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The making of my minuture truss tube
A 4.5" F/8
I'v always wanted to build a truss
tube telescope I was wanting to rebuild my 10"F/5
from the classic newtonian to a
truss tube for the portability part of it ,And the older I get the the
heavier it gets.So instead of that I decided to build a little one first
I thought it would be good experience and a way to refresh the ATMer in
me since the last scope I had built was in 1992.I knew I'd have to have
some help on this as far as the math part went so I went to astromart and
joined in on the forum and posted an ad there for the specs on a 4.5" F/8
scope.And with in hours I had two very knoweledgeable ATMers there who
give me what I was looking for the spaceing of the optical train.The most
important aspect of ATMing.And I'd like to thank Ralph and Rich for there
sound advise which I followed cause I knew they knew much more than I did.The
following pics and descriptions are short and brief I'v tried to cover
as much as I could without confusing myself and trying to toss in alote
of technical stuff.But building a telescope is not a nuts and bolt toss
together item it takes alote of technical figureing to do,And if your going
to grind your own mirror all the advise I'v seen says to start out small
and work your way up to the bigger things.Maybe the the next scope project
I do I might try may hand at a 6" mirror just so I can say I did it.
But that is another story.
The first thing I needed was the
optics after all you can"t build a scope with out knowing what to build
so
I placed an ad in astromart for
a 4.25" to 6" reflector all or parts.Wanted to get something cheap to keep
the cost down.Within a couple of
days I recieved a couple of offers and 1 was for a 4.5"F/8 primary
with a 1" diagonal and he would
throw in a .750 diagonal with a 1.25" focuser and and a mead 5x24
finder scope all for the cost of
$50.00 and he even paid for the shipping and within a short amount of time
I had my parts.Thanks Brian it
was a very good deal for me and the parts were more than satisfactory.
Now I need some material to build
the parts to hold the optics.I went to my dads and gathered up some left
over oak lumber that was in the shed this come from my dads woods he had
cut the tree down and had it sawn up to make a nice supply of oak lumber
my kitchen cabinets are also made from this oak.
Since this lumber came from my
home land this to will hold an appreciation for me.Some of the pieces including
the side bearings and the end rings for the top cell and the bottom base
board were made from oak ply wood for durabilty and to help easy the production
of the scope I did'nt think the solid wood was a good choice for some of
the pieces.
The
rocker box and the primary mirror box were both
made from the solid oak wood and
some small slats were also used from this wood in the secondary
mirror holder cell this wood is
hard hard hard!!!
I was concerned with splitting
it while work with it but the drilling of the holes before sinking in the
nails
it all worked out fine.I plained
it down to about .625" thick to help keep the size and the weight down.
The inside of the primary mirror
box was painted with a flat black enamel paint.The inside of the primary
mirror box measures 7 5/8" square And the outside is 8 7/8" and measures
7 3/4" tall.
This
is the mirror cell for the primary it is 6" in diameter and this was
also painted the flat black.The
mirror will have spacers placed under it the set on silicon pads then the
spacers will be removed after the
silicon sets up.I equally spaced three 5/8" wooden dowles then cut
notches in them to align the mirror
and it also helps to support the mirror.The pic does'nt show it but there
is three T-nuts under the center cover for the push pull bolts