Concept Stellar Chair

[Clarry (Clayton)]

I've been thinking about making my own stellar chair lately, looking at the designs available on the net, when I remembered a wine rack design I had seen recently. It got me thinking that it might just work for a chair too. So I whipped up this thing in Cinema4D. The back rest would slot into the base & the seat would slot into the variable height holes. It would pull apart easily into 3 or 4 parts (depending on if you wanted to remove the base support for transport). Maybe even a bag with shoulder strap for carrying, like a camp chair.
There's a lot of if's involved. Would the back rest be strong enough to take the weight, especially with the series of hole cut into it. Would the seat be stable with just the 2 side bars to stop it rotating. Another thought was to make the under seat rod square and the holes square so no side rods would be necessary.
Just thought I might get some opinions before I attempt to make a prototype.

[stringscope (Ian)]

Hello Clayton,

A very elegant design indeed

I guess my primary concerns would be:

1. The size of the foot. Probably OK on a level hard surface but I suspect possibly a little small for use on an uneven grass surface or with a little slope. Remember you need to feel stable and secure while sitting at the eyepiece in the dark

2. I agree with you in your concerns that the back rest may need to be heavier. You have pretty significant leaverage at the point where the backrest slots into the base. If you are planning to use a solid timber beam then I would have guessed at needing to use something like 100mm round clear KDHW with a lower brace running to the rear of the foot plate. I am assuming the seat peg would need to be in the order of 50mm diameter leaving only 25mm on either side of the hole. Using a built up girder design instead would give you a lighter and stronger seat back.

3. Given the potential for any unintended offset seating position, I reckon the side bars might need to be plates, say 80mm wide with crossbracing between to counteract any twisting moments. I suspect a square peg/hole might not be sufficiently rigid.

Cheers,

[Omaroo (Chris Malikoff)]

Hi Clayton

A very elegant design, and rendering. Very nice. If you intend to go into production your advertisement is already done. LOL!

I have to agree with Ian that the turning moment induced on the seat if you sat on, or crept sideways on, would kill those side pegs in no time. Maybe make the side pegs a little thicker and cross-brace them by a fixed full-width cap underneath (constructing a tunnel in which your main support pin sits) would alleviate that stress.

Top effort - I want one! I'm a little tired of my metal Stellar Seat. The darn thing's painted black and I can't count how many shins I've destroyed on it in the dark!

[asterisk (Geoff)]

Originally Posted by Omaroo

I'm a little tired of my metal Stellar Seat. The darn thing's painted black and I can't count how many shins I've destroyed on it in the dark!

And what makes you think you won't walk into this seat?

[Omaroo (Chris Malikoff)]

Originally Posted by asterisk

And what makes you think you won't walk into this seat?

Of couse you will, still... but it may not be as heavy!

[astronut (John)]

Those black ones are easily left behind.

[Clarry (Clayton)]

Thanks guys, you make some valid points. I guess with the base issue, most of us look to find some flat ground to set the scope up on, so most time the seat would share this ground. I suppose it's a case of trial & error.
After sleeping on it last night, I started thinking of a better method for securing the seat. Using 2 x 25mm dowel pegs embedded in the bracket, I reckon they would do the job if they fitted snugly into the backrest holes and extended all the way through.

[asterisk (Geoff)]

Originally Posted by astronut

Those black ones are easily left behind.

Thanks John - straight for the jugular

[Starkler (Geoff)]

I would love a chair to use with my big dob but a shortcoming I see with yours is that adjusting height would involve some mucking around.

The best designs IMO are those where you lift/tilt the seat front up toward the back rest to adjust height, and drop it back to horizontal to lock the seat height.

See "denver chair" and "catsperch" observing chair designs.

Also best stability on uneven ground comes from legs giving 3 points of contact on the ground.

[Gargoyle_Steve (Steve)]

Originally Posted by Omaroo

..... my metal Stellar Seat. The darn thing's painted black and I can't count how many shins I've destroyed on it in the dark!

I took to mine with a can of white spray paint - painted the lower 4-5 inches of each leg, plus did the entire inverted U loop at the top so now it's easy to see where the feet are and where to grab it to move it, and no more busted shins!

[Quark (Trevor)]

Hi Clarry,

Have to agree with Geoff, I built a Denver chair and the concept is so simple, you just lift the front of the seat to go higher or lower and your weight on the seat locks it in position. It fold up flat for transport or storage and is self contained, no loose bits to lose or put together.

Also it has three contact points with the ground so is inherently very stable, regardless of the surface it is setup on.

Regards
Trevor

[Clarry (Clayton)]

Thanks people, yeah I'm going cold on the idea now. I guess a simple Denver Chair design is easiest.

[Quark (Trevor)]

Hi Clarry,

Don't be too put off by this, it is really great that you gave some thought to create something that would benefit your observing. Some people never have an original thought in their lives. But, by the same token there is no point reinventing the wheel.

It is really stimulating to look at how things are done normally, then try to either improve what exists or to come up with a whole new process or product, keep punching.

Regards
Trevor