Box Section Joints

[Psychosaffa]

please excuse the Paint Aided Drawing.
what method do you suggest i use to join box section at a right angle?

this is what i have done in the past, and i hope that the drawing makes sense.

the orange colour is where the welds are.


im sure this method is better than just cutting the bits at 45 and joining.

is there a better way to do it?

 

[Welderpaul]

More faffing about making a joint like you have shown than simply mitring it at 45 degrees.

 

[Richard.]

45 degree mitre is a much better way of doing it. That drawing looks far to much of a mess about. The other thing about mitring the joints is they will be much easier to adjust up to get it true and square.

 

[Psychosaffa]

cheers. someone told me that a 45 degree mitre has a better chance of cracking under stress. i done it that way when i built the tray back for my pickup, but will do the 45 degree mitre for my welding table.

 

[steviec_lj]

As above, 45 degree mitre.

Quick and easy to cut, same if not more weld holding the parts together.

 

[Hitch]

If its just for a bench, i'd just square cut it all personally.
Mitres if it needs to look good and open ends arn't desireable.

 

[Jim Davey]

I'd go the same way as Hitch unless it was something fancy.

 

[Bobtail4x4]

like your pic, but with a couple of plug welds on the top flap.

90 mitres mean cutting both sections.

 

[Paul G]

The maximum permitted stress is higher on a butt weld than on an open outside corner

so the mitre is the way to go.

Paul G

 

[Spark plug]

I would mitre the joints as it just as easy for me to cut 45. And it looks nicer.

 

[DanielW]

I'll go with 45 deg,to be honest your method doesn't look that strong.

 

[pedrobedro]

It's easier to weld a mitre and tidy it up if you are going for appearances. The top thin piece that is blocking off the end of the upright is doing nothing to add strength you would be better welding to the face then blocking the end separately.

 

[backpurge]

Mitred joint for me too

 

[Kent]

Mitre, leaving the pointy bit square cut for a perfect corner2corner joint. I don't think I have ever seen the drawn joint you show specified

 

[Gramas]

I'd be looking to butt box up against other section and cap the open ends, simple , easier to do. Just remember to do caps 1st. Before welding brace corners by tacking bit scrap length in so to stop pulling

 

[Bsmith]

If its just for a bench, i'd just square cut it all personally.
Mitres if it needs to look good and open ends arn't desireable.

I'd be looking to butt box up against other section and cap the open ends, simple , easier to do. Just remember to do caps 1st. Before welding brace corners by tacking bit scrap length in so to stop pulling

You can buy plastic caps to whack in the ends, or weld steel pieces in if strength is important as said.

 

[Kent]

I'd be looking to butt box up against other section and cap the open ends, simple , easier to do. Just remember to do caps 1st. Before welding brace corners by tacking bit scrap length in so to stop pulling

Easier? seriously? your adding three runs and having to cut and tack a correctly sized plate. To get a mitre is just a 45 degree cut rather than a 90. Ok if you want a corner to corner you need a good saw and two cuts 1st at 90 second at 45 less one wall thickness as applicable if you want a corner to corner on the edge.

You know at places like gate bottoms I do as you say but step the jamb side slightly below the cill , sort of says " I am a joint " trying to get edge radius sorted and all in the polish up the joint proper is sort of pointless and too time consuming anyhow IMO

 

[Hitch]

If I was making a frame that needed closed corners and plastic caps were undesireable i'd mitre every time.
If plastic caps or open ends aren't an issue id square cut it all, I woudn't square cut and cap generally. Occasionally we get jobs drawn like that, and usually looks a bit scruffy like the plate is an afterthought.

 

[Gramas]

Mitres look better yes but only if good prep is made so when welded it sits right , good pen , not to high but not concaved , I've capped in past and looks fine if weld right, although was Ali box and tig neatly
Trying to 45 ends without saw isn't hard just mark and slit disc slowly keeping to mitre line
End of day it's persons preference really

 

[Gramas]

Easier? seriously? your adding three runs and having to cut and tack a correctly sized plate. To get a mitre is just a 45 degree cut rather than a 90. Ok if you want a corner to corner you need a good saw and two cuts 1st at 90 second at 45 less one wall thickness as applicable if you want a corner to corner on the edge.

You know at places like gate bottoms I do as you say but step the jamb side slightly below the cill , sort of says " I am a joint " trying to get edge radius sorted and all in the polish up the joint proper is sort of pointless and too time consuming anyhow IMO

For butt & cap yes very easy mate , don't take 2 mins to cut flat plate then corner to corner weld