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Denver Observing Chair

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#1 Speedy1985

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Posted 23 January 2021 - 06:52 PM

While I wait for the scope and accessories in my signature to arrive, I've been slowly gathering other items. Today, I took a crack at building the Denver Observing chair using these plans...http://www.denverast...nver_chair.html

 

Overall, it has come out pretty good so far. I'm hoping it is tall enough at its highest position for the scope. I still have some things to add and a few tweaks to make, like a non skid front or individual height stops on the back. Maybe some paint and cushioning as well. I already had some 3/4 oak plywood leftover from a project a few years ago that I was able to use for the seat structure. It cost me about $30 in materials, not including the new Dewalt 20v jig saw I treated myself to, lol!

 

tMdZyZV.jpg


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#2 DLuders

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Posted 23 January 2021 - 07:01 PM

It looks good!  smile.gif   You may get some ideas for enhancements by looking at this Cloudy Nights article, "So, you want to make an Observing Chair?"  


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#3 Speedy1985

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Posted 23 January 2021 - 07:10 PM

It looks good!  smile.gif   You may get some ideas for enhancements by looking at this Cloudy Nights article, "So, you want to make an Observing Chair?"  

Thank you, I'll give that a read!



#4 alphatripleplus

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Posted 24 January 2021 - 09:36 AM

That looks great - and I'm surprised at  how inexpensive the materials came out to be.


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#5 Speedy1985

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Posted 24 January 2021 - 10:08 AM

That looks great - and I'm surprised at  how inexpensive the materials came out to be.

Thank you. It probably would have been a little more, but I had some of the items already. It would likely have been even cheaper pre pandemic, but material costs have gone through the roof. A single 2x4 that used to be about $3 is now closer to $7. 



#6 John Fitzgerald

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Posted 24 January 2021 - 10:25 AM

I had to put a piece of rubber radiator hose on the back of the seat of mine to bear against the 2x4 to prevent slippage, or it was nearly unusable.   I also shortened the front foot as it was a trip hazard.  I use mine in my little dome with a refractor.


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#7 Speedy1985

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Posted 24 January 2021 - 11:39 AM

I had to put a piece of rubber radiator hose on the back of the seat of mine to bear against the 2x4 to prevent slippage, or it was nearly unusable.   I also shortened the front foot as it was a trip hazard.  I use mine in my little dome with a refractor.

Yes, I noticed it needs something to prevent that. I'm either going to do that or put in some individual stops on the back at set heights. I'll keep the trip hazard in mind. It's still a work in progress as I need to add a few other things as well.



#8 SonnyE

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Posted 24 January 2021 - 05:11 PM

I like it, looks great.

But watch out for splinters in your bum... bawling.gif

 

Maybe a pillow or some foam on the seat?


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#9 Speedy1985

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Posted 24 January 2021 - 05:24 PM

I like it, looks great.

But watch out for splinters in your bum... bawling.gif

 

Maybe a pillow or some foam on the seat?

Thank you and yes, cushioning on the seat is in the plan!



#10 Speedy1985

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Posted 20 February 2021 - 02:41 PM

So I made some improvement and upgrades to the chair. I added:

 

-Safety stops for the chair assembly to be sure it can't slide down. They are made from 1/2" OD x .065 wall 316 SS tubing, drilled, press fit, and glued in. I set them at 1-1/2" increments.

 

-A seat pad made from an industrial kneeling pad. I let it overhang the sides to maintain the factory bevel and keep from rubbing the edge of the seat with your legs. It's attached with spray adhesive.

 

-A hook to carry and hang the chair. 

 

-A small piece of 1 x 4 on the back leg for a little extra lateral support.

 

-A small clip to stow the spreader bar when not in use. This was made from a clip that is usually use to keep windows in place in a storm door. 

 

-Another, smaller aluminum strap that utilizes the same connection points as the spreader bar. This strap will be used to keep the chair in the stowed position.

 

-Black and yellow warning tape added to the front leg lateral support for tripping hazard awareness. 

 

-2 coats of polyurethane on all of the wood from a can I had leftover from a project a while back.

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#11 John Fitzgerald

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Posted 21 February 2021 - 11:17 AM

I greatly shortened that wide foot in the front of mine.  It got in the way.  I never used a back foot, as when you sit on the chair, you balance with both feet on the floor.  Mine is mainly used in the observatory though.

 

That's a good looking chair with refinements.


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#12 Speedy1985

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Posted 21 February 2021 - 11:49 AM

I greatly shortened that wide foot in the front of mine.  It got in the way.  I never used a back foot, as when you sit on the chair, you balance with both feet on the floor.  Mine is mainly used in the observatory though.

 

That's a good looking chair with refinements.

Thank you, and thank you for the tips. The back foot was just something I thought might help stability a little, especially is the ground is a little softer so it can spread the load. But it’s easily removed if I find it to offer no help. As with anything else, I’ll have to actually use it before I can make a true assessment!



#13 John Fitzgerald

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Posted 21 February 2021 - 12:51 PM

Thank you, and thank you for the tips. The back foot was just something I thought might help stability a little, especially is the ground is a little softer so it can spread the load. But it’s easily removed if I find it to offer no help. As with anything else, I’ll have to actually use it before I can make a true assessment!

On soft ground, you will likely need the back foot.  I think most "Denver Chairs" are intended for hard and relatively level surfaces.


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#14 Speedy1985

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Posted 21 February 2021 - 01:14 PM

On soft ground, you will likely need the back foot.  I think most "Denver Chairs" are intended for hard and relatively level surfaces.

With all of the snow and rain we've been getting around here, it might take until August to stop being "mushy"!



#15 John Fitzgerald

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Posted 21 February 2021 - 01:35 PM

A counterweight on the back foot is a good idea also.  They get forward tippy when the seat is in a low position.

 

Here's the Denver Chair I built probably close to 20 years ago.

 

 

Attached Thumbnails

  • denver chair 02212021.jpg

Edited by John Fitzgerald, 21 February 2021 - 01:46 PM.

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#16 Ron359

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Posted 21 February 2021 - 01:51 PM

On soft ground, you will likely need the back foot.  I think most "Denver Chairs" are intended for hard and relatively level surfaces.

As I know both inventors of the Denver Chair,  it was designed and used first and most of all on a city park grass lawn, so resists tipping or sinking in, as a single point 'foot' might still sink into the dirt, even if not 'mushy'.  If its mushy,  I might be more worried about my scope's tripod sinking and falling over...  Probably time to find some concrete to set up on or just stay home.   ; )


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#17 Speedy1985

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Posted 21 February 2021 - 02:50 PM

A counterweight on the back foot is a good idea also.  They get forward tippy when the seat is in a low position.

 

Here's the Denver Chair I built probably close to 20 years ago.

When I was testing it out, I did notice that I had to stay firmly planted on the full depth of the seat or it got a little "light in the rear".

 

As I know both inventors of the Denver Chair,  it was designed and used first and most of all on a city park grass lawn, so resists tipping or sinking in, as a single point 'foot' might still sink into the dirt, even if not 'mushy'.  If its mushy,  I might be more worried about my scope's tripod sinking and falling over...  Probably time to find some concrete to set up on or just stay home.   ; )

Yes, I can understand that it would likely be fine on a solid grass lawn. I just figured that wider foot would help if it was just a little soft, not necessarily mushy. I won't have to worry about the tripod issue though, I'll be using a dob on a standard alt az mount.  



#18 FoxIslandHiker

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Posted 21 February 2021 - 07:13 PM

So I made some improvement and upgrades to the chair. I added:

 

-Another, smaller aluminum strap that utilizes the same connection points as the spreader bar. This strap will be used to keep the chair in the stowed position.

This is genius.  I tried to the same thing with an eye hook and latch but it is difficult to get the little hook onto and off of the little eye.  I have a small piece of the aluminum bar left over.  I am going to use it just like Speedy1985.

 

Some of the mods I made to the original design:

 

• Increased leg length to 4'.  I would have had enough room to raise the seat high enough for my scope with the shorter legs but now I have a surprisingly comfortable back rest.  I mainly "perch" on the seat when observing but from time to time it is nice to lean back and look at the sky naked eye and give the body and the eyes a break.

 

Chair Front.jpg

 

• Like Speedy, I put a pad on the seat.  For this I used an old closed cell foam kneeling pad that is usually sold and intended for gardening.  We still have another one so the spare will not be missed.
• Just by chance I had a bolt for the seat that was long enough AND was fully threaded.  This turned out to be fortuitous as the threads bite into the back of the front leg just enough to keep the seat from slipping.  I hadn't even noticed until now but you can see the bite marks in the back of the leg in the attached close-up photo.  The fact that I used Doug Fir (a softwood commonly used for construction especially in the NW) and not hardwood helps give the bolt some bite.  I have had zero slippage of the seat when in use.

 

Chair Bolt Close Up.jpg

• I also added a wider foot to the back leg.  So far I have only used the chair on my concrete driveway but I anticipate using it on soft ground and this wider foot should help prevent the back leg sinking in.

• I cut out the bottom of the front foot.  You can see this in the photo.  This is in anticipation of use on rough, hard ground.  (I have an idea of a dark site in the Olympic Mountains that will most likely be on an old logging road or loading area which are usually packed down hard.)  Better for the outside edges to make contact and the inner part to bridge over for better balance.
• I used wood screws in lieu of glue and bolts mainly just because I had several partially used boxes left over from previous projects but over time they should provide a more rigid and less wobbly structure.
• The first time I used this chair, I had trouble with the aluminum bar not staying in place when I moved the chair around the scope.  I fixed this but putting a wingnut on the end of a bolt.  Fortunately, I already had two long bolts in my box of miscellaneous nuts and bolts.

 

Wingnut.jpg

I mainly used wood and hardware left over from other projects.  I had to buy the hinge, handle, aluminum bar and eye and latch.  I ended up spending $19.17 (before sales tax) so while not cost free, my tightwad nature is still pleased.  It works good in the driveway and I hope it will work good when I travel to dark sites.


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#19 Speedy1985

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Posted 21 February 2021 - 07:33 PM

This is genius.  I tried to the same thing with an eye hook and latch but it is difficult to get the little hook onto and off of the little eye.  I have a small piece of the aluminum bar left over.  I am going to use it just like Speedy1985.

 

Some of the mods I made to the original design:

 

• Increased leg length to 4'.  I would have had enough room to raise the seat high enough for my scope with the shorter legs but now I have a surprisingly comfortable back rest.  I mainly "perch" on the seat when observing but from time to time it is nice to lean back and look at the sky naked eye and give the body and the eyes a break.

 

attachicon.gifChair Front.jpg

 

• Like Speedy, I put a pad on the seat.  For this I used an old closed cell foam kneeling pad that is usually sold and intended for gardening.  We still have another one so the spare will not be missed.
• Just by chance I had a bolt for the seat that was long enough AND was fully threaded.  This turned out to be fortuitous as the threads bite into the back of the front leg just enough to keep the seat from slipping.  I hadn't even noticed until now but you can see the bite marks in the back of the leg in the attached close-up photo.  The fact that I used Doug Fir (a softwood commonly used for construction especially in the NW) and not hardwood helps give the bolt some bite.  I have had zero slippage of the seat when in use.

 

attachicon.gifChair Bolt Close Up.jpg

• I also added a wider foot to the back leg.  So far I have only used the chair on my concrete driveway but I anticipate using it on soft ground and this wider foot should help prevent the back leg sinking in.

• I cut out the bottom of the front foot.  You can see this in the photo.  This is in anticipation of use on rough, hard ground.  (I have an idea of a dark site in the Olympic Mountains that will most likely be on an old logging road or loading area which are usually packed down hard.)  Better for the outside edges to make contact and the inner part to bridge over for better balance.
• I used wood screws in lieu of glue and bolts mainly just because I had several partially used boxes left over from previous projects but over time they should provide a more rigid and less wobbly structure.
• The first time I used this chair, I had trouble with the aluminum bar not staying in place when I moved the chair around the scope.  I fixed this but putting a wingnut on the end of a bolt.  Fortunately, I already had two long bolts in my box of miscellaneous nuts and bolts.

 

attachicon.gifWingnut.jpg

I mainly used wood and hardware left over from other projects.  I had to buy the hinge, handle, aluminum bar and eye and latch.  I ended up spending $19.17 (before sales tax) so while not cost free, my tightwad nature is still pleased.  It works good in the driveway and I hope it will work good when I travel to dark sites.

I like the wing nut idea to hold the bar in place too. It’s amazing what you can with old parts and hardware laying around. That’s how I came up with the little bracket to hold the spreader bar when it’s stowed. Even the tubing I used for the seat stops was leftover from a job. For a future project, I’d like to make a welded aluminum folding version. Now that will be fun!


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