[NLRS] Elevation rotators for small stuff

Thu Sep 12 13:40:01 EDT 2013

I agree with general sentiments on this thread. I don't like hoisting heavy
stuff in and out of the vehicle. I also don't like the idea of a dish of
any size that is supposed to maintain alignment "hanging out" in 60mph
"wind" without the protection of a radome. I also don't like the idea of
the wind load of a radome given the price of fuel. So, I might mount
everything *but* the dish on a roof rack and set up 3 fastening points for
the dish; I'd house the "setup minus dish" in a mini car-top carrier. The 3
mount points would consist of holes in a framing piece (low wind load) that
would be part of the mechanical "lazy susan" or whatever to which the gear
and the feed are attached. There would be 3 corresponding holes placed in
the dish. After stopping at the operating location, the (lightweight) dish
would be removed from the vehicle, aligned with the mounting holes and
attached. Bolts and wing nuts would probably work but Cleco fasteners
inserted from the back side would allow for very good re-alignment of the
dish to the fixed framework. If you're not familiar with Cleco's, they are,
in essence, temporary rivets and are shown in this video:

http://www.flickr.com/photos/mouser-nerdbot/4382489461/

The drive mechanism, alignment and dish would only need to survive the wind
encountered when fixed, not while moving. After operating, 2 minutes and
you're back on the road with the dish and 3 Cleco's in the car and the rest
on the roof in a waterproof streamlined package.

73's
--Paul

*

Paul Beckmann*
*1882 South Ln*
*Mendota Heights, MN 55118-4328*
*wa0rse at gmail.com*
*612-414-0302 (cell, leave msg)*

On Thu, Sep 12, 2013 at 10:32 AM, Doug Reed <n0nas at amsat.org> wrote:

>
>
> Notice how this thread has changed from generic elevation rotors to
> 10GHz dish roving specific?
>
> Here are some links for the Dobson telescope article Ray mentioned.
> Look near the end for "Making the mount" in links 2 and 3.
>
> <http://www.sfsidewalkastronomers.org/index.php?page=building-telescopes>
> <http://www.raycash.us/sfsidewalk/intro.htm>
> <http://www.cdcc.usp.br/cda/telescopios/tie-jpl-nasa/>
>
> The third link is a Chilean site copy of the NASA TIE program
> telescope plans that were mentioned in the second link. I'd guess that
> NASA didn't have the funds to keep their web site active.... :-)  It
> also looks like the SF Sidewalk Astronomers site hasn't been updated
> in 3 years.
>
> I like the mount design for its simplicity. It provides some direction
> that I'd otherwise lack. Think of it as a homebrew Lazy Susan with
> Teflon bearing surfaces. I liked the comment about using a Formica
> sheet or countertop because an old LP record might be hard to find. He
> obviously hasn't visited many thrift shops recently... The "furniture
> sliders" they sell at "dollar stores" might be an alternative for the
> Teflon bearing points.
>
> It would probably work OK to mount the dish directly to their tube box
> so it is more or less centered and supported by the box. Or treat it
> like a 20" tube for design purposes. For our purposes, I could see
> making the mount out of 2x10 treated lumber for the box and cradle,
> but it will be heavy! I'm fairly happy with whatever we need to do to
> make it strong and stable.
>
> But I keep mentally adding metal parts; bearings, shafts,
> strengthening members, etc, to the design, in an attempt to "improve"
> things.... Eventually I'd be back to that 3-box design that John
> mentioned. The only real issue with the 3-box design is that at some
> azimuths the dish would be pointing through the fixed frame member.
>
> I'll end up needing a hoist to lift it to the car roof.... Maybe that
> 3' diameter fiberglass radome isn't such a bad idea..... :-)
>
> If you have a vehicle with a strong roof rack you might mount it to
> that. I'm thinking of my sedan without a roof rack. I can use a
> temporary strap-on ski rack (was $3 at a garage sale) to attach two
> frame members to the vehicle roof and bring them together at a third
> mounting point where a perforated square steel tube comes up from my
> trailer hitch. That should be fairly low impact and easy to remove.
> I'd use ratchet straps from the strap-on rack through the car door
> opening and tighten the ratchet inside to hold it to the car roof.
> Should work but probably not completely water tight....
>
> You could even use perforated steel tube to make the strap-on rack if
> you take some pains cutting 2x4 wood spacer blocks that fit the curve
> of your roof. Use a piece of leather belt or rubber sheet to protect
> the paint from the wood. Probably easiest to cut with a band saw but
> could be done with a coping saw or even a wood rasp.
>
> The two frame members can be the same perforated steel tube and the
> pieces can all easily bolt or pin together. The steel tubes are
> available at Menards, unless you want to buy galvanized instead. Maybe
> could use galvanized Unistrut instead? Comes in 8' or 10' lengths so
> one or two pieces might be enough. It is strong, HEAVY, and has an
> assortment of clamps that might make life easier...... Could be worth
> a look.
>
> I'd need to mount a flat plate in the triangle to act as the turntable
> bearing support. The Formica turntable surface can ride on Teflon
> patches attached to the triangle surface. It would be cute to run a
> cogged or toothed belt all the way around the outside of the turntable
> and use a stepper to rotate it. Bicycle chain? That would take care of
> the azimuth part of the project. So far this is all pretty much bolt
> together stuff.
>
> The tilt mechanism will need pretty sturdy uprights for the dish tilt.
> Or there is nothing to stop us from going back to a simple vertical
> pipe to mount the dish on the turntable and modify the existing dish
> tilt mount for motor adjust. Yup, I can reinforce the vertical pipe
> and just use the dish tilt mount with an electric screw driver or
> possibly one of the $15 linear actuator units from Surplus Center.
>
> Might be worth considering.... Except for the DIY Lazy Susan, it is
> all the way back to the original designs we were discussing, similar
> to what Jerry mentioned and what Bob W0AUS tried 10 years ago..... My
> only complaint is that the dish can't be laid horizontal very easily.
> I'd have to settle for turning the dish edge-on to direction of
> travel.... Pins or clamps to hold it on that direction while in
> motion?
>
> Anybody with an ENG (Electronic News Gathering) van they are not using? :-)
>
> 73, Doug Reed, N0NAS.
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