How accurate of a machine can be made from wood? I am considering building a
small 3"x6" slide table (x/y positioning device) but ultimately it will have
to be accurate to .001 so I am thinking I would be better off in some sort
of plastic or metal...

--A

I have bought and have made animation stands with that kind of accuracy.
Material was 3: of mdf with 2 part resin between the layers. It makes for a
very stable base.

Take a look here... http://www.patwarner.com/routerfence.html and read the
tolerance Pat specs it at. I built the fence when it was featured in FWW
two years ago and it's as accurate now as when I built it.

So to answer your question - yes you can as long as you use the right
materials and plan accordingly. Your design needs to include a zero
reference capability in both the x and y axis. Even if you make it out of
other materials you still need a calibration capability.

Bob S.

"Absinthe" wrote in message
s.com...
How accurate of a machine can be made from wood? I am considering building
a
small 3"x6" slide table (x/y positioning device) but ultimately it will
have
to be accurate to .001 so I am thinking I would be better off in some sort
of plastic or metal...

--A

You have to more clearly define the objectives. If the objective is to be
able to move this thing in precise .001 increments, then yes, it is easily
done with wood (I could push a noodle that close). If your requirements
include it being (and staying) flat and parallel to .001,, wood is not
going to do it. If, when moving in X, motion has to be confined to the X
axis only within .001, wood is not going to do it. Metal is your best bet.
Even with metal, if you are using unmachined stock, it will not fit the
requirements unless all you are looking for is linear positioning without
regard to variations in other axis. without equipment that is not normally
found in the home shop, just getting the slide surface parallel to the ways
is going to be quite a trick.
"Bob S." wrote in message
...
Take a look here... http://www.patwarner.com/routerfence.html and read the
tolerance Pat specs it at. I built the fence when it was featured in FWW
two years ago and it's as accurate now as when I built it.

So to answer your question - yes you can as long as you use the right
materials and plan accordingly. Your design needs to include a zero
reference capability in both the x and y axis. Even if you make it out of
other materials you still need a calibration capability.

Bob S.

"Absinthe" wrote in message
s.com...
How accurate of a machine can be made from wood? I am considering
building
a
small 3"x6" slide table (x/y positioning device) but ultimately it will
have
to be accurate to .001 so I am thinking I would be better off in some
sort
of plastic or metal...

--A

The device you seem to want sounds like a slightly larger version of the
mechanical stage used on microscopes to position slides at very high
magnification, such as 1000x. While I don't recall the exact parameters, I
do know that it's possible to locate a single bacterium, remove the slide,
do other things with the scope, then replace the slide and re-locate the
same bug within seconds.

To be fair, one usually reads the stage verniers relatively grossly and then
homes in on the subject by using landmarks within the field of view, but a
good mechanical stage is a fairly decent precision instrument. Other
manipulators allow one to insert an extruded glass syringe into the middle
of a single nerve cell - or an ovum. Good enough?

If you need more range than one of these stages can provide, could you
attach it to a moveable base that would allow you to position it grossly,
lock it down, and then use the finer capabilities of the stage itself?

http://www.greatscopes.com/acc.htm is just one location. They sell one for
$39. I've never dealt with them, so this isn't an endorsement of the
company, but Google "mechanical stage" and see for yourself what turns up.

You can go all the way from this low-end device to spending beaucoup de
bucks on a Zeiss. Also, don't overlook the used market. There are loads of
companies selling relatively inexpensive high-end microscope products in
outstanding condition that have been re-cycled, damaged in some way that
won't matter to you, reconditioned, upgraded, etc.

DanD

"Absinthe" wrote in message
s.com...
How accurate of a machine can be made from wood? I am considering building
a
small 3"x6" slide table (x/y positioning device) but ultimately it will
have
to be accurate to .001 so I am thinking I would be better off in some sort
of plastic or metal...