TASS Hardware Progress

[droege@wwa.com]

[snip]

This morning I turnd on the shutter to open and close every 4 seconds and
just let it run for a couple of hours.  So it looks like it will last the
life of the machine.  I have gone back to the parlor door scheme.  Not as
uniform an exposure as the sliding window scheme, but takes much less space,
and does not have as large an inertia problem.  I really like the model 
aircraft servos.  They are impressive in their degree of engineering 
perfection for the price.  They also generate a lot of force.  20 ounce 
inches for this one.  No moth is going to lay eggs on the rails and stop the
motion.  Looks like it opens in about 0.2 second.  Should not produce much of
an error for the expected typical 500 second exposure.  OK, not so good for
sky flats.  Can't have everything.  

Today I also wired up the first limit switch and got it working.  There are
just lots of connections to sort out and identify.  Get addresses right so
I am looking at the switch I think I am etc..   

The RA and Declination motors are hooked up and the Declination motor has been
tested.  It will cover about 70 degrees.  From near vertical.  The next
hardware will have much more motion in declination - I should be able to get
near 180/degrees which is more than what is needed.

The RA drive works, I have just not connected it up to the proper motor drive 
yet.  This is the one with the precision VCO.  I have changed the design for
the next version so I will be able to fast slew it where I want it.  This
version only tracks forward at sideral rate, then fast slews back.  This
makes it a pain to test as it takes a long time to make moves.  I made a bad
choice in mounting the drive so instead of 20 degrees of good motion I have
possibly 10.  That is enough for a longer exposure than I expect to make.
Again, the next version will fix this.

Now that I have metal bolted together I can see how I should have designed
it and where things should be mounted.  Still, this mount will be plenty
good for tests.  It can travel more than I can see between my trees.

The hope is to get the Mark IV up on the roof in a week or so.  

Tom Droege