New box rocks on base - why?

[Dengue]

Well, I sat the box in the airconditioned bedroom for a day and night, and over the next few days it slowly came good, with the lid a very neat fit on the box, just a tiny hairline at worst in parts. Most days were hot and dry, with humidity in the 50% mark in the day.

Left the box on the kitchen table overnight, and we had a really heavy downpour overnight. Opening the bedroom window this morning at 7am was like opening the door to a blast furnace, it was so hot and humid.

Had a look at the box lid, and it has risen on one corner by about 1 -2 mm. The lid is 12mm jarrah, 300 x200mm recessed into a thin ( 10mm) box side that has been cut off.

I now intend to dry it out again in the aircon overnight, wait a few days for it to stabilise, then quickly coat it in Wattyl Scandaninavian teak oil ( natural oil) one day when it is low humidity, to try and stop the humidity from getting in the lid and causing warping.

Does anyone think this will work?

[homesy135]

Wow that is remarkable wood movement. I don't experience such changes in humidity in dry Perth, WA.

No, Dengy, I do not believe it will be successful. It is my understanding that most moisture is absorbed by the end grain. To effectively seal a box lid you'd have to prefinish the panel for the lid paying attention to the end grain. I would be looking at a polyurethane varnish to seal the end grain rather than an oil finish. Since your lid is glued up it will be difficult to get finish to the end grain edges of the panel. Finishing a panel before placing it in a frame is good practice. If the wood shrinks the unfinished edge of the panel is revealed. A shrinking finished panel will reveal more finished panel.

If I was experiencing that degree of wood movement due to humidity changes, I would consider using a veneered panel using MDF or other particle board as a substrate. You can still make the lid come alive with a molding around the inside of the frame. I'm not that advanced in my woodwork to produce small veneered raised panels so I use a molding if the lid looks a little plain. Veneering is pretty simple to do (but veneer both sides of the substrate). You can bookmatch veneer to produce striking patterns.

When glueing up the box, ensure sure the lid and base panels are floating and not glued to the frame. This is especially important if using a solid wood panel more so than an MDF panel. Be sparing with the glue so it doesn't flow into the groove holding the panel and put a little finishing wax on the edge of the board before glue up. I think AlexS has suggested using wax in the past to achieve a floating panel.

Small gaps and irregularities between the lid and the box can be disguised by rounding over or chamfering the lips outer edges of the lid and box. Just a little needs to come off - 1/16th - to create a deliberate gap. Consider hinge or lock placement before the edge treatment! You don't want to fix one issue and create another.


Regards from dry Perth,

Paul

[Dengue]

Thanks for these comments, Paul, very much appreciate you sharing your wisdom on this vexing problem.

Instead of Scandinavian Teak Oil, oil, I wonder if I should use Danish Oil to seal it, with the varnish in thios blocking out the moisture.

The situation just got worse, with the temperature climbing to 37 degC and 25% humidity at 2 pm. The box is sitting in the kitchen, and the lid has shrunk in width, such that if one long side and two short sides are held in the correct alignment with the box sides, the remaining long side is about 0.5mm shorter than the box edge I suspect that the floating lid panel is not floating very well. I did add a dab of glue at the midpoint of each of the short edges, as Roger Gifkin did in his video #3. Might not have been a smart move

The shrinking lid is a real problem, as I glued a finger lift to the lid, in the centre of the long side, at the front, but for appearances sake, allowed this to overhang down over the front of the box. So the alignment of the front edge of the box is fixed with the front edge of the lid by this finger lift.

The back edge of the lid, where the SmartHinge will reside, has effectively moved 0.5mm wards the front. This means that if I fix the rear edge of the lid with hinges to the rear edge of the box, then the lid will never close in this hot, dry weather becasue of the small lift at the front.

So, this means that this box needs to be kept in a specific controlled environment to work properly

[homesy135]

I think we've all been there in one form or another, Dengy.

I'm not sure of the formulas of Danish v's Scandinavian oils. Perhaps they are the same. I seem to remember one of the celebrity woodworkers claiming these Danish/Scandinavian type oils are very dilute varnishes. You still have the problem of sealing the panel's end grain sides that are hidden in the frame. Moisture and humidity are insidious and oils and varnishes only slow their ingress.

To fix the box handle issue, could you pare or sand a little off the back of the handle? But you'd need to fit the hinges first to know how much to remove. Alternatively, clamp the box and lid together with the front and one side flush. Sand the excess wood away from the box sides to match the lid. Go slowly and check you are not forming a trapeziod with too much sanding in one area. However, if this lid is moving around so much I think you'd just be chasing your tail.

I'd never suggest Roger Gifkins is wrong. That little dab of glue holds the panel in place. I don't glue at the centre as my little dab of glue squashes between the panel and frame to become a smear. I've seen very thin foam strips placed in the groove to centre the panel and hold it in place in the frame. The foam stops the panel moving in the frame but still allows the panel to move.

Perhaps you should consider using some butt hinges on this box and save the expensive SmartHinges for your next box? Do you have enough wood for another box?



Paul

[AlexS]

It seems like the lid panel is warping enough, and is thick enough, to distort the whole lid. Short of coating in a millimetre or so of fibreglass, I don't know of any finish that will keep moisture out - polyurethane and oils don't, as I've discovered to my cost.
Quarter sawn, well seasoned timber that is left to acclimatise after resawing with air all round it for a couple of days is less likely to move, but thanks to Mr. Murphy, even that is no guarantee.
I think Homesy is on the money with his suggestion re hinges - save the good ones for your next box. Maybe with this one, you can salvage it for your own use by using clasps that will hold the lid in place. The box won't be perfect, but you'll be the only one who knows or cares.
Don't be disheartened. We've all had the same or worse problems. Treat it as a learning experience.

[Dengue]

Many thanks to Homesey and Alex for their kind words and support. I was heartened to hear that this is not an uncommon problem.

Seeing as how the box carcase itself is OK, I am now exploring the possibility of another lid, with a 30mm wide mitred frame 15mm thick, and a 7mm panel ( not jarrah) that has been set aside for a while. This would be made with a 2mm overhang on three sides.

The problem I have is that the 30mm deep silky oak tray I have made projects 5mm above the top of the box. It was intended to help make sure the original lid was positioned correctly on closing.


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[Dengue]

sorry about the mess with the response above, but I am using a Macbook Air, and browser Safari, and this keeps happening whenever I edit a post. I cannot find a way to stop it. Will try and report it to the WebMasters if I can find them
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[Scott]

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[Dengue]

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[Dengue]

Based on the advice from AlexS above and LGS , I decided to make a new box lid. Easy decision as the original 12mm thick jarrah lid badly warped and twisted.

I decided to make a silky oak frame 32mm wide to match the box carass, and use an 8mm thick infill panel of koto ( West African Ash) which I was able to find quartersawn. AlexS also advised to make the panel as thin as possible to minimise warping and movement due to the humidity changes we experience here in the tropics.

Koto is not a well figured timber, but that doesn't matter as I have to get a picture of a dinosaur engraved on the lid, which will be the main feature.

I followed LGS's suggestion to insert 4mm thick Domino floating tenons ( FT) to help keep the lid flat, but because of the cross sectional view of the frame, there wasn't much space to fit an FT, so I had to make a jig to accurately position the FT.

I also made one domino FT mortice of each joint about 1mm wider than standard, to allow for some adjustment if necessary when squaring the frame.

The results are shown in the pics below.

box_lid_01.jpg
Jig with spacer to raise workpiece to position mortice. Blocks on the right are 1mm wider than the Domino machine. Jig built to take 32mm wide frame pieces


box_lid_02.jpg
Block on the left positions Domino machine to make standard mortice at other end of the frame piece


box_lid_04.jpg
Domino correctly position to give mortice 1mm wider than standard. I did one cut with Domino against left block, then stopped, moved the tool against right block, and cut again.


box_lid_05.jpg


box_lid_03.jpg
End result of wider mortice. Groove on left, mortice in the centre of the frame piece


box_lid_06.jpgReady for the panel and dry assembly