120 degree bracket

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120 degree bracket
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jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28238
Location: escaped from Swindon

Posted: Sun May 15, 16 4:48 pm Post subject: 120 degree bracket
My search abilities are getting beaten here. I want to create a 3m diameter hexagonal mould to pour cements into. Some 120 degree brackets would make life simple. I can find images and can import them by the million from alibaba, but 6 would be a better option.

Nick

Joined: 02 Nov 2004
Posts: 34535
Location: Hereford

Posted: Sun May 15, 16 6:15 pm Post subject:
Make a wooden former? Eta. Are you after metal brackets to do exactly this? Doh.

Nick

Joined: 02 Nov 2004
Posts: 34535
Location: Hereford

Posted: Sun May 15, 16 6:55 pm Post subject:
https://www.ebay.co.uk/itm/271746822626

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28238
Location: escaped from Swindon

Posted: Sun May 15, 16 7:43 pm Post subject:
Looks very small, and seriously all the way from the USA for something that can't be that esoteric? Glad to see it isn't easy to find though, thought I was going daft.

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Sun May 15, 16 9:04 pm Post subject:
Make from plywood. Screw 2x2 (or whatevers handy) along ply edge to enable fixing to your mould.

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28238
Location: escaped from Swindon

Posted: Sun May 15, 16 9:18 pm Post subject:
a diy approach is clearly possible, but a lot more work and chance to be a bit off on degrees.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun May 15, 16 9:46 pm Post subject:
As the radius of a circle is the edge length of a hexagon it's easy enough to draw a hexagon on the ground using cord and marker tool. You can then mark the intersections with marker spray and construction your mould using these marks as guides.

Nick

Joined: 02 Nov 2004
Posts: 34535
Location: Hereford

Posted: Sun May 15, 16 10:10 pm Post subject:

jema wrote:

Looks very small, and seriously all the way from the USA for something that can't be that esoteric?
Glad to see it isn't easy to find though, thought I was going daft.

Well. I googled 120 degree bracket and it popped up. Do you know anyone in IT who could help you?

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Mon May 16, 16 8:16 am Post subject:

jema wrote:

.......... a lot more work and chance to be a bit off on degrees.

Nah.
4 foot square piece of ply, in the middle draw your hexagon with 1 foot sides, screw 2x2 to ply thus forming a hexagon of 2x2, number-up 2x2 and remove, cut out middle of ply (erring on large side as re-fitted 2x2 will still be at 120"), re-fit 2x2, cut whole thing into 6, voila 6 6inch long brackets.

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Mon May 16, 16 8:48 am Post subject:
OTOH if I was going about it I wouldn't make brackets. I would make a hexagon from 8 foot lengths of 4x1 laid flat (overlapping each other). Leave excess length at corners so they can be braced. That could give an accurate hexagon and brace the mould nicely.

dpack

Joined: 02 Jul 2005
Posts: 46235
Location: yes

Posted: Mon May 16, 16 9:54 am Post subject:

onemanband wrote:

OTOH if I was going about it I wouldn't make brackets.
I would make a hexagon from 8 foot lengths of 4x1 laid flat (overlapping each other). Leave excess length at corners so they can be braced. That could give an accurate hexagon and brace the mould nicely.

this

use a biggish 120 cornered bit of ply to set each corner of the mould and a short bit of wood screwed onto the top edges to create a triangle brace before fixing the end and lower edge by direct screws into the adjacent length.

this requires one end of the 4 x 1 to be cut at a perfect 90 degrees and a flat surface to work on (or use a spirit level and shims if you are constructing on a wonky surface in situ and need a flat level top to the concrete)

fixing the middle of each length with either a peg to the floor or by cross bracing to a bit of ply in the middle will keep the outside edges from bowing out when pouring.cross bracing makes it more difficult to use a plank to sweep the surface flush with the top of the mould so pegs are better.

remember to vibrate (or cut with a shovel) the concrete to remove air bubbles and compact the solids.don�t over do it or use a very wet mix as the lumps will all settle leaving only sand and water at the surface.

in something that size reinforcing mesh will help to prevent cracking .

there are many compositions of concrete but for a wide ,relatively thin slab i would probably go for

2 mixed aggregate,2 sharp sand,1 portland,1 lime

for a pale(or tinted colour ) i would use 1" to dust granite and snowcem /lime in a 4:1:1 mix

onemanband

Joined: 26 Dec 2010
Posts: 1473
Location: NCA90

Posted: Mon May 16, 16 1:32 pm Post subject:

Dpack, you're not wrong, but I think you slightly misunderstood my plan or missed the words "laid flat"
8 foot 4 X 1's laid flat on floor, alternately overlapping. Easy to set up as hexagon with a tape and a square. Once set up as hexagon whack in 2 screws at each corner, then add further braces across oversailing timber, thus triangularly bracing it.

You will need to make at least 2 of these. One for top, one for bottom. Fix mould faces to inside of the flat 4 x 1 hexagons.
4 x 1 laid flat will not bow out, so no need for cross-bracing and no obstructions to trowelling.

Tavascarow

Joined: 06 Aug 2006
Posts: 8407
Location: South Cornwall

Posted: Mon May 16, 16 3:05 pm Post subject:
Cut your mould from reasonably thick timber with a skill saw or bench saw set at 60 degrees & hold it together with a ratchet strap. When the cements cured loosen the strap & remove the mould. No brackets needed.

Tavascarow

Joined: 06 Aug 2006
Posts: 8407
Location: South Cornwall

Posted: Mon May 16, 16 3:06 pm Post subject:
Actually I think that should be 30 degrees each end. You can work it out.

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28238
Location: escaped from Swindon

Posted: Mon May 16, 16 6:26 pm Post subject:
thanks folks, I will have a play.

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