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Show Us Your Dobsonian Riser Platform

dob DIY equipment
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36 replies to this topic

#26 Napp

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Posted 27 August 2019 - 08:20 PM

But in my experience, sighting through a straight-through like a Telrad is never comfortable. I tried risers for the Telrad.  It doesn't matter.  In my opinion the best solution is to limit the time you look through the Telrad.  I only use my Telrad for the initial quick pointing in the neighborhood of an object.  Then I immediately switch to a RACI finder for star hopping to the location of the object.  Problem solved.

It’s all in how you define comfort.  The Telrad on the 10” on its riser and even the 16” was a pain literally.  I mean as in neck seizing up in excruciating pain.  However, adding a 4” Telrad riser on both made all the difference.  No more pain.  My definition of comfort.  grin.gif


Edited by Napp, 27 August 2019 - 08:28 PM.

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#27 Dana in Philly

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Posted 27 August 2019 - 09:06 PM

There's another reason for doing this beyond reducing neck stiffness as the night progresses: it gets the bottom of the rocker box out of the dewy grass. The dew can degrade the beneficial effect of soaping the azimuth motion components. I've noticed this. Sometimes the grass is so dang high that I can't use a tarp or groundcloth to mat it down. The solution then is to raise the rocker box.

 

Perhaps this isn't an issue on some tube dobs with wide, circular bases. But my ES truss dob has, on the bottom of its rocker box, a central bolt attaching three rotating arms with hockey puck feet at their ends. So grass can brush against the bottom surface of the rocker box.


Edited by Dana in Philly, 27 August 2019 - 09:09 PM.


#28 nof

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Posted 28 August 2019 - 01:41 AM

[looking at pic] Are you 8' tall? scratchhead2.gif Maybe one of the nephilim?

grin.gif
Mike


I made it high because of obstacles nearby and use a ladder. Using a ladder on this porch is not awkward but I certainly wouldn’t like that in the field

#29 Sarkikos

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Posted 28 August 2019 - 06:02 AM

There's another reason for doing this beyond reducing neck stiffness as the night progresses: it gets the bottom of the rocker box out of the dewy grass. The dew can degrade the beneficial effect of soaping the azimuth motion components. I've noticed this. Sometimes the grass is so dang high that I can't use a tarp or groundcloth to mat it down. The solution then is to raise the rocker box.

 

Perhaps this isn't an issue on some tube dobs with wide, circular bases. But my ES truss dob has, on the bottom of its rocker box, a central bolt attaching three rotating arms with hockey puck feet at their ends. So grass can brush against the bottom surface of the rocker box.

Have you tried sections of indoor/outdoor carpeting?  They are thick and heavy with rubber backing.  Ollie's discount store near where I live sells sections of these.  Much better than a tarp or cloth.  I always bring two sections of this carpeting to lay down on the field before I set down the telescope mount.  I bring them to the field rolled in an army duffel bag.

 

Mike


Edited by Sarkikos, 28 August 2019 - 06:03 AM.


#30 greenstars3

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Posted 01 September 2019 - 02:23 AM

To be able to see anything below about 40 degrees above the horizon with my 15" dob from my ROR (with 6 ft walls to block out street lights) I purchased a lift table for $700. The price point is up their but with a cordless drill I can raise the dob about 18" to help to see over the walls, it was a bit wobbly so I built some braces to steady the lift table at full lift and it is rock solid now. Most nights I need it I just lift the scope up and put the braces on and sit on my Catsperch knockoff chair and look at faint fuzzies.   

 

edit: the lift table is rated for 300 lbs

 

Robert


Edited by greenstars3, 01 September 2019 - 02:26 AM.


#31 Napp

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Posted 01 September 2019 - 03:44 AM

Perhaps this isn't an issue on some tube dobs with wide, circular bases. But my ES truss dob has, on the bottom of its rocker box, a central bolt attaching three rotating arms with hockey puck feet at their ends. So grass can brush against the bottom surface of the rocker box.

I place a 3’x3’ piece of plywood under my 16” DOB.  Provides a good solid surface for the base.



#32 MitchAlsup

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Posted 02 October 2019 - 05:52 PM

This topic got me back at work on my 13" F/3 build that I had been procrastinating upon.....

 

I built a raiser table for my 13" F/3 DOB that is not just a riser, not just a table, but also the ground board and <flex> rocker box::

 

base01.JPG

 

The angles that will control the altitude bearings have not been cut on the rocker corner pieces.

 

 



#33 MitchAlsup

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Posted 02 October 2019 - 05:57 PM

There is a little finger from the bottom of the corner piece that reaches out to the inside of the ring and these 4 fingers maintain the centering of the <flex> rocker in the "ground" board.

 

base03.JPG

 

The finger itself is simply a 1/4-20 bolt in a 1/4-20 thread in the finger. The 1/4-20 threads measure 0.246" so I drilled a hole in some aluminum (6061T6) and then turned the bearings on centers until there was an acceptable amount of clearance from the 4 fingers to the inside of the ring. The ring was originally cut with a router with radius attachment, but after gluing the two components together, I mounted it up on my rotary table and milled both inside and outside to 0.002" of tolerance (not bad for wood).


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#34 dave brock

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Posted 03 October 2019 - 05:43 AM

I make stands like this

 

stand 1.jpg

 

stand 2.jpg

 

stand 3.jpg


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#35 dave brock

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Posted 03 October 2019 - 05:45 AM

Looks like this

 

8inch 2.JPG

 

8inch.JPG


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#36 dave brock

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Posted 03 October 2019 - 05:48 AM

Need something higher?

 

004a.jpg

 

005a.jpg

 

008a.jpg



#37 InkDark

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Posted 06 October 2019 - 09:16 AM

Aesthetically, it is...rough. But it is solid like a rock. Probably an overkill, it will not shake under the scope. It can even surve for other puposes, like a bench. Not sure why the pictures lies on its side, but you get the idea. 

 

 

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  • 10 inch on Dob pod_e2019_3.jpg



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