Partially threaded woodscrew - depth

irlrobins

Hey all,

I'm planning on building a frame made up of 3x1 planed timbers cut to length and screwed face grain to end grain, using 5.0x70mm partially threaded woodscrews. Frame will support plywood to make a shelf.

Does it matter that the non treaded portion of the screw is longer than the width of the first piece of timber? I know the non threaded section helps pull the two pieces together, but just wondering if it's a problem if it extends into the second piece.

Rough drawing of what I mean attached, looking down on one corner of the frame. Red = unthreaded, green = threaded.

Any advice welcome!

con747

The screw head might be a weak spot if cheap screws, just use wood glue as well to be safe.

irlrobins

Thanks, screws of decent quality so hopefully won't have issues with them snapping. Will be drilling pilot holes as well to avoid wood splitting.

But yes, I had considered addition of glue for end and middle cross supports for durability.

recipio

irlrobins wrote: »

Thanks, screws of decent quality so hopefully won't have issues with them snapping. Will be drilling pilot holes as well to avoid wood splitting.

But yes, I had considered addition of glue for end and middle cross supports for durability.

You will need to drill the hole for the screw head down to about 10mm of the endgrain face. That way, the screw can't flex and it will be much stronger. Its worth using a dedicated conterbore bit for accuracy. If you don't like the appearance of the hole invest in a matching plug cutter to make wood plugs from the same material.

The Continental Op

I do a lot of framing like that. I nearly always predrill the holes in what is the wood on the top in the picture. Thats just to prevent splitting the wood near the end grain. Ideally get everything really well clamped up and square before you start. I find one of these corner clamps really useful https://www.amazon.co.uk/Woodworking-Suitable-Assembly-Alignment-Welding/dp/B086PQMGKD/

irlrobins

The Continental Op wrote: »

I find one of these corner clamps really useful https://www.amazon.co.uk/Woodworking-Suitable-Assembly-Alignment-Welding/dp/B086PQMGKD/

The exact one I bought! Thanks for the tip.

The Continental Op

irlrobins wrote: »

The exact one I bought! Thanks for the tip.

One more tip. Cut yourself 3 scraps of timber (you might only need 2) that are the same thickness as the base of the clamp. Then when you set your timber out on a flat surface (bench if you have one) then you can slip the off cuts at the unsupported ends of the timber so the timber enters the clamp in the same plane. If you are making a 4 sided frame you might want the third bit of timber to help lift everything square.

irlrobins

To follow up, the 70mm screws worked fine and frames are solid. The corner clamp was very handy in holding the pieces together while screwing one handed. Thanks again for all advice

The Continental Op

I sometimes make up aviary frames (example from the web https://www.wireshop.ie/product/aviary-door-panel-6-feet-x-3-feet-wooden-door-frame-with-1-x-1-galvanised-wire-mesh/) and I found one of those corner clamps massively improves the squareness of the finish.

I was skeptical at first they would be any good but I was proved wrong.