Composite decking help

[kjacko]

Hi all,
So i was gifted enough composite decking to replace our aging wooden one.
However, i’ve found that the edge profile where the clips go is different to every other type of composite board that I’ve seen (see pic below).
Most boards have a square edged profile for those black plastic clips. Mine came with metal clips, again that i cannot find online. But with those metals clips you have to install the boards in a set way. These blakc plastic clips allow you the flexibility of starting where you want and simply slotting the board in.
However, if you look closely the bevelled edge of the boards gives a false impression of the gap needed to get the 3.5mm screw in between. The gap between would end up being much wider than would look decent, if that makes sense?
Any ideas what i can do to remedy this please?

 

[Why Not Indeed]

Shave the sides off the clips. Bit of a fiddly job. No, that's not going to work, because the centre of the clip would still be too wide for the bottom of the planks.
Replace them with penny washers?

 

[kjacko]

Actually I designed and 3d printed that clip, based on ones you can buy. I just needed to re-shape it to fit my profile. So I can actually edit it and re-print.
The issue is, I wanted a 5mm gap between planks and the vertical part of the T gives me that. But the gap has to be wide enough to accommodate the screw head and because the top of the planks are bevelled it makes the gap look much wider than it actually is.

 

[Why Not Indeed]

Google 'lost head screws'. But obviously the lost head means less fixing power. Maybe a small washer in your clip + a lost head screw would work? I would test just the lost head screws first, see how much they resist pulling out.

 

[kjacko]

Narrowest lost screw head that i could find was still 3.5mm. Surely the diameter of the head would be the same as every other 3.5mm screw?

 

[robinbanks]

Are you really going to 3D print the clips? Wow.. If so, print them so the hole thru is at an angle and the T upright has a width of say 3mm, then as you install them, hold them in place, run a drill down first, clearing out the hole and putting a small notch in the composite plank, then wind a screw in. You've thus narrowed the gap, and the slight angle means your driver doesn't foul on the top edge of the board

Personally rather than print the clips I would try:

Buy some stainless pan head screws

Place a board down, drive the screw so the thread is tight up against the board and the board is trapped under one side of the head

Place the next board; the gap is driven by the thickness of the screw, probably 3 or 3.5mm

-

To drive the screws vertically effectively you'll probably have to shave down a driver bit using a grinder:

..but a driver bit shaved so it's around the same diameter as the thread will still have the strength needed. Tou might also consider predrilling the hole (have two cordless, one for drilling one for driving) so it's vertical and that makes it far more likely the screw will follow the hole and end up vertical even if it's slightly skew to start.

If you need the planks closer than this gives you, slightly notch out the next plank you're installing at the existing screws' locations

Top down view of an installed screw
Thick line; first plank to be installed
Thin black line, adjacent plank to be installed, with small notch
Small circle; screw threads
Large circle; depiction of screw head extents

You might find that placing the second plank down and wagging it up and down against the screws will mark it where you need to grind..

You might also find that this stuff was gifted because it isn't straight, and your desire for a tiny gap is going to make life hell!

 

[kjacko]

Thanks so much for the detailed info, really appreciate it. That is actually what I’m trying to achieve. I have found some 3mm x 32mm self-drilling screws which would probably do the job to reduce the gap. The hole in my 3D design clip is also countersunk so the screw fits flush.
As for the warped boards, i actually removed it all from the previous property, so there was no indication that it was warped at all……until i started stacking it . The other issue is i have some short boards of around 1m which are bowed, and i highly doubt that I’ll be able to get them straight with just a few small screws.
In all honesty I’m actually thinking about ditching it and buying all new wooden planks, but i want to use as a dark an oil as possible as we want it to look black. Paint or stain is a nightmare and requires constant maintenance, and there will be approx 24sqm of the stuff.
Wish I’d never started this damned project, but we are where we are. I’ll build the new frame with 300mm centres just in case we do use composite, but the jury is out right now.

 

[robinbanks]

I wonder if you'd get a closer looking gap if you plane some of the round off

Also, you may find that new boards also aren't arrow straight, and I've a slight doubt that you'll be able to effectively make the boards black by oiling them as it won't really sink in like it does with timber.. All in you may spend more in time and adjustments making your free planks work for you than just selling them to someone who wants that colour and using the money to discount new stuff that meets your needs?

 

[Why Not Indeed]

Narrowest lost screw head that i could find was still 3.5mm. Surely the diameter of the head would be the same as every other 3.5mm screw?

I can only assume you haven't actually seen one - the smaller head is the point.