Telescope Reviews: Re: Scrap Bin Observing Chair

Hi Ron

Have been accustomed to round conventional stools, and this one is about 12" diameter, like a lot of them. I figgered the round shape would 'feel about the same' if one were sitting at any angle thru a 180 degree arc on the stool. Maybe not that big a deal with a telescope seat, but possibly more useful as a general-duty shop seat which it might be good for as well.

Something not planned, but the column suffices not too bad as a 'semi reclining' back except when the seat is adjusted real high.

Wanted the column pretty narrow for the shop-use case, where a wide chair might be too hard to use. Also, I only had two old broomsticks, insufficient to make a wide seat frame (grin).

Thanks, will study on that.

New growth southern pine can be surprisingly light-weight, and it can be strong in big pieces. But I don't know enough about 'strength of materials' to skimp on such a relatively weak wood. New-growth pine is prone to split if it gets a mind to. Which is why the seat looks built like a tank. The seat isn't incredibly heavy, but didn't want to go to the bother of building just to have it break.

Initially planned a three-point support with no back foot. But after building it, I adjusted the seat to the top rung and intentionally played the fool leaning dangerously in all directions. Seemed risky not to support it wider in the back. If one made a sufficiently foolish maneuver with no back foot, the seat would be happy to dump the occupant. But a shorter back foot might work just as well as the wide one.

I was emulating other folks' removable-seat astro chairs, but hadn't found a good picture of what their locking mechanism looked like. So was copying what I imagined it must look like. A much better shape could probably be thunk up.

So here are details, and apologies if it is too lengthy painful detail. I don't know much about this stuff, so 'its all new to me' and I don't know what is or is not obvious.

Decided that a 24" front foot is as wide as would be convenient to tote out a 36" door. Looked up the height adjustment range of some commercial seats.

Used basic geometry to figure the depth of the chair to make a 24" equilateral triangle. Then solved another simple right-triangle problem to arrive at the length of the column pieces, to monkey-see-monkey-do the adjustment range of a commercial seat.

Cut the column pieces and tacked em together at the correct angle. Drew a line down the middle of the angled column piece. The seat main piece is doubled 2X4's, so laid a 2X4 on the angle column 'horizontal to the base'. Cut two little pieces of broomstick and drew X's thru them. Set the broomstick pieces on the center line on each side of the 2X4 and measured the distance between dowel centers. Then clamped both columns together and drilled all the holes that distance.

After the frame was assembled, I cut the doubled 2X4 'core' for the seat, long enough to have space at the top-back for a 2X2 'stop piece' behind the top dowel, and long enough to extend out the front for 13" to make room for the 12" round seat. I just set a 2X4 in the gap, adjusted it until a 2X2 block would sit behind the top dowel, then measured 13" out from the front for the seat.

Then drew markings of where the seat 'core' would hit the bottom dowel. Cut a staight line with the bandsaw, with a radius on both ends of the cut, so the cut line would end right before the bottom dowel position. Wanted to leave the back at least 2" thick, because perhaps a lot of strain can happen back there after a feller who weighs an eighth of a ton sits on it (grin).

I cut 1X4 pieces angled to sit on both sides of the doubled-2X4 core, so they would bear on the frame and not put all the weight on the top and bottom dowels. Then laminated 2X2 'wings' on both sides of that, and cut it into a circle with a jigsaw. Routed the top edge with a 3/8" roundoff bit.

This is the part which failed due to the polyurethane glue, probably my fault somehow. So the 7 plugs on both sides, cover 3" counter-sunk screws reinforcing the repair joint of TiteBond III. Since the inside core pieces were also glued with polyurethane, that is why there are extra screws also visible on the lower part of the seat. I didn't bother to cover those with plugs. Hopefully the center pieces don't get as much stress and the polyurethane will hold, but no tellin.

Here are pics of the front, side, back of the seat.

Here is mating detail, side and top.

Apologies for such a long-winded message.

--------------------
CPC 1100, C102SLT, SV F80, Meade 70 & 60 AZT
Q70 38mm, Pan24, Meade 5K 18mm UW, Axiom LX 15mm, Nagler 13T6, Axiom LX 10mm, Expanse 20mm, 9mm, 6mm, BO/TMB 5mm, 2.5mm

Post Extras