Big Bending Job

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Ok, this one is pretty cool, so I thought I'd show it on here even though there isn't any welding on it yet.  I am bending parts that will make up the frame rails on a retro style pickup called the Southern 358.  If you search for Southern Motor Company you should find more on the truck.  Anyway, the main frame members are going to be 4" OD x 1/8" wall round bent steel tubes.  All of the bends are on a 6" centerline radius.  The following pics are of the rear section that kicks up over the rear axle.  I am operating right at the capacity of my bender doing this job!  The capacity of the machine is right at 31,000 ftlbs of bending torque, and this one theoretically is in the 28,000 ftlb range.Here is the weapon:Close-up of the tooling:Here is a picture of the tube on the machine:Another:Close-up:Completing last bend:Finished part with Zap's patented "dime scaling device":Close-up of bend:I hope you enjoyed these....Anyone need 4" exhaust??Jason
Reply:Combination exhaust -and- structural member!Waiting to see the rest of the project pics!
Reply:Great stuff...I'm saving my pennies for a mandrel bender.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:You have all the fun toys.. Maybe you should make me up a 5" for the diesel.. You guys and your dimes.. ...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:This part will be purely structural.  I think it's going to end up with dual 2.5" or 3" side exit exhaust rather than going over the rear axle.  I'll get to make those, too!I have a mandrel for 4" x .065 wall for doing diesel exhaust or whatever in a thinner wall.  I also have a tighter bend die - 4" CLR in the 4" tube!Jason
Reply:Oh, and believe it or not, but this bender was built in a guy's garage from scrap yard metal back in the 60's!  It is like a Pines #3 but with more power.  A 20hp 3 phase motor makes it go...  Supposedly one of the early jobs this machine got was bending the roll bar tubes for the Granatelli turbine Indy Car's way back.  Nice pedigree, eh?Jason
Reply:Originally Posted by TubularFabOh, and believe it or not, but this bender was built in a guy's garage from scrap yard metal back in the 60's!  It is like a Pines #3 but with more power.  A 20hp 3 phase motor makes it go...  Supposedly one of the early jobs this machine got was bending the roll bar tubes for the Granatelli turbine Indy Car's way back.  Nice pedigree, eh?Jason
Reply:That's a nice machine for being built!John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:That is so cool, a really beautifully formed tube.I like the idea of using it for exhaust, or how about fuel or oil, you know like they do in motorcycles these days.
Reply:That bender does a nice job, no kinks at all.  A 4" CLR die on 4" pipe sounds like a REALLY tight bend.
Reply:That is really cool! I bought a model 3 bender recently, but am still learning how to make it do what I want. I do have a question though, why did you use EWS and not DOM, wouldn't the seam be a weak point especially on a frame or does the size and thickness of the tubing make up for it? THIS IS NOT CRITICISM, I know you know what you're doing and I'm just trying to learn!Sure, I can fix it... I got a welder!!!
Reply:Id give my left one for that.hell, I might give em both.Why use such large tube instead of a smaller dia like 2" .120 or cromo tube?Have we all gone mad?
Reply:Nice machine and nice bends too.  I'd love to own a mandrel bender.  Some day...
Reply:That is awesome. Oh, and screw you! hahaha. I wish I had a nice bender like that one! I have the JD2 model 4 and I am still trying to figure out how to accurately get repeatability for my bends.Nice job. Maybe you and ZAP could put a class together for us! We can bend and weld up something crazy and then try to get it home through an airport! hahahaLincoln Power Mig 210MP MIGLincoln Power Mig 350MP - MIG and Push-PullLincoln TIG 300-300Lincoln Hobby-Weld 110v  Thanks JLAMESCK TIG TORCH, gas diffuser, pyrex cupThermal Dynamics Cutmaster 101My brain
Reply:Why round tubing instead of the more standard box?
Reply:that truck is gonna be SHORT!My Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:"Id give my left one for that.hell, I might give em both."they worth that much! can see it now in the shop....very good sirnice bit of machinery..will u pay cash?mastercard?visa?... a couple of wrinkley old balls??  the day you stop learning in this tradeis the day your in your grave
Reply:That's a Tim Allen, "more power" machine if I've ever seen one.WeldingWeb forum--now more sophomoric banter than anything else!
Reply:Originally Posted by paretroopera couple of wrinkley old balls??
Reply:Thanks for the compliments!  This frame is being made from ERW for a couple of reasons that boil down to about the same thing - cost.  ERW is less expensive than DOM for one thing.  Also, DOM is work hardened by the drawing process, and does not like to be bent on a tight radius.  It just tears when you try to bend it without annealing it first - and the annealing adds more cost.  These rails are getting other brackets and crossmembers, etc that will all add stiffness.  Oh, and the cab is going to be structural rigidly fixed to the frame rather than mounted on 4 rubber mounts like most trucks.Here are a couple more pics to illustrate how it's going together:The parts:The layout:
Reply:Beautiful! How are you doing this on a repetitive basis? If it's built long ago than I assume it's not cnc bender. If no cnc retrofitting, you rock!
Reply:C'mon guy... I KNOW there is a hand bender there at the shop, and you are just playing with us saying you used some fancy machine to do that. Show me you bending that in your model 3!!!!! It looks really nice, great bend quality.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by TubularFab Also, DOM is work hardened by the drawing process, and does not like to be bent on a tight radius.  It just tears when you try to bend it without annealing it first - and the annealing adds more cost.
Reply:Most of the chassis you've seen that are made out of DOM are going to be in the neighborhood of 1.75 OD x .095 or .12 wall tube bent on a 6" to 8" centerline radius.  When mandrel bending the complexity of the bend is determined by 2 different ratios: 1. The "D" of the bend is the centerline radius divided by the diameter of the tube.  For instance, a 2.5" OD tube bent on a 5" centerline radius is called a "2D" bend.  For the common chassis stuff you're usually looking at something like 7" CLR / 1.75" OD tube = a 4D bend.  The lower the D number the harder the bend.  These frame rails are at a 1.5D bend, which is really tight.2.  The wall factor is the second consideration.  You divide the diameter of the tube by the wall thickness.  So, for common roll cage DOM you'd see something like 1.75 / .120 = 14.6.  With this one, the lower the number the easier the bend is to make.  As the number gets higher you need more advanced tooling including things like ball mandrels and wiper dies.  The wall factor on this tubing is 4.0 / .120 = 33.3.  That's not terrible, but definitely in the full mandrel tooling range.Both of these numbers together are used on a chart that determines the difficulty of the bend.  And, the difficulty boils down to how much stretching has to occur.  You can find an example of one of these charts here: http://www.bendtooling.com/mandrel_&_wiper_charts.htmSo, to answer your question, these bends are much tighter and in thinner wall tubing relative to the DOM chassis stuff you are used to seeing.
Reply:You do some great work and congrats to you for getting all that work, but I have to comment.I'm familiar with the pickup you're doing the work for, and thought it was impressive that a company was doing something like that.  It's cool that there are still people who can jump in to the new car business without being owned by one of the big 3 or have ties with them.  But I guess their thinking on this irks me.  I'm sure "Tubular Chassis" is a big marketing ploy, but when I was working at my previous job, most of our frames for farm implement equipment was using ERW tubing and about every run there would be at least one tube that came to us with a cracked weld.  I guess to me a regular c channel frame would've been more cost effective and better in the long run IMO.Looking good Jason....Got any pics of the truck? Originally Posted by sn0border88Just curious, if DOM "tears" when its mandrel bent, why is it very commonly used on tube chassis and roll cages?  Ive seen hundreds of roll cages and tube frames with very complex DOM bends that have taken serious abuse with no faliure and have never heard of it tearing.
Reply:Hes right about DOM tear, anything you would have seen would be around a 6" CLR. I got some plans and built a bender that utilizes a 1.75" 6.5" CLR. Best of all I got a ram from harbor freight that is hydro/air powered so I hook it up to compressed air and watch tube bend!
Reply:i need that!
Reply:Is the lathe-chuck at the end of the tube used simply to connect the pipe to a DRO, or is there some other reason for it that I don't see?  End support? Great machine!  Is there any springback to consider at all when bending tube like that?
Reply:Good link ZTFab!TubularFab:  So, is the brass part in the 1st and 2nd picutre the internal support to keep the pipe from deforming?   Is it difficult to remove the internal support after the bend?  I've heard that sometimes the pipes are pressurized.  What process uses a pressurized tube during bending?Thanks in advance!Eddie
Reply:HokieEd - the 3 jaw chuck is mounted to a worm drive gearbox that is in turn mounted on linear bearing tracks.  The gearbox allows me to exactly dial in the plane of rotation between each bend.  It also helps support the tube, which is much more important when dealing with such big tubing.The brass colored areas are actually Ampco aluminum bronze bearing alloys that support the tube at the point of the bend.  Basically they contain the tube where the bending occurs to make sure the tube maintains the same diameter.  The aluminum bronze wears nicely, and is much less expensive than hard chrome plated tool steel which does wear a little better.  But keep in mind you're looking at $7000 worth of tooling there!  The mandrel which has a nice slip fit inside the tube stays stationary while the tube slides over it in the bend.  The mandrel is mounted on a long rod to a hydraulic cyclinder that makes extracting it from the bend area possible.I have no experience with pressurizing tubing to bend it, but it seems like it would take a LOT of pressure to make it work.  Hydroforming uses extreme water pressure to expand a tube to fit a carefully shaped cavity - is that what you're thinking of?Here is a picture of the truck chassis starting to go together.  I did not do the welding!
Reply:That is SICK!!!!!!!!!!! Millermatic 175 MIGMiller Spectrum 375 PlasmaLincoln AC/DC 225 BuzzboxM-Tech NE5 Tube bender withcustom CNC machined 3/4" think main arms
Reply:wow, that is just too cool.  Great pic.Yes, Hydroforming was what I was thinking of.  If I need some tube bending advice in the future, I may have to call on you.  Do you have any other pictures of neat projects?
Reply:There are some pics in my gallery - http://tubularfab.com/GalleryJason
Reply:Keep them coming!!! This stuff is so cool... You get all the fun jobs.....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:wow, great pics in your gallery.  Thanks for the link.  Are you the primary fabricator on-staff?  How many employees do you have to help out?  It looks like most of your pieces are one-of and you might have an assistant or two.  Is 15 years of experience just you or combined with others?I did see that episode of monster garage too.  Pretty neat thing to do.  Did they work you all like dogs?  And do you still use those tools?Thanks again for sharing.