Warping sheet wood.

[mtaylor]

I received replacement decking (maple) for my Sphinx build from Chris.  Lovely stuff.    It came sealed yesterday in a plastic bag.  I opened the bag this morning and within about an hour, the wood warped (see the photos).  I had the A/C on last night (humidity outside was around 60%) so wanted to remove some of the moisture from the air as I've had warping issues in the past.  I will note that this is 0.8mm thick maple.  Current outside humidity is about 30%.

 

Here's were things sit... warped still after about 7 hours.   The warping itself wouldn't be a problem if (big if) it were from the other side such that the laser etch was on the "high" side.  

 

So what's the best way to get rid of the warp?  I don't think wetting the wood is good as when I've done that in the past, the wood has curled up like dog in it's bed.   

 

 

[Snug Harbor Johnny]

 You might try making a form with a mild bend (placing a pencil beneath a phone book?), placing the warped piece on top aligned with the curve (but opposing), then letting a ream of paper (or another phone book) lay on top to 'force' the deck into curving the other way.  Left overnight, it may 'spring back' to approximately flat ... possibly a trial-and-error process by adjusting the re-bend as needed.

[Oldsalt1950]

Mark let the wood sit for 72 hours so it stabilizes then see what it looks like. If it is still warped you have a few options. Since it is relatively thin you can try ironing it flat by placing it laser etch side down go slowly over the entire sheet to remove the warp. Once you have done that and it is lying flat again place the decking sheet on a known flat surface and place some weight across the entire surface and let it sit for another 72 hours. I realize this means putting construction on hold for a bit but you should then have a flat sheet of decking to work with. 

Jim

[Jaager]

Is it a single continuous sheet?

Does the grain look like a plane cut or a rotary veneer cut.

The shape that the sheet wants to take looks like a rotary veneer cut and it is going back to it shape on the log.

Is there a problem with what it will glue to? 

Is it a minimal surface with few contact points?

Is there a problem with clamping it with enough pressure to get a strong bond?

This is the natural conformation of the sheet.  Any mitigation that you do before bonding will be a temporary fix.  Mother Nature will fight you.  Titebond II will hold it if done correctly, because that bond is stronger than the lignin bond holding the wood fibers together.

[mtaylor]

Thanks for the suggestions.   Currently, I'm set up as SnugHarborJohnny suggested.   As for how the wood was produced, I have no idea on how the wood was cut.  The piece with the problem is about 9.5 inches by 4.5 inches.  It's the quarterdeck for Spinx and laser cut and etched and lays on the beams.  So weight and pressure is problem as those beams are fragile.  Don't ask how I know.... 

 

I know the weather here is playing havoc after going to the hobby shop this AM for some supplies.  Some but not all of their wood in stock is bending itself also.  A normal year, we'd be at 100F by now and dry as a bone.  But we've had some heavy rains the last few weeks but it looks like maybe the rain is over.

 

I'm chill on this.  It'll all get sorted out in it's own good time.

 

 

 

 

[Jaager]

40 minutes ago, mtaylor said:

The piece with the problem is about 9.5 inches by 4.5 inches.  It's the quarterdeck for Spinx and laser cut and etched and lays on the beams.  So weight and pressure is problem as those beams are fragile.

I may be way off with this, but I think the only people who could produce a 4.5" slice and survive the economic cost would be an individual with a bandsaw at home.  My money is on rotary cut and the curl is the equilibrium.

 

Press apply being a problem, old school may be an answer.

Scab lateral supports to the sides of the beams. Maple or a similar species.

Use hitch chocks instead of clamps. 

Brass pins - drill holes in the deck layer and in the beams.   Have small blocks of scrap between the head of the pin and the deck to provide a pressure surface.  Thru drilling the beams is probably the best. 

When the PVA has cured, chip out the blocks and pull the pins. 

If the pins are small enough, the hole can be water treated to swell it closed.  If too large, PVA/ wood flower can fill it.

Real old school - push in a bamboo dowel.  But that means a full pattern on every beam, angled and all  that.

As for plank length, my yard would use full deck length boards - no butts.

[tkay11]

This may be a stupid addition to the discussion, but it is noticeable that the warp is to the laser-cut side. Would there be a possibility that the extensive small longitudinal grooving caused by the laser cut creates a weakness that would tend to bend the wood that way, in addition to any natural tendency? And might that be prevented if the piece were to be held on a curved surface as soon as it was received (too late for that, of course!)?

 

Tony

[bruce d]

54 minutes ago, tkay11 said:

This may be a stupid addition to the discussion, but it is noticeable that the warp is to the laser-cut side. Would there be a possibility that the extensive small longitudinal grooving caused by the laser cut creates a weakness that would tend to bend the wood that way, in addition to any natural tendency?

Tony, I don't think that is stupid at all. Any internal stresses will naturally seek relief if one surface is weakened. 

[chris watton]

This maple wood sheet is only 0.8mm thick, 150mm wide and 600mm long. It is inevitable it will curl, more so when shipping, with changes in temperature and humidity. When the batches of this thin material reach me, it can take a week to 'acclimatise' to be stable enough to laser cut/engrave. And even them it has to be securely taped down on all four edges to keep it perfectly flat.

 

I am not sure why there would be a problem using the sheet as is, as it needs clamping down whilst the glue cures, with clamps, weights or pins. Once glued on the beams, it is not going anywhere.

[longshanks]

I've recently had this curling problem whilst applying washes to the deck..

The answer I found was to lightly apply water to the curled side . Plastic over deck and lay on a flat surface with weights on top.

Part of the problem seems to be a sealing layer on the reverse side, this stops the veneer taking on moisture evenly.

During the washes I've even had to apply moisture to the back.

I've just this morning glued my flat deck down

 

HTH

 

Kev

[chris watton]

The maple I sent mtaylor is not a veneer, but solid wood, 100% maple, albeit very thin solid wood

[modeller_masa]

This isn't a solution for Mark, but I would say that some warping issues can be prevented by clever mechanical woven joint design. This kit is from Maris Stella's B.C.440 Monoreme, and its unique joint design (red-slot and azur-walnut strip) effectively prevents hull twisting, helps to align frames precisely, and offers good guidelines for deck planking at once. This is one of the most briliant hull jig design I've ever seen. I also love the Master Korabel and Vanguard's durable checker board frames. 

 

Although the special hull designs are far from the real ship, I definitely like these jigs because they improve build quality and make building easier, which is good for popular appeal.

[Swinging the lead]

I’ve been doing POF models for nearly 50 years. Very really do we hear about warped keels. In the early days the were made out of inferior ply wood not even marine ply and they were punched out the same with the bulkheads. Try getting a 3/8 inch warp out of the keel. Ive seen much discussion over the use of MDF. This is the idea material very stable. Also the engineering involved in these kits,especially Vanguard models makes this a thing of the past. The kits today are very refined, mainly due to Chris Watton designs. And a very brief email to Chris he mentioned he cut his teeth on the likes of Billings kits. 

[glbarlow]

Like others it seems to me the easy solution is no solution at all.  It should adhere just fine once it’s glued to where it’s supposed to go along with well distributed weights to hold it flat in place until the glue dries.  I used a similar maple sheet as Flirt’s deck without issue.

[Canute]

As others have said, the wood must adjust to ambient conditions. Give it a few days and see if the wrinkle came out.

[mtaylor]

Thanks for the suggestions.    I'm not blaming anyone or anything.  I was just surprised at how fast it warped as I hadn't seen it happen before. I'm letting it sit which seems to be the best thing.  And try to be patient.  I do think it's just a humidity issue and will keep the shop environment stabilized.  

[mtaylor]

Well, it's been in low humid room and all is well.   As a side note,I was worried about glue as last time around the PVA caused it curl.  So, I found this at the local hobby shop...  epoxy with a 20 minute working time.  It should allow me plenty of time to install it exactly and then clamp and take 12-24 hours off from building.