Tying frame sections together

[Hangman]

Hey everybody!! Been lurking on here for a little while and just decided to join, with questions of course.

Right now I'm building a custom truck frame using 2x4x.188 tubing. Where the tubing had to be cut, I beveled the edges and welded together, then ground smooth to match tube. Question is, what size joiner plate should be used to lap from tube to tube? Right now I have 9.5" plates cut, but can I go smaller, like a 2x3.5" diamond? I want it to be strong, but look good too. This truck when done is just going to be a street vehicle.

Thanks in advance.

Did I put this in the wrong section??

[wyoming9]

Tell me you didn`t just butt weld the frame splice!!!!!!!

That is the worst possible thing you could have done.

A frame splice should be done with a zee or at least one side pointed and the other side notched to accept the point.

With tubing it is possible to use a tube that will fit inside the frame tubing extended from the splice at least a foot in both directions . Then bolted with 3 bolts on both sides of the splice in a triangle pattern

Then you can get away with just a butt splice

NEVER in a straight line with any other method.

Make your fish plates as long as possible.

Will you be able to get away with your butt splice ?? perhaps ??

If it starts to crack in the HAZ one good bump will be all she wrote thats why fish plates are made as long as possible.

If your confused by the above statements feel free to ask questions

[Hangman]

The seams that are butt spliced are angle cuts. I knew at that time I was going to use the fish plates, just wasn't positive on the length required. I tried to make the frame as straight as possible to eliminate splices, but you know how that goes. Guess I can add some plates on the bottom of the frame rails too, just for peace of mind. All the fish plates I made are from .188" material, same as wall thickness of tubing used.

I have actually seen one street driven truck that only had butt welds and nothing for fish plates. Wonder how long that lasted...

[jackalope]

When I chopped my Pete n Jake's Model A frame, I cut it in such a way that when the pieces were set up next to each other, they actually rested into each other for the strength/shear factor.
For the reinforcement plates, I used large "s" shaped plates that were 3/16" thick or 1/4". I can't recall.
Anyway, they sit in the middle of the 2x4 tube and are very rounded to prevent any stress points.
As mentioned above, you want to make sure you use a plate that spreads the load over a larger area and is done so as to provide as much surface area weldment as possible to support the forces imposed on the frame.

[jackalope]

Let's see if this shows.
http://www.offroadfabnet.com/forums/...9&d=1313453501

The back section is sleeved in a way. There is tube inside but it does not provide the kind of support from a shear standpoint. Those back gussets are 1/4" and there is a LOT of weldment there.

You can see the front section but not really how the frame was cut. If I still had my templates I would take a picture. Unfortunately I don't.

Hope this helps

[Hangman]

Originally Posted by jackalope

Let's see if this shows.
http://www.offroadfabnet.com/forums/...9&d=1313453501

The back section is sleeved in a way. There is tube inside but it does not provide the kind of support from a shear standpoint. Those back gussets are 1/4" and there is a LOT of weldment there.

You can see the front section but not really how the frame was cut. If I still had my templates I would take a picture. Unfortunately I don't.

Hope this helps

I was actually checking out your build after work this morning. In your second pic of the frame, I can see what you did for the cuts. As I said, I'm using .188 material for the fish plates that are appprox. 3.75 x 9.5 inches, and probably adding plates on the underside too. If need be, I can cut longer ones for the higher stress joints. Gotta love running a laser for a living!


Awesome build by the way!!!

[wyoming9]

Know you should also bolt your fish plates as well as welding.

When welding stay away from welding the corners to prevent causing stress risers .

If you want added strength you can put a plate on the top of the frame think of the frame as a suspension bridge .

When I repair all to often Toyota frames I have 1/8"x6"" strip bent into 2"X4" angle I use to enclose the whole frame making the pieces as long as I can fit them in.

[jackalope]

Originally Posted by wyoming9

Know you should also bolt your fish plates as well as welding.

When welding stay away from welding the corners to prevent causing stress risers .

If you want added strength you can put a plate on the top of the frame think of the frame as a suspension bridge .

When I repair all to often Toyota frames I have 1/8"x6"" strip bent into 2"X4" angle I use to enclose the whole frame making the pieces as long as I can fit them in.

I'll take your advice and bolt it as well! Thanks. When I stop learning, it is time to call it a day ;-)

[floundering]

Here's how I did my last one: