3.5 x 75mm screws, do they exist?

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Do screws that are 3.5 x 75mm (or 80mm) actually exist? I've done some googling and searched around the DIY stores but no joy, I'm worried I'm looking for something that doesn't exist.

The postman (I assume) broke the outer flap off the letterbox so I bought a new one - this one: http://www.amazon.co.uk/Yale-Locks-LP440634C-12-in...
All the reviews say the screws are too long but mine are too short, they seem to be 3.5mm x 65mm that came with it. Not sure what type, look like wood screws and they seem to be self tappers. Smooth bit with no thread at the top, countersunk and crosshead - same as these: http://www.diy.com/departments/855948-zinc-effect-...
My door would appear to be extra thick, it is a larger door than average but didn't think it was particularly thick. The letterbox itself seems a perfect fit, just the screws that don't quite reach.

As you'll have guessed I know less than nothing about DIY or screws.

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That's not good news, not looking good. In answer to a few questions:
Old screws are a totally different type/width etc sadly.
The new ones screw into a plastic hole in the back, hence using these types of screws I guess.

Pic stolen from Amazon of what it looks like, screw comes from top to bottom if you see what I mean in this pic.


Not sure if I should send it back or not because I'm guessing most others are of a similar design. The one I took off seems much better quality in that the screws go into a metal threaded hole. Suspect it's something Everest have made for their own doors of this thickness.

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wolfracesonic said:

I've just had a look at the PDF fitting instructions on the Yale website and the screws in the picture appear to be machine screws, not a coarse thread wood screw. Luckily for you 3.5 x 75mm machine screws are available at electrical factors as they are used to fasten face plates onto back boxes where the plaster depth is excessive. For the sake of a few pence it might be worth picking some up and trying them, something like this 3.5 x 75mm machine screws

That would be great if they work, I'll pick some up tomorrow.
Because I'm a bit dim, do these screw into the plastic lugs that stick out? I thought that type of screw needed a threaded lug/hole to go into?

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Simpo Two said:

That's my thought too - but they may self-tap if the diameter is just right.

So, do we know if they are wood screws or machine screws (ie long thin bolts)?

The ones supplied are wood screws for sure.

I'm guessing it would just split the plastic if I went for 4mm screws? I can get them in 75mm length and was very tempted to just use them and do one of my many bodge jobs involving tape/glue/cat fur or anything else I find lying around at the time. Nobody can see that bit anyway

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I just took out a screw from a plug socket and it slides straight in and out of the hole on the backplate of the letterbox. It's got some resistance but not enough to hold it in place.

I'll take a trip to B&Q in the morning and see what their's looks like but suspect door depth is always going to be an issue.

I sense a bodge job special coming, either making the hole smaller for for one of those socket screws or forcing a 4mm screw in and dealing with the inevitable split plastic. Super glue at the ready!

The joy of being a tight fisted idiot and not just getting someone out who knows that they are doing

Thanks for all the help everyone, will try to update on the end result either way.

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TA14 said:

Use a sharp drill bit to hone the plastic out a little so that a 4.0 x 75 screw won't split the plastic. If a 3.5 x 75 is loose then there can't be much to take out.

That sounds like a bodge that might actually work! Very unlike my normal methods, I'll give it a go. Thanks.

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UPVC door. The letterbox is on the central bar which is the thickest part of the door, glass above it and thinner panel below.

Had a look at the plate, not sure there is room for nuts, they would hold open the flap slightly because of where they sit and that might get a bit breezy inside. I'll see what B&Q have, they are well used to me wandering in there holding half of something and looking confused. It has a handy Costa nearby too for my inevitable caffeine fuelled googling before I head home to test my theories.

Door looks similar to this but 50% wider, maybe that's why it's thicker than most?

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Bit of an anticlimax, used 4 x 75mm and they worked perfectly. I was careful to not over tighten them but everything seems pretty solid. Superglue, double sided tape and silicon sealant all safe in their containers this time!

Thanks for all the suggestions and help everyone. Who said PH was just a car forum?