Wednesday, July 7, 2010

Fun With Machining

I spent a bit of time resisting the urge to use inappropriate language while working on a caster set for the Stellarvue Walnut Tripod used on a number of their mounts.  I have a customer in Peru who runs a telescope store there, and he has apparently sold quite a number of mounts with this tripod--and wants a rolling solution.

Anyway, after a lot of experimentation, I produced a fascinating and infuriating prototype out of acetal that some lucky customer will get at a bargain price:

I have since come up with something that does the same thing, but that is dramatically simpler to make, and uses mostly off-the-shelf parts:

That piece of wood is a just a chunk of pine that I have planed to the dimensions of the Stellarvue tripod leg, plus or minus a few thousandths of an inch.  The hole in the underside is threaded for a 3/8"-16 thumbscrew.  It turns out that the tripod leg will be held in just by friction for the vast majority of customers, but a thumbscrew provides a way to secure it.  I put the hole in the underside so that any marring that the thumbscrew makes on the leg won't be particularly visible--and using a 3/8" diameter bolt means that the pressure will be applied over a large area, allowing the same force to be applied to be applied at a lower pressure, causing less damage to the tripod leg.  Using a thumbscrew also discourages the customer from using a wrench, which would certainly mark the tripod leg.

This is considerably simpler and faster to make than the prototype, and without any temptation to curse!  I think it also looks better, and unlike the acetal that I have previously used, any shavings or leftover parts from this are aluminum scrap that can be recycled, to protect Mother Earth, and ScopeRoller's botttom line, which is the more important definition of being Green.  There are several new tripods that I now have to support, such as the new Losmandy GM-8 tripod--and this is definitely the direction of the future for ScopeRoller.


  1. Perhaps a bit of shim behind the screw hole would help protect from marring?

  2. Not a lot of meat @ that thumbscrew area and only a few threads at best...are you concerned about stripping?

  3. I have to wonder if there isn't a way to make a more universal base that tripods can simply stand on.

  4. There's no real load for the thumbscrew--it's just to add a small amount of friction.

    There are universal bases from my competitors, but they suffer from their own set of problems inherent to their design. Visit and look under "Our Competition" for some of the negatives.