[Kleftiwallah]

The cover on our garden parasol has had it,  the structure is of six 'legs' each 55" long.  I have some blind material which is 92" x 75". 

I also have some other blind material size unknown.  Is it possible that by inserting a triangular piece of the 'other material into the main piece with the apex of the triangle at the centre of the rectangle thus moving the radius of the rectangle apart I can get the larger piece to fit the structure.  Turning the rectangle into something of a truncated cone?

I've been mucking about with bits of paper and I think inserting more than one triangle is required, but perhaps some clever person will solve it!

Well, t'is a wet afternoon and ther's nowt ont' telly.  Cheers,   Tony.

[mumofstig]

Just pin the fabric around the parasol frame, covering as much of it as you can.  Add in any extra fabric where necessary for complete coverage. Cut and sew as necessary to complete the cover...
Don't worry about geometric puzzles - just go down the practical route 

Easy peasy 

[Kleftiwallah]

Good evening Mum, 
I've resorted to scale drawings,  cut out a piece of paper the size of the ex blind and cut a triangle to see how many I could fit and obtain from it.  Getting there, no sewing, glueing.  Just got to find a waterproof, flexible glue for a man made fabric.

Cheers,  Tony.
 

[mrs bouquet]

Too difficult,  just stay out of the sun or buy a new parasol     Mrs Bouquet

[snowdrops]

I’d have opened the parasol & drawn around the triangles on a large piece of paper or card to make a pattern & if necessary cut it multiple times & fitted them to the fabric, inverting them to fit, leaving a seam allowance. If you should go down this route of sewing the pieces together you might need to do a French seam to strengthen the seams.

[Kleftiwallah]

It has to be glue as my skinny blister won't let me play with her sewing machine!

Cheers,  Tony.

[wighty]

If you are going to glue them then you need a product called SBR which you can get from a builder centre.  It's latex based and about the only water proof outside glue than we can think of. Hope that helps.

[Kleftiwallah]

Good evening everyone,

Mrs Bouquet,  I have spent days in front of the computer looking at Gurgle, Limpopo etc for a replacement pergola cover, extremely rare.
Wighty,  SBR many thanks for that.   That project is on hold now as I've got to repair an emergency light box to use across in the garage on the trike during the dark days acoming.

Cheers all.   Tony.

[grinling]

could you not take the original cover off and use that as a template.
If you are thinking of leaving it out in the rain, you will need to wash the fabric first as it will shrink.

[Kleftiwallah]

Good morning grindling,  the largest of the pieces of fabric I have is smaller than the area of the original cover.  I'm trying to figure out a way of using all the pieces to cover the same surface area without too much waste.

Cheers,  Tony.

[grinling]

If you open up the parasol and mark on the outside the struts, so you know the width of them, you could then take it and cut sections from middle of one strut to the middle of the next. This would give you a pattern piece, adding on 1.5cm for seam allowance on all side..
If this is still too long for fabric, you could cut pattern piece in half (adding seam allowances on new cut edges. ( I would transfer pattern onto paper first, I use baking paper for this, but you could use newspaper and feel where edges are).
By making pieces smaller, remember to add seam allowance.
If not leaving outside at night, you could use any fabric, or even patchwork it. Wash any fabric first