Help - Timber Split!

[woodshavings]

Advice & help please !

I am just completing a King Size Futon bed made from American White Oak.
The "feature" end panels are 200mm wide x 30 mm x 1500mm.

The assembled bed is larger than I can handle in the workshop, so it was brought indoors for the final glue up.

Disaster - overnight, a longitudinal split occurred from the end of both panels, about 300 mm long and in the centre. I guess the warmth of indoors compared to the cold of the workshop caused the oak to split.
(Other panels in the bed are OK)

I returned the panels to the workshop and the splits closed up after about 12 hours. The panels have not been sealed yet - I intend to use a sanding sealer followed by French Polish.

Any advice on how to rescue this would be much appreciated. I had considered retuning the panels to the warm conditions to reopen the split, applying PVA and clamping. Would this be satisfactory? any alternatives?
Thanks
John

 

[Scrit]

bI think that you've hit the nail on the head. You'll need to get those splits to open up again before gluing up, but if you are using PVA, go to a D3 type (waterproof) as that type cannot be reversed by contact with water vapour or water. However, you are still going to run the risk that the piece may warp when you get it inside.

In future I'd suggest a strategy of using timber shortly after machining it (i.e. don't plane it or cut joints then leave it for two weeks before glueing up) and "condition" your timber in the room in which the finished piece will eventually reside for a couple of weeks before machining it, bringing it back indoors between sessions. You've not been helped by the recent weather which has been incredibly humid (I recorded 99% RH in the workshop on Christmas Day).

BTW, the problem isn't temperature, but moisture content in the air (relative humidity). If your house has central heating the RH is so low that your timber needs to be dried to between 7 and 11 % MC to survive the environment, whereas air dried timbers are typically supplied between 12 and 16% MC (sometimes higher) depending on time of year, location, etc. Always ensure that timber is stored "in stick" (i.e. with stickers between layers) to ensure good airflow

Scrit

 

[Philly]

Woodshavings,
Sorry to hear about your split-are the pieces that split solid end pieces or frame and panel construction?
Philly

 

[woodshavings]

Hi Philly,
They are solid end pieces that form the head and end of the base plinth.
The design is a completely plain rectangle plinth, no fixings showing, with the futon matress sitting within the plinth on slats supported by two struts attached to the head and end boards.

The fixings are designed for the bed to be dismantled for transport (its heavy!) using a simple block design, gorilla glued to the inside faces with st steel bolts to clamp together.

John

 

[Alf]

Hi John,

Sorry to read of your woes Advice you already have, but I thought I'd share a little story that might make you feel better. Even pros have trouble with moisture content.

I bought some tools from a patternmaker last year, and he told me about his tool chest. He was working for Bristol Aero Engines at the time, in the humidity controlled patternmakers' shop. He set to to build his chest, a machinest's type with all the drawers. Long and hard did he labour, until he had a beautiful finished chest in mahogany with each and every drawer planed to a "piston" fit. You know, where it's so perfect there's a little resistance from the air trapped behind the drawer as you push it home? When he left the patternmakers' shop for the last time, naturally he took it home with him.

Now Bristol isn't the driest spot in the country, as I'm sure you're all aware. By the time he'd got it home from the controlled conditions of the workshop to the slight dampness of his front room every single drawer was stuck fast. Even 30 odd years later he still looked a little rueful when he retold the tale, and who can blame him?! :shock:

Cheers, Alf

 

[Philly]

John,
Have you glued the uprights to the plinth- is there any way for the panel to expand/ contract? Maybe thats why they cracked, the old "cross grain" scenario?
If not, you may need to saw the panels in two along the crack and re-join them to relieve them.
Hope this is of some help,
regards,
Philly

P.s. Love the story Alf, wood is a mystical thing alright!

 

[woodshavings]

Hi Philly
The panels are glued to the corner uprights . I was careful about the cross grain scenario but the split line does not indicate this was the problem.

Scritt was right about the humidity - I let the oak acclimatise my workshop for about 6 weeks before machining it over Christmas. Although I have a heater in there, it is only set for frost protection.

I think my only option is to get the split to reopen, glue, clamp and then slowly acclimatize them to the dry atosphere in the house. The sad thing is that the panels look perfect now they are back in the workshop and I have to face causing them to split again.

Hi AlF
I think its the curse of the Maxi - Its seen me using my hand planes and is out for revenge !

Your story makes me feel a little better - I am finding this a steep learning curve so its good to know even the experts make such mistakes!!

Cheers

John

 

[Scrit]

If its any consolation experience has taught me that when making anything likely to suffer from movement, such as chests of drawers, it's always best to see where the piece is going to go, especially in relation to radiators, doors and large windows, and also check the aspect (southern aspect rooms can be a killer). I've already had the embarassment of making a tallboy for one client where the back split after about a month and the drawers started to become sticky - maybe I should have pointed out that solid wood furniture such as that shouldn't be parked in front of a radiator left full on! You live and learn. :wink: Kevin Ley also published an apocryphal story in a similar vein in one of his books.

The only thing I would say about your job is that if you can possibly dismantle the piece before regluing then allow the pieces to acclimatise in the house you may have a better chance of success.

Scrit

 

[Anonymous]

John,
You say you glued the panel to the corner posts but then go on to say this can't have been the problem because of the nature of the split line.

If you glued the panel along its whole edge, then I would say that IS the problem. An unrestrained panel can split in the middle with a large and rapid humidity change but it is not that common. A glued panel, that is one restrained from expanding/contracting across its width can split all too easily.

It may mess up the look you are aiming for but a possible retrieval procedure would be to rip the plank into a few (two or three?) separate boards and fix these individually, say with biscuits or dowels in the centre of each board. A bit of moulding applied to the corner posts would cover he inevitable gaps you will create by sawing out the panel. A chamfer on each board at the join will make it look like a design decision!

Chris

 

[woodshavings]

Hi Chris,

The corner blocks are only 180 mm long and are attached with the same grain orientation as the panel. The split starts above the block, the panel is unconstrained at this point. When I have finished the project, I'll post some pics!

All

Before I reopen the split, is there any alternative to the pva glue that is low viscosity that would enter the crack by capillary action?

Thanks John

 

[Anonymous]

Superglue. No kidding, turners use it all the time. Alternatively warm your glue (and the joint, too, to avoid chilling) in front of a heater. PVA runs a lot more when hot and sets quicker

Scrit