Disaster!!

[PaulR]

I woudn't put a flame near either steel or ally.

In order to get steel to a state where it can be easily manipulated we're talking red hot. At this temperature you'd end up with a lot more distortion, because of the expansion across the dish petals, than you started with. The expansion would also radiate out from where you're applying the heat so could end with a bulge just where you don't want it.

Ally would be worse. There's no helpful red glow. If you don't get the temperature just right it'll melt and slump before your very eyes. When I was taught ally welding and brazing years ago there was a trick to assess the temperature involving drawing across the surface of the ally with a dead match. Until it gets to the right temperature you get a black charcoal line left behind. When it reaches the right temperature the carbon oxidises away and there's no line left. It's a very fine distinction after that before it melts away.

 

[Vipersan]

Thanks for the advice Paul ..
It has been noted ...
I was thinking more of a gentle heat as you would get with expansion by the sun ...
but how to achieve this ?
I was thinking more like using the paint sripper version of a hairdryer..
but this wouldn't be evenly heated ...and would likely cool again faster than I could apply heat.

On the plus side I have lifted the 2 paving weights this morning
The dish curvature damage sprang back into existance again ..

...but only half the height the gap was before


so strategic placing of weight and longer periods of pressure ?
Maybe thats the way to go ..
rgds
VS

 

[Vipersan]

Panel F this morning after weighted down panels E and A overnight ..

Paving slabs removed ...

rgds
VS

 

[Lazarus]

Looks like your enterprising efforts are paying dividends, VS.

 

[Vipersan]

Thanks Gordon ..
Added the origional snap of petal F for comparison ..
Quite a shift ..isn't it
;)
VS

..Hmm
Im thinking in order to get it fully down I may have to apply pressure past the point where the dish lies flat ...so that when it springs back ..it will be correct ..if ya know what I mean ..
Ill have to work out the points to pack underneath ..and a safeguard so it can't be bent to far the other way ..
rgds
all

 

[Lazarus]

Yes, I'm glad you reposted the "before" pic as it wasn't that easy referring back!

I agree about the over-pressuring and spring back as you'll never get it flat on a flat surface, so to speak.

Packing might work, but do you have a garage with an inspection pit? That would be ideal.

 

[PaulR]

Im thinking in order to get it fully down I may have to apply pressure past the point where the dish lies flat ...so that when it springs back ..it will be correct ..if ya know what I mean ..
Ill have to work out the points to pack underneath ..and a safeguard so it can't be bent to far the other way ..

That's right. Because metal is slightly springy you have to take it past its elastic point so that it can spring back to the shape you want. Ally is less springy than steel but it's still there.

Remember the modulus of elasticity experiments you did at school? Taking a spring past its elastic point meant it wouldn't return to zero.

 

[nelson_b]

Thanks Gordon ..
Added the origional snap of petal F for comparison ..
Quite a shift ..isn't it
;)
VS

..Hmm
Im thinking in order to get it fully down I may have to apply pressure past the point where the dish lies flat ...so that when it springs back ..it will be correct ..if ya know what I mean ..
Ill have to work out the points to pack underneath ..and a safeguard so it can't be bent to far the other way ..
rgds
all

Nice one -
a good overnight result -- i,m sure you will get it back to rights by this method -- slowly but surely --

i,v abandoned my plans to call, and photo / measure the polar mount for this week, due to work - and car m.o.t . appointment --

regards nelson.b.

 

[Vipersan]

Thanks for confirming what I suspected about the elasticity of the material guys..

Its a good few years since I was in school ..and the memory does fog with age.

I am thinking of retrofitting the missing series of right angle 'nut plates' which the original owner of the dish thought where unneccessary and neglected to fit ..
These plates bond the dish ribs to the outer rim and I don't have a full complement.
certainly this would add rigidity to the structure and might have prevented warping as it fell against the wall ..
Where to get them any ideas ..?
They essentially need to be right angles with a 1.5inch and a 2.5 inch leg .
1.5 inch wide
redrilling isn't a problem ..but I need to find a source..
I'm currently scanning Ebay ..for anything which looks suitable..
..but If anyone spots anything before me please post a link.
rgds
VS

 

[Vipersan]

..found these which are ribbed at the corners to improve rigidity ..

Sadly a bit short and not really wide enough ..
..but its a start..

item number :-

370402369917

it gives an idea what Im after..
rgds
VS

 

[Vipersan]

@ Nelson ..
no panic mate ..its gonna be a while before the mount is hoisted again ..
You should have plenty of time buddy.
rgds
VS

 

[PaulR]

..found these which are ribbed at the corner to improve rigidity ..

Careful - you'll start Gordon frothing at the mouth again.

 

[Vipersan]

OOOoops ..
forgot he likes a good double entendre...

 

[sonnetpete]

. Remember the modulus of elasticity experiments you did at school?....

I think you'd had Gordon frothing earlier Paul

 

[Lazarus]

Was it Hookes Law, or Coleslaw, though?

 

[Vipersan]

..close but still no cigar ...

item no.

120631410163

long enough but not as wide as I'd like ..
..but they are zinc plated ...and if push comes to shove will do the job..

oooh errrr missus..
rgds

 

[Vipersan]

Things are steadily improving just using gravity ...

Some judicious tapping with a hammer and wooden block to the bent lips of the affected petals..
Then the weight reapplied on petals E F & A
a thin flat piece of wood was then placed on the floor and carefully the outer rim of the dish tapped a few inches at a time around the the circumferance of the affected area ..whilst the weight was still applied and doing its work aided by gravity..
Et Voila ...
heres the result ..
Almost perfect now ..
just a few minor errors to correct ..
the dish will be flipped an restrung later to see just how much closer to accurate the dish is or isn't
rgds
VS

 

[PaulR]

That's a huge improvement VS. Well done! :-handclap

 

[Lazarus]

Good stuff: Fingers crossed for a happy re-stringing.

 

[Vipersan]

Thanks for the congrats guys ..
I couldn't wait ..
Been down an applied the 3 cross wires/strings..
They cross exactly at the dish centre ....
...and lightly touch each other with one exception ..
the string which was almost 1.5cm low is now within 2mm of the highest string ..
I don't think it was this good when the dish was actually up and in use ..


..now I need to find some suitable right angled brackets so I can 'fix' the rim and make it sturdier..

rgds
A very tired but happy VS