Frame material for DIY job?

[doug hodder]

I'd just lay it on the underneath side and gusset it back to the channel. Probably should extend back at least to the 2nd crossmember . Doug

[angib]

Every thing is 3/16” thick streusel steel.....My frame has been gone over by a professional engineer

Chuck, I'd love to see what calculations the engineer did. It's fairly easy to work out how strong a trailer frame is - the difficult bit is deciding how strong it needs to be and there aren't many engineers who know the answer to that question.

Andrew

[dguff]

http://tnttt.com/album_ ... ic_id=6689[img]

I have had great results on two different tears using 2x2x1/8" angle iron with a 2x3" 1/8" tongue with everything bolted together. This picture shows the frame upside down with the Flexiride stub axle bolted on. Good luck with your build.

Jerome [/img]

[brian_bp]

..the frame material of my current build is 1x2x3/16 forged "C" channel...very strong and at 5x9, it is lighter(and cheaper) than the last one(4x8) made of 2x1/8th tube...

Sure...
1" (wide) x 2" (tall) x 3/16" (thick) C-channel: 0.75 in2 cross-sectional area
2" (square) x 1/8" (thick) box section: 1.00 in2 cross-sectional area

That tube is 33% heavier (per unit of length), and no doubt stronger. Maybe 2" tall x 1" wide x 0.100" thick box (0.60 in2) would be a better comparison.

The C-channel is efficient enough, and very practical for fabrication... it's just not the optimum for light-weight construction. Angle, on the other hand, makes no sense to me for frame rails.

[Nitetimes]

Angle, on the other hand, makes no sense to me for frame rails.

I'm curious as to why???

It made perfect sense to me, easy to use, strong enough for the application and it also provided a good low mount for the floor.

[len19070]

It's fairly easy to work out how strong a trailer frame is - the difficult bit is deciding how strong it needs to be and there aren't many engineers who know the answer to that question.
Andrew

Andrew, that is one of the best statements I've heard in a long time.

It should be on a plaque or chiseled in Marble somewhere.

Happy Trails

Len

[shoeman]

I can see how both angle and square tube have merits. And obviously both work fine, judging from the amount of Tears built both ways with no issues in use.
The fact that the wooden "superstructure" and framing is bolted/screwed/glued together and incorporated into the frame makes these almost into a composite construction overall. The light weight and light loading when being towed also helps. I would not build a car-hauler out of angle, but we're talking about glorified utility/motorcycle trailer loading levels in this case. Not real high stress stuff.

[shoeman]

I just called the local steel house. Is 2x2x .125 too thick and/or heavy to use? I don't want to build a battleship outta this thing. They also have angle in the same dimension and C-channel in 3/16" as well.
Angle is half the price of square tube ($1.16/ft vs. $2.40) and C-channel is $2.10/ft. 3"square in .125" for the tongue (too big?) is $3.92/ft

Too many choices!!

[angib]

I think it's important to recognise there are two different things here: how strong does the tongue need to be, and how strong does the rest of the frame need to be?

Tongues do fail (occasionally) but failures elsewhere are unknown - OK, someone will prove me wrong, but I'll use the "exception that proves the rule" defence....

So that's why I did a web page on tongue strength, because anything better than cooked spaghetti will do for the rest of the frame. Two bits of that 2"x2"x0.12"(~1/8", 11ga) square tube makes a good A-frame tongue for even a heavy teardrop and a single tube will do for a lightweight teardrop. You could go lighter or use the angle for the rest of the frame - the angle provides you with a ready-made flange to bolt the floor to, but it does give you some fit-up work to assemble it.

Andrew

[Chuck Craven]

Every thing is 3/16” thick streusel steel.....My frame has been gone over by a professional engineer

Chuck, I'd love to see what calculations the engineer did. It's fairly easy to work out how strong a trailer frame is - the difficult bit is deciding how strong it needs to be and there aren't many engineers who know the answer to that question.

Andrew

Sorry Andrew I can’t get the calculations to you. The engineer is a retired railroad bridge engineer worked designing and inspecting steel bridges for 45 years. This is the Information that we came up with for the static trailer and he calculated the moments of motion from this: Steel type # A-36 carbon steel hot roll, Square tube is hot roll welled seem, curb weight 2000 Lbs., 2/5 of the weight behind the axel, travel speed of 70 MPH on road, 20 MPH off road gravel/ stone/ dirt with a max 20% grade and pot holes of 6” depth.
My original design had a truss brace under the tongue tube 6’ long center brace was under the front cross tube, with two angles from the front cross tube to the front of the tongue. The angles from the front cross tube to the tongue added only side strength to the tongue and no vertical strength. The 2” by 3” tube was by it’s self would just handle a 3000 lb trailer before it flexed bound spring back and bend the tube. With the truss brace it was over 5000 lb trailer rated. By moving the angles under the front cross tube and back to the second cross brace and removing the truss the tongue was near the same strength. By removing the truss the tongue now has equal + / - spring motion. He felt that would be better on the hitch on the car than having a stiffer tongue.

Chuck

[brian_bp]

Angle, on the other hand, makes no sense to me for frame rails.

I'm curious as to why???

It made perfect sense to me, easy to use, strong enough for the application and it also provided a good low mount for the floor.

Almost no one actually takes advantage of this possibility of lowering the floor a couple of inches, although that's one slick setup! I'm not really sure, though, what the wood set into the angles does, other than serving as a nailing strip for fastening the body (which is a worthy function in itself). Since it's laying right on the frame structure, it doesn't seem to have much structural purpose.

Since very few of the teardrops I've seen on this site even use drop-beam axles, it seems that there is very little concern with keeping the floor low, anyway.

Channel is just about as easy to use, and stronger for the same weight. Strength is always a relative thing: just about any shape is "strong enough" if you use a piece which is thick enough... angle is just the simplest shape other than flat plate or solid bar.

[shoeman]

You could go lighter or use the angle for the rest of the frame - the angle provides you with a ready-made flange to bolt the floor to, but it does give you some fit-up work to assemble it.

Andrew[/quote]

Leaping to the next question that arises from that, how would one then attach the walls if the channel covers the outer edge of the floor? I suppose you must arrange it so the floor itself sits above the flange, only the sub-floor studs would be "inside" the angle?
I like the idea of gaining that small bit of ceiling height.

[Nitetimes]

Almost no one actually takes advantage of this possibility of lowering the floor a couple of inches, although that's one slick setup! I'm not really sure, though, what the wood set into the angles does, other than serving as a nailing strip for fastening the body (which is a worthy function in itself). Since it's laying right on the frame structure, it doesn't seem to have much structural purpose.

You got it right on the nose. It's main purpose is as a nailer, but it is kinda structural as it ties the box and frame all together. It was cut to fit the height of the inside of the angle. If you use angle in this configuration it gives you a mounting place for your spring hangers but it just leaves and 1/8 in strip of steel on top. If you use deck screws to attach the 2x's it keeps everything pretty simple.
The way I built this one makes all square cuts on the steel, no miters or notching to fit it up. The tubing was just used for a little extra strength for the tongue mount, really wasn't necessary.

[bobhenry]

If you have a couple handrails handy they make a dandy frame too !

[shoeman]

You got it right on the nose. It's main purpose is as a nailer, but it is kinda structural as it ties the box and frame all together. It was cut to fit the height of the inside of the angle. If you use angle in this configuration it gives you a mounting place for your spring hangers but it just leaves and 1/8 in strip of steel on top. If you use deck screws to attach the 2x's it keeps everything pretty simple.
The way I built this one makes all square cuts on the steel, no miters or notching to fit it up. The tubing was just used for a little extra strength for the tongue mount, really wasn't necessary.

Now I see what you did. Brilliant! Place the angle such that the nailer strip (which I think takes the place of the long side floor subframe strip) is exposed on the outside of the frame. Screw the floor sheet to the top and the wall base to the sides of that strip and you've got a tidy simple joint. Is this correct?
I see you used square tube for the end of the frame too. How do you attach the floor there?
One more question, aint I a pain, typically how many cross pieces are needed or used for an 8' frame? Seems the two end pieces and two more in the middle would do, along with the axle.