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How to Build Cage

Old 02-19-04, 03:01 PM
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How to Build Cage

Hey guys, I was wondering if there was a book or something on how to build a rollcage? Please no responses saying that you shouldn't build it yourself but trust it to the professionals b/c they obviously had to learn sometime Thanks
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Old 02-19-04, 03:15 PM
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Yeah, they went to school to learn how to weld..
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Old 02-19-04, 03:52 PM
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I agree with SilkWorm because you REALLY need to be a good welder/fabricator to get the job done right. I will be contacting a local acquiantance for my buildup in the next weeks although I could get a decent MIG and tubing for what it will end up costing. Some things you just CAN'T do yourself and do right.

I would still like to understand how the heck they determine where the bars go, aside from the "triangulation" schpiel I've been given before.

Most of the guys I hear building cages don't have a ME degree and do FE stress analysis, etc...

SCCA rulebooks provide a basic guidebook, but surely there is some automotive engineering text on the methodology of cage design/rationale for putting a bar here and there....anyone? I looked around probably 2-3 years ago when buying my rollbar to try and have an understanding of which was better and why, but never found anything. I guess the next best thing would be a book on chassis construction or become a "good 'ole boy" and get schooled by a NASCAR shop in Charlotte.
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Old 02-19-04, 08:21 PM
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Originally posted by bond007
I agree with SilkWorm because you REALLY need to be a good welder/fabricator to get the job done right. I will be contacting a local acquiantance for my buildup in the next weeks although I could get a decent MIG and tubing for what it will end up costing. Some things you just CAN'T do yourself and do right.

I would still like to understand how the heck they determine where the bars go, aside from the "triangulation" schpiel I've been given before.

Most of the guys I hear building cages don't have a ME degree and do FE stress analysis, etc...

SCCA rulebooks provide a basic guidebook, but surely there is some automotive engineering text on the methodology of cage design/rationale for putting a bar here and there....anyone? I looked around probably 2-3 years ago when buying my rollbar to try and have an understanding of which was better and why, but never found anything. I guess the next best thing would be a book on chassis construction or become a "good 'ole boy" and get schooled by a NASCAR shop in Charlotte.
books on chassis construction... that might be good...
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Old 02-19-04, 10:28 PM
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Mostly I've learned by trial and error. First cage was a real POS and thank god it is now rusting away in a field in upstate NY. Second cage I did I tested myself the "hard way". First was a 90+ mph shot into the guardrail at LimeRock then two weeks latter in the same car head on with another FC. I was stopped he was doing about 50 mph. I walked away from both but learned a ton. You need to visualize the load paths applied to each point of contact with the body. Make dam sure that that path does not end with a bar pointed at your scull. I would suggest working with a cage builder to learn the basics before diving in.
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Old 02-19-04, 10:34 PM
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Are there any books besides those on chassis construction? It seems like that would be my best bet
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Old 02-20-04, 12:12 PM
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Steve Smith Motorsports has all kinds of books on racing stuff.
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Old 02-20-04, 04:49 PM
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Make friends with your local SCCA club racing tech inspector. If he knows his stuff, drain his brain! I'm fortunate in NC to have a local guy like that, he built one of the best looking cages in an ITD Yugo that his son won the championship in a few years ago.
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Old 02-20-04, 07:08 PM
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I agree with what E-prod says, but first you need to know how to weld. Your life is in your hands, if you can't get a good weld going, you can have the best designed cage in all 50 states and still have it come apart on you. And I'm not talking I welded a hole closed on a fender either.

PaulC
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Old 02-21-04, 06:50 AM
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What silkworm said is very true. And to add to it you need to weld often to stay good at it. When I haven't done any cage work for a while I can see the quality of the word go down. I try to do some practice stuff first to warm up and get used to things again. Also having the right welder is important. 110v or a stick will work in a pinch but is not what you want to use. Most people that are doing one cage in there own car are not willing to buy a $3000 machine and do it right.
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Old 02-21-04, 02:09 PM
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Louis, attached is an address with some candy for you. Go on out to a SCCA track event, ask some questions & find a car like yours or similar. Fill your eyes & ask more questions. If your not a SCCA member or if the the event is closed to spectators ask if you can enter as a Region guest.

I have never viewed a book on cages but then there are a lot of things I have never viewed.

www.bimmerworld.com/cages/cagepics.htmy

Have Fun ; )
David

ps: I tried the Bimmer link & received the "The Page Can Not Be Found" crap. Within this "The Page Can Not Be Found" click on the Bimmer link again & the Bimmer page comes up. Then click on "Custom Cages" & then at the bottom of the Custom Cages page click on "View our Design Scrapbook". CANDY..................

Last edited by ddewhurst; 02-21-04 at 02:28 PM.
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Old 02-21-04, 05:10 PM
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Originally posted by rotaryspeedracer
Make friends with your local SCCA club racing tech inspector. If he knows his stuff, drain his brain! I'm fortunate in NC to have a local guy like that, he built one of the best looking cages in an ITD Yugo that his son won the championship in a few years ago.
I know that guy and frequent that shop.

--Ashraf
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Old 02-21-04, 05:26 PM
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Old 02-22-04, 01:12 AM
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Tubeing, and a fishmouth jig! thats all and learn to weld, make sute your welder has a argon gas thingy. so that the weld is clean.
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Old 02-22-04, 02:08 AM
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Mandrel bender and griders would be good too

And lots of brake cleaner.
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Old 02-22-04, 04:41 PM
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Originally posted by Louis M
Are there any books besides those on chassis construction? It seems like that would be my best bet
If you plan on doing anything resembling serious racing (i.e. not drifting, sunday driving, auto-x ) then you'll need to buy or borrow every Carroll Smith book.
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Old 02-22-04, 08:04 PM
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I'll second the C.S. idea. Slightly out of date in some respects but a welth of information. Skip Engineer to Win though untill you are a full on addict.
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Old 02-22-04, 08:12 PM
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really newbie question, but what are the big differences between the $200 and the $2000 mig welders?
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Old 02-23-04, 02:12 AM
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you shouldn't build it yourself but trust it to the professionals

haha just kidding good luck with the cage man.
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Old 02-23-04, 06:23 AM
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Duty cycle and the feed mechanism are big differances. Duty cycle is the amount of time that a welder can sustain the chosen voltage. If your welder is over heated in the middle of a long bead your penitration will suffer. A smooth feed system is important again for consistancy. There are also electronic differances although I do not know the details. What I do know is that the $2800 welder I have now works about 1000 times better then the $800 unit that it replaced.
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Old 02-23-04, 01:35 PM
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I have also been looking into building a cage/chassis for my Lotus. I can weld quite well (LE training), got a few of the C.S. books, and I own a LE Tig 175 Pro. I've been looking into design for quite some time, but anything else that someone could add would be a real help.

Oh yeah, Bonus Material: http://e30m3performance.com/tech_art..._symposium.htm
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Old 02-23-04, 02:46 PM
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I strongly suggest the Carrol Smith books also. They are invaluable when trying to do any project, be it choosing a bolt or welding a cage. Also, you could take technical college courses to learn the basics of welding. The instructors at these places usually have quite a bit of experience, though not necessarily in the automotive industry. Learn, learn, learn. Or pay someone who already has

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Old 02-23-04, 03:34 PM
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cool.... thanks guys!
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Old 02-25-04, 05:17 PM
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To find where to place the bars, length, and thickness (i know there are certain bar mandates) you need to run some static analysis. YOu can do this fairly easily witha prgram such as ANSIS. Building a cage is a pretty massive undertaking. I'll probably design my own cage and have mitch piper weld it up for me. The only reason i'll be designing it myself is because i've got access to 100k+ of software and i'm working on the engineering degree. I'd just go over to piper motorsport and have them build you one, it'll be cheaper, better (nothing is very good the first time you do it, why screw up on your fd.) Carol smith books are really good, too bad they didn't let him name nuts and bolts, "screw to win" haha
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Old 02-26-04, 08:50 PM
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The REAL difference between the cheap and expensive welders is that the cheap welders will teach you how to weld improperly, to the point that if you get to where you can make two pieces of metal stick together with a cheap welder, when you finally use something worth a **** you won't know how to weld.

Sort of like teaching yourself how to do something, but teaching yourself completely and totally wrong.

Trust me: it's worth the extra bucks for a good Miller, Lincoln, or Snap-On (basically a rebadged Lincoln). There are a couple others that are good, but stay away from anything at Harbor Freight. You're better off using Elmer's to attach your cage...
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