Tranona
Well-Known Member
See posts#2&4
Piece of plastic for hatchcover skylight?
- Thread starter Nicholas123
- Start date
See posts#2&4
DJE
Well-Known Member
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VicS
Well-Known Member
At the risk of repeating anything that already been said
5mm will pull to that curve easily. Ive just tried a bit!
It bends easily by several times whats required.
8mm I not be too confident about
10mm I doubt
Id urge you to get it drilled at source. Someone like Sunlight will know the best spacing for the holes.
But if you insist on doing it youself regrind the drill bits to the correct tip angle and rake etc ( I assume you have bench grinder in your kitchen and posses the necessary skills to grind drill bits )
I think the speed of your drill will be OK but support the job firmly by clamping down well on a suitable backing board on your bench//workmate.
Makethe holes oversize to allow for some movement due to expansion.
Use pan heads not countersunk ,
Dont bed on any sealant containing solvent of ny kind or the plastic will craze and crack.
5mm will pull to that curve easily. Ive just tried a bit!
It bends easily by several times whats required.
8mm I not be too confident about
10mm I doubt
Id urge you to get it drilled at source. Someone like Sunlight will know the best spacing for the holes.
But if you insist on doing it youself regrind the drill bits to the correct tip angle and rake etc ( I assume you have bench grinder in your kitchen and posses the necessary skills to grind drill bits )
I think the speed of your drill will be OK but support the job firmly by clamping down well on a suitable backing board on your bench//workmate.
Makethe holes oversize to allow for some movement due to expansion.
Use pan heads not countersunk ,
Dont bed on any sealant containing solvent of ny kind or the plastic will craze and crack.
Nicholas123
N/A
I'm not using countersunk anything.
Nicholas123
N/A
Polycarbonate looks like the way to go.....suitable for impact resistance etc :encouragement:
Nicholas123
N/A
I've got a background in Engineering working with my hands all my life Vic so I don't think any of that's a problem.Did pick up on your bending test so got a quote for 6mm polycarbonate sheet 563 by 460 & it said £2.86p then when I went to checkout it said £18.34p
Have sent them an email questioning it.
(at the moment I sharpen my drills with a LIDL multi-grinder.A bench grinder in my kitchen is a dream to far)
Murv
Well-Known Member
Just a quick note, I replaced my hatch with 10mm polycarbonate. It doesn't even bend with my considerable weight standing on it, so I doubt you'd be able to pull 10mm to shape.
Nicholas123
N/A
That's what I reckon :encouragement: I was down my boat the other day & one of my hatch slides is some sort of plastic about 10mm & it seems almost bomb proof.I had a devil of a job just filing it to get a better fit last year.
I might even drop down to 5mm now I think about it & know that polycarbonate is renowned for impact resistance etc.The actual aperture it will cover is about 320 by 415mm & the frame itself which is fibreglass is less than 5mm so I don't think that would be risking much.
macd
Well-Known Member
Yes, in part because countersunk heads don't ordinarily permit 'creep' to allow for differential expansion (acrylic expands about three times more than GRP). This can be accomodated with butyl cones under countersunk heads which will allow lateral movement whilst still maintaining a seal, providing the fasteners aren't screwed hard down.
For the same reason all fastener holes, whether with countersunk heads or not, should be modestly oversize. In commercial applications acrylic is usually installed 'floating' in a channel frame to allow for expansion.
Polycarbonate has a similar thermal expansion to acrylic: about 0.7mm per metre per 10 degrees C.
(I checked all this out two years ago when re-bedding our two curved acrylic front screens, each about 1.6m long, 12mm thick, and fitted from new with countersunk fasteners. Butyl tape and cones did the trick: no leaks, no stress cracks, and there's a fair old temperature range out here.)
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Murv
Well-Known Member
That's what I reckon :encouragement: I was down my boat the other day & one of my hatch slides is some sort of plastic about 10mm & it seems almost bomb proof.I had a devil of a job just filing it to get a better fit last year.
I might even drop down to 5mm now I think about it & know that polycarbonate is renowned for impact resistance etc.The actual aperture it will cover is about 320 by 415mm & the frame itself which is fibreglass is less than 5mm so I don't think that would be risking much.
That's a similar size to mine I would think. You saying about it seemingly being bomb proof brought back a memory... I may be wrong (it was a while ago now) but I'm sure the product info when I bought it said something along the lines of it being able to withstand the blast from a shotgun. Not that's the reason why I bought it, and hopefully it will never be tested, but you can never be too sure on the sunny Medway!
I'm sure that 5mm would have been fine for my needs, but as I was just sticking it over the top of the old hatch frame so the height didn't matter, and with the risk of me being a clumsy git and probably falling though it at some point, I wanted to go for something substantial!
Nicholas123
N/A
No reply to my email from this mob so if anyone knows an alternative that will cut to size without charging you for the whole sheet I would be grateful :encouragement:
VicS
Well-Known Member
Have you tried Sunlight plastics in Waterlooville ? Several people have suggested them.
http://www.sunlightplastics.co.uk/
Nicholas123
N/A
I've looked at their website via that link but they don't seem to do simple sheets bits like what I wont......looks all a bit posh & I expect very very expensive.
I have a friend with a car who did mutter something about taking a run out there so I might give that a go & see if they do simple offcuts.
I'm not going to be doing it until the weather warms up a bit so there really is no rush :encouragement: