Re: Question, can you assist?

--- In CAD_CAM_EDM_DRO@y..., "kf6peq" <kf6peq@y...> wrote:

> 2. Since the item has contour to it, I need to CNC on 3 axis, what

is

> the best software for laying out the part. I have tried Rhinoceros
> and
> liked it alot, however in an attempt to convert to G-code, I used

the

> Aceconverter(DXF-to-G) and then tried both CutViewer & FlashCut to
> try
> and see if the part would be successfully reproduced. In both cases

I

> saw that the axis seemed mixed up and all I received was errors

StlWork lite(under $200) or StlWork2(under $400) can work very nicely
with Rhino STL files. Both have a 30 day full working trial period.
Links to download StlWork lite are ONLY found on my group discounts
page, (see signature below). These programs will create 3D toolpaths
from a solid model. The output is suitable for driving most hobby, 3
axis controllers for engraving, milling, or routing.

> 3. What type of surface finish can be achieved? How smooth can I

mill

> a curved 3d surface?

The surface finish is a tradeoff between machining time and hand work
time. An organic surface finish is directly related to the distance
that you step the cutter between the back and forth cutting passes.

On aluminum you will want to probably use an abrasive pad or
something like 3M Scotch Brite to polish out the tool marks, then a
buffing wheel for a hi gloss polish. There will always be tool
marks, they can be sanded and polished out. You will find a point
that smaller stepovers will increase the cutting time but not improve
the machined finish. Back off the step over a bit (make it larger)
and you should have the best cutting strategy for the tool, machine,
material, and other cutting conditions.

This varies with each machine, material, the condition of your
cutter, coolant used, your cutting speed (rotation) and feed rate.
With aluminum you usually can't rotate the mill spindle fast enough
to hit the theoretical best cutting speed 500-700 sfm or so, 1/4
cutter = 10,000 rpm, 1/8 cutter = 20,000 rpm.

One trick that I have seen used to good effect is to tilt the spindle
or the work so that the tool never cuts with the center of the ball
radius. Using a flat bottomed cutter with radiused corners (called a
Bull nose cutter) is another way, but can't 100% cut concavities and
small slots and details. Both techniques will dramatically increase
the quality of the surface finish.

Best Regards, Fred Smith- IMService

Listserve Special discounts and offers are at:
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