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Plywood Equatorial Mount

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#1 ww321q

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Posted 18 September 2019 - 08:43 AM

I wasn't going to post this till I got to test it but it may take a while longer for Celestron to ship my telescope to High Point Scientific so they can ship it to me. Anyway it's kind of a funny story. This started because someone was having trouble getting a good image through a smaller telescope. I pulled out my dumpster scope Bushnell that has a severely damaged mirror. I was looking at Saturn and was surprised by how much I could see. That started me thinking that I've never looked through a small refractor telescope. I knew I could pick up a used one eBay for cheap. So I started searching around and ended up on the High Point Scientific web site. They had a Celestron 120mm Omni XLT Refractor OTA for $399.95. Thats really more than I wanted to pay but then I saw the $12.91 a month payment. Well I had just canceled my Netflix account a few days before and that was $12.99 I think. My okie logic said that having that telescope was cheaper than the Netflix that I had been wasting my time and money on. So I ordered one! The reason I liked that telescope was it was the biggest offered without a mount at a cheap price.
I really liked the equatorial fork mount that I built for my 6"f8 reflector. I was trying to come up with a similar design for a refractor. The problem was any thing that I thought of was going to have trouble going from north to south and would also need  a counter weight. So I ended up with a design based off the movement of the German equatorial mount. I had some scrap 3/4"11 ply left over from the other build.

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#2 ww321q

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Posted 18 September 2019 - 08:44 AM

Needs more sanding and paint

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#3 ww321q

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Posted 18 September 2019 - 08:46 AM

I have plenty of scrap teak laying around for a tripod

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#4 ww321q

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Posted 18 September 2019 - 08:48 AM

Crank up riser and spreaders

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#5 ww321q

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Posted 18 September 2019 - 08:51 AM

Part of the polar axis . It has enough adjustment for the whole state of California.

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#6 ww321q

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Posted 18 September 2019 - 08:57 AM

I'm using adhesive backed felt from Hobby Lobby and vinyl sheets. The vinyl keeps that Rustoleum 2X paint from bonding to whatever it touches. There is also some UHMW adhesive backed tape for a bearing surface. 

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#7 ww321q

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Posted 18 September 2019 - 08:59 AM

other stuff

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#8 ww321q

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Posted 18 September 2019 - 09:01 AM

Riser up !

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#9 Chucke

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Posted 18 September 2019 - 01:49 PM

Looks good.  I've seen metal mounts made with a similar design that worked well.

 

How are the two plates of the dec attached to each other?  I would be tempted to put one or two webs between them for reinforcement.


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#10 Chuck Hards

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Posted 18 September 2019 - 01:55 PM

I was thinking the same thing, Chucke, it could use a gusset or two.  Otherwise terrific work!  I remember a similar mount in S&T many years ago.  If well-executed, they perform flawlessly.


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#11 ww321q

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Posted 19 September 2019 - 06:33 AM

Yeah I had planed on a couple of plywood gussets but forgot them and had epoxy coated all the plywood and started painting them . I could add some aluminum ones if needed The joints are all glued and screwed and the wood is 11 ply and pretty stiff. The telescope is about 12 lbs and the counterweight is 5 lbs. I spent probably less than $25 on paint and hardware for the mount and base. Most was junk laying around the shop. Patiently waiting for Celestron now. 


Edited by ww321q, 19 September 2019 - 06:44 AM.

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#12 Kiriakos_GR

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Posted 26 September 2019 - 05:03 PM

Very recently I was have to repair - restore, the wooden tripod of a 60mm refractor.

This is the classic tripod made in millions copies at 90s.

Most damages to it, they was caused because of the ultra long screws at legs clamping point.

 

First thing which I did was to replace all by new and even trimming them down to up-solute necessary length.

The chances from now and on to see a deformed one, this is at 0%.

 

My new rule of thump, this is that anything protrude more than 1"  (25mm)  (screw & knob) from the square collard, it is like you looking for trouble (accidental impact statistics rate gets extremely high). 

 

Nice job at the wooden legs, the aluminum collards this is risky choice with out welded nuts on them (made of aluminum naturally).

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Edited by Kiriakos_GR, 26 September 2019 - 05:05 PM.

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#13 ww321q

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Posted 27 September 2019 - 06:11 AM

Very recently I was have to repair - restore, the wooden tripod of a 60mm refractor.

This is the classic tripod made in millions copies at 90s.

Most damages to it, they was caused because of the ultra long screws at legs clamping point.

 

First thing which I did was to replace all by new and even trimming them down to up-solute necessary length.

The chances from now and on to see a deformed one, this is at 0%.

 

My new rule of thump, this is that anything protrude more than 1"  (25mm)  (screw & knob) from the square collard, it is like you looking for trouble (accidental impact statistics rate gets extremely high). 

 

Nice job at the wooden legs, the aluminum collards this is risky choice with out welded nuts on them (made of aluminum naturally).

Yeah the length of the screws was because of the length of the bolts I used. I didn't cut them down because I figured I wasn't done with brackets . I was thinking of welding bungs on the brackets . I'll probably put steel inserts there when I have trouble with the aluminum threads. I could have welded a thicker piece of aluminum on the end to hold more threads but didn't have any bar stock to cut some from.      



#14 ww321q

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Posted 27 September 2019 - 06:13 AM

The telescope for this gets here Monday so I'll be able to do some testing then and see how if functions .



#15 Kiriakos_GR

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Posted 27 September 2019 - 06:37 AM

If you decide to keep aluminum parts (non anodized) you better use clear color lacquer for protection against oxidation. 

 

If I ever decide to make a tripod as you did with oversized legs, I will use exclusively iron 0.121" (3mm) and black paint.

I do have the tools about making new screw threads.

 

Clamping power this is of tremendously importance, for the safety of any telescope. 

My 0.2$ of advice, complete Equatorial Mount testing, with out deployed tripod legs for now.      


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#16 ww321q

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Posted 29 September 2019 - 09:05 AM

If you decide to keep aluminum parts (non anodized) you better use clear color lacquer for protection against oxidation. 

 

If I ever decide to make a tripod as you did with oversized legs, I will use exclusively iron 0.121" (3mm) and black paint.

I do have the tools about making new screw threads.

 

Clamping power this is of tremendously importance, for the safety of any telescope. 

My 0.2$ of advice, complete Equatorial Mount testing, with out deployed tripod legs for now.      

I usually prefer making stuff from steel. Aluminum is lighter and easier to work with in some cases though. I had some 1 1/2"x 1/8" alum. flat bar that I used for the bottom clamps. The other ones are from some 1 1/4" x 1/8" strips I cut from scraps from sheets. All the aluminum parts were DA sanded and clear coated before assembly. 1/8" aluminum is plenty strong enough for the task at hand.



#17 Kiriakos_GR

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Posted 29 September 2019 - 12:38 PM

You seem to be in the right path, and therefore I lost my chance to get hired as engineer project assistant. lol.gif 

 

These double clamps per leg they might save you the day.

Thanks for the conversation!


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#18 ww321q

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Posted 29 September 2019 - 05:57 PM

 therefore I lost my chance to get hired as engineer project assistant. 

Well I can tell you you're not missing out on much as Head Engineer on all jobs coming out of my shop the only pay is entertainment.  



#19 ww321q

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Posted 29 September 2019 - 06:01 PM

New telescope comes tomorrow! I ordered it on Aug 23 So it seems like forever. Testing the mount Monday night ! smile.gif



#20 ww321q

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Posted 30 September 2019 - 06:53 PM

  I would be tempted to put one or two webs between them for reinforcement.

 

I was thinking the same thing, Chucke, it could use a gusset or two.  Otherwise terrific work!  I remember a similar mount in S&T many years ago.  If well-executed, they perform flawlessly.

1/8" aluminum gussets are going to be added in 2 places. There is also a little problem with interference with the aluminum telescope to mount plate hitting. You can see it sticking up on the left top. post-306191-0-94785500-1568814550_thumb.


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#21 ww321q

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Posted 30 September 2019 - 07:07 PM

D'oh !

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#22 ww321q

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Posted 30 September 2019 - 07:10 PM

It's on there

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#23 mikerepp

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Posted 01 October 2019 - 06:55 AM

I wanna come over and play in your workshop!   Mount looks great! 


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#24 Kiriakos_GR

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Posted 01 October 2019 - 09:19 AM

There is a tag on the focuser, I think it says .. Remove before flight  lol.gif  

 

Nice !!


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#25 ww321q

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Posted 01 October 2019 - 10:28 AM

I wanna come over and play in your workshop!   Mount looks great! 

Come on over ! I got tools for everything. grin.gif




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