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Flycutter design

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andyf:

--- Quote from: maybecnc on February 03, 2011, 05:22:58 AM ---
..... You can make a new flat end for it and silver soldering it to the flycutter. Finishing it after that on the lathe/mill.
This way you can put metal back covering the milled slot. You will get a nice flycutter with a square hole for the toolbit and a minimum amount of removed metal from it.

Jose

--- End quote ---

Hi Jose,

That's very like what I have done, except that I bolted the piece back on the bottom, leaving a square tunnel for the tool. At speeds up to 800 rpm, it seemed fairly close to balance, and worked well, and that is about the highest speed at which the tool will be used. I was truing up the slightly convex sides of some square aluminum tube, and I thought somewhere around 400 surface feet per min. would be right for aluminium. 800 rpm with the tool sweeping a 2" circle gave me around 400sfm for the final 0.002" deep pass. The first roughing cuts, about 0.01" deep, were done at about half that speed.

The tube is to form part of the casing for a power feed on the mill. After several sessions of 20 minutes each, very slowly traversing the table by hand over a distance of 11" with my feet getting colder and colder on the concrete floor, I have decided that a power feed is definitely a good idea!

Andy

bp:
To avoid vibration the flycutter that I saw at work was about 125mm (say 5") in diameter about 20mm (3/4") thick steel, a big flywheel.  The cutter was a piece of 3/16" HSS inserted at the periphery at about 45 degrees, with only about 3mm exposed to do the cutting, secured in the steel disc with one or two set screws.  This was run at high speed with a fairly shallow cut.  It was used on a B'port, and on anything that required flycutting, steel, aluminium etc.  The finish that I saw on a piece of 6061 T6 was almost optical.
Whilst I must admit I've planned to do something like Andy, only with an MT3 blank arbor to better fit my X2, I've often wondering about making a bigger diameter one, maybe 50mm diameter.
cheers
Bill Pudney

andyf:
Bill, I must admit that the range of mine is a bit limited. With the 38mm blank ended arbor I used, the minimum swept diameter is (with a bit of cheating, like shims above the tool) about 40mm. The max is about 80mm, though that would involve the tool protruding 16mm - perhaps a bit too far for comfort, especially on hard materials. Perhaps that's why commercial ones often come in sets of three different sizes.

Mine was made from a 38mm arbor because I already had one, and it was just the right size for the job I wanted to do. For me, it's only rarely that things turn out so serendipitously (that's my word of the week).

Andy

maybecnc:

--- Quote from: andyf on February 03, 2011, 08:29:17 AM ---That's very like what I have done, except that I bolted the piece back on the bottom, leaving a square tunnel for the tool.
--- End quote ---

Andy,

Oh, you did it. I was thinking you have bolted 2 small parts with the slot. But of course it wouldn't make sense to mill first.
So it works ok. That's good to know.

Jose

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