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Tom's Scope Cooler

Like several others who own an LX200, I liked the idea of a scope cooler but had a problem swallowing the $129.00 price tag.  After looking around on the web for alternatives, I found several sites where you could build your own.  This was very appealing since the "build your own" price was about 1/6th the price of the commercial one.

Like any project, I just couldn't do it the same as everyone else.  Here is mine.

   

Parts list:

Quantity Item Description
1 18",  3/4" schedule 40 PVC pipe
1 2", 3/4" schedule 40 PVC pipe (for offset)
1 1" - 3/4" PVC coupler
1 1 1/2" - 1" PVC coupler
1 2" - 1 2/1" PVC coupler
1 3" - 2"  PVC coupler
1 3" PVC cap
1 1/2" threaded PVC cap
1 Small can of clear PVC glue
1 6' wire (two wire zip cord works good)
1 12 cigarette lighter plug ( fused or unfused ) ( I used unfused )
1 12volt cooler fan ( Radio Shack, part #TA-9002510 )
1 Plastic filter guard 60mm ( www.cyberguys.com  part# 148 0260 )
1 Metal fan guard 60mm ( www.cyberguys.com  part# 148 0201 )
8 #6-32 x 3/4" machine screws
8 #6-32 nuts
8 #6 toothed washers
2 Self tapping screws ( to secure 3" cap in 2"-3" coupler )
2 Filter material,  I used forced air vent filters ( Home Depot #721404314127 )

Tools:   small saw, Dremel Tool (optional), soldering pen w/ solder, screwdriver, needle nosed pliers, Xacto knife

Here are some detail photos:

 

Construction Notes:

IMPORTANT:  The 3/4" pipe cannot touch your secondary mirror.  Verify the correct length (remember 1" for fitting into the coupler) before cutting the pipe.  An 18" pipe (17" exposed) works in my 10" LX200 but the pipe for an 8" will be shorter and a 12" will be longer.  *** MEASURE FIRST! ***

The 2" - 1 1/2" coupler does not fit all the way into the 3" - 2" coupler.  I cut the 2" coupler down so that it fit completely into the 3" - 2" coupler.  After gluing the remaining couplers in place, I cut the ends off so that they were flush with the 2" - 1 1/2" coupler.  After gluing this assembly into the 3" - 2" coupler, this left a flat surface with a hole in the middle when looking inside the 2" - 3" coupler.  I then used a Dremel Tool to shape the hole to more of a funnel shape to help air flow into the pipe.

The offset was a 2" long by  3/4" wide piece of 3/4" pipe trimmed to set flat on the pipe.  When glued into place, it allows a place to lock the cooler in with the thumb screw of the eyepiece holder and also allow air from inside the scope to escape when cool air is blown in.

Cut a hole in the center of the 3" cap just large enough to see only the fan.  Mount the fan inside the cap and the fan guards outside the cap.  Be sure to mount the fan the right way.  It needs to blow the air into the scope.  The fan will NOT run in reverse with reversed wiring.  

I did not glue the 3" cap into the 2"-3" coupler.  This allows access to the fan and the filters.  I cut the filters to the same size as the outside diameter of the cap.  When the filters are placed into the 3" end of the coupler and the cap is secured into place, the cap will securely hold the filters in place.

I had to remove the back of the plastic fan cover and cut two notches to accommodate the fan screw heads.  Mount the guards rotated evenly from the fan screws. 

I made a hole barely large enough for the wire in the 3" cap.  Insure that the wire does not freely move in the hole.  I then knotted the wire inside the cap so as to not accidentally pull it out.

Drill 1/4" holes near the top of the pipe after the plug has been glued into place.  Slant the hole so that they direct the air back towards the fan assembly.  Insure that the holes are thoroughly cleaned of any shavings and  scrap.