Jump to content


Photo

Deforking Powerstar III 8"

  • Please log in to reply
8 replies to this topic

#1 Madratter

Madratter

    Fly Me to the Moon

  • *****
  • Posts: 6376
  • Joined: 14 Jan 2013

Posted 11 February 2013 - 01:56 PM

I want to defork my Celestron Powerstar III, 8". I want to mount it on my CG-5. As far as I can tell, Celestron only sells CGE dovetails at this point (and I have one).

Options are to either use the CGE dovetail and an adaptor to Vixen style, or find a vixen style dovetail that will mount directly. I know Farpoint sells one for about 75$. Frankly that seems out of line with the cost of what I paid for the CGE dovetail. However, it is in line with the cost of the adapter.

Any suggestions. This problem has to come up constantly, but I just can't find a cheaper solution.

#2 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15567
  • Joined: 06 Jul 2007

Posted 11 February 2013 - 04:58 PM

There are plenty of alternatives. Starting with Scopestuff.com, ADM, and Losmandy.

#3 Madratter

Madratter

    Fly Me to the Moon

  • *****
  • Posts: 6376
  • Joined: 14 Jan 2013

Posted 11 February 2013 - 09:00 PM

There are plenty of alternatives. Starting with Scopestuff.com, ADM, and Losmandy.


Thanks. And by the way, I enjoy your blog a great deal.

I had seen the Scopestuff and Losmandy versions but not the ADM. Unfortunately, none of them are near as cheap as what I paid for a much better CGE (Losmandy) dovetail. It makes no sense, but it is what it is.

I have bought a couple of things recently in part because of your blog. (Skytools, and Nebulosity). Some of your posts on the CG-5 also were read with great interest since I was getting a scope that used one.

#4 Geo.

Geo.

    Mercury-Atlas

  • *****
  • Posts: 2859
  • Joined: 01 Oct 2008
  • Loc: Upstate NY

Posted 12 February 2013 - 10:32 AM

I've adapted the ScopeStuff $24 Vixen format bar by machining a flat on the end of the bar and fitting a custom machined radius block. Figure the machine time is worth about $50-75 and I get a functional, but less than professional looking product. So when I see a dovetail setup for a C8 come up for under $50 I jump on it.

A friend just bolted a short Vixen format bar to the under side of the CGE bar.

Or eBay the mount and you'll get the funds for a decent bar.

#5 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15567
  • Joined: 06 Jul 2007

Posted 12 February 2013 - 12:12 PM

I've adapted the ScopeStuff $24 Vixen format bar by machining a flat on the end of the bar and fitting a custom machined radius block.


I've used the Scopestuff bar for years and it works fine. Not sure what you had to customize and modify. Mine worked fine outa the box... ;)

#6 Madratter

Madratter

    Fly Me to the Moon

  • *****
  • Posts: 6376
  • Joined: 14 Jan 2013

Posted 13 February 2013 - 06:40 PM

Well, I have gone ahead and ordered the Scopestuff kit. I'm still a little boggled that adding a Vixen style dovetail is a 79$ proposition (MDC8) instead of adding a Losmandy style dovetail at 32.99$. Especially since the Losmandy style dovetail is so much more substantial.

#7 Geo.

Geo.

    Mercury-Atlas

  • *****
  • Posts: 2859
  • Joined: 01 Oct 2008
  • Loc: Upstate NY

Posted 14 February 2013 - 12:17 PM

I've used the Scopestuff bar for years and it works fine. Not sure what you had to customize and modify. Mine worked fine outa the box... ;)


The bar will not bolt directly to the 1.75" O.C. mounting holes found on most C8s, some form of radius block is needed. I started with the type in the photo, but have changed my approach every time I've done the job. A mill [insent] isn't necessary to cut the 4.5625" radius, but I found runnig the aluminum bar over a 10" table saw blade at an angle a bit too exciting. The mill is slower and setup for a one off is a PITA. So I'm still trying to come up with an easier way to get this done.

I find that by machining a flat on the dovetail bar I can get it closer to the tube, eliminating a front block and reducing flexure. This also lets me use 5/16-3/8" aluminum bar, which is more common in the offcuts at the metals monger and makes the connection to the block more secure. At this point I am using 3/16" rivets to fix the dovetail bar to the block.

Attached Files



#8 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15567
  • Joined: 06 Jul 2007

Posted 14 February 2013 - 01:28 PM

The hardware I received with the Scopestuff rail worked fine. No mods nor extra parts required. Two bolts are used as stabilizers in lieu of a radius block, and nothing else was needed...

#9 Madratter

Madratter

    Fly Me to the Moon

  • *****
  • Posts: 6376
  • Joined: 14 Jan 2013

Posted 15 February 2013 - 10:15 PM

I got the Scopestuff dovetail and mounting plate today and put it together. It required more hands than I had (I needed to borrow my wife to help), but it went together nicely and seems quite secure.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics