Which joint is stronger?

[chopnhack]

When welding up rectangular tubing, which is stronger, a butt weld - one tube ending on the face of another or a mitered corner weld?

Fixed thanks, Mike

[MikeGyver]

I think you mean corner, not edge.
If you're talking about making a 90 degree angle with 2 lengths of square tubing, I'd say mitering the ends at 45degrees is probably stronger.

[David R]

I find coping the corners is stronger. Miters don't work out too well because the outside corner is a bitch to weld.

David

[DSW]

The more weld length you have, the "stronger" the joint is because the forces are spread over the largest area possible. As David mentioned, a coped joint usually has the largest joined area, hence it's "stronger" than many others. That said, the joint is only as strong as the weakest point, and often that is the base material itself if the joint is welded up properly. Tube can be a bit harder to cope well, and miters tend to simplify things.

[HOBART]

how would you cope square tube or angle? given both pieces are the same size

[DSW]

Originally Posted by HOBART

how would you cope square tube or angle? given both pieces are the same size

Here's a pict of a coped angle one of the other members here did a while back.




Square tube would be done similar. You would leave the back section of one tube intact to cover the open end of the 2nd tube, and cut away the other sides rounding the corners for a good tight fit. It's harder to do well with square tube, but I've seen it done by several people. Think of it as 2 sets of angles both coped.

[Scott Young]

even in a coped joint you have an outside corner. The coped joint doesn't seem to pull as much to me. also if you don't have an very accurate means of cutting 45s then coping is quicker and more accurate. You don't have to wast time fiddling with your saw.

[morgaj1]

Here is a good tutorial on coped joints:

http://www.newmetalworker.com/Howto/copejnts.html

[David R]

A little bit of everything

http://weldingweb.com/attachment.php...4&d=1214169045

Try again

http://weldingweb.com/attachment.php...4&d=1214169045




Got it! one more. I built this for a customer. June of 08. Still running around.



I think the shape of trailer dictated mitered joints. It was fun to build.

[HOBART]

thank you DSW and morgaj1. i like the looks of those way better than a butt joint or a miter.

[chopnhack]

Thanks for the input guys. David, that cart came out awesome, I read the older threads when it was still being made. Looks good in orange. Don't know if I would leave copper on a reel with wheels if you know what I mean!

[Dantheman]

If it's welded well i doesn't matter. The less weld the better.

[Pangea]

I worked in a fab shop that made custom nursery equipment meant to drag through the dirt behind large tractors by mouth breathing knuckle draggers. We butted one tube into the edge of the other and put a scab plate covering the open tube plus extended onto the side of the butted tube. 2X in length in relation to the tube size. Very strong.

You could make the plate longer, past the end of the tube for an attachment point if needed also.

[bhardy501]

I build a good number of racks and such using square tubing. I use my Milwaukee 14" metal saw for coping the corners. When I set it up I use a square head of my combination square to set it up on a 45 and then back to 90. Works great and gives nice tight joints. I use a set of 45 clamps, like picture frame clamps, to secure it together to tack it up. Has worked well for me so far.

[chopnhack]

Originally Posted by Pangea

mouth breathing knuckle draggers.

LOL, nice! That is an interesting idea, thanks!

[chopnhack]

Well, not too bad, but I think I have to practice on the miter joint that is vertical, I did manage to poke a hole through one section of the 11 gauge steel...

heh, go figure my best weld is blurry

the second to last shot is the mitered corner ground down, the light made the center look dished, but its not it comes to a point.

The square came out square, but its a small square only about 6.5".

Thanks for the advice.