Constructing a dob

B&Q Swords also had Al tubing of about 27mm od in stock. I think it was in the TV hardware section as an Antenna mounting pole.
Have a look!

Another option would be to try angle Al, again from B&Q. Mount two pieces back to back so that you form a 'T' section with the horizontal nearly twice the length of the vertical, use an adhesive to stick the two vertical faces to each other. With a solid adhesive ie some thing like super glue rather than a flexible glue like a Bostic you may get enough stiffness- need to experiment first!

Thanks Rice. I plan to do a visit to a few hardware stores tomorrow.

Looks like this is coming together well for you Michael, can't wait to see it. :!:

With all the bad weather we have of late, rumour has it that you have 8 spare aluminium poles. I'll take them out of your way for you if you want...

Well; I tried it with six poles (less to carry in the car) but found that collimation was affected by me using my 2 arms as the 7th and 8th pole. :lol:

Can you describe what kind of box and packaging did they use to ship the mirror. Looks like they coated the mirror with magnolia paint. :lol:

Can you describe what kind of box and packaging did they use to ship the mirror.

Came in a cardboard box. Mirror was wrapped in layers of bubble wrap and then the remainder of the box was filled in small bits of styrafoam.

Looks like they coated the mirror with magnolia paint. :lol:

I was wondering alright why it didn't look shiny.

Designed up the mirror cell in the last couple of days.
Went to B&Q this morning and got some metal. Got the following:
1 no. 25mm wide x 4mm thick steel (for supports to triangles) (€6.28). Cut into three lengths of 160mm.
2 no. 25mm x 25mm box section steel (for cross bars in mirror cell) (2x€10.22). Cut into 3 lengths of 430mm.
1 no. 30mm x 6mm steel plate (for side plates of mirror cell) (€8.66). Cut into two lengths of 340mm.
1 no. Hacksaw (€7.95)
Below is a photo of the parts cut (cut by hacksaw, so it ain't too pretty)

www.astroshot.com/Dob/2.jpg

Next, I need to join them together. Might use angle pieces to hold them together for the mo and then weld them afterwards.

I plan to get the following parts:

* Aluminium Poles (will phone B&Q tomorrow re aerial mast poles. Walked all over B&Q Liffey Valley today but saw none. However, saw them on their UK website this evening though.)
* Spider (Plan to buy it from Astrosystems )
* Secondary Holder (Plan to buy it from Astrosystems )
* Teflon (Plan to buy it from Astrosystems )
* 3mm thick sheet of steel for the mirror cell suport triangles - diy shops don't seem to have this.
* Kydex - any suggestions for a source for this? I'll need a roll 55 inches long x 11 inches high.
* Tube fasteners on secondary cage - ideas anyone?
* Tube fasteners on mirror box - ideas anyone? Ideally I'd like to mount them on the inside of the mirror box.

Cheers,

PTFE is actually TEFLON.

PTFE tape used to seal pipe joints is widely available and very cheap- you might get away with using it to wrap around bearing surfaces - but its quite thin and needs careful handling.

The aerial extension pole was in the aisle of B&Q in Swords (Airside) along with the TV aerials and accessories.

I dont know if using steel parts for the mirror mounts is such a good idea- weight and thermal expansion/contraction characteristics would make me wary - unless you have thought about some sort of gasket/buffer to relieve any direct pressure on the mirror edges.

I'd hate to think of the effect of contraction of the steel against the mirror edges as the temperature falls on a very cold night!