Re: Is this doable on a CNC mill?

Hello,

Sure, it's do-able. Using your picture as a starting point:

Lower your right hand until the wheel is at an angle that places the
outward sloping inner wall of the slot vertical. Then use your left
hand to raise the rim until the "fan blade" angle is similarly
vertical. Place this double angled setup on a rotary table. Now
simple vertical slot cutting will reach three of the required walls.

Use an endmill with a modified tip--like a drill bit--means with an
angle which will make the bottom of the slots correct. (Tool grinders
do this kind of mod for machine shops all the time.)

So here's the whole project, summarised:

1) Using a lathe or mill with rotary table, mount the part flat and
make the rough shape. (The outer round, inner hole and "dome", AND
the back side "flat details.)

2) set up the compund angle described above on a rotary table and
mill the slots.

3) working from the back side of the part-likely flat- finish the
slots--the fourth wall that you cannot reach from the front.

You might want to exchange steps 2 and 3.

Yes, it's do-able. 3 axis mill and a rotary table. (likely how the
original pattern was made.)

You could look into edm'ing the slots instead. Still rough them with
a mill, but use the electrods to get the "sharp" and "square" corners
in the slots without risk of endmill breakage.

Ballendo

P.S. Yes, they make endmills that small.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Adrian Kole"
<AdrianKole@H...> wrote:

>
> The following link shows a real car rim and a 1:8 model of it:
>
> http://www.fineartmodels.com/e/model/auto/royale/royale_123.htm
>
> The objective is to make a 1:43 model of the rim and I am wondering

if

> this is doable on my mini mill. My concern is not with the general
> cylindrical shape, but with those curved slots with *angled* fins
> going around the perimeter. I do not not if it critical for the

fins

> to actually angle (like a fan or propeller for directing air

through

> the hub).
>
> My question is: is this doable and how could it be done?
>
> I figure at that scale, the slots are only about 0.9 mm at the

widest

> points. Realizing that even that size could not duplicate the

finer

> detail, are end mills even available at that size? Would it even

be

> practical to use tools that small or would deflection and breakage
> just make it impractical to make these parts?
>
> I know this is borderline for the list, and it may be off topic, so

please, let's discuss the design of the machine for such a part.

>
> Would I need a 3 axis mill, or 4 axes ? 5 axes ???
>
> Would it be easier or better to try to move the head or the part ?
>
> Is milling the best way ? Is there other technologies that would

offer something better ?

>
> Also, would you please comment on what advantages a moving head

might offer over a rotary table ?

>
> Please try to keep the topic within the topic of machine design and

builing and not on how to use the machine. (ie, please don't comment
on feed rates and such)

>
> TIA,
> Adrian