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Equipment Discussions >> Mounts

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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Beautiful Homebuilt GEM new [Re: orlyandico]
      #6027124 - 08/15/13 12:52 PM

Find a good scrap metal yard- the good ones sell by the pound, not some guy looking at what you've got and trying to ratchet the price on you. If there are other machine shops in your area, they will be discarding stuff similar to your parts. So, there is one of these here in Tucson (Tucson Iron and Metal) I hit on Saturday mornings from time to time. What I am looking for are scrap aluminum pieces which have dimensions and features close to what I am trying to make. This is an enormous improvement for being able to get parts made since it can eliminate a huge amount of sawing pieces off, machining odd shapes to the right starting configuration, and limiting total material removal.

And yes, keep it really simple. If you want to put beautiful surface finishes on, hold that to last. Get everything cut and fitting together. You can buy a little grinder very cheaply and put a polishing wheel on it and continue the work at home. Conversely, polishing is slow work- if you put that in your build path, you will have half the mount built when you run out of time.

-Rich


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sternenhimmel
super member


Reged: 06/06/13

Re: Beautiful Homebuilt GEM new [Re: Starhawk]
      #6027243 - 08/15/13 01:54 PM

Okay I'm convinced. I'll start sketching out a design based around pillow block bearings, but try to capture some of the recommendations given here. I'm also going to see if I can track down some of those books, or at least, PDF versions if available.

Here's an instructable that I am finding to be incredibly helpful and inspiring:
http://www.instructables.com/id/Homebuilt-6-F15-Refractor-and-Mount/?ALLSTEPS


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Sean Cunneen
Let Me Think
*****

Reged: 08/01/07

Loc: Blue Island Illinois
Re: Beautiful Homebuilt GEM new [Re: sternenhimmel]
      #6027256 - 08/15/13 01:58 PM

Aw shucks, I'm blushing. The build thread here on CN is WAY more detailed though, click on "Fred" in my signature...

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sternenhimmel
super member


Reged: 06/06/13

Re: Beautiful Homebuilt GEM new [Re: Sean Cunneen]
      #6027281 - 08/15/13 02:09 PM

Oh, doh! I should have recognized it in your avatar! This is excellent Sean, and Fred is a beauty. How does Fred perform as an astrophotography platform? Perhaps not with that scope, but in general.

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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Beautiful Homebuilt GEM new [Re: sternenhimmel]
      #6027285 - 08/15/13 02:10 PM

The instructable you found is an unusually good one. I would suggest making the mount head a type of dovetail, though- that makes it vastly easier to swap scopes.

-Rich


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Sean Cunneen
Let Me Think
*****

Reged: 08/01/07

Loc: Blue Island Illinois
Re: Beautiful Homebuilt GEM new [Re: Starhawk]
      #6027310 - 08/15/13 02:31 PM

I am in the midst of adding steppers and driver hardware. Once that gets in place, I'll give AP another shot. Optically, AP was a blast. Setting up the mount for a run was a process, but once dialed in, I could track at 500x for 20-30 minutes, no problem. The crazy thing was with all the extensions, I had the equivalent of 1100x to stack those shots. The disk of the planet to me was little more than an amorphous blob. I took about 6000 frames of which I stacked 1000 good ones to get that level of detail.

I stopped AP because I couldn't keep up with buying new laptops and new cameras AND keep building scopes, so I sold my AP gear and got into classic scope resto's. I feel the itch every now and then, we'll see...


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Sean Cunneen
Let Me Think
*****

Reged: 08/01/07

Loc: Blue Island Illinois
Re: Beautiful Homebuilt GEM new [Re: Sean Cunneen]
      #6027328 - 08/15/13 02:37 PM

I just checked and none of my Signature links worked, The threads have been archived... That means either: I am getting old or: My scopes are getting old!

Off to the scrap heap I guess!


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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Beautiful Homebuilt GEM new [Re: Sean Cunneen]
      #6027478 - 08/15/13 03:46 PM

Here's something which shows the guts of a CG-5 , and will let you see how the clutches for the RA and DEC axis are done to leave the drive engaged with its gearing yet allow the axis to move.

http://www.astronomyboy.com/cg5/

-Rich


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sternenhimmel
super member


Reged: 06/06/13

Re: Beautiful Homebuilt GEM new [Re: Starhawk]
      #6028331 - 08/16/13 12:16 AM

Sean, you should put the links back up, just link to the Archived posts. I was reading through the build thread, and it seemed like you had a lot of wobbles you were fighting. Your mount look so beefy, that this was a surprise to me. I know you replaced the Dec axis completely, and that the RA axis was what, 6"?

I'm looking at a load of roughly 25lbs. What size shafts could you recommend from your experience? Also, I saw the altitude adjustment for the wedge portion, but how did you incorporate lateral adjustments?

Starhawk, it's definitely nice to see the guts of tried and proven mounts, and it's not something I get to see very often.


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sternenhimmel
super member


Reged: 06/06/13

Re: Beautiful Homebuilt GEM new [Re: sternenhimmel]
      #6028410 - 08/16/13 01:30 AM

I also found this in the depths of the internet. Another beautiful homebuilt GEM:

http://home.comcast.net/~charles.wicks/GEM.html


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dmcnally
super member
*****

Reged: 03/17/12

Loc: Lompoc, CA
Re: Beautiful Homebuilt GEM [Re: sternenhimmel]
      #6155537 - 10/24/13 01:06 PM

I just found this thread and it's been very interesting, and informative, to read.

sternenhimmel: Please post an update. I'd be interested to see what kind of progress you've made, or if you've decided to abandon the project.

Sean & Chucke: Your mounts are awesome and thanks for sharing.

As for me, I've got the "bug" to build a mount, but I'm still in the research and idea gathering phase.

Dave


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hjd1964
member


Reged: 05/24/12

Re: Beautiful Homebuilt GEM new [Re: Sean Cunneen]
      #6219382 - 11/27/13 01:33 PM

I DIY'ed a GoTo system for my G11, it works well (meeting my expectations) and wasn't terribly expensive. Not in terms of dollars spent anyway. Check my website, it's easy to setup (as these things go) and runs on a lowly Arduino micro-controller with the help of two Allegro a4988 (or similar) bipolar stepper drivers. Still need to tackle building in multi-star alignment. I use my T-Point like system to overcome this limitation for now and plan to roll it into the micro-controller eventually. Slew speeds were topping out at 1 or 2 deg./sec. (best case), but recent improvements make it fast enough that your motors (and fear of damage to your telescope/self/others) will likely be the limiting factor. Use an Android phone as a hand-controller, ASCOM driver, partial Meade LX200 protocol compatibility, PEC, etc.

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Megabusa
professor emeritus


Reged: 05/28/12

Loc: Page ,AZ
Re: Beautiful Homebuilt GEM new [Re: hjd1964]
      #6219672 - 11/27/13 03:40 PM

I wish I had the smarts to make that ,I did steel and Aluminum fabrication work most of my life so I've been around Machinist ,but never thought to try to pick it up ,Now when I look back I wish I had ,

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