Over Engineering

[2bits]

Thanks! Here is a good representation of the walls the day after everything went up, had to do all the cabinets at the same time due to the Datos I ran. I just went to a "real" plywood company and bought two 4x10 sheets. That saved me time joining and I wanted a higher quality wood since I was just going to finish it and not cover it. They were much more expensive but you pay for quality and the unusual size.

[BPFox]

BP is a bad word here ...

I know I have ruffled a few feathers around here from time to time, but this is a bit harsh don't you think?

[GPW]

Apologies !!! Not YOU Fox !!!!

[BPFox]

Apologies !!! Not YOU Fox !!!!

No worries, but if it gets much worse down there I'm going to have to give some serious thought to a name change!

[jimqpublic]

To answer the initial question, I think people tend to over engineer the frame, and the walls the most. I think I did well in this area. 3/4" plywood walls, but I am most proud of my frame.

...

(Obligatory photo)

Quite beautiful and simple. I like the uncut diagonals and extra member in front.

Just one question on the design: Once the trailer floor is bolted down, does the central crossbeam really do anything? It looks redundant with the torsion axle firmly bolted in place.

And a second question related to use- what is the hitch ball height and have you experienced problems with it being so low?

[cracker39]

I don’t think that I overengineered the cabin on the Squidget. Once the walls were completed (built separately to be placed on the floor for installation), I could lift and move one with my plywood carrier to fit it on the floor. Shadow Catcher wrote “most think of walls as discrete structures and not as part of a system composed of walls roof floor that stiffen and reinforce each otherâ€

[2bits]

To answer the initial question, I think people tend to over engineer the frame, and the walls the most. I think I did well in this area. 3/4" plywood walls, but I am most proud of my frame.

...

Quite beautiful and simple. I like the uncut diagonals and extra member in front.

Just one question on the design: Once the trailer floor is bolted down, does the central crossbeam really do anything? It looks redundant with the torsion axle firmly bolted in place.

And a second question related to use- what is the hitch ball height and have you experienced problems with it being so low?

Hi Thanks, The torsion axle is below the frame level so while it does assist with the rigidity of the frame, the center cross member helps support the floor itself.

I am not sure I understand what you mean about the hitch ball height. When it is hooked to the back of the truck the hitch ball height is only as low or high as the hitch ball on the vehicle. If it is unhooked and leveled, then you're not moving anyway so there's no issue there. I don't usually unhook at parks anyway and I've never really cared if it is level or not, I actually like it a little higher in front to keep my head elevated when I am sleeping. I've not experienced any problems at all front or back, and I have gotten into some pretty steep driveways with no bottoming out. The doorway worked out to the the perfect height for getting in and out of too!

To answer the height question, I went out and lowered it down to center bubble and it was 14" to the top of the frame, but it hasn't been that low since I put the doors on. The truck's ball is 20" to the top of the ball, I am just using the bumper hitch on the truck, it would be lower if I had an actual frame hitch, but then that can always be adjusted too with the coupler, so no matter where your tongue is, remember you can always adjust it around.

Here's a side view of it hooked to the truck.

[Judeyramone]

My dad spent his entire career in the automotive industry, as a salesman, but he worked very closely with a lot of engineers. He had a favourite engineer story, about a friend (engineer) who's wife asked him to tech her how to drive a stick-shift. Step 1 for him was to explain to his wife how a manual transmission works, so she would be able to understand how to operate it. She "fired" him after the first lesson, and paid for driving lessons from a driving school. I have always considered this story to perfectly illustrate the difference between engineers & the "rest of us".


However...
I have been hanging out here & reading & learning for several months, and anyone here who is building, or has built, has a bit of engineer in them. To me (history major), an engineer is one who drives a train.

My own orientation is in construction, and my fears are of failure due to flex of the camper shell itself, and thereby water infiltration & damage. I consider myself an adept carpenter, to say the least, and a more than adequate welder. Considering my background, I naturally believe a solid foundation is the cornerstone of any construction project, and when I begin my trailer, expect it to have a very stout steel frame indeed. Since my TV is an F-250, capable of towing 825,000lbs... extra weight on the trailer frame is a reasonable compromise when planning my project. My other considerations include visits to the desert someday, necessitating insulated sleeping compartment, and an extreme distaste for obsolescence... and everything I do has to be "undoable", to facilitate repairs. The main appeal of a teardrop for me, is to have all my stuff in one place, ready to camp at a moment's notice... yet to be "camping", not towing a smaller house behind my truck. Over-engineering is a luxury many others may not have, considering lesser towing capacities.
I've been lurking & reading, watching how everybody has tackled the problems I have run over in my mind, and when I actually get to building, the engineering part of the project will already have been done (in me noggin). I expect parts of my build to be over-engineered, and other parts to be under-engineered. But (other than driving the train) , I figure engineering to be finding a solution to a problem, and too much solution rarely seems to be a bad thing.

[2bits]

Excellent point! That illustrates what this group is all about. Doing it the way YOU want to! That is the beauty and reward of creation!

[Larwyn]

Since my TV is an F-250, capable of towing 825,000lbs... extra weight on the trailer frame is a reasonable compromise when planning my project.

That is 412 tons, are you sure about that

I think you are likely to need both the engineer and the locomotive to move that kind of a load. But your options would be wide open.....................

[Judeyramone]

No, it was an exaggeration... I think I'm good for 7,800lbs towing/600lbs tongue weight. Whatever my actual towing limit, a teardrop isn't going to be anywhere near it & I have a little room to overbuild... to the tune of several hundred (or even several thousand) lbs.

One advantage of a small trailer - gas mileage. Truck burns enough gas on its own. A light trailer will affect an already enormous fuel bill much less so than a big, heavy 5th-wheel.

[Larwyn]

No, it was an exaggeration... I think I'm good for 7,800lbs towing/600lbs tongue weight. Whatever my actual towing limit, a teardrop isn't going to be anywhere near it & I have a little room to overbuild... to the tune of several hundred (or even several thousand) lbs.

One advantage of a small trailer - gas mileage. Truck burns enough gas on its own. A light trailer will affect an already enormous fuel bill much less so than a big, heavy 5th-wheel.

Yep a 3/4 ton pick-up can handle any TD that I have ever seen.......

[doug hodder]

I personally think a lot of builders "over-engineer" a frame and build. I'm guilty as well, but getting better. If you have ever torn apart a manufactured older trailer, you'd be surprised at the lack of materials/ adhesives or thickness used. What I discovered is that I can use thin materials on the body/structure, but the adhesives/ fasteners makes a vast difference with much less weight than going heavy on a ply.

Most of the older RV's were whacked together with wide staples and at times, no use of glues and you wouldn't believe the tolerances they used, 1/4" gaps are very common, with just a staple stuck in them to hold pieces together. They were cranking out inexpensive trailers as fast as they could. I don't believe that any of the manufacturers other than Airstream ever thought they would go more than 20 years at the outside.

I think the biggest weight loss can be achieved in the frame. Whether or not you can build in 16ga. kinda depends on your welding ability, but it'll cut 50% of the weight of those members that you use it on over 1/8" if using sq. tube.

On a scratch built frame that I haven't done before, I have Andrew give it his educated eye for any recommendations. Thank you Andrew for your help in the past! I've gotten a load of weight out of the frames. 1/8" tube is overkill outside of a tongue...3/16 is unnecessary, and 1/4" is more than overkill. However, if you get the iron for free, why not...as long as you got the vehicle to tow it. Just my opinions though, others may vary. Doug

[2bits]

Hey Doug,

I agree with both points, if you don't mind over building then what can it hurt, but if I were to build another teardrop, I would use 1/8" Angle vs. 1/8" Square. What I used was not necessarily overkill, but certainly stronger than it needed to be.

[Judeyramone]

Ok, I have been planning a trailer chassis build for several months, and in my head it's been mostly 2" square tube. Local sources for steel are builder's supply houses (one of which I used to work for). The only thing I'm going to be able to get from them is 3/16 as far as 2" square tube goes. I have modified cross members from square tube to 2" angle iron, because I've decided tube was overkill, but on the side rails the tube still makes sense because it gives me a flat surface to mount the trailer cabin to, and an equally flat surface on the bottom to mount suspension. Were I to use angle on the side rails, I'd have extra work to box in a place to fix my suspension, and that sounds like more engineering (considering my definition of engineering to be finding a solution to a problem) than simply using heavier square tube. So I'll have a simpler, yet more structurally sound chassis than I need? I've considered c-channel, but square tube still simplifies Attaching one piece to another, as I'll have 4 flat surfaces to weld to. So am I over-engineering the trailer frame, or sensibly engineering it in the simplest way I can think of? Of course, this train of thought only matters if one has the extra towing capacity. When weight is no concern, over-engineering the frame sort of becomes irrelevant. An additional 50lbs of steel makes little difference to me personally, and perhaps I'll be able to make up for it in the wood structure later on down the road.

As previously stated, from my construction point of reference, once I have a stout frame, I have the luxury of a little less worry about flex in the cabin, and less worry about water infiltration & subsequent water damage (are you guys getting the point that I'm worried about waterproofing issues?).