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Posts Made By: Dave Burtrum

December 7, 2004 04:31 AM Forum: Telescope Making

Proto-star curved secondary holder

Posted By Dave Burtrum
I'm working on another scope, an 8" f6. I'm trying to decide which spider/secondary holder to use. I'm looking at the Proto-Star curved holder (really "U" shaped, www.fpi-protostar.com/curved.htm ). Has anyone got any experience with this? I'm concerned that it would be difficult to adjust collimation (hard to center accurately in the tube) and that it would not hold collimation well. Maybe the 3 vane spider would work better and still have less diffraction than a four vane. Any comments would be appreciated. Thanks

Dave Burtrum

January 16, 2005 08:39 PM Forum: Equipment Talk

Hey Tom Hole, More Info on Curved Spider?

Posted By Dave Burtrum
Hi Tom,
Back about Christmas you posted that you installed one of the ProtoStar Curved secondary holders grin . Have you had a chance to use it and form any options? I just ordered one for the 8"/f6 I'm building and was wanting to get any info I could regarding installation, performance, etc. Thanks
Dave Burtrum

February 16, 2005 09:46 PM Forum: Telescope Making

Dob Tube Insulation

Posted By Dave Burtrum
I'm building an 8" f6 dob and using a 10" aluminum tube. I heard that I should insulate the tube but I'm not sure why. Is it so the the tube does not dew up as quickly? If so, shouldn't the insulation be on the outside? Is it to help with tube currents? If so, shouldn't it be on the inside?

I'm using a tube 2" larger than the mirror and an open back mirror cell, so I don't expect tube current problems. Would I gain anything by cutting ventilation slots directly above the mirror to allow for a laminer air flow? Any thoughts would be appreciated.

Thanks
Dave Burtrum

April 22, 2016 02:02 PM Forum: AstroMart FAQ

Problems posting pics in ads

Posted By Dave Burtrum
I tried to upload some pics with an ad last night and it failed, said AM was notified. This morning I notice all of the recent ads have no pics. Anyone know whats going on?

Dave

November 24, 2004 02:11 AM Forum: Equipment Talk

Feathertouch base: Tilt or not?

Posted By Dave Burtrum
Hi Tom,
I've used both, bases with and without adjustment screws. The adjustable bases are MUCH easier to get square with the world than using shims to adjust. Since the base has four places where it attaches, and three points determine a plan (or in your case plane?) wink , if you shim the base, you'll always be looking for the correct thickness for one of the corners you don't adjust. With the adjustable base, just turn the screws til everything is lined up. Of course YMMV, just MHO.

Dave

December 10, 2004 02:00 PM Forum: Telescope Making

Truss scope ideas

Posted By Dave Burtrum
Get the book "The Dobsonian Telescope" by Dave Kreige and Bill Berry. Avaialable at Willman-Bell ( www.willbell.com/tm/dobtel.htm )and also on the Obsession telescope web site. It will answer ALL of your questions.

Dave

September 22, 2005 12:25 PM Forum: Equipment Talk

ServoCat Jr

Posted By Dave Burtrum
Hey Floyd,
In the yahoo groups Servocat forum, go to the "Cableless" folder under Photos to see how I designed a rack and spur drive for the altitude and eliminated the cable. Just another option for the alt drive.
Dave Burtrum

November 12, 2005 01:59 AM Forum: Telescope Making

Commercial Mirrors

Posted By Dave Burtrum
Jon Hall at Pegasus has turned out excellant mirrors. I have an 8"/f6 that he did for me that is great. I also have several friends with larger Pegasus mirrors in their scopes. All perform very well. BTW, just to throw another hat in the ring, Bob Royce of Royce Optical is supposed to do good work as well, but I have no personal experience with his mirrors.

Dave Burtrum

April 1, 2006 01:55 PM Forum: Star Parties

Nat. Astro. Day 2006-Walk Thru Solar System (MN)

Posted By Dave Burtrum
Hi Ken,

Sounds like a neat idea. If you wouldn't mind, how about posting the distances and size of the sun and palnets for your scaleing. We could do it ourselves, but why re-invent the wheel. 8) Thanks

Dave Burtrum

October 16, 2006 08:04 PM Forum: Star Parties

Twin Lakes Star Party

Posted By Dave Burtrum
I have taken all week off, after last week at work even a star party with a little rain beats being at work smile . I'm in SW Missouri and leaving in the morning, 'bout a 7 hr drive. I hope to meet a few friends that will brave the rain later in the week. I'm bringing the camper and the satellite TV, so I can at least watch some movies and visit if the weather doesn't cooperate. If it's' too muddy for the trailer on the observing field, I'll stay at the state park about 2 mi away. I head back home on Sat. The weather channel forecast looks like the rain might be done tomorrow, until Sat night or Sun. You might as well come out and join the rest of us ducks wink

Dave Burtrum

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