Jeep Enthusiast Forums banner

Pipe Strength

887 views 6 replies 5 participants last post by  jason m 
#1 ·
I realize that 1.75 DOM is the tube of choice for a structural rollcage, however 1.75 is bulky and takes a mile to bend, so I would like to cut the pipe size down on 75% of my cage. I'll use 1.75 for the roll bar behind the seats however I'll move to 1.5 for the front rollbar and spanners 1.25 on most of the other bars. I'm not building a offroad machine, I'm building an expedition machine that will go offroad so I have fabrication problems concerning water tanks, gas tanks, gear storage etc.

My question is 'should I move to a heavier tube on the 1.25 tube or should I start looking at light weight pipe? And how will the thicker walled material weld to the .120 tube?

Weight is ALWAYS a concern when I build, the lighter the better since this vehichle is heavy already

Thanks
 
#3 ·
I don't think I'd go any smaller than 1.5" (except for maybe gussets).. especially for a vehicle that's gonna be setup for "expeditions". To me, that means lots of spare parts, gas, water..etc. which is gonna have the rig come in on the heavy side. Last thing I'd want with a heavy rig is a spindly cage. Maybe do your A and B pillars out of 1.75" and the rest out of 1.5".. However, I don't think you're really going to see all that much in the way of weight savings. I bet you more than offset any savings with the weight of one cooler full of ice and drinks.
 
#4 · (Edited)
It's not only weight it's the physical size of the pipe and the room it takes to make bends, I was thinking of 1.25 for the brush/grill guards, gussets, seat belt mounts, etc.

PS You're right about the vehichle being heavy, but I usually travel by motorcycle and I'm a champ at using light gear, however we both know things such as spare parts etc. do add up quick.
 
#5 ·
Most of the bending dies use the same radius for 1.75 or 1.5. I would do the main supports out of 1.75 .120 wall DOM then do the spreaders out of 1.5 if you really have to. I am going to do everything but the seat brackets out of 1.75 on mine to save on cost of benders, difficulty of notching, and also ease of replacing a bent piece. Currently my main B piller is 2 inch and everything else is 1.5. Most of your bends are going to take place in dead space anyway. IE overhead.
 
#6 ·
I never thought about the dies being the same size but you're right, the smaller pipe will bend tighter but only if you have a smaller diameter die

Hmm, that's interesting as I wanted to frame my grill in the same shape as the grill roughly 1 1/2" - 2" from the actual grill, two pipes would tie into the front pillar right below the dash and reappear here where they would intersect the grill frame. Since the engine compartment tubes will be overkill I was going to go 1 1/4 to make a smaller bore as it comes through the grill and to match the 1 1/4 of the grille guard itself

I've also found large rubber grommets for the bore holes where the cage intersects the body

Hmm, how do I make tighter bends on the 1 1/4 for the grille guard?

EDIT: I may be speaking too soon, let me see what radius dies are on my buddie's bender, he owns a large muffler shop and he thinks his bender will handle 1.75 .120 without crushing it, but we haven't tried yet as I want to buy all my tube at once, which means I need to cement my design and pipe sizes

I'll stick with 1.75 for my main cage and spanners as I'll have cuts left over since I'm buying all 20's
 
#7 ·
1 1/4 SCH 40 pipe has a OD of 1 5/8'' and its not a true ID eather, it messures around ( ID ) about 50 thousands bigger ( ever stick is a little different ), 1 1/2 SCH 40 has a OD of 1 7/8 and the same theory for the ID. the wall thickness for ( your avarage ) SCH 40 is .134 wall thicness. SCH 80 holds a more true ID and a .200 wall but the same theory is true for the OD as the SCH 40.

there is several types of pipe, the sh*t pipe is the stuff used to make fence's and gates avoid this pipe, next is the black iron A-53 grade ( its steel but called black iron ) this is used for sprinkler, gas fitting, water and most all hand rail's this would be OK to use in a cage but better for rock sliders and outside protection. theres much stronger grades like A-500 ( has a green coating ) used for HYDRO applacations and high pressure but very expensive, there is a strucual grade thats made from HOT rolled 1010 and is all most the same as COLD rolled 1020 DOM very close to tensle and yeild but is messured as a pipe ( SCH ) not as a tube. so dont get confused when ordering you might get somthing bigger than what you wanted, jason.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top