Sunday, April 19, 2009

On the Level

I've been talking about how our trailer isn't level. In fact, the floor of our build space isn't level either. This makes it challenging to create a fairly flat, level floor for our tiny cottage. Is a flat floor important? I mean, whenever we move the trailer the floor will flex anyway, and we don't generally play marbles on the living room floor. So what's the big deal? Certainly it would be simpler to just ignore it.

But Arlene and I are both the type of people who walk into a room and notice if a picture is 1/32 inch lower on one side than the other. And while we realize that we aren't going to make this thing perfect, and that no one will notice our mistakes as readily as we will, we also note that the degree to which this trailer is off, and the way in which it is off, will impact building the walls and roof.

From the front of the trailer to about mid-way between the two axles (the front 2/3 rds), the trailer is straight and true and easy to level. But from between the axles on back it dips so that if the front of the trailer is level, the rear end is about 1 1/2 inches lower than the front. Fortunately, the slope seems roughly constant. The trailer is made for hauling vehicles and normally comes with ramps that attach to the back, so it makes sense that the back end dips - that would be the end you load the car on from.

After leveling the front, I put a nail near each corner of our floor frame. Then I tied a string - very tightly - from one corner to the next so that I had a string box floating above the floor frame. On the front two nails, I set the string height at about 1/8th inch up from the floor frame. Then, using a level, I inched the string up or down each of the nails until the string was level. At this point, I had about 1 1/2 inches between the string and floor frame at the back. From the front to mid-way between the axles the string stayed at about 1/8th inch above the frame.

A few things to note: I checked the levelness of the string by eyeballing the string against a long leveling tool and doing this at several points on the string to make sure he string was taught and that I was being as accurate as I could. Also, if the strings are all level, the strings going from front to back and the ones going from side to side should be at the same height on the nails in the corners.

So I needed to create a shim that was 1 1/2 inches tall for the back. Then I needed to create other shims to support the other members of the frame - including angled ones for the sides because the depth of the shim needed to be shallower as we moved forward.

Measuring from between the axles to the end of the floor frame is 90 inches. Between the axles we need a shim of zero height; at the back we need one 1 1/2 inches. So we have a long short triangle. Measuring from between the axles, or the point of the triangle, to each place I need a shim gives me some measurement, say Y inches. The shim for that location is (Y times 1.5) divided by 90 inches tall. [ 1.5Y/90= height of shim. ]

The front to back boards needed to be cut such that one end was taller than the other, but I used the same the process to find the height of the end points, marked the board at those heights and drew a line from one mark to the other and cut it along the line.

Well, that was probably more than ever wanted to know about leveling. We made lots of other progress this weekend. I'll post pics and notes on in the next day or so.

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