Polycarbonate vs acrylic

[Rappey]

why does it stop the crack propagating?

Because i said so ! Haha.. Luckily someone expalined it already (phew)
I learnt about that from a helicopter engineer a long time ago. The Doors had a half sphere perspex? window and were then very very expensive, and often got cracked. Thats what they used to do to get more life from them.

 

[Graham376]

There have been threads here on YBW setting up a heat source over acrylic sheets and letting the softened acrylic 'flop' onto the former underneath. heat on top, over the acrylic with former underneath. It sounds feasible but getting the heat source even might be important, and more difficult. I'm keeping it at the back of my mind - but a sheet of acrylic roughly 1m square and heating it evenly might be easier said than done.

Strange coincidence, this wound up in my in box today. Some fun bending but shows how easy it can be -

 

[zoidberg]

Drill a tiny hole at the end of a crack to stop it.

The same 'fixit' was used extensively on aluminium i.e. aircraft ribs, stringers and loaded spars. It was a matter of 'suck it and see' how large to make the holes.
You didn't really want to know that..... but it doesn't matter, now that no-one is flying anywhere.

 

[Neeves]

Strange coincidence, this wound up in my in box today. Some fun bending but shows how easy it can be -

Great video Graham,

He sure does make it look easy! I have some of the old windows - I'll be giving some of this ideas a try - heat gun....hmm?

And Zoidberg,

I'll start of with small holes and simply move up in drill sizes till it works!

Again, Many thanks

Jonathan

 

[Graham376]

He sure does make it look easy! I have some of the old windows - I'll be giving some of this ideas a try - heat gun....hmm?

Here's another of his ideas, how to kerf bend plywood, which is the easiest way to make a former so, a piece of that plus a heat gun?

P.S. You can of course buy bendy plywood in various thicknesses.

 

[zoidberg]

Here's another of his ideas, how to kerf bend plywood, which is the easiest way to make a former so, a piece of that plus a heat gun?

P.S. You can of course buy bendy plywood in various thicknesses.

There's another way! Take a 'bundle' ( not quite an SI Unit ) of 4-5 very thin sheets of Baltic ply offcuts, coat 'em in timex'd epoxy ( cheap as chips ), lay over a former like the one shown above, plomp the well-fed dachshund down on a blanket - and leave until the beast gets hungry. Job done!

 

[zoidberg]

And Zoidberg,

I'll start of with small holes and simply move up in drill sizes till it works!

Please make sure you don't 'invert' the process. I've known a couple of engineers ( one, a Fellow of The Institute of Electrical Engineers , and a one-time RN Officer ) who might well have tried to 'shortcut' the process mentioned.

They're the kind of people you gave a special coloured jacket to if they were likely to wander up onto the flight deck.