Frame Drawing - Feedback Needed

[MisterGraphic]

Hello Everyone,
I started a build thread and this is my first question!

Here is a drawing of my frame plan :


Dimensions : 5" x 8"
Main Frame Square tubing : 2" x 2" x 0.125"
Tongue Square tubing : 2" x 2" x 3/16"
Axle : one piece Torsion will "add" a crossbar

Goals :
- Having a frame that is 2" thick all the way
(Tongue not being lower than the frame)
- I also don't want it to be too heavy.
- Floor pine framed + 5.2mm Meranda with 1" foam in the middle (reason for the tongue extending further back)

Questions :
- Should I add angle support for the tongue ?
- Is this "overkill" ?

Thanks of the feedback!
Denis

[Steve_Cox]

Very adequate looking frame. The tongue, if drawn to scale, is fairly long. I don't know if it needs "angle support". but I would add it. It would also be a good place for a little storage.

[kennyrayandersen]

In order to really tell, we’d need some more information like how much your expected weight will be and how long the tongue actually is.

It looks plenty stout to me, but I’m an engineer and used to making things no heavier than they have to be. The tongue sizing table of Andrew’s in the design library is quite easy to use and you should use that for sizing the tongue (shorter tongues are better for strength). Single tongues, especially long ones, can sometimes have lateral problems (dynamic), but the 2x2 section is pretty robust. Keep in mind almost all first-time builders tend to overbuild, but then find out that when everything gets bolted together it gets pretty strong (like those really cheesy metal shelves that you assemble!).

Almost everyone says they would build the second one lighter. In fact, if you built a robust box, not much frame is actually required (so your cross members and even the perimeter frame could be 1X2s (2 inch dimension vertical) without sacrificing much strength or stiffness). Only the tongue takes the entire load whereas everything else is strengthened by the box.

[Wimperdink]

My opinion, (not a professional here) is that it looks over adequate. Might end up very heavy but definitely looks strong. Personally If I was to build my own trailer, I'd borrow and modify the ultralight trailer frame in Angib's design library. (posted in the links at the top of the page) Hope you don't mind me linking to the photo Angib.

http://www.angib.pwp.blueyonder.co.uk/teardrop/tear57.htm



I'd use the 2" x 2" square you mention for the tounge like shown with some stubs going back to hold the axle you mention. Then put an angle iron rectangle on top of it for a lil more support, then build my floor on top of that out of wood. I would expect the angle iron would be much lighter than full 2" tube depending on the gauge of iron you use and significantly lighten your load.

Like this... (I love sketchup) (again just my unpro opinion) I think you'd end up with a stiffer tongue and the rectangular angle iron frame should be plenty strong enough.

[kennyrayandersen]

My opinion, (not a professional here) is that it looks over adequate. Might end up very heavy but definitely looks strong. Personally If I was to build my own trailer, I'd borrow and modify the ultralight trailer frame in Angib's design library. (posted in the links at the top of the page) Hope you don't mind me linking to the photo Angib.

http://www.angib.pwp.blueyonder.co.uk/teardrop/tear57.htm



I'd use the 2" x 2" square you mention for the tounge like shown with some stubs going back to hold the axle you mention. Then put an angle iron rectangle on top of it for a lil more support, then build my floor on top of that out of wood. I would expect the angle iron would be much lighter than full 2" tube depending on the gauge of iron you use and significantly lighten your load.

Some of Andrew's best work. It's easy to make stuff fat -- there is elegance in simplicity and lightness.

[aggie79]

One thing that you may want to consider is having a receiver at the back of your teardrop so that you can add bike racks, etc.

[MisterGraphic]

Thanks everyone,

My main concern with angles was the attaching
of the walls after the floor fits in the Angle frame.

Starting with you nice Sketchup drawing, would it be
wrong to flip the angles to get a flat top working surface?
(That way I can rest my walls directly on the frame and
attach them to my floor from the side)

The only problem I see with that is I would have to
notch the angles where it meets the tongue's A-frame.
I'm wondering if that would cause structural weakness.....

I'll try to draw something up this afternoon!

Denis

[MisterGraphic]

Well,

Couldn't resist taking a break from work and
drawing what I described in my earlier post.



Would it be wrong to "notch" the front angle
where it meets the tongue ?

Thanks for your help!

Denis

[planovet]

One thing that you may want to consider is having a receiver at the back of your teardrop so that you can add bike racks, etc.

I wish I had added one to the back of mine

[tinksdad]

Just my non-professional opinion; but I don't see notching the angle iron frame being a problem structurally (I'm assuming you are going to weld them in place). The main triangulation will be the strongest portion with the rectangle mainly being a means to attach the body. Don't forget to take into consideration the thickness of the side wall (plus the fillet on the interior corner) will decrease the clearance to the swing arms on your torsion axle. Every 0.125" counts!!!

[Wimperdink]

Don't forget to take into consideration the thickness of the side wall (plus the fillet on the interior corner) will decrease the clearance to the swing arms on your torsion axle. Every 0.125" counts!!!

Or small wheel wells if need be to clear the stubs... The fenders would cover that anyway.

Tipping the angle iron upside down shouldn't cause any issues at your cutouts at the front as long as they are welded properly. You could also cut some lil triangles to weld in at that point to strengthen that point.

Like others suggest a hitch in the back would be nice, but, then you might need to make the back like your original design to handle it. That would increase weight and $. If your concerned about weight like you mentioned in your original post.... the added steel, the hitch mount rack and whatever you put on that rack adds a bunch of weight to the build.

[MisterGraphic]

I thought of the rear receiver and it's not necessary.
If needed we can put the bikes on the car's roof rack.
I would like to keep things relatively light.

I'll have to show the plan to the trailer dealer and see how
much room we need for the swivel part of the torsion axle.
It would be nice to have the wheel close to the walls as
this trailer is already pretty wide.

I'll also build the rectangle frame and A-frame before ordering
the axle so I'll have the exact measurements

Tinksdad : Good points on the "fillet" inside the Angle; didn't think of that

Wimperdink : Little wheel wells would complicate things but I
may have to go that route to same a few inches of width.....

We'll see once I talk to "the axle guy"


Denis

[Wimperdink]

Sorry Tinksdad, I didn't pick up what you meant on the lil fillet on the inside of the angle until Mister mentioned it again. That lil fillet inside should be compensated by the round over edges on the square tubing so the thickness of the angle iron should really be all to look out for.

[KenC]

Hello Everyone,
I started a build thread and this is my first question!

Here is a drawing of my frame plan :


Dimensions : 5" x 8"
Main Frame Square tubing : 2" x 2" x 0.125"
Tongue Square tubing : 2" x 2" x 3/16"
Axle : one piece Torsion will "add" a crossbar

Goals :
- Having a frame that is 2" thick all the way
(Tongue not being lower than the frame)
- I also don't want it to be too heavy.
- Floor pine framed + 5.2mm Meranda with 1" foam in the middle (reason for the tongue extending further back)

Questions :
- Should I add angle support for the tongue ?
- Is this "overkill" ?

Thanks of the feedback!
Denis

Hi Denis,

The fabricator I used recommended 2 X 3 for the frame which is stronger and won't flex.

I just completed my frame, which is 2 X 2 inch steel with a 3 x 3 inch tongue. I have 2 x 6 wood framing with 1/2 ply on top and 1/4 on the bottom with 1 1/2 inch insulation, I know it is over built, my only excues is it is my first build.

I think your 2 X 2 framing will be fine, I to would recommend additinal support from the tongue back to the frame, less flex and you can add a tool box, etc for more storage. you can see my build progress by cliking on the website link below

[angib]

Would it be wrong to "notch" the front angle
where it meets the tongue?

Either notching the angle or just cutting it either side of the tongue is OK - and cutting it means you can keep the top of all parts level with each other.

The one problem that this raises is a nasty 'pinch point' where the stiff toe of the angle hits the equally stiff bottom face of the tube.


To visualise this, think of the red tongue tube held rigidly and now you pull down on the ends of the two blue angles - you will see that the downward leg of the angle is trying to crush the tube and because it is pressing on the flat sides, they don't have much resistance until you get right to the bottom where the bottom face of the tube makes it very strong. So all the bending load is being concentrate into those two little spots shown by the arrows and one day they will start to crack.

A simple solution is to weld a small bit of flat bar across the two toes as shown in green below.


Believe it or not, but this would be better if it is not welded to the red tongue tube but just to the two blue angles. This is because a fillet weld running across the tongue tube at this point would put a stress in the tongue that would weaken it, and again a crack may one day start there.

I missed wimperdink's comment about little triangles - these would be just as goiod and I assume he means something like this:



In this case, welds to the toingue tube are no problem as they are along its edge, not across its bottom face.