Balancing

[greealilee]

Looking for some advice please. I have just added a DLSR to my WO Z73 (have been using small SX Ultra C before) and I can not get it to balance in DEC to it been so heavy to the back end. Yes move the scope forward on the dove tail bar but then that will foul the focus knob with the locking knobs and also the thumb screw to lock the focus on the under side. Am I missing a trick here?

[LightBucket]

Can you fix the rings further forward on the vixen dovetail bar...? As I see you can’t move the scope any further forward in the rings...

[LightBucket]

Otherwise you only option is to add weight to the front, with an extra weight balance kit...

[Peter Drew]

Possibly another bar between the finder/guidescope and the WO Z73 would allow you to move the finder/guidescope further forward.   ?

[greealilee]

LightBucket, thanks. Can you point me the right direction for a weight balance kit. I really don't see another option.

[LightBucket]

 

You basically need a bar through the top of the dovetail that you can add weight to, now you could just buy a length of m10 threaded bar and add a couple of nuts to hold in place then buy some of the ADM screw on counter weights...

something like this

https://www.firstlightoptics.com/adm-counterweight-kits/adm-dovetail-counterweight-kit-v-series.html

or just these..

https://www.firstlightoptics.com/adm-counterweight-kits/spare-counterweights.html

[vlaiv]

Two possible options - one is CW in front, have a look at this one for idea of what is needed:

https://www.teleskop-express.de/shop/product_info.php/info/p752_Baader-Balance-Weight-1kg-with-Vixen-Level-Clamb.html

If your dovetail is slotted or has needed bore you don't need clamp - you can use just counter weight and thread it to dovetail - but having clamp makes things more easy - you slide clamp and weight on bar for fine tuning of balance.

Second one would be as Peter suggested, adding bar between main scope and guide scope (not mating scope rings directly to each other) - this would give you two options:

- move guide scope forward and use it as a balance

- rotate main ota so that focuser is on top side. As is - it will not clear guide scope, but with added bar guide scope would be placed further from main ota so you will have enough clearance between the two to be able to fit focuser shaft. This will move focuser out of the way and let you slide main ota forward to achieve balance. Focuser will be in "awkward" position - but it will not matter - just use it like you normally do to focus sub and leave it there.

There is another option that you could try - it might work, but I can't be sure from the image - put focuser at 90 degrees to one side - back side in the image because on this side you have clamp locking bolts. If it can fit there you will be able to move OTA forward, just make sure focuser knobs don't hit anything while scope is moving in DEC.

 

[greealilee]

Thanks all, I will give the guide scope move ago first before the counter weight. Small weights are so expensive.

[Klitwo]

On ‎30‎/‎12‎/‎2018 at 01:46, greealilee said:

Thanks all, I will give the guide scope move ago first before the counter weight. Small weights are so expensive.

If all else fails...use a bowling ball.  I used an adult-sized 16 pound bowling ball for a counter weight on my homemade all-plywood 10-inch f/4 Dob Buster (including a 2-speed horizontal sled focuser with my humble homemade 2" 30mm five element PVC Erfle eyepiece (5th image) & 40mm periscope style off-set finder).  It worked for me!  Try a kid-sized 6 pound bowling ball first.  They are very easy to drill a hole thru.  The entire Dob Buster (1/4" - 1/2" all-plywood) project was tooled with just a saber saw, electric drill, screw driver, wood glue, hand sanded...and finally some redwood stain.....no machining required.

P.S.  I hand-ground and polished the 10" Pyrex f/4 primary mirror back in the early 1960s.  With a new aluminum coating...it still has found use in the Dob Buster....which was completed in 2009.  It has a four brass knob primary mirror alignment system located on each corner of the primary mirro's optical box. Optical alignment is accomplished while the observer is looking thru the horizontal sled focuser's 2" PVC eyepiece holder and adjusting each brass knob independantly via the black O-rings and four large and small wooden pulley wheels.  The 4th wooden pulley wheel (middle - largest) locks the primary mirror in place once aligned (last image).  For those interested..The Dob Buster's design and construction has appeared as a story in Sky & Telescope, Astronomy and Astronomy Technology Today....

Klitwo

 

[Paul73]

Rotating the whole scope 180° should allow you to slide the whole scope forwards on the dovetail.

Popping a couple of spacer washers under the guide scope rings would raise that clear of the focuser if needed.

Paul

@  Kiltwo : Your Scope is an absolute masterpiece.

[Klitwo]

Thanks Paul....

Yeah...hand sanding all the plywood and staining it was probably the most time consuming part of my Dob-Buster project.  It might have even turned out a little nicer looking if I hadn't run out of Burgundy....ha

Klitwo