Converting the DSI Pro II monochrome camera to a more
practical filter system without spending too much money.
So far it's only a manual wheel but I have enough clearance
around the filter carousel to put a toothed belt, glued inside
out around it's circumference.
A small dc motor/reduction gearbox I have will mesh with this
nicely.
Total thickness from nosepiece endplate to T-thread the other
side is 22mm...but I could probably shave 3mm off of this and
get 19mm....comparable to the ATIK wheel.
Nosepiece is from the DSI, Baader IR is fitted in it's end.
Impressive Steve. The advantage of doing it this way is that the Meade filters fit in the wheel. I don't think the 19mm Atik wheel has enough clearance for the Meade filters to fit in it. I had to get a lower profile set of filters to fit the 19mm wheel I bought.
You going to get it anodized black for that sexy finish?
Nope Alex, I quite like Royal Blue
Update: Filter wheel will stay manual for now, I couldn't find
anything that would reliably glue the rubber belt to the thin
platter edge.
So I knurled the edge in the lathe to add some thumb grip.
Some pics....all ready for testing
Yesterday I finally got the courage up to do the 48mm chop
to the OTA of my 12"Newt to allow the filter wheel/ camera assortment
to reach focus.
Quite an easy job, saw the 12" F5 mirror up close for the first time
I spotted the terrible light leak that Alchemy talks about in his very
informative 'chop your Dob' article....got a photo of it here.
Some pics attached, I can reach focus!
It was funny, until I actually did a test last night on Rigel, I was
a bit panicky....It's not like I can add 48mm back on the tube
Where is the light leak coming from? is that from the focuser? or leaking in thorugh the filter wheel?
Alex.
Yes Alex, it's coming from the badly fitting Crayford style focuser
on the GSO.
The base flange has a curvature to possible fit a 10 inch scope
ideally, and it looks like they try to get away with it fitting a 12inch.
Bottom line is that it has 4 points of contact with the OTA and that
lets light in.
Alchemy's article clued me up on it, however when I saw the leak for
myself I couldn't believe how bad it really was!
Why go to all the trouble of making such a lovely job, only to do silly stuff
like that...
So whats the plan? find the point where the light is leaking in, and seal it up with something? Maybe of all dodgy ideas, melt some plastic over it... or silicone?? As a temporary fix, some duct tape
A cork or neoprene rubber gasket may be the go as a more permanent fix
So whats the plan? find the point where the light is leaking in, and seal it up with something? Maybe of all dodgy ideas, melt some plastic over it... or silicone?? As a temporary fix, some duct tape
A cork or neoprene rubber gasket may be the go as a more permanent fix
Hi Alex,
As we discussed in chat, I'll probably baffle the tube and fit a baffle close
to the leak.....and fill it with something as you say.
I can't see the point trying to file a curvature on the flange to suit
the OTA, not worth the effort....
How about this idea. To fix the light leak, remove the focuser from the OTA, remove the mount from the focuser, clean the underside of the focuser mount, get some JB weld or similar aluminium 2part filler. Mix it up, Apply to area where light leaks in. Temporarily fit back into OTA so filler takes the shape of the tube (make sure you use release agent of some kind, gladwrap works well. Let dry, remove from OTA, trim off waste, repaint. Done!
I would probably try to do this on a dummy OTA. ie 2 segments of mdf cut to the required radius and covered with a section of tin or gal, or use an old cake tin or tupperware container, as long as it's the same dia as the OTA. The reason, you don't want the filler dripping onto your secondary or getting stuck on anything useful.
How about this idea. To fix the light leak, remove the focuser from the OTA, remove the mount from the focuser, clean the underside of the focuser mount, get some JB weld or similar aluminium 2part filler. Mix it up, Apply to area where light leaks in. Temporarily fit back into OTA so filler takes the shape of the tube (make sure you use release agent of some kind, gladwrap works well. Let dry, remove from OTA, trim off waste, repaint. Done!
I would probably try to do this on a dummy OTA. ie 2 segments of mdf cut to the required radius and covered with a section of tin or gal, or use an old cake tin or tupperware container, as long as it's the same dia as the OTA. The reason, you don't want the filler dripping onto your secondary or getting stuck on anything useful.
Cheers
Michael
Michael,
what a brilliant idea!
Using the curvature anywhere immediately adjacent where the focuser
was should do ok.....
I have some Fullers liquid metal too!....
Thanks mate!
Steve,
Michael is another of those great people from M.A.S!!! very helpful.
Just as a side bar to your problem.
My 12" Lightbridge is coming up to 3 years old, the base plate on it fits flush with the curvature of the tube.
When I bought the Bintel (G.S.O) 10:1 focuser, the supplied base plate had the same problem as yours.
I've noticed this on ALL the G.S.O scopes.
Now the Lightbridge series are all made by G.S.O. They must of made the base plate especially for the size of tube.
Steve,
Michael is another of those great people from M.A.S!!! very helpful.
Just as a side bar to your problem.
My 12" Lightbridge is coming up to 3 years old, the base plate on it fits flush with the curvature of the tube.
When I bought the Bintel (G.S.O) 10:1 focuser, the supplied base plate had the same problem as yours.
I've noticed this on ALL the G.S.O scopes.
Now the Lightbridge series are all made by G.S.O. They must of made the base plate especially for the size of tube.
Hi John, Michael,
I reckon the base plate is made for the OTA of a 10".
It is close, but not close enough.
I did the job today, just as Michael described....
I'll give the liquid metal a good 24hrs before I touch it.
Seems to have done the job perfectly......pics to come
I always did want to get a lathe one day, 
nice work.
very helpful.
