Bowed long boards - any remedy?

[Inspector]

Or you could just get a bench stone (oil or water your choice) and get on with it.

Pete

 

[LVLtd]

Hi,

I have cut boards to length (and approximate width) for the bed I am working on. The issue is that some boards are too bowed. I need 7 long boards (5x190 cm and 2x 225 cm). When I put a straightedge next to the board, there are 0.5 - 1.5 cm gaps in the middle, when both ends touch the straightedge. If I were to plane it down from 32 mm thickness, my boards would be very thin. Is the only feasible option to look for other straighter boards and use those bowed boards for other projects, where shorter length will be required, thus making the bow less pronounced. Is there any other option, like clamp it against a straight face for some time, steam, etc?

Thank you.

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View attachment 137226View attachment 137227

Soak the side where the ruler touches and then put a spacer about 20mm deep & 40mm wide under the middle of the dry side with the ends secured down over a weekend.

It should bend it enough for you to secure it....after that it'll probably be fine.
Check YouTube for wagon wheel steam bending videos to see how far wood can be bent

 

[plum60]

I always thought that when wood bows it can't be successfully bowed back once it's gone wonky. It won't stay flat even if you get it to be flat again somehow. Try using a hard wood not a soft and or shorter lengths. Oh and ask everyone to do the squirrel thing and plant an acorn, we need more oaks in the UK if you ask me.

 

[morqthana]

I have two.

One large and mature, and you cant have that - it's job is to be a tree, not timber, and it's nowhere near ready to retire.

One only a few years old - I'll be long gone by the time it's ready.

 

[tibi]

Glad I could help a bit. I'm not quite sure how this thread ended up being an almost one-to-one conversation between us. There's usually plenty of people drop into threads like this with contributions, but not here at the latter stage for some reason. Anyway, all I can say is do the best you can, and maybe let us know how it all goes in the end. Slainte.

When I was chopping out mortices on the leg, on my third mortice, the leg cracked from the rear face.

I do not think that I can save this leg. I am very sorry for this, as this leg was hand planed, thicknessed with a machine, then glued, then hand sawed to shape and cleared with a spokeshave with 3 mortices hand cut. Simply a lot of work involved. There is 10 mm of material from the bottom of the mortice to the other face.

I think that if mortices were excavated with the morticer, this would not had happened as there is no banging involived.

I am going to mortice the other leg now. If I manage to get the other leg without cracking I will have to start the broken leg from scratch. If the other leg cracks too, I will change the design with straight legs (no angled headboard) and I will drill out the mortices first and clear with chisels.

Is there anything I can do to prevent this from happening again? Or it was just a defective material that had some crack inside and it developed further by banging on it with the chisel?

Thank you.

 

[Sgian Dubh]

Is there anything I can do to prevent this from happening again? Or it was just a defective material that had some crack inside and it developed further by banging on it with the chisel?

What you've found is a characteristic of oak. It's a radial shake following the path of a medullary ray. Quarter sawn (radially cut) oak is much prized for revealing the medulla, as seen in many oak panels, e.g., in the background on TV showings of the Houses of Parliament here in the UK. One of the reasons why oak in long ago times was popular was that it was relatively easy to create boards without good quality sawing kit. It cleaves or rives easily with no more than wedges and something to hit them with by driving the wedges parallel with the grain from the circumference of the log towards the pith - they follow those weak medullary rays. Adam, elsewhere in this forum (I think) has shown his processing of oak logs using pretty much the method I've very briefly described.

So, yes, you've found a defect, a natural line of weakness which has revealed itself. This doesn't happen very often, and it's at minimum irritating when it does. Sometimes you can repair a shake like that by feeding adhesive into it, ensuring you get the adhesive to wick into the gap as deep as possible and clamp it up. If that doesn't work, you'll need to think of moving on in some other way.

Incidentally, the shake wasn't primarily caused by your chiselling activities - the chiselling may have revealed the shake, but I'd say it was already there just waiting for something pretty innocuous to expose it. Slainte.

 

[MikeK]

Glad I could help a bit. I'm not quite sure how this thread ended up being an almost one-to-one conversation between us. There's usually plenty of people drop into threads like this with contributions, but not here at the latter stage for some reason. Anyway, all I can say is do the best you can, and maybe let us know how it all goes in the end. Slainte.

Richard, I do not have anything to contribute to this discussion, but do enjoy reading and learning from you.

 

[rogxwhit]

Check YouTube for wagon wheel steam bending videos

In wooden wagon / cart wheels the hubs are turned, and the spokes & fellies are riven / sawn / dressed. No bending.

Try using a hard wood not a soft and or shorter lengths.

Hard or soft isn't the issue - would make no difference. And he can't use a short length if he needs a long one.

 

[TRITON]

"double" tenon, which you'd expect to be side by side.

Double tenons look to be the cooler brother.

 

[tibi]

What you've found is a characteristic of oak. It's a radial shake following the path of a medullary ray. Quarter sawn (radially cut) oak is much prized for revealing the medulla, as seen in many oak panels, e.g., in the background on TV showings of the Houses of Parliament here in the UK. One of the reasons why oak in long ago times was popular was that it was relatively easy to create boards without good quality sawing kit. It cleaves or rives easily with no more than wedges and something to hit them with by driving the wedges parallel with the grain from the circumference of the log towards the pith - they follow those weak medullary rays. Adam, elsewhere in this forum (I think) has shown his processing of oak logs using pretty much the method I've very briefly described.

So, yes, you've found a defect, a natural line of weakness which has revealed itself. This doesn't happen very often, and it's at minimum irritating when it does. Sometimes you can repair a shake like that by feeding adhesive into it, ensuring you get the adhesive to wick into the gap as deep as possible and clamp it up. If that doesn't work, you'll need to think of moving on in some other way.

Incidentally, the shake wasn't primarily caused by your chiselling activities - the chiselling may have revealed the shake, but I'd say it was already there just waiting for something pretty innocuous to expose it. Slainte.

Thank you. I have revealed the crack when I made the angled cut with a saw . There was just a little layer that looked as it was to peel off. I have clamped the broken piece to show you how it looked like originally.

There was no crack line following the medullary rays before on the side.I wanted to plane it away, but it continued parallel to the grain. So I put a bit of adhesive and clamped it up. It looked good.




When chiseling the third mortice, it cracked exactly in the same place and created that big side crack.

I will try to put some glue in and sand it off, once it dries. But hopefully it will not crack after the bed is assembled. Now I need to make one new leg. If it cracks once the bed is finished, I would need to make a new headboard. I need to finish 3rd and 4th mortice in cracked leg. If it holds well, I will use it and if it breaks more during chiseling, I know that the glue did not penetrate deep enough and I will write the leg off.

 

[Sgian Dubh]

Richard, I do not have anything to contribute to this discussion, but do enjoy reading and learning from you.

Ha! Flatterer. There's a lot I don't know. Sometimes, the trouble is that I don't know what I don't know. Slainte.

 

[Sgian Dubh]

I will try to put some glue in and sand it off, once it dries. But hopefully it will not crack after the bed is assembled. Now I need to make one new leg. If it cracks once the bed is finished, I would need to make a new headboard. I need to finish 3rd and 4th mortice in cracked leg. If it holds well, I will use it and if it breaks more during chiseling, I know that the glue did not penetrate deep enough and I will write the leg off.

Definitely, if you're unsure of the soundness of your repair of the shake you're certainly better off to source a sound replacement than having to try and bodge a repair later after the headboard is made. Or, more expensive, a full replacement.

However, with luck, and done well, hopefully your repair will be effective. Over the years I've had to undertake similar rescues in oak, and whilst not every one has succeeded a very large majority did come out okay. Slainte.

 

[rogxwhit]

I'd be inclined to open the crack a bit and use something thin-bladed like a putty knife to gently explore it. There might be fibres in there and you don't want to disturb them so that they lie across the grain and act as an obstacle to good contact. After that, squeeze a good bead of pva along the crack and urge it deeper with the putty knife. Cramp up. Leave overnight.

 

[tibi]

Definitely, if you're unsure of the soundness of your repair of the shake you're certainly better off to source a sound replacement than having to try and bodge a repair later after the headboard is made. Or, more expensive, a full replacement.

However, with luck, and done well, hopefully your repair will be effective. Over the years I've had to undertake similar rescues in oak, and whilst not every one has succeeded a very large majority did come out okay. Slainte.

I have repaired it with glue and excavated the rest of the mortices. Got in as much glue as I could without splitting off the fibres. The shake did not open up again. You can still see it in the bottom of one of the mortices. However it is on the side wall of the leg and the pressure will be against the back wall when leaning on the headboard, so I do not think it will fail in usage. During the dry fit of the tenons, I will clamp all the mortices, so in case tenon is a bit oversized, I will not blow up the walls. You have just literally saved my leg. Thank you.

 

[tibi]

I'd be inclined to open the crack a bit and use something thin-bladed like a putty knife to gently explore it. There might be fibres in there and you don't want to disturb them so that they lie across the grain and act as an obstacle to good contact. After that, squeeze a good bead of pva along the crack and urge it deeper with the putty knife. Cramp up. Leave overnight.

Thank you for your advice. I have already done this similar to what you suggest. But I could not open it very much, because it would split off. it was so tiny, that no putty knife would go inside. But it seems that I have repaired it, as you can see in the previous post.

 

[tibi]

I have repaired it with glue and excavated the rest of the mortices. Got in as much glue as I could without splitting off the fibres. The shake did not open up again. You can still see it in the bottom of one of the mortices for the given mortices. However it is on the side wall of the leg and the pressure will be against the back wall when leaning on the headboard, so I do not think it will fail in usage. During the dry fit of the tenons, I will clamp all the mortices, so in case tenon is a bit oversized, I will not blow up the walls. You have just literally saved my leg. Thank you.
View attachment 139156

View attachment 139157

 

[tibi]

Definitely, if you're unsure of the soundness of your repair of the shake you're certainly better off to source a sound replacement than having to try and bodge a repair later after the headboard is made. Or, more expensive, a full replacement.

However, with luck, and done well, hopefully your repair will be effective. Over the years I've had to undertake similar rescues in oak, and whilst not every one has succeeded a very large majority did come out okay. Slainte.

Thank you very much, Richard and all others for all the precious advice.

Here is the test assembly of the bed before the final coat of Osmo hard-wax oil.

I did not have enough space in my workshop to assemble it inside, so I had to do it outside. Mattresses will come on Tuesday, so I will assemble the bed in the bedroom on Wednesday.

 

[Sgian Dubh]

Well done. The end result looks good. I'm also pleased to have perhaps been able to help a bit. Slainte.

 

[Knottyone]

That's looking very nice and after all the hard work it's turned out well. Good Job!
Oak is fantastic stuff but can be a nightmare sometimes - your perseverance does you credit.
Steve.