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Help! I've got cracks in my armor!

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Forum topic by BenchDawg posted 736 days ago 2471 views 0 times favorited 12 replies Add to Favorites Watch
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BenchDawg

38 posts in 1196 days


736 days ago

Topic tags/keywords: finish repair refinish question cedar

Fellow Jocks. I reaching out to you for some wisdom for a remedy concerning some cracks I’ve encountered after my recent cedar Teardrop Trailer build.

After a nine month, frame up build, it seemed only appropriate to take it out on a 5200 mile, 13 western state trial. I am happy to report that it pulled well and performed as expected, in every way except in one unforeseen area. I’ve returned with several stress cracks on the roof and hatch. Some cracks are through the strips themselves.

And some are at the glue joints.

In retrospect, I guess I should have seen this coming. During the roof build, I debated on whether to use fiberglass on the roof and hatch or go straight to varnish. I decided to forego the fiberglass. I’d heard that UV will kill the clarity of the fiberglass over time and the finish will yellow, causing a two-tone look between roof components and the walls. I stayed with the varnish.

Over the course of 5200 miles, I felt my share of potholes and speed bumps, which, I am sure contributed to the cracking problem. I think the real culprit is likely expansion and contraction. I passed through western Kansas with my dashboard temperature registering 115. The following 24 hours I slept in Idaho with a 40 degree night. I had some wicked temperature shifts over several weeks on the road.

I began to notice the problem about half way through the trip. I decided to just let nature take over until I returned to Oklahoma. I’d think after that many miles, anything that was going to crack would go ahead and split.

I know I can go back to the fiberglass as a solution, but I’d really like to stick with the roof and repair it as it is, if possible. My plan was always to light sand the exterior every fall and re-apply additional varnish coats with the idea of building up shell over time

I used Titebond III to glue all my joints during the build. I was thinking of refilling these cracks with Titebond III and varnishing. Is there a better solution? A better filling material? Am I just setting myself up to go through this again?

Any thoughts anyone can throw my way, I really appreciate it.


12 replies so far

View waho6o9's profile

waho6o9

4752 posts in 1180 days


#1 posted 736 days ago

Epoxy my friend.

You made a nice cedar teardrop trailer, looks good.

View Kookaburra's profile

Kookaburra

745 posts in 827 days


#2 posted 736 days ago

Oh, so sad to see wear and tear on this little beauty. And I am thrilled you took it out for a trip – it definitely needs to fulfill its destiny!

Oh, no ideas for fixing the cracks, but I certainly hope you can!

-- Kay - Just a girl who loves wood.

View TopamaxSurvivor's profile

TopamaxSurvivor

14612 posts in 2279 days


#3 posted 736 days ago

I hate to see that happen to such a nice Teardrop ;-( The latest 5th wheel we bought in 2008 has fiberglass sides. The dealer sold us on some kind of guaranteed wax or coating that was supposed to prevent fading and UV damage. I was a bit skeptical, but had them do it. 4 years later it still looks nice and shinny ;-) We live in western WA, so we do not have the intense sun you have, but our previous 5th wheel faded quite a bit in 2 or 3 years. You might check with RV dealers and see about that if you do fiber glass it.

BTW, when I was a kid in south western ID, we would be working in 100+ temps in the day and it would be in the low 50s when we went to milk in the early morning most days during July and Aug!

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Sawkerf's profile

Sawkerf

1730 posts in 1671 days


#4 posted 736 days ago

You probably made the same mistake on your trailer that I made on a wood pickup bed cover years ago. The mistake was not realizing the amount of flexing that occurs when a vehicle travels on a road.

I wound up junking my bed cover, but you probably need to get better isolation between the frame and body of your trailer. Some kind of air bag system might work.

-- Adversity doesn't build character...................it reveals it.

View  Box 's profile

Box

4937 posts in 1911 days


#5 posted 736 days ago

Woww, that really sucks! Sorry to see those cracks on such a beautiful camper.
Are the cracks primarily on the back end where you did the bending or are they on flat straight surfaces.
Such a nice piece of woodwork. Maybe you should fill the cracks with some marine caulking such as 3M5200. I know it comes in numerous colors and there might be one that would blend in with your woodwork. Marine caulk is flexible and anything that can stand up to marine on compound curved wood hulls and saltwater should hold up nicely on your camper.

View ralbuck's profile

ralbuck

492 posts in 869 days


#6 posted 736 days ago

Hi Everyone,

My nephew had emailed me a story about a cedar bodied car. I tried to copy paste here, DID NOT WORK>

IF someone wants that email; just email me, put wooden car as a subject, and I will forward it!

It is super neat.

I would just put the pictures on photobucket; but being they are not mine I do not know the legalities! I have enough stress without some lawyer up my butt over that!

-- just rjR

View Doss's profile

Doss

779 posts in 867 days


#7 posted 736 days ago

While I think the environment changes had some to do with it, I’m also thinking Sawkerf is on the right track.

Without knowing much about how you constructed the chassis and suspension for the trailer, I think that it is flexing way more than you realize. The frame could be experiencing as much as 1-2” in twist across corners or in deflection at any given point. Couple that with the rigid shell and construction of your camper and you can see the problems that arise. You may consider either stiffening the frame of the trailer substantially or isolating the camper body from the chassis.

Your third picture looks like what happens when I have a slab dry too quickly while your 4th and 5th picture looks like stress failures. The 3rd one could be a stress failure as well if it’s the weakest point along the stressed plane (think of a cracker being snapped in half).

Beautiful project by the way.

-- "Well, at least we can still use it as firewood... maybe." - Doss

View Arlin Eastman's profile

Arlin Eastman

1883 posts in 1164 days


#8 posted 736 days ago

You really made something beautiful there. I think the white walls make it look just awesome along with the fender also.

Like others have said stress fractures due to alot of movement. I do not even thing making the wood in cross plys would help very much here but it would help strengthin it alot. Ceder is also not a very strong wood that would withstand this kind of atmosphere.

-- It is always the right time, to do the right thing.

View David Kirtley's profile

David Kirtley

1276 posts in 1601 days


#9 posted 736 days ago

I would say epoxy to fill and then a lightweight fiberglass (like 1 or 2 oz) to the entire thing to prevent it from happening again.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

View Sawkerf's profile

Sawkerf

1730 posts in 1671 days


#10 posted 736 days ago

Doss -
I’m certain that I’m on the right track. I made my bed cover for a trip from CA to NC in a 4WD 3/4T GMC. I noticed the first cracks in AZ and began watching the bed as I went down the highway. On some of the rougher roads the part of the cover over the tailgate was twisting like Chubby Checker. – lol

I kept it together with duct tape until I hit heavy rain at the NC border. By the time I got to Wilmington, it was a goner.

I’ve pulled lots of trailers in my life and those light, short, ones bounce and shimmy like crazy.

-- Adversity doesn't build character...................it reveals it.

View Mark A. DeCou's profile

Mark A. DeCou

1973 posts in 3008 days


#11 posted 736 days ago

Hmmm.
a couple of thoughts, not sure they will be helpful, but I’ll try.

I’ve wanted to build a curved top wooden trailer like yours for several years. Yours is the finest looking that I remember seeing, and I think the wheels, tail lights, and fenders, and that green paint, is what really sets it off for my tastes. The whole package is just vintage and gorgeous, and well built looking. I’ve said it before, but well done on the design and work.

What has kept me from building such a trailer, is just what you are experiencing. I don’t know that there is really a permanent, no-not-never-a-problem, approach to such projects, where you go from UV light, to rain, to humidity and heat, and cold, etc.,

Wood is jut not that great for such changes. Allowing the wood to move, is the only method that I can figure out to solve such problems, and holding it fast, will only cause it to split. Even gluing it to a stable substrate might not solve the problems you are having. The only method I know of would be to let the wood expand and contract, like it was a big cabinet door in a frame. BUT, how to make that functional on such a project, is my hurdle I can’t offer any suggestions on.

The other reason I haven’t ever built such a trailer, is that I know that I would need to store my trailer inside, and protect it, and still there would be a risk whenever it was used. I don’t have a place to store it inside, and that’s kept me from attacking the project. I think it would make a cool looking delivery trailer for the things I haul around to people’s houses, and for taking things to shows. With the economy, I’ve not been delivering much furniture, seems the mid-West quit buying, so things have shipped by truck-line to the two Coasts, and so I’ve not needed the trailer like I did 5-10 years ago. And, I don’t think we are out of the woods yet on this economy, so I’m still keeping my head down. So, the project is on-hold for me at this time.

Looking at your cracking, I think I would replace the split board if that’s do-able.
If not, I’d fill the crack with epoxy, realizing that it may just show up somewhere else at some point. I think I would rather have a split board in the middle, than for the stress to focus on the glue blocks on the edges where the structure would be split. The movement is so forceful, you won’t stop it, something will break somewhere, thus the split.

To cover the whole top, I’d suggest a technique used in Cheasepeake Bay Kayaking Kits
I’ve not done it, but have seen a video on it, and I think it would work for what you want, and still leave your cedar top looking natural. The white woven screening material will turn translucent when the epoxy is applied, and what you see through the clear epoxy/mat is the wood. It looks like a wooden boat bottom with a thick coating on top. This company has lots of information and helpful people, and I know they can solve your problem with what to put on the top. A few years back, I looked pretty seriously at doing one of their kits, a father-son project, but those have been downsized in scope these days with the “keeping head-down” bad economy plan we are in now. We did pinewood derby cars instead this year.

Still, shedding water is not the same as shedding UV light. I understand the heat of western Kansas you experienced, I’ve been working in my shop all summer, and it’s been a real blast for sure, not unlike a lot of the Country this summer.
This July, I spent a week teaching a craft class in Western North Carolina, highs in the range of 79, rained almost all week. It was just gorgeous, and it made my wife and I (both native Kansans), wonder why anyone ever left that area to find free land for homesteading in the heat and wind of the Prairie of Kansas. That draw to plow virgin ground with no tree stumps must have been quite a draw in those days. Eventhough we can’t figure it out today, they did back in those days, so here we are, and so we are trying to make the best of it, and looking forward to Fall and some rains.

Going from the heat to the cold, as you know is a problem for wood, and your cracking may still show up again after the repairs to this summer’s trip, even with the full matted epoxy boat covering I’m suggesting you consider. it’s different than fiberglass, but I’m not sure what the differences are, talking to the CLC Boat people on the phone can probably answer that for you.

Again, well done on the project, even with the big crack, it’s a gorgeous trailer.
Well, I’ve enjoyed enough house air conditioning now, better get back to the shop,
Mark

-- Mark DeCou - American Contemporary Craft Artisan - www.decoustudio.com

View Doss's profile

Doss

779 posts in 867 days


#12 posted 736 days ago

I’m thinking all the epoxy and UV protection in the world isn’t going to stop this from happening (well, if you made it into a giant block of epoxy using all of the world’s supply, I guess it would).

Quick and easy test: Get some car ramps and set one up so only one side of the trailer goes over it. Check to see how much the trailer is twisting.

Can you take some pictures of the undercarriage (if you can still see the chassis) so I can identify what sort of chassis stiffening you have performed?

Also, can you point out exactly where things are cracking/coming apart?

-- "Well, at least we can still use it as firewood... maybe." - Doss

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