable solution to cut down the thickness of material, as I have been using the ends of my 4 flute endmills to do this, and they are all getting dull on the ends.---the cutting tool in the flycutter, being carbide should last longer. any tips or suggestions, people?---Brian

 

[Tin Falcon]

IMHO use the carbide tools on the lathe and grind some HSS for the fly cutters I was told in trade school carbide does not like interrupted cuts.
Tin

 

[ksouers]

Brian,
As you've already found out the fly cutter is good for removing material from a large area in one pass. However, you should not have to run it in reverse. Yes, the cutters are the same as you would use in a lathe. Are you trying to use a left-hand tool bit? Try grinding a right-hand bit and I think you will find it works just fine the right way round.

Remember that you are making interrupted cuts, so a little slower on the RPMs than you would normally use for that diameter of a cutter. Check your feed charts for the correct RPM. 5 thou sounds about right, though I've taken more off aluminum. I wouldn't dare try more than that on steel. Now for finish cuts in aluminum I have run at full RPM but taken only .001 or less off for a pass.

Have fun with it. The fly cutter is great for putting a smooth finish over a large area. Try one with a large radius cutter.

 

[rake60]

Brian the most important thing to keep in mind is Light Cuts!

A flycutter can quickly damage a machines spindle bearings if it
is taking too big of a bite. The machine will tell you, all you need to
do is listen to it. If it's hammering or rattling back the depth of cut
off a little.

It's a trade off.
A flycutter can cover a wider area per pass, but it can't take much of
a cut depth.

I also preferr HSS bits for my home made flycutter.

I do have a face mill that uses carbide inserts.
You may want to consider one of them as your hobby budget allows.

Rick

 

[jwsvandr]

I got my mill last week and also used the flycutter from Busy Bee. You have to use the left hand carbide tools (used to cut from left to right) for it to work properly. I bought some HSS bits and will try them out shortly

 

[Mcgyver]

this comes up so often i'm just going to cut and paste what i;ve written before.....do a search, lots of good stuff here and on the other forums

using a right hand tool won't work very well - look at the slot and its offset of centre. using a left hand tool will kind of work but we can do better........

the other thing with flycutters is that most people use an incorrectly ground tool. it seems popular to take a lathe knife tool and slap it in a flycutter, however this will produce less that ideal results and the geometry is wrong. as per pic, the knife tool is ground to cut in the direction of the green arrow, whereas a flycutter cuts in the direction of the red arrow. it'll sort of work because there is some front clearance on the the knife tool, but its not ideal

http://i20.photobucket.com/albums/b201/michael0100/cutter2-1.jpg

you need instead a grind like you'd use for a facing tool, something like

http://i20.photobucket.com/albums/b201/michael0100/Assembly2.jpg

and

Will using a knife tool work? yes, it will remove material same as a lathe knife tool will do a facing cut. However the objective is to minimize the cutting forces involved - that increases the capabilities of light duty machines. The mill head is equal and opposing force to the cutting force and a large dia tool such as a flycutter gives a lot of leverage to the cutting force. Whatever you do to reduce the cutting force reduces the forces on the machine, makes it easier on the machine and lets you take more depth of cut.

Here is a thread with some pics I did to try and illustrate the point for fly cutters

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

and here is the bit i use in flycutting - exactly the same as a lathe facing bit with chip breaker.

http://i20.photobucket.com/albums/b2...facingtool.jpg

you are also better with hss than carbide as you will get a more acute angle to the cutting edge - this shortens the shear line and that also contributes to less cutting force.

to proceed, first indicate the mill to table (bet its off, right?) then set yourself up with a cutter like above. make sure the z axis is locked and everything is tight. go slow and with a slow feed until you figure out what the machine can handle.

Lastly, you minimize the hammering by having the tool enter the work almost at a tangent. Also, use the best sized tool holder for the cut, this is advantageous for picking the right cutting speed

 

[ksouers]

Ok, I guess I added to the confusion. I was thinking a right-hand cutter cuts on the right side of the tool, and thus a left-hand cutter on the left side. It seems I have those backwards. Damn if that ain't confusing ???

My apologies.

 

[Mcgyver]

yeah i agree, would have made more sense the way you describe

 

[kvom]

Here is a flycutter I built in class recently. It uses 3/8" HSS blanks, and is straightforward to machine.

 

[Brian Rupnow]

These are pictures of the flycutters and the (possibly) bass ackwards cutting tools that BusyBee sold me. And yes, they have to revolve in the reverse direction to all my other mill tooling to work.---Brian

 

[Lew Hartswick]

Brian, you need bits that point the other way. It will do two things, 1 reverse the rotation and
2 put the force against the fixed part of the holder rather than the set screws..
...lew...

 

[Bogstandard]

Brian,

Go back to Busy Bee and tel them to stick their bass ackwards cutting tools up heir tass.

John