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Equipment Discussions >> Mounts

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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Mount balance, meridian flip and automation. new [Re: Peter in Reno]
      #5703165 - 02/27/13 10:10 AM

The Mach 1's stiff axes prevent this.

However, this problem gives me an interesting idea for an invention.

-Rich

Quote:

Quote:

I generally have no issue guiding, but when I image something to the north so that the scope can keep on imaging right through from east to west, it gets to a stage where it just goes crazy and starts bouncing back forth. This has already ruined my attempt at m81 a couple of weeks back.




Does that happen when crossing the Meridian when the counterweight shaft is parallel to the ground and rocks back and forth like a see-saw?

I imaged M82 last weekend with my Mach1GTO and I didn't see anything like this.

Peter




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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Mount balance, meridian flip and automation. new [Re: Starhawk]
      #5703354 - 02/27/13 11:47 AM

That spacer really has me thinking as well. Did you consider a machined aluminum one?

-Rich


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averen
Vendor Main Sequence Software
*****

Reged: 01/20/09

Loc: Austin TX
Re: Mount balance, meridian flip and automation. new [Re: Starhawk]
      #5703384 - 02/27/13 12:07 PM

Quote:

That spacer really has me thinking as well. Did you consider a machined aluminum one?

-Rich




Are you referring to my spacer?

If so, yes, I did consider a machined aluminum one. But the cost was considerably more than my MDF spacer (less than $1 and about 30 minutes of my time). The MDF spacer has been in service for a while now and has worked just fine. MDF is very dense and stable so I see no harm in using it for this application. I primed and painted it to keep the dew away from the MDF...which is really the only weakness in this application!

Aluminum would have been the "ideal" choice, but given the cost of the two MDF is more than adequate. I could probably make a couple of hundred MDF spacers for what an aluminum version would cost me. And when it's dark no one can tell...here's the spacer painted.



Jared


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ksipp01
member
*****

Reged: 01/04/10

Loc: Minnetrista, MN
Re: Mount balance, meridian flip and automation. new [Re: averen]
      #5724889 - 03/10/13 10:54 PM Attachment (10 downloads)

sorry for the double post...I just posted in DIY and stumbled on this pertinent thread(although I had seen this on flickr) Here's another thought for the same problem, different mount (CGEM).

so far its a 1/2 inch PVC cap that w/ gentle twisting and firm inward pressure, will actually thread right into the polar scope threads. the spring is attached to the center and held by another 6-32 screw. the outer collar is a 3" PVC DWV adapter, (#70330) (I'll cut unused half off later) The threaded portion of the PVC adapter was opened a small amount w/ an oscillating sander (about 1/2 the thread height) and it actually screws on snug and is held in place by 3 screws that line up with the semi-circle mounting screw channels. the torsion spring is held to that by a thumb screw to a small aluminum spacer attached to spring w/ set screw. I could only find a 90 degree torsion spring at the hardware store, 360 degree ordered online, will be here soon. I'll update once complete.

I put a couple brief videos on my website http://www.scopefocus.info/cgem-torsion-balance

Comments and suggestions wanted!
Thanks
Kevin


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orlyandico
Post Laureate
*****

Reged: 08/10/09

Loc: Singapore
Re: Mount balance, meridian flip and automation. new [Re: ksipp01]
      #5725116 - 03/11/13 02:06 AM

That is a pretty cool approach! (spring in the polar scope bore). The question is.. does it interfere with GoTo slews?

Rich - the Mach1 is not immune to "easy heavy preference," stiff axes or no. I've measured the PE at 6" peak-to-peak when west-heavy, versus 3.5" peak-to-peak when east heavy. So the bias is still there, but most people would have no trouble guiding out 6" (uncorrected).

After PEM, it's 0.4" p-p east-heavy and 0.9" west-heavy.


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ksipp01
member
*****

Reged: 01/04/10

Loc: Minnetrista, MN
Re: Mount balance, meridian flip and automation. new [Re: orlyandico]
      #5763239 - 03/28/13 09:39 PM Attachment (4 downloads)

With a bigger spring (270 degree) and more torque this actually works. It has no effect on slews. I was able to briefly test under the stars the other night...guiding was great on both (extreme) sides of the meridian with no balance change at all. It held up fine but next step get some machined parts made ;-).

video, new pics and guiding screen shots posted here http://www.scopefocus.info/cgem-torsion-balance


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