Re: CNC Plasma Help

I have a commercial unit and it has rack and pinion drive on both X and Y. The servos, gear reducers and drive pinions are
mounted on a spring loaded mount that allows the drives to be engaged or disengaged from the rack. This removes the backlash
between the rack and pinion. Rotary encoders are also driven by the pinion shaft. This arrangement negates any backlash from the
gear box.

You don't need to go overboard on high precision drive components on a plasma or O/A burning table. The nature of the cutting
process will not yield a high precision edge regardless, unless you're running a "High-definition" plasma torch or laser. If
you can hold .010 inch, you are doing good.

More important is the ability of the drives to negotiate the contours of the cut at the proper velocity at any given point along
its path. This requires the software to look ahead and allow for corner slow down for sharp cornering, but allow constant
velocity on gentle curves. Software that allows a slight pause anywhere along the cutting path, will introduce a defect into the
part being cut. Likewise, taking a sharp corner at a high velocity can cause over travel of the torch and or over stress the
drive components. The momentum of the gantry flying down the track can be substantial.

The good news is if most of your cutting is thicker material, than the torch doesn't have to move very fast. But if you mainly
need to cut thin gauge material, than you need higher cutting speeds to achieve a quality cut.

Hope this helps.

Jay Hayes
Weston, WV

Don Robertson wrote:

> From: "Don Robertson" <dnrobert@...>
>
> The surface will be flat and the shapes will have all kinds of curves and
> angles. Accuracy well I think the ball screw method will be best from what
> I have seen in comerical units.
>
> What kind of motors would I use with ball screws?
>
> I assume I will build a rack system to support the axises and hold the
> torch. Any suggestions on bearing configurations?
>
> The mechanics dont really seem to be the problems the real problems are with
> wiring the motors to respond to computer.
>
> Software Well I am open to suggestions there I plan to scan graphics and
> convert to line drawings that the plasma will cut like a plotter prints.
>
> Thanks Don
>
> --------------------------- ONElist Sponsor ----------------------------
>
> GRAB THE GATOR! FREE SOFTWARE DOES ALL THE TYPING FOR YOU!
> Tired of filling out forms and remembering passwords? Gator fills in
> forms and passwords with just one click! Comes with $50 in free coupons!
> <a href=" http://clickme.onelist.com/ad/gator4 ">Click Here</a>
>
> ------------------------------------------------------------------------
> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the discussion of shop built systems in the above catagories.
> To Unsubscribe, read archives, change to or from digest.
> Go to: http://www.onelist.com/isregistered.cgi
> Log on, and you will go to Member Center, and you can make changes there.
> For the FAQ, go to http://www.ktmarketing.com/faq.html
> bill,
> List Manager