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Tripod Spreader Design

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#1 eacmen

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Posted 19 September 2019 - 02:10 PM

New user here but long time lurker. Hoping this great community can help me understand the forces at play when using a tripod spreader. I have some spare aluminum and trying to diy a spreader for my CGEM tripod.

The name spreader would imply that the purpose is to push the legs out away from the center. But I've read a few posts that claim the spreader pulls the legs into the center to snug them up to the eyepiece holder.

I suppose you could do either depending on the height you attach the spreader to the legs. But what which method yields the most stability?

Thanks in advance.


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#2 Devonshire

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Posted 19 September 2019 - 03:20 PM

eacman,

 

Are you sure about what stability problem you're trying to solve?  That'll help you sift responses, for your best solution.

 

In my case, resisting gravity was not a problem, and shakiness was not a problem.  My problem was that the stock spreader pressed out against the legs with zero friction between stainless leg and spreader, and the cutouts in the spreader did not grasp the legs so as to completely prevent side-to-side motion.  Skipping details, there were scenarios where legs could shift a bit as the scope moved, and affect my PA.

 

Adding a bit of slit vinyl tube to my spreader ends to create friction, and cranking the center rod tighter was probably an 85% solution.  But nothing succeeds like excess, so I built a DIY spreader as well :-)

 

It's designed to absolutely prevent both side to side and in and out leg motion.  Pic attached.  The leg clamps are just bull bar/roll bar light clamps off ebay.

 

 

SpreaderInstalled.jpg



#3 eacmen

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Posted 19 September 2019 - 03:30 PM

eacman,

Are you sure about what stability problem you're trying to solve? That'll help you sift responses, for your best solution.

In my case, resisting gravity was not a problem, and shakiness was not a problem. My problem was that the stock spreader pressed out against the legs with zero friction between stainless leg and spreader, and the cutouts in the spreader did not grasp the legs so as to completely prevent side-to-side motion. Skipping details, there were scenarios where legs could shift a bit as the scope moved, and affect my PA.

Adding a bit of slit vinyl tube to my spreader ends to create friction, and cranking the center rod tighter was probably an 85% solution. But nothing succeeds like excess, so I built a DIY spreader as well :-)

It's designed to absolutely prevent both side to side and in and out leg motion. Pic attached. The leg clamps are just bull bar/roll bar light clamps off ebay.


attachicon.gif SpreaderInstalled.jpg


Thanks for that info. I am trying to combat the shakes. Granted I mostly observe from our elevated deck so it's probably a losing proposition. But even out in the grass there is a fair amount of shake. The anti vibration pads help but looking to get as much stability as I can.

I'm also pushing the weight limit of the mount, which means I'm likely pushing the weight limit of the tripod. So adding a spreader should mitigate some of that concern.


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#4 Devonshire

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Posted 19 September 2019 - 04:43 PM

Ahh... elevated decks... been there, and done that (long ago), and there is no cure for that, that I know of :-)

 

Grass was also a problem for me - the legs tend to settle and mess up the PA.

 

I'm currently on concrete pavers, and I find that much better.  Patio slabs on sand/stone chips would be equivalent.  We have trains in our current location, and a set of celestron-clone vibration pads, with 1/8" cork sheet glued to their bottoms works surprisingly well.  I think it's not so much that they suppress vibration, as that they do a poor job of transmitting it!


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#5 photoracer18

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Posted 19 September 2019 - 04:47 PM

I put a TPI spreader on the bottom of my CGEM tripod and that seems to work for me. Now thinking about getting the shelf they have for it so I can put a big battery on it to dampen any vibration.



#6 t-ara-fan

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Posted 20 September 2019 - 01:25 AM

I put a TPI spreader on the bottom of my CGEM tripod and that seems to work for me. Now thinking about getting the shelf they have for it so I can put a big battery on it to dampen any vibration.

I got the TPI spreader and tray. It made my HEQ5 Pro rock solid.  I put a 50lb 75Ah battery on the tray. Excuse the Cable Monster.  I also got the TPI leg levelers, really nice for uneven ground. And because the mount has a bad ALT adjustment bolt, I just used the TPI leveller on the north leg to adjust altitude of the mount when doing PA.

 

 

hXucetj.jpg


Edited by t-ara-fan, 20 September 2019 - 01:32 AM.


#7 eacmen

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Posted 20 September 2019 - 10:36 AM

Thanks everyone for your responses so far. The tpi product looks awesome except for the price tag. I can understand the price with it's all aluminum construction and precision milling and pocketing in that center disc but I can get the raw aluminum for 1/3 of the cost and diy it. Might not be as well finished but should provide the same amount of stability, functionality and corrosion resistance.

Not trying to win any beauty pageants here. Maybe I'll end up with another pile of scrap aluminum and end up buying the tpi anyway. But I think I can do it.





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#8 dpaigen

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Posted 20 September 2019 - 10:44 AM

Good luck!  I've been watching this thread and thinking about a diy in wood, or maybe combined with an accessory tray from another tripod.  I haven't found clamps that I like yet, and I am wondering about how to make it quick and easy to set up and take down.



#9 Xeroid

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Posted 20 September 2019 - 03:22 PM

dpaigen,

 

Take a peek at this previous tip:

 

https://www.cloudyni...e/#entry9630884

 

 

Good luck!  I've been watching this thread and thinking about a diy in wood, or maybe combined with an accessory tray from another tripod.  I haven't found clamps that I like yet, and I am wondering about how to make it quick and easy to set up and take down.



#10 Kunama

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Posted 20 September 2019 - 03:27 PM

Make one, I did grin.gif here:  http://www.iceinspac...kunama spreader

 

and here: https://www.cloudyni...er#entry8450400


Edited by Kunama, 20 September 2019 - 03:35 PM.


#11 junomike

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Posted 20 September 2019 - 07:23 PM

New user here but long time lurker. Hoping this great community can help me understand the forces at play when using a tripod spreader. I have some spare aluminum and trying to diy a spreader for my CGEM tripod.

The name spreader would imply that the purpose is to push the legs out away from the center. But I've read a few posts that claim the spreader pulls the legs into the center to snug them up to the eyepiece holder.

I suppose you could do either depending on the height you attach the spreader to the legs. But what which method yields the most stability?


Thanks in advance.


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IMO you need both forces (inward/outward) to keep the Tripod legs rock solid.

I along with others have made less aesthetic versions out of common hardware store items. (mine is post #7)



#12 Devonshire

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Posted 21 September 2019 - 11:48 AM

 

I haven't found clamps that I like yet, and I am wondering about how to make it quick and easy to set up and take down.

You have examples of both lighting clamps and bull bar clamps above.  Both are cheap-n-cheerful, and either can be done and undone with a simple knob.  My bull bar clamps grip the legs with one set of screws, and the spreader is attached with a separate bolt-and-knob.  Not (in my case) a convenient fold-and-go, the spreader arms and shelf are an assembly that would be a separate take-down, but not hard to see how one could do that if needed.  



#13 NinePlanets

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Posted 21 September 2019 - 05:20 PM

You could build it into a coffee table?  smile.gif

 

1"x3/8" aluminum bar stock screwed to the bottom of the plywood.

 

 

Attached Thumbnails

  • BinoMtCoffeTable_500.jpg


#14 biz

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Posted 21 September 2019 - 07:36 PM

Here are a couple I have built for my tripods 

This first one couples straight onto an ioptron inch and a half tripod via the stock socket screws

Z mount folding tripod spreaders and tray 007b.jpg

 

cheers

Graham


Edited by biz, 21 September 2019 - 08:08 PM.


#15 biz

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Posted 21 September 2019 - 07:46 PM

This second one fits onto a tripod I machined up myself . I used a different coupling system by machining up some circular leg clamps which allow me to slide them up the legs to get the correct pre-load on the legs. On both systems the tray is simply removed and the spreader arms fold up with  the tripod.  These spreaders have certainly stiffened up the tripod and removed most if not all any vibrations.

cheers

Graham

 

custom tripod and feet 001a.jpg

 

 



#16 biz

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Posted 21 September 2019 - 08:07 PM

Another photo which shows the spreader arms and center disc.

All  hinged so as they fold up with the legs.. The tray is fitted in such a way it braces side ways movement which can occur when the mount is slewing.

New Tripod, custom built 010b.jpg

 

I'm sure all of you who has built and fitted lower spreaders have found an improvement in stability  .. well worth it in my opinion.

cheers

Graham




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