re:Subject: Re: Re: Make your own linear scales
Posted by
Elliot Burke
on 2002-03-01 14:59:52 UTC
Jon Elson wrote:
T>he etching of glass scales is pretty easy. The TOUGH part is getting
is easy then to electroplate some copper on it to make the film more robust.
For that matter, you can remove the lacquer from the back of a (second
surface) mirror, and you'll be looking at a copper plated silver coated
piece of glass.
If you have a master scale you can use as a reference, a little step and
repeat exposure machine can be be made with a LED light source, a slit, and
a lens. Make those little marks one at a time. A multiple slit mask can be
place in front of the LED to reduce the expose time requirements, also this
will average out short term random errors a little.
Then you need some photoresist. Expose, bake, put in solvent to remove the
resist, etch with acid to remove unprotected metal film, and you're done!
If anyone does this, we'd sure all like to hear about it.
I've made a few reticles this way, it works OK. A good enlarger lens can be
used to reduce artwork to very small dimensions, you can make any sort of
reticle or pattern you want. Some people do this for putting artwork on the
side of model train cars.
At electronic parts stores you can find the necessary chemical, used for
making printed circuits. Some use an aerosol can to spray the resist on,
which is much simpler than the usual spin coating.
Another technique I've used doesn't use chemistry at all, and is metalwork
related:
A properly make tool will scrape off silver off the glass. It isn't hard to
see how to make a scale this way. No etching is needed.
Diffraction grating ruling engines cut grooves in thin aluminum coatings on
glass. Grating a meter on a side are not unheard of (but rare). To be
useful the errors in position and straightness of the grooves have to be on
the order of a microinch or better. These machines are pretty cool, very
extreme in every way. There are amateurs who have made them. Sort of the
ultimate in numerically controlled cutting machine accuracy.
Elliot
T>he etching of glass scales is pretty easy. The TOUGH part is getting
>the metal depositied on the glass. This is generally by vacuum deposition,There are chemical processes for silvering glass that are rather simple. It
>which would take a LOT of exotic metalworking to build a vacuum
>deposition chamber! It might be possible to use those first-surface
is easy then to electroplate some copper on it to make the film more robust.
For that matter, you can remove the lacquer from the back of a (second
surface) mirror, and you'll be looking at a copper plated silver coated
piece of glass.
If you have a master scale you can use as a reference, a little step and
repeat exposure machine can be be made with a LED light source, a slit, and
a lens. Make those little marks one at a time. A multiple slit mask can be
place in front of the LED to reduce the expose time requirements, also this
will average out short term random errors a little.
Then you need some photoresist. Expose, bake, put in solvent to remove the
resist, etch with acid to remove unprotected metal film, and you're done!
If anyone does this, we'd sure all like to hear about it.
I've made a few reticles this way, it works OK. A good enlarger lens can be
used to reduce artwork to very small dimensions, you can make any sort of
reticle or pattern you want. Some people do this for putting artwork on the
side of model train cars.
At electronic parts stores you can find the necessary chemical, used for
making printed circuits. Some use an aerosol can to spray the resist on,
which is much simpler than the usual spin coating.
Another technique I've used doesn't use chemistry at all, and is metalwork
related:
A properly make tool will scrape off silver off the glass. It isn't hard to
see how to make a scale this way. No etching is needed.
Diffraction grating ruling engines cut grooves in thin aluminum coatings on
glass. Grating a meter on a side are not unheard of (but rare). To be
useful the errors in position and straightness of the grooves have to be on
the order of a microinch or better. These machines are pretty cool, very
extreme in every way. There are amateurs who have made them. Sort of the
ultimate in numerically controlled cutting machine accuracy.
Elliot