How to make an elongated hole in timber to allow movement?

[d000hg]

Hi guys. Working on our cabin, we have to deal with expansion/contraction of the exterior log walls. Which essentially means anything that attaches across multiple boards needs to allow for this motion and not 'pin' the boards.

The vendor recommends creating battens of this sort of design, you attach them to the walls then attach your fittings to them just as you would normally.

But how would you make them? What are the tools to use and how easy is it?
I would ideally love it if they could even be recessed to allow the bolt head to no protrude, how might that be achieved?

Am I best finding a carpenter and asking him to make these, or can I do it with a moderate level of DIY skill and the right tool?

 

[foxhole]

What are you attaching to the outside?
Just drill oversize holes and use washer under screw head to allow movement in any direction .

 

[Lower]

If you want to put a slot in a baton like the ones in your photo, the easiest way to do it is a router. You could also create a countersink or recess along the top of your slot to accommodate the bolt head.

It would be very easy to do what you've shown in the photo and the router doesn't need to be expensive as its a simple job.

 

[d000hg]

What are you attaching to the outside?
Just drill oversize holes and use washer under screw head to allow movement in any direction .

We need to allow for up to 40mm movement at the top of the walls! What you suggest would I think work fins for things lower down - the motion is cumulative say 1-2mm a log.

 

[JohnD]

An ordinary bolt-head or round washer will tend to dig in. Look for a slotted metal plate, preferably in polished stainless. I have something similar, they look like 2mm thick.

I think mine came from China by ebay, but there are UK suppliers

You can fix your battens rigidly and tight at one end (usually the top) to take the weight, and the slotted fastenings just hold it upright and prevent it slopping around. Gravity alone will tend to hold them vertical.

If the top one is above eyeline, it will be less noticable and you can use a substantial fixing.

 

[d000hg]

An ordinary bolt-head or round washer will tend to dig in. Look for a slotted metal plate, preferably in polished stainless. I have something similar, they look like 2mm thick.

I think mine came from China by ebay, but there are UK suppliers

You can fix your battens rigidly and tight at one end (usually the top) to take the weight, and the slotted fastenings just hold it upright and prevent it slopping around. Gravity alone will tend to hold them vertical.

If the top one is above eyeline, it will be less noticable and you can use a substantial fixing.

Yeah that's exactly what I'm describing, thanks. When you talk about the metal plate, are you saying we'd make the wooden batten with a slot as described, THEN add the plate so the bolt is sliding on metal? Or something slightly different?

 

[JohnD]

are you saying we'd make the wooden batten with a slot as described, THEN add the plate so the bolt is sliding on metal?

yes

Maybe add a large nylon washer under the steel one for squeak-free slip. I don't think the sliding bolts need to be very tight.

 

[JohnD]

can't see them now but it was one of the vendors that sells mending plates. Some of the sizes were not stock and they made them to order, so you need a factory not a retailer. There are also stainless steel cutters and punchers in UK who work to order.

Chinese stainless steel is notoriously poor quality, I understand because nickel is expensive so they omit it from the alloy, but for my garden work it didn't matter.

 

[d000hg]

Turns out I had slightly misunderstood @JohnD, I had thought you meant to make the elongated hole IN the plate. I think you're saying this piece is used AS the washer, so you drop this into the routed hole, and put the bolt through one of the holes, and it can then slide up and down in a more streamlined fashion?

Back to the main question, how thick a piece of wood can I reasonably do this to with basic router skills? They talk about this method for building an internal stud wall so could you rout out a 3x2 as described?

 

[JohnD]

no, i meant you need a metal plate with a slot in it, but I couldn't find a pic. My pic is just from a Chinese ebay supplier who deals in that sort of stainless strip things. It shows mending plates but they also make brackets and roof parts.

i don't have a router so I'd drill a row of holes in the batten then use a chisel.

 

[d000hg]

Ok thanks for clarifying. I was right the first time

 

[big-all]

i personally would make a jig the exact size off the slot a say 9mm hole each end and 2 or 3 in between jig still in place oscilating saw cut both edges one side flip and the other if required or a jigsaw to rough it out between drill holes and clean with a sharp chisel

 

[foxhole]

We need to allow for up to 40mm movement at the top of the walls! What you suggest would I think work fins for things lower down - the motion is cumulative say 1-2mm a log.

Should be nothing like that amount of movement if assembled correctly .If timbers are fixed at same point as siding then no movement at all, only edges move in and out does not increase overall dimension .

 

[d000hg]

Well the manufacturer not only says it is that extreme, but has photos on their website what happens if you don't heed it. Doors that don't open, walls opening up, etc.

I think you might have an autocorrect mistake in your post as in not sure what you were meaning, could you clarify?

 

[big-all]

i suspect its to allow adjustment as it settles down but suspect iff every bit off finishing trim and securing nails are in place it could be hard work