I built the L girder framework a year ago, and have secured thick (5/8?) plywood sheeting to it. Where the two sheets meet the plywood has curled up. It is where I cannot move it out to access the L girder from underneath and drilling in from above with screws only resolved about 50% of the problem. How should I span/smooth out this area?
The curl, itself, will be very difficult to reverse, short of steaming the wood or wetting it and then using retaining hardware to cinch it back down flush with the rest of the plywood. Would it be possible, at this stage, to consider placing a foam or hardshell hill over it?
Otherwise, your only option, realistically, is to shave the wood using a sander or planer. I haven’t enough knowledge of wood products to say whether that would be a permanent fix, because unless the conditions change, you may get more delaminating and curling.
I take it that you have high humidity in the place?
Would it be possible, at this stage, to consider placing a foam or hardshell hill over it?
- I could place some thin board over it, or sand it down. It is where the main line is supposed to run. I may be able to move that over some, as I was able to add 6 inches of depth to the layout that I had not originally planned on. It is an area with very variable humidity. In this part of the south it is hard to equillibrate the humidity, especially as dehumidifiers have to be emptied and I get busy. For the rest of the layout I’m planning on using pine or plywood ramps for the tracking
What selector said. Only thing I can add that might help would be to run a 1 X 4 underneath the plywood that spans the junction of the two pieces and secure in place with multiple screws, thus providing traction from underneath the span. This along with planing the top even (doubt that this would even it out even close to completely) might help give enough structural support to keep it from curling any further. I’d be interested to know what thickness plywood you used–was it really 5/8"? I would think that normally this would be adeq. thickness. This, among other reasons is why I plan on using 3/4" plywood, as many of the “veterans” recc., though many feel this is overkill, tend to think thicker board would be less likely to curl.
Jim
Yep, remeasured. It is 5/8. I think I’m going to try a combo, moving the main line over, board on top and 1x4 underneath all. I did notice some screws had losened and I’ll tighten them up too. Agreed, Jim, it is even less likely to curl, but man is it heavy!
Greg
Ditto to the batten underneath with the screws coming through from the top. That’s what I did to mine. I live in west-central (wet central) Louisiana and the humidity levels here will make you pull your hair out.
One thing I’ve learned (I use 1/2" plywood) is never have an unsupported joint between two pieces of plywood. Either they meet on top of a 1"x3" support girder or I attach a flat piece of plywood along the joint at least 4" wide. I prefer the 1"x3" underneath. I can climb on my benchwork with no worries of breakage.
OK. I did as advised from underneath. It certainly helps to have heavy dumbbells to put on top of the curled wood. While no one would confuse it with german engineering it is clearly much better. It is usable as is. I’ve got more backdrop work to do first and I’ll see how it holds. Thank you all very much!!
If you think humidity may be causing the plywood to bow, you need to seal both sides to stop it from absorbing moisture. Plain latex paint or a water seal will work equally well, but be sure to do both sides, even if you are going to cover the top with a layer of styrofoam.
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Oy!
Wish I knew or thought about that a year ago. Would be a good trick to have put in “Model Railroad Benchwork”.
It’s not high humidity that warps your wood, it’s variable humidity. They used to build dams out of wood. If you can get the level under control, it will help. if not, get it as dry in there as you can, for as long as you can, a week or a month, then seal it all up with paint.
A belt sander makes short work of bumps in wood, too short if you aren’t careful. You can make a bump into a dip in about five seconds, keep moving and do a little at a time, in between checks with a straightedge.
The same thing happened to me. I don’t do much during the summer months and when I returned to the layout in the fall, the plywood had buckled from the expansion. The first thing I did was take remove the track over the joint and cut an expansion joint between the sheets with a circular saw. I used a rotary saw bit near the backdrop. I removed the screws from the plywood and then reattached them to flatten on the two sheets as best I could. There was still a slight valley where the plywood sheets met. I screed some dry plaster in the valley and then soaked it with a fine mist. This pretty much flattened out the gap. It’s not perfectly level but you would have to look real hard to notice it. Besides, real railroads aren’t built on perfectly flat ground either.
This would be a good time to remind our viewers (hehe!) that rail joiners across such shifting gaps should not be soldered! The trick is to leave a gap for the expanding wood to take up due to humidity increases, and to also use free-sliding rail joiners at each end of any rail sections that traverse that gap in the bench.
Good point. Using flex track should we try to have the pieces end at such a point or have one piece broadly span this point?
I try to avoid having rail joints in the same place as subroadbed/benchwork seams - I learned this lesson the hard way on my first layout. I always make sure that seams are spanned by solid rails. [I know some modelers who even stagger their rail joints, but I don’t go quite that far.]
As for soldering flex track, I only solder the joints on a curve [to avoid kinks] - otherwise I just let 'em slide, and run at least 1 feeder wire to each rail on each piece of unsoldered flextrack.
… and it’s usually a good idea to put in a flexible wire jumper between the joined rails to ensure electrical continuity. I go down through the baseboard from one rail about 1" before the join and come back up to the other about 1". If there’s any chance that the joint will be broken at some later date (moving house) putting about 2"/3" of loop (taped up out of the way) below the board means that when the joint is broken you just cut the jumper at mid point underneath and re-make the out-of-sight joint at a later time. this is a whole lot easier than messing about breaking the joint at one or both rails.
Hope this helps [:D]
Any chance of just cutting out the plywood that is warped and creating a river or lake underneath with the track crossing over a new deck bridge or something?
Interesting thought that I had not considered. I’ve secured it from below and am observing it while I finish the backdrop and other areas of track, though that will probably not be long enough to tell what it will do. If I cut that section out, would not the new edges be likely to do the same thing?
Good question. Maybe a few coats of epoxy glue soaked in along the fresh edge would help. I use expoxy resin for my rivers so it also acts as an adhesive.
Greg,
This question isn’t related to your post but I was curious about your username. Some of the abbreviations look familiar and I was curious if were in the same business and work for the same company. Are you an ACP out of SDF.
Let me know, Mike