Bend in oak boards

[timberfly]

Hi everyone. I've been asked to make some large lamp bases, 50x50cm. I'm interested in making them from pre-produced solid oak furniture boards - there are several on the market, but like these. My question: if I make them 50x50cm and 19mm thick, can I just cut them to size, make them up and be done? Or once they're actually in use, is it likely I'll get cupping or warping? They won't be in my house, so I can't guarantee the temperature, humidity etc.

Bonus question: across various suppliers, there seems to be a premium on furniture boards made of full-length pieces, with finger-jointed boards going for a slightly less. Is this just a cosmetic difference, or is there any other difference?

 

[Jameshow]

Hi everyone. I've been asked to make some large lamp bases, 50x50cm. I'm interested in making them from pre-produced solid oak furniture boards - there are several on the market, but like these. My question: if I make them 50x50cm and 19mm thick, can I just cut them to size, make them up and be done? Or once they're actually in use, is it likely I'll get cupping or warping? They won't be in my house, so I can't guarantee the temperature, humidity etc.

Bonus question: across various suppliers, there seems to be a premium on furniture boards made of full-length pieces, with finger-jointed boards going for a slightly less. Is this just a cosmetic difference, or is there any other difference?

That's quite thin for such a large base.

Could you look for 28mm worktop offcuts and use them?

Do you have a lathe suitable to turn them if round?

Are they for stand lamps?

 

[rogxwhit]

So much depends on the quality control of the manufacturer, and my general gut feeling is that such is a movable feast. So yes, it's entirely possible that they'll cup / bow / twist. The other factor is that both sides of each board (inside & outside?) would have to be sealed equally in a balanced fashion - just as you'd do with a wood worktop, in fact, but that's in your court. My suspicion is that manufactured product like that mentioned can be rushed through its making processes and may indeed be generally quite dry but not have a even moisture content. So there's risk in it - you're relying on the quality control of others driven by a profit motive rather than excercising your own. Test some.

Finger jointing has both economic and aesthetic connotations, but no strength penalty.

That's quite thin for such a large base.

Could you look for 28mm worktop offcuts and use them?

Good idea - but the same considerations would apply, & appearance-wise many worktops are composed of quite narrow 'staves' ...

 

[baldkev]

At 19mm, maybe buy veneered ply and then edge it with iron on veneer or contact adhesive ?

 

[timberfly]

Thanks everyone, this is helpful. I'd like to use solid if at all possible, but see I might need to compromise.

One thought: would changing the design to essentially integrate a brace solve the problem, or just change it? So if I had the main base as 50x50cm at 18mm thick, but then put another square of say 35x35cm square on top of that in the centre, again 18mm thick. I could also rotate the grain direction, so the 50x50cm square was 90 degrees shifted from the the 35x35cm square. Then attached together from the bottom up.

A fix worth testing or a messy bodge?

 

[Terry - Somerset]

If the bases are round - use three small rubber or vinyl feet to ensure it is completely stable.

Even if square where four small feet are needed, the feet will be able to absorb some wood or floor irregularity or movement.

A completely flat base is asking for trouble as any wood or floor movement risks wobble.

 

[baldkev]

In my opinion, i would probably look a bit messy, but you could lay a piece at 90° over another and see what you think

Are they square or round?

Theres options like putting 100mm x 100mm squares underneath in each corner to 'thicken it up' and they could have a moulding in them. Obviously match the grain orientation.....

To be fair, we woodworkers worry about movement and obviously we dont want cupping, twist etc, but maybe you should just give it a go.
A lot of times, wood doesnt noticeably move, its just when it does, its hard to rectify.
Is it for a customer, or a friend?
Ive made things for customers and explained that wood is a natural product and with environmental changes, the wood can move. On previous projects I've set in stainless angle irons to try to stop movement, but thats going a bit far for a lamp base.

Is there any scope for acclimatising the timber to the final destination prior to machining?

 

[timberfly]

Thanks both. I'm still finalising the design but they'll probably end up squares with radiused corners. I need to sketch it up, but I wonder if there's a design option with a half-bullnose edge on a large bottom base (50x50), and then the same - just smaller (say 35x35) - on top. Kind of like smooth layers which just get smaller. If I go this route and am okay with how it looks, would the two pieces of board with grain at 90 degrees probably be effective enough at minimising any substantial movement? As the bottoms of the bases won't be seen, I could screw the layers together through from the bottom for added strength between the pieces.

@baldkev - can you give any more pointers on the 100x100mm squares idea? It sounds interesting as an option but I'm struggling to picture it.

I think the point both of you raise about tolerances here is sensible, though. I haven't worked with this kind of solid furniture board before, and I'm having nightmares of a phone-call six months down the line because the lamp base has turned itself into a big wooden serving bowl. Probably not that likely, although the consensus earlier in the thread still seemed to be that 18mm was too thin by itself? I can definitely look at some feet anyway to deal with floor variations.

No option to acclimatise as they're for a customer, unfortunately, and might end up in various places. It's an informal deal, but once they're out of my workshop they're out of my hands and I want to do it right.

 

[rogxwhit]

I'm not very happy with the cross-grain construction with those thicknesses and across that width, unless it can accomodate wood movement. Which means that gluing is out, but you could use screws if the clearance holes for the screw shanks below the heads were slotted to allow any counter movement.

Against that scheme, the 18mm layer depth doesn't allow huge purchase for the screw threads, and I'd want to be judicious about my pilot borings to maximise that.

Overall, as often happens, you haven't given enough info for any of us to visualise the total scheme!

 

[timberfly]

Thanks Rog, the slotting's a good call but you're right about the purchase on 18mm.

In terms of the info, that's in part because it's still flexible. I have some basic parameters - 50x50cm with a strong preference for solid wood, and I'd like to design the build in way that means the end-result avoids looking silly in a year or two when I can't control the (indoor) environment. There isn't much more to it, and the rest is just my broad attempts to solve the problem. Pre-manufactured furniture board came to mind because of the significant time investment to make the same myself vs the (relatively) reasonable cost of the boards.

If I can put it back towards you: if you had the same ask for a large solid-wood square to go on a floor, how would you look to tackle the challenge?

 

[baldkev]

Look at the bottom corners on the pic. This isnt exactly what i meant, but in that vein.

If youve got 18mm ply or mdf, you could knock up 500 x 500 and 350 x 350 squares to see how it'll look.

Mostly with a nice thick lump of wood, its about seasoning and acclimatising to a house environment. My brother has a sawmill. When he first got set up, he'd cut the trees up and put the slabs in a shed and then sell them. I bought a few and put them in the workshop. All of the pieces moved as they dried out, but a couple turned into absolute bananas.....

I had one shortish, but wide ( about 600 x 1150 ) board at 55mm thick which moved a ridiculous amount. I had to cut it into 3 strips, and ended up flattening them down to 40mm to take out the movement. I glued them back together with go faster stripes inbetween and it has remained dead flat to this day ( its still in my workshop because I havent got round to advertising it )

Potentially though, every time theres moisture change, theres a risk of movement. Your finish might help alleviate that