Re: [CAD_CAM_EDM_DRO] CNC Process

Hi Jeff,

Maybe I can answer a few of these questions:

cadman@... wrote:

>
> I am new to using a CNC machine. I built a small (made of wood) 3
> axis mill so I could play and learn with. Later I will purchase a
> Drill/Mill and convert it. As of today I am using CNC-Pro
>
> I don't have any problems with the CAD/CAM software side of things.
> It is running the machine that has me stumped. The areas that I have
> questions are:
>
> 1. Home position.... When I press the Home button it moves my
> axis all the way to one side and sets the coordanants to 0,0,0 should
> this be left at 0,0,0 or should I touch my tool on top of the material
> and call that 0 in the z-axis?

(for our small Sherline/MaxNC sized machines)
Setting the top of the stock to 0 is usually most convenient. Draw in
CAD and set your origin in what would be the lower left corner, top of
the stock, then generate the Gcode. Mount the stock, zero the axis on
the same, lower left hand corner of the stock. Top is 0 Z. (edge
finder!)

> 2. When I need to change a tool I will loose the z-axis tool
> location. do I again touch the tool on the top of the part for z=0 or
> should I re-home?

Yes, touch the stock, or use a thin piece of paper (of known thickness),
and "touch" the paper (slight drag felt). Re-adjust that axis to 0,
allow for thickness of paper. This has been explained in previous posts
to a GREAT detail, so I won't repeat here.

>
> 3. If I rough the part and loose the top of the material (by cutting
> away all the material on top) How can I set the tool again?

Arrange to leave your "origin" intact! OR, a similar thickness piece of
stock can be temporarily placed near the origin, and used to regain the
Z zero. For X and Y, try to start from a "finished corner", if
possible.

>
> I am so confused about setting the machine up for a job. I have the
> limit (home switches) set at the far positive position in all axis. Z
> moves up. X table moves to the left. Y table moves to me. So this
> means that the tool in relation to the table will move Z-up, X-right,
> Y-Away.

Think in terms of the "TOOL". It moves up in Z, to the right in X, and
towards the rear in Y. Same as on your CAD drawing! One of the first
things I had to get through MY head, when starting with Vector CAD/CAM
and the mill. Make this connection, and everything falls into place!
After you master this, then when you NEED to move the origin (sometimes
it makes sense to be in another position), you'll still be in the right
"frame of mind", and the correlation's will be obvious to you.

>
> When I use the homing feature it sets 0,0,0 at the home position.
> This means that I always cut in the negative space. Is this correct?
> What is the best method?
>
> Thanks
>
> CADMAN

Cutting below 0 seems to work well. Sounds like you have homing
switches? Pretty good for a homemade mill! I don't have any yet on my
little Sherline.
Good luck, and why not tell us a little more about your home made
machine!

Alan KM6VV