need help with small trailer design

[oldboyscout]

I need to build a 3 1/2' x 5' trailer with some 2" - 1/8" angle I have. It will only have a GVW of 1000lbs or so, but I would still like it to be rigid. I'm wondering if it would be worth the trouble to set the cross members INTO the side rail angle, rather than the usual way of welding them underneath. I think this would stiffen the structure up, but it's a good amount of extra work. Is it worth it?

 

[bcp]

Lots of far higher capacity trailers are build with crossmember angles under side angles. Angles aren't very stiff when twisted anyway, no matter how rigidly the end is held.

If you have extra angle and want stiffer crossmembers, weld it into a channel or square. i would do it in channel configuration so it could be kept rust-free easier.

Bruce

 

[hodge]

oldboyscout, I built a 3 1/2 by 5 utility trailer, and wanted to keep it light but rigid. I used 1 x 1 1/2 rectangular tubing, mitering the corners. I then laid 1x1 angle on top of that, creating the outer perimeter for the decking. I made the sides out of 1x1 square tubing, and I have had well over 1,000 pounds on it, and it doesn't flex. I estimate the trailer to weigh less than 200 lbs.
trailerloaded008.jpg picture by br549_red - Photobucket

That was 26 full buckets of flooring adhesive, at least 40 pounds a bucket.

 

[oldboyscout]

Bruce, I was thinking of making tubes out of the angle, and I know that would be very rigid, but I also want to keep this as light as possible.
It's for off road pulled by a 4 cylinder Jeep Wrangler.
Hodge, that's a really interesting design, very nicely done. I was thinking of buying 1x2 tube also, but I'd like to use the stock I have. I'm somewhat poor right now...

 

[oldboyscout]

Also that's agood point about the heavier trailers. I have a 5x10 made of angle. It's plenty strong, but it does flex corner to corner.
I need this trailer enclosed about 20" high. I'm not sure how the flex will twist the sides to breaking?

 

[bcp]

Sounds like you need to copy the military 1/4 ton Jeep trailer. That's about the size you mentioned.

From:
http://www.jeepdraw.com/

View attachment 270404



http://www.naxja.org/forum/showthread.php?t=103020&page=4



Bruce

 

[oldboyscout]

I actually have one of those, in need of total rebuild. An M100. They weigh almost 600 lbs empty. Problem is I need something right now for camping and kayak hauling. The M100 is a future project when I have time and money.

 

[bcp]

Hard to beat these for a starting point for a lightweight trailer. Weld it together, then use your angle iron to make it the size you want. Put on larger tires if needed.

Heavy Duty Utility Trailer - 870 Lb. Capacity

40-1/2" x 48" Small Utility Trailer - 1090 Lb. Cargo Capacity

600 Lb. Capacity Boat Trailer & Other Small Boat Trailers
----------------------------
Modified:

http://www.kayakfishingstuff.com/community/showthread.php?t=65865

http://www.yakangler.com/forum/20-water-cooler/75-kayak-trailer

http://www.jaxkayakfishing.com/phpBB/topic19607.html

http://www.bckfc.org/showthread.php?7791-Kayak-Trailer-Ideas/page2

http://www.texaskayakfisherman.com/forum/viewtopic.php?f=1&t=140933

http://www.shortypen.com/projects/misc-small-sailboat-trailers/

 

[Attono]

I don't think you'd be gaining anything at all. If you weld the rectangle onto the top of the cross members, they are supported on top of it by more than just the weld joints you'd have if you welded them into the side rails. If you get a good weld where the side rails sit on top, you'll have the same amount of lateral stiffness.

YMMV, but I wouldn't waste the extra time or effort.

 

[oldboyscout]

Wow great links on the kayak trailers.
I am leaning towards the traditional plan, and just using plywood for the floor and sides. Quick and simpler than the sheet metal I had planned. Someday I'll get that M100 done (if it's not too heavy)

 

[Renze]

I used to work at a light to medium trailer builder. The deck-over designs had a truss frame from 2x2" tubing, and the cheap ones with the wheels beside the deck, had no real frame, the sideboards were integrated which gave it its strength.
when building tubes from angles, you either have a lot of welding to do, or if you dont weld them fully, rust is guaranteed. Water will come between them, and brown traces of rustwater will seep out.
For my manure spreader i use either C channel, or in case of tubes, i throw in some old engine oil before welding the ends shut, so there will be oil vapour throughout the hollow frame: Just open an old tractor that has sat for a couple of years: they dont rust that much from the inside because of the oil vapour.

 

[Attono]

That's an interesting way to do it, but how do you prevent it from flashing while you are welding it? Isn't oil vapor flammable?

 

[bcp]

Use linseed oil in tubular frames.

From:
aircraft tube oil

"Ever since there has been tubular steel aircraft, the standard method of tube interior corrosion protection is boiled linseed oil. Not to say that there isn't a better method, however, only linseed oil has passed the test of time."

 

[Oliver1655]

As long as your are planing to have fixed sides & front on the trailer, it should be stiff enough using the angle iron for the frame. However when building heavier trailers, I would recommend using channel iron for the frame box.

 

[bcp]

When looking at trailer websites, one stood out for have material sizes listed for many of their trailers. That can be useful information for designing your own.

Here is one of their small trailers:

Utility Trailer Mini: Equipment Trailer Mini From Carson Trailer

Bruce

 

[Renze]

That's an interesting way to do it, but how do you prevent it from flashing while you are welding it? Isn't oil vapor flammable?

Yes it is, when heated enough. So i weld everything shut, all but the endcap on the upper end. then throw oil down into it, and weld it shut: When the source of heat is so far away, the oil doesnt get hot enough to catch fire.