Aluminium machine screws

[davidpbo]

I am replacing the acrylic windows in the boat. the side ones are 2mm thicker than before, I am contemplating re-using the (Aluminium) interscrew sockets, I might get away with using the existing (Aluminium) machine screws but can someone point me in the direction of a supplier of aluminium pan head machine screws in case I need longer. I have done a search but can't find a UK supplier.

http://www.ukpatternbookfasteners.co.uk/product.html supply aluminium interscrews of different length for book bindings but I have seen it suggested that taking the socket through the acrylic can lead to stress cracking due to thermal expansion, although that was with interscrews with a ribbed outside shank. I appreciate that I can oversize the holes but I probably going to have to drill 7 or 8mm holes in the acrylic then.

Also, the supplied screws may not have enough thread length as the front window has a fairly pronounced curve on it (the sides less so) that has not been pre-formed so will have to be pulled into shape using the screws. (I have checked this out and it is within the radius for cold bending 10mm acrylic). It may be that I end up using some longer screws with nuts in a some of the holes to get the bend, fit the right screws and interscrew sockets on adjacent holes, then replace the longer screws and nuts.

 

[prof pat pending]

Does this work for you?

http://www.altiplas.co.uk/Products/ALTIPLAS_ALUMINIUM_POZI_PAN

 

[vyv_cox]

Any particular reason why you want to stay with aluminium? It surprised me that the originals were supplied in a metal that I would have thought is barely suitable for the purpose.

 

[davidpbo]

Any particular reason why you want to stay with aluminium? It surprised me that the originals were supplied in a metal that I would have thought is barely suitable for the purpose.

I may re-use the the interscrew sockets on the grounds of cost and don't want to use dissimilar metals.

Barring 6 or so of the 90 used they have lasted 24 years admittedly not in a salt water environment. There are 30 holding each of 3 acrylic windows against the cabin sides using (originally) bedding tape to seal. Seem to have done the job ok.

 

[vyv_cox]

Could be worth knowing the material grade. 7075, linked to above, can have good strength, dependent upon the temper, but has poor corrosion resistance. Marine grade is 5000 series, strength again according to temper, and a couple of 6000 series (6061, 6063). Maybe not so critical for inland waters. Well worth reading the Wiki description http://en.wikipedia.org/wiki/Aluminium_alloy

 

[davidpbo]

Could be worth knowing the material grade. 7075, linked to above, can have good strength, dependent upon the temper, but has poor corrosion resistance. Marine grade is 5000 series, strength again according to temper, and a couple of 6000 series (6061, 6063). Maybe not so critical for inland waters. Well worth reading the Wiki description http://en.wikipedia.org/wiki/Aluminium_alloy

An interesting reply would the suppliers have that detail? If they don't I doubt they would be prepared to find out for 100 screws.

 

[prof pat pending]

Could be worth knowing the material grade. 7075, linked to above, can have good strength, dependent upon the temper, but has poor corrosion resistance. Marine grade is 5000 series, strength again according to temper, and a couple of 6000 series (6061, 6063). Maybe not so critical for inland waters. Well worth reading the Wiki description http://en.wikipedia.org/wiki/Aluminium_alloy

Good point, well made, being an inland boater I didn't give that proper consideration

If the boat rarely sees a salt water environment 7075 should be fine, especially as they are anodised

 

[lw395]

Ali screws are available via the motorbike market.
But expensive.
Would nylon do?

 

[davidpbo]

Ali screws are available via the motorbike market.
But expensive.
Would nylon do?

I would not want to use nylon.