Re: [CAD_CAM_EDM_DRO] help with old equipment

Hello Vance,
I use a digitising tablet to derive the 2D control data for milling
replacement or scale parts. For example, the water pump casing for a
scale race car engine is a fairly tricky shape. Sit the full size unit on
the tablet and trace around it using the 'pointer' pen to which is fitted a
plastic collar of diameter equal to your proposed cutter times the scale
factor for your model.
Many tablets use software based on the Sumagraphics standard, so if
you have not got the original software drivers try these. A simple Basic
program can return the co-ordinates of the pen position to a disk file.
The 2-button pen can be programmed to start, stop and end the data logging
from the pen 'nib' movement plus button operation. The pen 'nib' can be
fitted with a conical tip which can locate irregular hole centres. Note
that broken components can be super-glued together to enable them to be
digitised.
My tablet software includes a test routine which gives a readout of
the absolute X-Y coordinates on the monitor. Mounting the tablet under a
small overhead router with the puck clamped to an extension arm from the
router table gives cheap and easy DRO for routing model aero/boat/car
parts.
I wrote an article for Model Engineers Workshop which shows this
application in the current (May-June) issue running under the Compucut DIY
CNC system. The tablet is the cheapest 12*12 available here in the UK but
gives a resolution of 2540 lines per inch.
Hang on to them, they are good for useful fun.
Regards, Richard Bartlett.