Mitre Joint vs T Joint

[kraythe]

I have been working on a welding table plan and I was currious if anyone knew if there was a difference in strength between a mitre joint and a corner T joint. My suspicion is that the mitre joint should be stronger because there is more welded surface but that is more of a guess.

Anyone know ?

[Sberry]

Normally T joint is stronger but,,, usually any of them are strong enough. I don't like to cut miters so simple is good. Don't always use the strongest joint, but one that is adequate.

[TripleTrophy]

Mitres have an elegance to them, but are harder to fit up. I suspect a well made mitre may be marginally stronger than a well made T, but, the differences aren't all that great (maybe 1.41X in one direction). However, it is harder to fit up a good mitre than a T, so the T would usually win out. I go with what is easy to fab.

[Dmaxer]

Properly welded, I don't think there is any difference between the strength of the two joint types.

[walker]

The T joint you are likely talking about is not a true tee joint, it is only a half a T (L???) I have seen many gates made with this joint and its weakness comes from the fact that the end of the tube is left open and it tends to rack easier. This is on thin wall tubing though. If you close the end then I think the joints would be near equal.

[Sandy]

wouldn't the shape make a difference?

[walker]

The shape of what?

[davedarragh]

I have been working on a welding table plan and I was currious if anyone knew if there was a difference in strength between a mitre joint and a corner T joint. My suspicion is that the mitre joint should be stronger because there is more welded surface but that is more of a guess.

Anyone know ?

Both of these are "fillet" welds. Welded joint designs are selected primarily on the basis of load requirements.

Your welding table is a "Statically Intermediate Structure," or a "Ridgid Frame" design.

As with your trailer project you were contemplating, you'll need column anologies and simulated stress of applied loads to the elastic areas.

Once these results are determined, then joint selection can be made.

[Sandy]

The shape of what?

The shape of the pieces you are joining together. Hollow rectangle, angle, C channel, I beam, etc..

[kraythe]

Both of these are "fillet" welds. Welded joint designs are selected primarily on the basis of load requirements.

Your welding table is a "Statically Intermediate Structure," or a "Ridgid Frame" design.

As with your trailer project you were contemplating, you'll need column anologies and simulated stress of applied loads to the elastic areas.

Once these results are determined, then joint selection can be made.

I think only the inside of the corner would be a fillet weld in a mitre joint. The outside corner would be just a corner weld (easy) and the tops would be only a butt weld. The inside weld would have to be a fillet weld.

Sure to perform a pure analysis to say without a doubt that it is capable within x PSI I would need some fancy computer programs and math and possibly a few thousand in consulting fees. However, that doesnt necessarily have to be done for every project. Furthermore, that wouldnt answer the isolated question of which joint is usually stronger.

There seems to be no consensus on the issue but it is interesting to think about. There also may be a difference between C channel, Tube and Angle on this as well.