--- Original Message ---
"Aaron Coffey" <[EMAIL PROTECTED]> Wrote on
Thu, 28 Sep 2000 21:17:27 +0800
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<SNIPO>
Is a 3 or 5 axis CNC router used to mill wing molds?
What is considered acceptable accuracy in the mold? .5, 1, 1.5,
or 2
thousandths of an inch?
Are there any sites dealing with making a router?
<SNIP>
Hi Aaron,
most of the CNC cut molds in the soaring community are cut on
3 axis machines. A ball nosed end mill is used to contour tangent
to the curved surfaces. Whenever the surface is perpindicular
to the spindle axis, the only contact point is at the theoretical
center of the mill, which is essentially just pushing tha material
around. This is where all that nasty mold polishing comes from.
If you can make your molds on a 5 ax machine, (GET YOUR MONEY
OUT)you can adjust the spindle to cut at 5-10 degrees off perpindicular
and do away with a lot of the polishing.
As far as accuracy goes, I would think you could get away with
as loose as 0.01" in some places. The profile of a surface callouts
usually associated with airfoil shapes found in jet engines and
wind tunnel models is 0.002", and you would need a good coordinate
measuring machine to tell you how close you get. Most good pattern
makers can measure with a loft gage and get within 0.005".
Repeatability is more important than the accuracy on any CNC
tool. The routers you see are good for 0.005" -0.010" depending
on the material and how fast you want to go.
My CNC mill is an older one and it is good for about 0.002"
or better with a little of that "machinist tricks" added.
Our new Mori-Seiki mills are good to 0.0002" accuracy and 0.00005"
repeatablity. You can expect to pay (like, WAY more) than $10,000
for one of those.
Winch Doc
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