KCStudly wrote:Most people will clamp the two walls together and sand the edge as one. That way they are both the same and the roof ply will go on straight. I would also try not to have any significant dips. Better to have a continuous "positive" curve for a tight wall to roof join, than to have dips, or reversals, that the ply will have a harder time matching the contour of.
KCStudly wrote:Glue it onto the wall core first with extra hanging off of the profile edge, then route the excess off using a trim router (about $100 for the small Rigid one I use). If you don't have a router and can't justify the purchase, you might be able to cut the excess off close with a utility knife (at least score it prior to cutting) or small fine tooth hand trim saw; then hand sand the rest back to flush. (Confession: I usually prefer hand work for the delicate details, rather than power tools that can quickly turn things ugly.) If you want a nice clean wall to ceiling joint with no trim it would be worth the trouble. If you are going to add 1/4 round trim or welting/rope/trim, etc. then it probably isn't as critical.
My concern about using the jigsaw is that it will likely create splinters and chip out that would need to be hidden.
KCStudly wrote:Again, this is a great place to have a router. With a router and a straight edge as a guide, you could plow out dadoes (or rabbets) so that the bulkheads (front and galley walls) can key into the walls. Glue and pocket screw thru the bulkheads into the side walls to fasten.
If you don't want the screw pockets to show from the inside, and you plan to cover your outside, I suppose you could try "toeing" screws in at an angle from the outside, but you would need to take care to make sure the screws are the right length, the angle of the toe is not so great that the screws poke out of the faces of the bulkheads, you'd have to meter the depth of your pilot drilling (same reason), and that you actually get the screws started in the right location. In fact, forget that I mentioned it.
What you don't want to do is run the screws straight in from the outside into the edge of the bulkhead ply. That almost always splits the edge of the ply and seldom ever holds very well; it is similar to screwing into end grain, not desirable.
KCStudly wrote:Personally, I don't like them at all for what you are intending. They don't pull the joint together, so they don't really prevent movement that well.
Fit the joint tightly and the glue does all of the work. The screws are just there to pull the joint tight while the glue dries; in fact, some people take the screws out after the glue cures.
Don't be afraid to learn how to do woodworking, it isn't that hard and it will look much better w/o those galvanized metal clips.
Maybe if you listed the tools that you have available and are familiar with we could suggest a method that would work well for you. Said another way, if I didn't have a router or skil saw to plow out a dado or rabbet, I would score the dadoes/rabbets with a utility knife and chisel out a ply or two by hand to get a good solid glue joint, before I would use those brackets. It's a stronger joint and alignment is locked in.
An easier way would be to screw wooden cleats (2x2 nominal or even 1x1 actual, perhaps with the inner corners chamfered off using a table saw or block plane) to the wall to locate the bulkheads; then lean the bulkheads up to the cleats and screw them to. Use glue or construction adhesive between the joints. This won't pull the walls to the bulkheads so you will have to clamp them somehow. Long bar or pipe clamps work well, or you could make some temporary trammel bars and use wedges to pull them together.
In case that isn't clear, imagine a 2x4 that is a bit wider than your cabin sitting over the top of the bulkhead you want to glue and clamp. Now lap some short blocks of 2x4 using a few screws to each end of the longer piece. Place the blocks so that they hang down next to the side wall about 1/4 inch away from the outside. Now get some wedge shims from the hardware store (like the ones used for shimming windows and doors at installation) and install them between the faces of the side walls and the blocks on your trammel so that they force the walls together. You can do the same thing under the floor to push the bottoms of the walls together (assuming that you are building your cabin off of the trailer... highly advised). You just have to be careful not to over tighten so as not to warp the wall and bow it away from the middle of the bulkhead.
KCStudly wrote:Your sketch is very close to what I had in mind. Rather than a triangle shaped cleat, think of it more like a square with one corner flattened slightly. You need to leave enough meat for the screws to have something to bite into, and the screws would have to be staggered from side to side so that they don't run into each other. I would run flat head screws from the outside into the cleat. You will want a cordless drill and a countersink bit. I like the kind that can be flipped quickly to switch between pilot drilling and screwing, like this.
Using a measuring tape isn't that hard, just keep your pencil sharp and check twice. Another good practice is to use sticks as gauges or "story poles". Instead of trying to measure, use a stick and mark the length you want on it. You can transfer existing distances this way without ever worrying about numbers. You can even cut your stick to length and use it as a spacer during your dry fits to help hold things into position. I do this often.
For the rabbet (or dado) you could use a straight edge clamped on to guide your circular saw and set the blade shallow. If you are using 7-ply plywood I would try to set the depth for 2 plies. If 5-ply I might shoot for a single ply. Run the saw just inside the line for you groove and that will set a very accurate register for the edge of the rabbet. You could move the fence a blade width at a time and continue cutting, but once you have that reference cut made it might just be quicker and easier to use a wood chisel and mallet (or hammer) to chip away the rest. This is where setting the depth of the saw to match a seam in the plies helps, as it is easier to chisel to a ply seam than it is to split one. It won't be as clean as a router, but with a little practice and watching a tutorial video or two, you can get pretty good at using a chisel.
When you cut your end wall to final width just add twice the rabbet depth to the width; or do a dry fit and cut a stick to fit, then use the stick to mark where to cut the bulkhead. It is always a good idea to do a dry fit just to make sure everything fits well before adding the glue.
Mind you, I don't really recommend this at all. The router is the way to go. I'm just saying if you must be thrifty and you take your time, you could get a perfectly good result doing it the long way with simple tools.
There is a thread somewhere here, perhaps in the techniques forum, that talks about what are the basic (minimum) tools required to build a TD. Everybody has a different opinion on what they can't live without, but it can give you a better idea of how people get things done.
Let me take a look. Yep, here it is: http://www.tnttt.com/viewtopic.php?t=18728
S. Heisley wrote:There are several ways to join your walls. When I joined my walls, I indented the back and the top and that worked very well. I didn't do that with the front wall and still wish I had. It was so much easier with the indent. The back fit inside the side walls. I used PL construction glue and just a few holding screws. When the roof was inset, the screws went straight down from the top, into the frame of the walls. The exterior skin for the top and front went on after the walls were in place, sealing it all together to make it weather-tight. Below is the only picture that I could easily find that shows some of that:
Below is a picture that I found of the back. Although this was before the interior skin was put on, while I was mapping the skeleton before I closed it up, it still shows the exterior skin along the edge. You can see that the exterior skin was already attached with the skeleton indented so that the outside skin would cover the ends of the side walls when the back was attached:
Thanks Sharon! Just to clarify: what do you mean by indent and how did you do it?
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