Author Topic: Tube joint intersections  (Read 1980 times)

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Offline Jonny Hotnuts

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Tube joint intersections
« on: February 10, 2011, 09:27:27 PM »
Ok, this may be a stupid question but when you are connecting tube joints at a 90 degree to a main tube the 'tails' of the fish mouthed pieces will hit.

Is it important or better to remove equal amounts of material from each section or can you make the concession in one tube?

Also....

As a rule I see most intersections at the same point, meaning that the cross member section and vertical section are always together. (*making it necessary to remove stock from on or both of the tubes from the above question). 
If the cross member tube is located slightly ahead or behind the vertical tube no stock would need to be remove for them to fit and hence more weldable area.

I cant see any structural advantage by locating the sections in the same place, but could see the more weldable surface being better (admittedly likely nominal ).


Any thoughts????
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Offline BALS aSALT

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Re: Tube joint intersections
« Reply #1 on: February 10, 2011, 09:37:40 PM »
after you have fish mouthed the tube, i grind the tube around the cut to remove burrs made from the hole saw. it also makes so when welding, the upper and lower lip, they don't burn or melt into the rod while tig welding. if the "lips" are ground, the two connecting tubes should not touch. if thats what you're asking
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Offline Gwillard

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Re: Tube joint intersections
« Reply #2 on: February 10, 2011, 10:19:18 PM »
After fishmouthing the tube, grind the thin areas off so your weld will be on full thickness of the tube. A lot of people don't and it can cause problems later on.
Structurally there is a difference in whether the crossmembers attach at the same point as the uprights. It is all in how stress is transferred through the structure. A more direct path for stress is always better. You really don't want to make the stress flow through a winding path at a simple junction.
If you know which member will be normally under tension, that is the one to attach first. Members under compression don't need as much weld area. However, if you aren't sure, just go with whichever is easiest for you. If you do a good job of prep and place sound welds on the joint, it will hold more than the structure leading into it.
Will weld for beer :cheers:

Offline fastman614

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Re: Tube joint intersections
« Reply #3 on: February 12, 2011, 11:03:21 PM »
Will weld for beer  :cheers:

Gwillard..... do you ever get up into the Pacific Northwest?..... I was thinking that I would put you to work on a welding project or two just for the pleasure of saying that I was glad to pay you and help consume the profits.....
No s*** sticks to the man wearing a teflon suit.

Offline Gwillard

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Re: Tube joint intersections
« Reply #4 on: February 12, 2011, 11:35:58 PM »
Will weld for beer  :cheers:

Gwillard..... do you ever get up into the Pacific Northwest?..... I was thinking that I would put you to work on a welding project or two just for the pleasure of saying that I was glad to pay you and help consume the profits.....

Lol! No, I've never been to that part of the world but if I get up that way I'll be sure to look you up.
Will weld for beer :cheers: