The Work Envelope Problem
 

On Aug 21, 11:38 am, "Doug Goncz" wrote:
In a weightless environment, a machine tool slide can be designed to move a
distance equal to its own length, facilitating machine tool
self-reproduction (MTSR). However, here on Earth, such an arrangement
results in premature wear of the mating slide base, and so we have the Work
Envelope Problem preventing MTSR: If we cannot move a part its full length,
we can't reproduce its length feature, that is, the work envelope of the
machine tool is *smaller* than the size of the work to be produced.

I can think of one work around, if you have the rigidity: Use a tool
which has a work span which makes up for the loss of working
envelope. If for example you flycut or face mill a table top, you can
cover a larger area than the motion of the table alone. The problem
with this is that I can only see it working with flat surfaces,
anything with a profile (rabbets, dovetails, and the like) would still
be limited to the relative motion of spindle and table, and thus
subject to "work envelope creep", unless you were willing to make such
features out of additive pieces themselves made up of flat surfaces
(ex: a rabbet made by adding a rectangular prism rather than
subtracting a rectangular area, or a v-way made by adding a primatic
bar) which forfeits many of the self-alignment and rigidity advantages
of machining the pieces from solid to start with. I did say it was a
work-around...

--Glenn Lyford