A Tale of Two Telescopes

As I mentioned before, I am building a 4.25" spotter / CCD imaging scope to attached to the main assembly. This is not to be confuser with the actual finder scope which with direct the telescope.

For this task, I chose to refit an old OTA I had laying around (my first telescope as a matter of fact).

For those of you interested in building a similar scope, here is the link to the plans I used back in 2001: http://www.lymax.com/cosmicone/4inchdob/4inch01.pdf

Anyway, I started by finding a 5.5 I.D. 6 foot length of 6061-T6 aluminum tubing at the local scrap yard (Frank Sahd Salvage Center in Columbia, PA) and convinced them to let me cut off a shorter 6-foot piece (it was 16 feet long originally, and I suspect it was some sort of street light pole). Then I trimmed it to 48"in length.

Next, I came up with a primary mirror holder and collimation design by scrounging the internet. I eventually adapted a design used by Rick Scott for his Lurie-Houghton Project and located here: http://members.cox.net/rmscott/lh_scope/scope_rear_view.html

After settling on the design and having the parts machined ($150), I shifted my focus to the tube itself. It was in pretty rough shape when I got it, so I sanded the outside down until it was shiny and touched up the surface with a bunch of hand sanding.

Next, I determined where all the holes should go, namely that the focuser hole should be located exactly 37" from the rear mirror mount bolt holes and the secondary spider close by that. I was able to find a local metal finishing shop to commit to polishing the tube with a high shine and anodize it blue, so after drilling all the appropriate holds, I will drop the tube off next Monday, so stay tuned for the results!

As for the focuser details, I settled on the Orion 2" Crayford style Focuser available here: http://www.telescope.com/control/product/~category_id=focusers/~pcategory=accessories/~product_id=13039/~sSearchSession=a0b27e12-903e-4088-861a-b3ff5ea7c714

I had contacted Orion about a month ago, but despite speaking with several top managers, I was turned down cold on a donation. Thankfully though, after a month of stewing on the problem, the thing went on sale for $65, and even with shipping, it was still $25 cheaper than it could have been.

I also purchased a cheap, but awesome 60mm neon blue LED case fan to mount on the back of the primary mirror assembly, both to act as a cooling device when setting up, and to make the thing look awesome, since the OTA will also be blue anodized.

Here's the link from Newegg: http://www.newegg.com/Product/Product.aspx?Item=N82E16835119021

Suffice it to say, it looks awesome, though I will take more pictures upon final assembly. I also centered the fan on the hole in the mirror plate and drilled and tapped 4mm metric bolts holes for some stainless steel hardware.