Quote:...added a Mauro Da Lio baffle...
Quote: In a tube, a rear fan also creates a vortex which scrubs and lifts much of the boundry layer away too.
At least it does in my 10" f/5.
C10NGT, Z8, 150 Rumak, XLT 150, C6, C5, SW5 Newt, 4.5 Ball, C102GT, C90, ST80, A70LF; 15x70, 25x100; Burgess BV; Paracorr II; T6 2.5, XO 2.58/5.1, Ethos-SX 3.7, Delos 4.5, TV Plossl 7.4-26, BCO 10, Hutech HC 12.5, Sterling 12.5-25, ES100 14, CZJ H 16/25, CZJ O 16, M5k UWA 24, T5 31, Ultrascopic 35, Titan-II 40; Bino Pairs M5k UWA 6.7, Baader Zoom 8-24, M5k SWA 24, TV Plossl 26, RKE 28.7; Zooms NZ 2-4, NZ 3-6, Leica ASPH 8.9-17.8, Baader 8-24; Baader Zoom Barlow, VIP Barlow
Quote:That looks like it could be very usefull as I have two scopes with fans so it could be used on either scope to mess with the fan speeds , it would save the trouble of fitting pots to both scopes , come on spill the beans where do you get such a device :-).
ATM project around a Coulter 17.5" mirror COMPLETE with Intelliscope C.O.L Apogee 6" F8 refractor, CG-5 mount, Coronado P.S.T Criterion 4" F12 Dynascope
Quote:nevy,Quote:That looks like it could be very usefull as I have two scopes with fans so it could be used on either scope to mess with the fan speeds , it would save the trouble of fitting pots to both scopes , come on spill the beans where do you get such a device :-). Exactly. The less after-market cutting, splicing and wiring I have to do the better!Mike
Quote:Detail on Ganymede. Bionic eyes?
10" F/4.7 Modified Skywatcher Reflector, 38mm Orion Q70, 17mm Modified Ultima LX, 10mm TeleVue Delos, 7mm Pentax XL.
Quote:Maybe I'll get lucky and see the footprints on the moon too.
150mm MCT f/13, 31% CO
"People say I'm in denial. I disagree."
Quote:Quote:Detail on Ganymede. Bionic eyes? Not at all. At least 8/10 seeing and preferably about 400x though you can see it with less. It's an uncompromising kind of feature that demands a steady image. I've tried with 7/10 which is still good seeing but its too soft at the magnification needed to show some albedo here.
Quote:Just wondering something here,Would it be ok to use a 9 volt battery on my 12 Volt fan? I tried it and the fan spins....but I am wondering if the battery will get too hot and malfunction over time?
Quote:Hi Don, It's De Lorme, If you don't remember I have a old 17.5" Odyssey. Do you think 3 39cfm would be enough? I had planned on putting them in the rear. But after reading that a side one really makes a difference I'm going to put one on the side to. Do you know of anybody that has a picture how it should exactly look. You Know every picture tells a Story! LOL. I had not even considered this option. I really appreciate you Veterans here on CN pointing me in the right direction. Thanks again! De Lorme
Quote:The only other really successful application that I have seen for fans is a recent encounter with Dan Kleppner's 10" Starmaster with a rear blowing fan and 4 holes strategically placed above the primary mirror to exhaust the flowing air.
Quote:It seems like when you are installing a side fan or fans blowing across the mirror with vent holes on the opposite side... the vent holes on the opposite side might benefit from exhaust fans? Otherwise it seems to me like the side fans blowing across the mirror will hit the opposite side and break up around the vent holes, causing further turbulence inside the mirror box or tube.Or is there pressure created by the side fans that causes the air to vent smoothly without exhaust fans?
Quote:You can use what they call a "hole saw". It's like a cup with teeth on the rim and it attaches to a drill. There's a center bit to guide it in straight.You can get these saws up to fairly large sizes on-line, but most larger hardware centers typically have them up to 3".I did this to create a focuser hole in a tube I had and it's how carpenters put holes in doors for door handles. <Author switch>Thank you. I had seen these, but always thought they were meant for wood, not metal. They have no problem cutting a hole in a metal tube?
Quote:Another potential thermal problem with my Obsession mirror box is the top hole, the round baffle hole at the top of the square box, which also holds the lid in place and helps prevent stray light from getting in the mirror box. In the photo you can see I have covered the baffle with black protostar flocking. I'm tempted to put holes in the top around the edges of the baffle, because it seems like the baffle could be preventing the air from exiting to the side of the mirror and might actually be re-directing thermals back into the light cone. Any thoughts?
Quote:If you get the "bi-metal" kind (usually a red metal), they will quite happily cut through metal. A friend that owns a machine shops uses them to saw holes in thick stainless steel, a very tough metal to drill through. Take it slow, at a lower RPM on the drill.
Quote:Here is a picture of the rear sucking fan embedded in the mirror cell sandwiched in Sorbothane. The MagLev fan and back of mirror cell is fully enclosed in the rear of the mirror box so it creates a venturi effect. The combination of the front blowing fan and the rear sucking fan also seems to evenly cool the primary mirror. With the rear sucking fan running only at high speed, the primary tends to become overcorrected due to apparent improper cooling of the edges of the mirror without the center being sufficiently equilibrated.
Quote:I use a 6volt flashlight cube batter to my 5" DC fan behind the primary. Matching the voltage to the fan rating is overkill in my experience. Six volts pushes that fan fine and quiet and vibration free. Even the 80mm boundary fan is running at half its rating or less. There's a lot to be said for quieter fans too.
Quote:I reversed my rear fan so it too was sucking instead of blowing air up the tube. For me with its closed tube it was a disaster. Every single exhaled breath no matter how calm would rise up and fe sucked down the tube killing the images terribly. It was awful. Too the secondary fewer up n thirty minutes. What little heat is a ails me after the fan blows the air up the tube never allows secondary dewing. Residual heat at this low per centage now is actually benefitting my system - and to no ill effects. Boundary is running too.
Quote:Mike try the blocky 6 volt battery on two fans too. It's the boxy looking thing about 2.5" wide and 4" tall with coiled springs sticking out the top. And brother they last. I've had one since the half doz obs since thanksgiving and its still humming fine. My sessions are often three hour run times.
A nice gentle power source for low noise vibration - looks badass too. Lol.