Roll bar fabrication - lots of pics!

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Several weeks ago I got an email from a guy in Ohio wanting a bolt in roll bar built to SCCA solo II (autocross) specs for a Panoz Esperante that he uses for track days at various road racing tracks.  He found my website by searching google and since I had so much Panoz knowledge he decided to have me do it.  The problem was he happens to be several states away.  He told me he could have the car in Atlanta at my shop for 2 days this week then he would go to an event at a road race track in Alabama on the weekend.  The challenge on this car is the convertible top takes up a lot of space where a roll bar would normally go - plus the top had to go up and down over it all!So, I started out by borrowing some parts from Panoz.  I got an old rear subframe, a used carbon fiber top well from a wrecked car, and a couple of the parts of the convertible top frame and set them all up on a welding table.  This effectively gave me all of the car I needed - and no paint of interior to damage.  After spending some time in a finished car at Panoz measuring to see how high the bar could go and still clear the top I got started.Here is a pic showing the inner most convertible top arm just clearing the main hoop in the up position:Here it is when the top is down - you can see I had to dogleg around it.  I hate to have a bend in the rear diagonals like that, but there is nothing structural that far back in the middle of the car to mount to.  So, instead I added a harness bar between the diagonals from outside of bend to outside of bend.Here are a couple of shots of the joint fit up:And now a couple of shots of the welds.  I know you guys would ask for these if I didn't add them.  I didn't spend a ton of time on them - I'd consider them "production quality" - plenty strong and not unattractive but not all out show level...
Reply:Humm - didn't know about the 10 photo limit per post...  19 just didn't work!  So here is the second half:Ok, that's enough of the construction pics.  Here's a few showing it in the car.  The top clears perfectly, and the rollbar is high enough to get the driver's head under it so it's a success!  Top up: Top coming down:All the way down:So, there you go.  I hope it was enough pictures!  There are several design features on this bar that had to be compromised a bit from optimal to get it to fit, but all in all I am very pleased with how it turned out.  I would normally want the rear diagonlas to go from the top of the hoop or at lest middle of the upper bends straight back to the mounting point, but that just was not possible in this car.  They do at least meet the SCCA guideline of being connected within the top 1/3 of the main hoop.Jason
Reply:Nice work.What are you using for making notches?
Reply:How many hours do you have in it and wha type of welder are you using?
Reply:I can not see any of your pictures, only little boxes with red Xs
Reply:Really nice work, great joint fit-up, great welds, tight fit in the car.
Reply:Originally Posted by Giant GuyI can not see any of your pictures, only little boxes with red Xs
Reply:Great work Tubular! Extremely precise fit-up. I think I have the same EXACT cold cut saw that is in your shop. Is it 3-phase?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Thanks guys!  The paint is a bit lacking on this one, but that's a long story.  There wasn't any time in the schedule for powdercoating, so spray bomb it was.  The owner actually ended up doing it after wrinkle paint didn't turn out so hot.  I think from now on I'm going to a strict policy of either bare steel or powdercoat...  Unless anyone has ideas for a very easy, very durable spray finish.  Might try Hammerite once...The welding was all done with a Miller XMT 300 CC and Miller S-54 wire feeder.  The notching was done in a small horizontal mill I have dedicated to tube notching:Micro - it's an old Scotchman cold saw I bought locally off Ebay.  The fan on the back of the motor was broken up, so I simply removed it.  It is such a short duty cycle when you use it that it could care less.  I have set up a stop on it before and ran it almost steady for half an hour and it's still cold to the touch...  Also, somebody had removed the normal 2 speed switch and added a trigger switch - so to change speeds I have to rewire the switch.Jason
Reply:The better the fit up..The better the weld up.. Splendid!Nice job Jason.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:DAYM you are good!DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:...very easy, very durable spray finish. That, right there, is a contradiction in terms! Nice fittin' roll bar!! City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:I´d say we need more pics!that´s a great job...how fast can that car go? any specs?Nice design I like it...and the fit-up is amazing!My Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:Hey, we need some pics of the whole car! Looks really good though.HH 187Miller Bluestar1EAHP AlphaTig 200X
Reply:Beautiful work.Nice professional fit and finish.Miller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:Thats a sweet setup, beats my chop saw and die grinder. WHat are you bending with?
Reply:great job on the cage. i have one thing to say especially being that the tubing looks like chromoly why is it that more than 50% of chassis builders do not sand the ends of the tubes before welding? but very nice cage looks like it fits great.
Reply:Very nice fitup.  Isn't it true that for certain sanctioned race events that all roll-bar weldments have to be tiged?Common sense in an uncommon degree is what the world calls wisdom.
Reply:Originally Posted by BrainfarthVery nice fitup.  Isn't it true that for certain sanctioned race events that all roll-bar weldments have to be tiged?
Reply:Originally Posted by fordmanNope. Nascar doesnt even tig weld their cages.
Reply:Once in awhile a NASCAR race car will be at Thompson Speedway on display..Saw Kurt Bush's Crown Royal Ford that he actually drove in a couple of races when with Rousch..All migged..The whole thing..And to me..Not so good in places..I wanted to take close-ups of the welds but they would not let me get that close.. ...zap!Last edited by zapster; 11-04-2007 at 09:10 AM.I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:And I have stated this before..Tigging a race car of any type takes alot of time..1/4 the time with a Mig..Makes no sence to tig a stock car together when it can be wiped out in the first turn of a race..Drag cars on the otherhand you see racing for years and years...Some cars are raced for 30 years with no problems..Stock cars will never see 30 years unless they are in storage..All in the cost factor also..Stock cars will never be "show cars"..Drag cars that race are "show cars" in the winter.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:To clear up any misconception on the welding procedure..This is under "General Rules" in the N.H.R.A. rulebook..This applies to any car..Hope this clears things up.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:TublarFabWhen your prepare a cage do cut all material and then put it together or is some fitting after bending is done.What is your technique for getting the measure of tubing that will be place at a diagonal?What is your technique for cutting a miter on one end of a tubing, then flipping it and determining if the other end will be lined up as necessary.  For instance, two intersection 45* miters like a picture frame or parallel miter like railing balusters.I don't do roll cages. I have build a lot of pipe rail and am always looking for a faster way to lay stuff out.Thanks.
Reply:Originally Posted by tapwelderTublarFabWhen your prepare a cage do cut all material and then put it together or is some fitting after bending is done.What is your technique for getting the measure of tubing that will be place at a diagonal?What is your technique for cutting a miter on one end of a tubing, then flipping it and determining if the other end will be lined up as necessary.  For instance, two intersection 45* miters like a picture frame or parallel miter like railing balusters.I don't do roll cages. I have build a lot of pipe rail and am always looking for a faster way to lay stuff out.Thanks.lurkin
Reply:Originally Posted by zapsterTo clear up any misconception on the welding procedure..This is under "General Rules" in the N.H.R.A. rulebook..This applies to any car..Attachment 13681Hope this clears things up.....zap!
Reply:Very nice work and very hard to do without the car. Im going to fabricate a full roll cage for my rally car soon as well. I liked your notching technique, never thought of doing it that way before, though Im pretty sure those milling drills at that size are worth a few hundred and we dont have them that big. Might be worth it for me to buy a hole saw notching jig for the drill press.3rd Year Boily.EDIT: TRADE QUALIFIED! WOOPWOOP
Reply:Originally Posted by BiGsVery nice work and very hard to do without the car. Im going to fabricate a full roll cage for my rally car soon as well. I liked your notching technique, never thought of doing it that way before, though Im pretty sure those milling drills at that size are worth a few hundred and we dont have them that big. Might be worth it for me to buy a hole saw notching jig for the drill press.
Reply:You're not kidding that those dedicated notchers cost a small fortune!  The Mittler Brothers "Ultimate Tube Notcher" is one that I've used and was not impressed with.  They use some great components making them except for the design of thier bed - the milling head is mounted on a standoff from the base plate and it allows flexing - the one I've used gets the job done but chatters a LOT.  Mine is based on a little Nichols horizontal milling machine.  The neat thing about the milling machine is the cross feed (one you use to notch) is on a rack and pinion with a fast feed lever.  A regular leadscrew type takes a lot more cranking to achieve the same feeds.  This one you turn the big lever you can see in the pics about 45 degrees to make a notch.  This mill also has a pneumatic feed in that direction that is fully automatic, but it all needs rebuilt.In reference to the earlier post about sanding the dark finish off the tube prior to welding.  I actually contemplated doing it on this one and in the end decided not to.  The main reason was asthetics.  Once the tubes are bent and notched you would have to use a small 3" angle grainder and roloc scotchbrite disc the whole way around the tube to sand that layer off.  You would have to be extremely careful to not make any makes that would then look bad after painting or coating.  On DOM tube that layer is very very thin, and when MIG welding it really does not cause any problems to leave it.  As Zap had shown with his excerpt from the NHRA rulebook the sanctioning bodies do not require TIG welding unless you use 4130.  Except for the NHRA most sanctioning bodies would prefer you stayed away from 4130 due to the difficulties in welding it - i.e. properly stress relieving it if you use a cromoly filler or sacrificing a little joint strength if you use a mild steel filler.  But anyway, it is probably a much better idea for the sanctioning bodies to encourage amateurs building racecars to use mild steel tube and MIG welding.  There are some extremely scary cages out there on the tracks every weekend proving guys that aren't ready to build cages are doing so anyway.  I think the sanctioning bodies take the mindset of not encouraging them to try more complicated processes when building a cage.  My shop is located about 1/2 mile from Road Atlanta, and I go over there for many SCCA and also vintage races and it's really terrifying to see some of the "safety cages" that pass tech inspection (keep in mind these guys usually know less about welding than the guys deciding to weld a cage together with a 110volt Home Depot welder).  I don't believe I should be offending anyone by making these statements because if you are new to cage building but you happen to be reading this you're already doing the research to help you learn the correct way to do it!  The amateurs I'm talking about would not have taken the time to find a welding website and read about it first.
Reply:You could get away cheap with a small or mini lathe, too.  Add a milling attachment for centering or make specific blocks for different tubing.Then, the end mill would cost more than the setup.Thanks supe for your comments.TubularFab please check out my last post.  Post #24.  Thanks
Reply:[QUOTE=  But anyway, it is probably a much better idea for the sanctioning bodies to encourage amateurs building racecars to use mild steel tube and MIG welding.QUOTE]It's probly better if the sanctioning bodies don't encourage amature builders to build racecars.s.r.
Reply:Originally Posted by tapwelderTublarFabWhen your prepare a cage do cut all material and then put it together or is some fitting after bending is done.What is your technique for getting the measure of tubing that will be place at a diagonal?What is your technique for cutting a miter on one end of a tubing, then flipping it and determining if the other end will be lined up as necessary.  For instance, two intersection 45* miters like a picture frame or parallel miter like railing balusters.I don't do roll cages. I have build a lot of pipe rail and am always looking for a faster way to lay stuff out.Thanks.
Reply:DO you know how to run the math to figure out, given a bend center and degree of bend where to start the bend? I use the 90 degree trick right now and my main hoops are all good, but I need some tricks with a pillars and such. I just got a new welder so I think I am going to start building some hoops and cages and such.
Reply:Nice job Jason.    but I'm more partial to symmetrical diagonal braces (X-brace) instead of the single diagonal.  But that's probably just me.
Reply:Fordman - I do know a few tricks, but I still tend to gravitate towards the computer on everything.  I am just so used to using 3D CAD to work out the stuff that that is my quick tool for figuring it all out.  Bendtech SE is great, too, but I prefer to use a real CAD program to generate the data for bendtech.
Reply:Originally Posted by zapsterTo clear up any misconception on the welding procedure..This is under "General Rules" in the N.H.R.A. rulebook..This applies to any car..Attachment 13681Hope this clears things up.....zap!
Reply:Thanks Moonrise!  I like the X myself, but in this application minimal obstructions in the car was the goal.
Reply:I guess the question of what I bent it on has come up twice now.  I have a couple of machines to choose from to bend roll bar tubing, but this one was done on my big mandrel bender.  It has a wimpy 45,000 FTLBS of bending torque, so this rollbar stuff didn't even make it work.  It will make the 90 degree bends you see in the main hoop on this rollbar in around 2 seconds per bend unless you throttle it back a bit!  Here it is:I could have also done it on my small homebuilt bender which is capable of about 6500 ftlbs of bending torque.  Only thing is it's much slower and does not have the indexing head to position the tube.
Reply:Nice job.  Keep posting up more pics!What size/thickness tubing do you normally use for a roll bar/cage?Miller Dynasty 200DX Tig Welder
Reply:Kikas bender!Nice stuff!...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by TubularFabFordman - I do know a few tricks, but I still tend to gravitate towards the computer on everything.  I am just so used to using 3D CAD to work out the stuff that that is my quick tool for figuring it all out.  Bendtech SE is great, too, but I prefer to use a real CAD program to generate the data for bendtech.
Reply:Originally Posted by fordmanI wish, I am just an 18 year old kid trying to learn build my car and some stuff for other people! Sounds out of my price range
Reply:Actually there are some free CAD programs out there that will do a lot.  Through this forum I found out about Alibre (http://www.alibre.com) and it is a pretty powerful 3d CAD program.  You just get a few annoying sales calls at first if you register it, but they have long since stopped calling.  I just never had much time to sit down and learn it so I keep going back to a 1998 version of Microstation that I've been using forever.Also check out Bend Tech  (http://www.bend-tech.com/) and look into thier trial version.
Reply:Originally Posted by fordmanDO you know how to run the math to figure out, given a bend center and degree of bend where to start the bend? I use the 90 degree trick right now and my main hoops are all good, but I need some tricks with a pillars and such. I just got a new welder so I think I am going to start building some hoops and cages and such.
Reply:That mandrel bender is the shizel, i bet its worth a pretty penny. I think im going to dish out for a hand operated one, my bow and arrow one just wont do it justice.3rd Year Boily.EDIT: TRADE QUALIFIED! WOOPWOOP