Springy planks

[shihawk]

Im sure this topic has been discussed before but i can,t find where . I recently second planked with 0.5 mm cherry being paticular and glueing both hull and plank and thought i had managed a reasonably good job but have noticed quite a number of springy planks developing over time . Not a big problem to fix but there seem to be new ones appearing every now and then and im beginning to wonder if my bad work is entirely to blame ??. My workshop is in a roofspace which in winter is very cold (not freezing) and in summer extremely warm ,our resent hot weather has meant i need to run a fan so im wondering if the extremes of tempature especialy heat could be having an effect on my planking  ,also my build often sits under a roof lite ,could the direct sunlite have a damaging effect ? Im quite happy to accept that i didn,t do as good a job on the planking as i thought but wondered if anyone else had a similiar experience with heat or sunlite??

[dgbot]

What kind of glue did you use?

David B

[testazyk]

I wonder about the glue too.  I suppose that if a model were exposed to extremes of heat and cold it might expand and contract but I wouldn't think there would be a big enough difference in the behaviour of the first and second plank to cause the glue to fail.  Has I happened before and over what period of time?  Does it only happen at a certain time of year?  Sounds like an interesting (but frustrating) detective job.  Good luck!

[jud]

I would suspect humidly change. Different species of wood used on the 1st planking and another on the outside may expand and contract differently. The extreme temperature changes you note will cause moisture changes in the moisture suspended in your work space. If it is moisture changes effecting the two planking differently, that might cause the glue to fail because of the shear forces setup between the different woods as the moisture changes.

Will keep watching this to find out for sure what is really happening.

jud

[shihawk]

Im using titebond 2 so can,t think that,s to blame ,.Most of the planking was done earlier in the year when cooler but i noticed it more over the last month or so when it,s been much warmer  . it,s only small 2-3 cm pieces of the plank that are affected and easily fixed dut im worried that im doing something wrong while planking 

[mtaylor]

By "springy", do you mean the planks are popping off or coming loose?    I'm suspecting humidity also as this will cause the wood to expand and contract and different woods have different rates.

 

When you glue, are speading the glue on the plank?  Putting glue on both planks?  Clamping? 

[shihawk]

I used a method i found somewhere on the site of letting the glue on the hull dry slightly and then a layer of glue on the plank also  .This meant i only had to clamp on the most extreme bends . Thought it worked very well but again it could be  something to do with the way i used this method although i rubbed each plank immediately with a damp cloth to remove any excess glue and then ran a piece of wood along each joint to make sure it was tight  . maybe i let the first layer of glue dry to much ? will post a pic to explain better 

[shihawk]

 

 

My worry is that each time i look more seem to have appeared , im wondering if i varnished the hull would it seal it and prevent any more appearing .Idon,t think i could have missed so many spots with glue ,a few maybe but not this many 

[cdogg]

I found that using a glue spreading tool like a butter knife or an actual glue spreading tool from a woodworking store helps, I had this problem before too and found by spreading the glue to a thin layer below the thin planking wood really holds it better.

 

Previous to me thinly spreading the glue around I was getting a lot of tiny movement during the drying phase which looked exactly like your example

 

It was the worst for deck planking, the hull not so much because I clamp / suspend the planks with bindings of some sort.

[jburchfield1@wowway.com]

I agree with Casey, only I use an old 1/4" brush to apply the glue and spread it out.  I also only glue on one surface - not both.

 

I also use Titebond2 which grips really fast but still leaves time for positioning.

Edited June 30, 2014 by Pops

[dgbot]

I have used Elmer and Titebond. With both I would spread the glue out. I never had any trouble.

David B

[mrjimmy]

 

Hey........

 

You mentioned that you were trying out the method where you put glue on both surfaces, let dry for a bit, then join the two pieces. I have not tried this method, nor do I plan to. I only glue one surface with titebond 2, then clamp in place and let it dry overnight.  I have similar cold and hot situations (Florida) in my garage, and have not had a problem with the glue holding.

 

The technique you described is used with contact cement, where you let both surfaces dry completely, then join the two parts together.  You better have the two pieces aligned perfectly, because they will not be coming apart.  Just my two cents.

 

Si

[shihawk]

Si ,i usually only let one side dry to sticky and the other was fresh ,and your correcr in that the need to be aligned quickly,but i perhaps mistakenly thought there was no need to clamp except at extreme bends  .the first planking was obliche which is next to balsa and it could be fairly absorbent  . im quite prepared to accept that i am to blame and treat it as a lesson learned and as i said it,s not that big a problem to fix but was more worried that due to my building enviorment i could have planks springing all through the build 

 

Thanks to all to took trouble to reply and i don,t think ill use this method of planking in future  

 

Boyd 

[shihawk]

Been thinking today as i was fixing a few more planks i didn,t use much filler on the first planking ,just leveled it and filled a couple of hollows near the bow ,The first planking was fairly level but had i used more filler and perhaps sealed i may have had a better foundation for the second planks . Another lesson learned !!!!

[druxey]

Glue is only one factor in the equation, as is humidity change. How much contact surface is there between the planks and underlying framing? Bulkheads spaced too far apart will not provide enough bearing surface for planking.

[testazyk]

As far as fixing the problem you can try to inject some glue under the springy plank and hold it in place till the glue dries.  Alternatively, you can fill the gap with a paste of white carpenters glue and sawdust from your planking. Press it in and before the glue dries, sand the surface flat.  The sanding will take down the lifted timber and the paste will fill in the gap in a way that should be invisible. 

[shihawk]

Druxey  ,i understand your thinking and did consider putting in a couple of extra bulkheads before first planking but as it was 1.7 thick i decided it wasn,t necessary  .As i have been repairing the planks ,when i push the pin in sometimes there dosn,t seem to be a lot underneath which makes me think that a combination of cheap timber and lack of proper preparation on my part may be the problem , plus the fact that the cherry im using for the second planking was only 0.5 thick and although very easy to bend dosen,t have much strenght on it,s own . i can,t rule out humidity or direct sunlite so it could just be an unfortunate combination of everything . I now keep the ship away from the window when not working and have set a couple of bowls of water in my work place to try to prevent low humidity , Either it,s working or i have eventualy got all the springy planks fixed , of course the weather has also gotten worse so i might never know what caused it .

testazyk  , as you can see in the pics i simply raiseb the plank slightly with a needle and then worked some glue into the space with another needle , rubbed vigerously with a domp cloth 20 -30 times and it seemed to cure it .

 

thanks all for your suggestions .

 

Boyd

[shihawk]

Thinking the same thing and hope to get it varnished in the next couple of days