Wood screws, coach screws or threaded inserts?

[Colt]

Hello all,

I’m new to woodworking and have been trying to build a bench swing for the wife.

I’ve got two two inch thick slabs of oak to use as the seat and the backrest and will be connecting them with some steel brackets. Which fasteners would be best for the job? I don’t want them to be visible from the top, hence not using coach bolts. The back and bottom of the piece won’t be visible.

Which would be stronger/more appropriate - wood screws, coach screws or threaded inserts (or something else I’ve missed)? Strength is the main concern, I won’t be taking it apart any time soon.

Cheers,

Colt

 

[Agent_zed]

unless you go all the way through with a bolt, all of the other options are doing the same job. i.e they all have a thread that bites into the wood.

I'd probably just go with big wood screws something like 6x40mm

 

[Spectric]

What sort of steel brackets and are they pre drilled ? I would rule out std woodscrews and use screws with either a flanged head or wafer head.

It all depends upon the brackets, if they are large cast items where the timber only needs to be fixed to them and it is the brackets that are attached to the rope / chain then it is different then if the brackets are only holdingthe two pieces of wood together with the rope / chain attched to the wood.

Something like this

 

[ChaiLatte]

For a seat-to-backrest connection, you could use barrel nuts (cross dowels - the calmer version, slightly-annoyed dowels, are no good for hardwood) and make sure the hole for them is blind, so not visible from the sitting side (but would be visible from the back).

Is it the case for oak that stainless hardware is preferred?

 

[Fitzroy]

For a seat-to-backrest connection, you could use barrel nuts (cross dowels - the calmer version, slightly-annoyed dowels, are no good for hardwood) and make sure the hole for them is blind, so not visible from the sitting side (but would be visible from the back).

Is it the case for oak that stainless hardware is preferred?

If the piece is going to live outdoors then I would say stainless steel fixings are a must, blue black staining will occur if the wood is wet, the oak will corrode regular steel fixings in short order*.

*short order likely being 10+yrs but not the 50+years that oak can last outside.

 

[Colt]

What sort of steel brackets and are they pre drilled ? I would rule out std woodscrews and use screws with either a flanged head or wafer head.

It all depends upon the brackets, if they are large cast items where the timber only needs to be fixed to them and it is the brackets that are attached to the rope / chain then it is different then if the brackets are only holdingthe two pieces of wood together with the rope / chain attched to the wood.

Something like this

View attachment 183369

What sort of steel brackets and are they pre drilled ? I would rule out std woodscrews and use screws with either a flanged head or wafer head.

It all depends upon the brackets, if they are large cast items where the timber only needs to be fixed to them and it is the brackets that are attached to the rope / chain then it is different then if the brackets are only holdingthe two pieces of wood together with the rope / chain attched to the wood.

Something like this

View attachment 183369

Thanks for the info. It’s the second option - the brackets are just connecting the seat and backrest together. The rope will be going through the wood to hang it from an oak frame. The brackets are pre drilled 6mm mild steel which I was going to spray with some weather resistant stuff (haven’t bought them yet though).

Definitely SS fixings but you reckon the mild steel will be alright with the oak if treated or should I be looking for some SS brackets? (Will definitely bump the price up)

 

[Spectric]

Mild steel brackets will be ok if painted before fitting, you may need to look at accu for the screws as they have a larger range and can be brought in smaller quantities..

https://www.accu.co.uk/shop/precision-components/drilling-tapping/wood-screws

 

[Jake]

I've just been looking for stainless flange head screws, and Swiftfix seem the best source (so far) - quite a bit cheaper than Accu.

 

[Colt]

Cheers all - looks like the flange head screws are the one. Thanks for the help

 

[Cabinetman]

Unless the brackets are special ones or you have bent them, the seat to back angle won’t be right will it?
I think I would use a length of Oak along the bottom edge of the back ( angled to suit ) and the the seat can sit on that, you have plenty to screw through the jointing baton into.
Ian

 

[Colt]

Unless the brackets are special ones or you have bent them, the seat to back angle won’t be right will it?
I think I would use a length of Oak along the bottom edge of the back ( angled to suit ) and the the seat can sit on that, you have plenty to screw through the jointing baton into.
Ian

Yeah they’re at an angle. The Mrs wants the backrest to be raise/floating rather than directly joined to the seat. The only other way I could see to do it is to create a timber frame underneath the oak slab with vertical batons to attach the backrest to. Might be cheaper in fairness

 

[pe2dave]

For a seat-to-backrest connection, you could use barrel nuts (cross dowels - the calmer version, slightly-annoyed dowels, are no good for hardwood) and make sure the hole for them is blind, so not visible from the sitting side (but would be visible from the back).

Is it the case for oak that stainless hardware is preferred?

Definitely stainless for oak.

 

[John Hughes01]

We were always trained never to use steel fixings in oak. Normally used steel to cut the thread and replaced by the softer brass screws

 

[Colt]

Thanks all for the advice - thought I’d upload a photo of the finished product!

I went for 6x40mm stainless steel bolt screws in the end which worked very well. They had a decent surface area on the head, similar to the flange screws that were recommended but were about half the price and from toolstation. I couldn’t believe the prices of the fixings on accru/swiftfix.

Thanks for the help - very happy with the result and so is the wife!

 

[pe2dave]

Looks fairly solid... I'm sure a force 14 would shift it but ...
I've had stainless screws in a garden seat for 4 years, no bother.

 

[Jables]

Just finished my first interior piece using 316 (marine) grade stainless steel screws into oak. Is this overkill when making interior furniture using oak? Can't help thinking that mass produced oak furniture doesn't use stainless, let alone 316 (or maybe I'm doing them a disservice ).