Well I finally finished it, well pretty much. Put the mirror in this afternoon
and colinmated it. Focusing on a distant tree line a few kms away I was able
to almost bring in to focus using a low powered 30mm SV. But needed more
in focus for the XW. So I have trimed poles down a little bit still trying to
leave a little extra. It looks like we might be able to give it it's first star test
tonight, as there is a patch of blue to the south. It will either be pretty close
or may need as little more trimming. Once I have that sorted I going to drill
and screw the lower truss connecter to the mirrorbox. She isn't as top heavy
as I thought it would be, but I think I'll need a 1.5-2kg counter weight in the
box.
I'm a little surprised the weather looks like it's going to give a little piece of
sky to test with
anyways here a couple of picture of the finished scope. Thank you to all for
the help and advice I have gotten along the way.
Well it's first star test was excellent, it was nice to look through a scope
again. I've trimmed the pole too short by about 5mm for my longest FL
ep's. But no great problem there as I have a couple of fixes. I'll need
to add the counter weight to help balance things up when the finder
scope is attached. I really like it's movement compared to earlier versions
as some people say smooth as butter. Jake is pretty happy with it which
is the main thing. Just need a nice clear night and perhaps build an
adjustable observing chair.
Now I can focus on getting the parralellogram mount finished
Here's a few pics of the evolution of my scope/optics.
The mirror cell turned out better than expected. I wont need to make
knobs for the colinmation bolts as you can easily turn them by hand.
I'll upload a picture of the cell soon, when I can get a picture of it lol
great stuff rob .. where did you get to see a star ?.. Im thinking a wiper motor and blade down in my mirror box might be the go with this weather .
My calculations were that is was Enif in Pegasus or around that area, for
a few minutes. Been on star watch ever since I dont think we have had
as bad observing weather in a long time. Haven't even been able to check
out the sun spot group currently transiting o'l Sol with the PST either
They're predicting better weather this weekend, which would be awesome
wont have the boy's, I'll be a free man for a couple of days.
Ok, next step is I want to make a shroud. What material does one use. I've
seen William's and Peter Robsons big SDM's but I didn't enquire about the
material used. So I'm after the name of that stuff if anyone knows. Apart
from that anyone else have luck with a particular material? and where you
can get it from.
Well, I've got my parrallelogram mount working. Just need a few tweaks here
and there, a lil striction built into the main arm would be good. Needs to have
the finishing touchs put to it. But I wanted to see if it was going to do the
job. The counter weight bar is just taped on for now, eventually you'll be
able to slide it up and down to change the setup for different bino's. The
main arm base post is removable, you simply lift it off the mount.
Actually I'm pretty happy how it works machanically.
When I was over in Lismore yesterday, unfortunately most to the steel
suppliers closed for the year the day before, Doh'. But did managed to
locate one that was open. I got a 1m length of solid mild steel 25mm x
25mm. I had it cut to 250mm lengths. Each peice weigh in at 1.254 kgs,
which was quite fortunate as (according to my maths) I needed 2.5kgs
to counter weight the 8" truss dob (with my heaviest ep, 20mm t5).
The scope is nicely counter weighted now, although a lil bottom heavy
with the 59gm U/O HD Orthos near the zenith. But perfect with the XW's
and 20mm t5 which start around the 390+gms
Just need a night of clear skies and NO moon would be nice to give it
a good test. I've only managed to see one measily star so far
But I thought I give an update. Projects are never finished when you think
they are. Once you have built your project there always a lil bit of tweaking
to do.
The lil 8" truss dob works a treat, and I'm surprised that on repeated setup
you only need to tweak the collination. The only problem I really had was
mirror shift between horizon to zenith. So I installed a sling which has worked
a treat. I moved the counter weights from being cable tied to the tailgate
to bolted on the sides of the mirror box. The balance is good and is a little
bottom heavy near the zenith, I'm going to drill some holes in the counter
weights to tweak this.
I also have pretty much finished my parralellogram mount. Tweaks included
making milk bottle washers to the "L" bar on the tilt and pan axis. This has
made the action of panning around a one hand operation. I also need to
apply some sort of friction brake on the main arm since I extended it's travel
to about 80 degree, there are some weight issues at the extremes. I have an
idea how to fix this using a snatch block and cable and applying a brake to
the snatch block.
Images included of the two projects, along with the new owner Jake and
his truss dob.
all looks great rob .. time to copy it now you have it all sorted .
I havn't seen it so green out your way for many years ..half the population
over the back fence there eh ?
Thanks mate I've still to make a light shroud for Jakes scope. I brought
some Rip-Stop Nylon from Spotlight in Lismore. Now I just got to figure out
how to work the ex's sewing machine . On copying it I have been
thinking it might take awhile to afford a bigger mirror so my thoughts are
possibly make a 12" in the mean time to give me a bit more aperture while I
save for a 16" or 18" (or possibly a 20" ) or try and buy a 16" direct from
GSO. The GSO 16" sound ok from the reports from the Lightbridge owners.
Anyways something to think about. I'll have to start thinking about building
a shed to stick them in. My son is losing realestate in his bedroom lol
Gee, you have been a busy boy Your young lad looks real proud of his truss dob. Now that I have access to more tooling, might consider a go at one myself down the track.
rob I found my az motion getting a little stiff the other night so much so my mirror box was trying to move inside its cradle before it would move on the base...that texteured formica we both have seems a little more abrasive on
the teflon than my old gso base .. and will likely need a clean more often imo
bit of metho and a wipe with mr sheen and its good again
.
for a couple of days.
, but I'm still waiting for that clear night 
queue with ya rob 
. On copying it I have been 
