Bridging a Trailer

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I'm going to try this again. I'm building a gooseneck " toy hauler" trailer, first of all I know what all of you are going to say that it's easier to just buy one. I'm having more fun building it myself. I know that I've read it on here 100's of times "don't waste your time on a fifth wheel frame" their too flimsy without the camper built on them. I found one with a 5" channel iron frame, that looked pretty good to me. The front of the trailer (the part that goes over the pickup truck bed was built really flimsy, so I removed it completely.  I decided to add 10' to the front of trailer, previous owner had cut the 4' off the rear of trailer. The tandem axles were now at the rear of trailer, I moved axles forward 4' leaving me 10' of trailer (5' over the tandems) and 5' toward the front. I ended up with 14' of useable deck space from tandems forward. I didn't feel comfortable engineering my own gooseneck hitch, so I bought certified gooseneck trailer plans. I built the hitch to exact specifications, using 6" channel iron (10,000 lb) trailer specs. Okay back to the trailer frame I butt welded new frame to old frame, and spliced (fish plated) with 1/4" thick diamond shaped plates on each side. I also added additional 5" channel cross members every 2' from the  front to rear of trailer. I know this is a long span for a 5" channel iron frame, and I'm NOT going to be hauling bulldozers or backhoes. I plan on putting a over the cab pickup truck camper (1,200 lbs) on front and a 1945 Willys MB Army Jeep (1,500lbs) over tandems. I did change out the 3,500lb axles and installed 6,000lb axles. I want to do what I believe is called " bridging " a trailer? The best way I can describe it is what an up side down suspension bridge would look like built on the bottom of the trailer frame. I'm going to try to describe this as best as I can, the center support (tower on bridge) would be welded across the bottom flange vertically where the trailer was spliced together I'm thinking 4" down from flange ? A length of 1/4" flat stock  would be centered on bottom of vertical (tower) welded and each end would be angled upward towards bottom of frame flange and welded. other smaller vertical (towers) would be spaced out equally and welded. each side of frame would have this done on bottom flange equally on each side. I also thought about " arching " the trailer before doing this? Whew! I wish I could get pictures and drawings to upload on this forum, haven't figured that out either! Okay let the hazing ritual begin.Last edited by Tooth; 03-21-2016 at 09:53 PM.
Reply:I'm sorry but last night I got this all done (the question ) NOT trailer  and then I lost it somewhere. Thank You Tooth.
Reply:If you look in the reply box you will see the emotes (smiley face). The next section you will find the "insert image" icon click. Then find the picture you want to display from a file. Now we can see what you are talking about.Easy except finding the file to upload. you can use the older way and do a browse to upload the after you get the location of picture you have to click "upload file".Klutch 220si mig , stick, and dc tigHobart 140 AHP ALPHA 200X 2016Lotos LTP5000DSmith O/P
Reply:So you built like an upside down truss system underneath? I know exactly what you're talking about. Best way to do that is to tack it in the center. heat the strap your bottom strap and work it from the center outward, tacking it on each stand off as you go. The purpose of heating it as you go is to expand the strap so when it cools it'll load it, otherwise your frame will have to flex a fair distance for this system to help. I hope this makes some sense...We're DEFINETLY going to need some pics!!!-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:No I haven't built anything yet on the "bridge effect " bracing, and YES what you describe is exactly what I'm thinking about doing. I didn't think about heating the bottom strap to create tension. I thought about setting the trailer up to arch the frame before welding bottom strap. I think I could do this by securing front of trailer then jack up the center section evenly where the bracing would be added using gravity to "arch" trailer? The tail end of trailer would be supported by jack stands. I haven't did anything yet. I'll try to upload some pictures later. Thank You for Your advice. Thank You again, Tooth
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Reply:Originally Posted by Tooth
Reply:In welding quantity doesn't necessarily equal quality. I agree w/ Zap in that the weld he quoted looks awfully cold.                               MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Yeah that was my first one I'll post some pictures of the ones I'm able to do now living and learning
Reply:What about the other stuff anything good or is it all
Reply:You are welding cold And putting Points on the diamond fishplates.
Reply:Originally Posted by Tooth
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Reply:Well I bought the camper for $100.00 at a salvage yard, had a small leak in roof (no black mold) fixed it. I don't like it on My truck if it would have messed up My truck I would have pushed it off into the burn pile! No I don't really like the bright red paint but do enjoy the truck. We were on a trip to the Easyrider Rodeo in Chillicothe, OH. That's why I'm building this gooseneck trailer, put camper on front Jeep or a side by side on back take to camp site drop it camp it. The Jeep had broke down and we had to pack up truck to go get parts, sucked forgot to plug in camper taillights. I'm from Michigan and rodeo was in Ohio I don't blame those Buckeyes for hating us Wolverines especially the ones that have NO TAILIGHTS! I could take this to Trucks Gone Wild in Hale, MI. drop it at my campsite come back in a couple of days and party like there's no tomorrow.
Reply:Yeah that's what happens when you find out your going Thursday night leaving Saturday morning and you load it on Friday night /early Saturday at 1am after a 14hrs at work and leave at 5am for Ohio. we did that on our return trip it was day light but still had a hangover.
Reply:Not going to beat you up I just want to offer my opinion as if I had that project come into my shop...1) Be sure you grind before you weld on any rust/paint!! These are CRITICAL welds you're making...try to give yourself as much of a chance at success as possible!2) I agree they do look to be definitely on the cold side.3) Your fish plates are awfully small. Attached are some examples of the fish plates I make.4) I would've put the large gusset plate that you use to support the upper portion of the gooseneck on the outside instead of using your two small fish plates.5) I would tend to agree with what DSW has stated in your other thread. I'm not necessarily convinced you need one either. If it were me I'd use a much longer fish plate instead. It'll allow more flex.What are you using for a wirefeed welder?Another note. (not saying you're stupid just want to make sure you're aware)Anywhere you but weld 2 pieces of material bevel the ends to a point to be sure you're getting full penetration. Then grind it down flat before installing your fish plate.Good Luck!!-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:Originally Posted by Tooth
Reply:I'm using a Lincoln 180C 220V Mig with .35 wire 75/25 Argon shielding gas wire speed set at 4 voltage set at "H" ( lowest voltage being "A" and highest voltage being "I" Max) in other words one notch below "MAX"  by the way Thank You for the advice
Reply:I'm sure the nuns will have a lawyer that will sue me for everything including my first born child, it's the American way money fixes everything! Yes it's turned into a "throwaway society " and I'll buy one that is better than my neighbors ( that'll teach him to respect me) because I'm better then him. Nobody builds anything anymore they just sit on the couch, drink mt dew, smoke dope, play video games, and whine to their mom because she didn't wash their clothes! Oh and I'm sure you'll be the star witness for the nuns, that way you're sure to get in the BIG house above.......
Reply:Tooth, I'm proud that you ventured into a site that is so very negative about home built trailers....I got my own trailer build going on but will never post pics of it here...............anyway, the ZAP is correct that the weaving weld you posted pic of is way too cold, PLUS it was performed on rusty old steel you did not grind clean....I know you now know this now and I'm still looking forward to all of your build.You have decided to take on an ambitious project and folks here will chew chunks out of your butt, but hang in there and allow good suggestions to get thru.Tooth, you need a hotter welding machine...The 180 can't do what you are attempting....borrow a 250 amp machine and grind weldment areas really clean, then burn them deeply.Or simply stick weld that thang...YOU CAN DO IT!Last edited by wornoutoldwelder; 03-23-2016 at 06:44 AM.
Reply:I'd have to disagree Wornoutwelder. Typically trailers never have anything thicker than 1/4" on them and that 180 with hardwire should be capable of that. However, It'd have to be maxed out, and obviously everything ground clean, even mill scale. Also everything appropriately beveled. It goes without saying a 250 would be more ideal though.I also prefer to use smaller wire in smaller welders. I'd be using .030 instead of .035. Then crank it up and really burn it in.IMHO of course though...-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:Well I did grind every piece of steel welded, The trailer is painted a type of primer, and welds have been exposed to weather (not by choice) kind of hard to paint at 7 degrees out side and these are 2nd passes root passes did penetrate. I'm NO professional for sure, but I do appreciate the advice of smaller wire I will try it, Thank You ToothNo problem. Glad to help! I run .024 wire in my little HH 140 it's amazing how well it welds with a little machine cranked all the way up verses .030-.035.-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:go buy yourself some dualshield flux core welding wire works awsome really penetrates deep especially after grove it out and clean it upU.S. Combat Veteran O.I.F. II 2003-2005Airco Dipstick 160Airco Bumblebee 300Lincoln IdealarcAirco Mighty Mite 3
Reply:I have a spool that came with my welder when it was new, but never tried it. now I have a reason to. Thank You for the recommendations Tooth
Reply:The Fluxcore wire that came with the machine is NOT dualshield. Dualshield is designed to use not only the flux in the wire, but a shielding gas as well (gas used varies based on what dualshield you have). Two totally different things. You can't simply add gas to normal fluxcore to get dualshield, or use dualshield without the shielding gas.Also most machines that come with standard fluxcore wire don't really have the power to run dualshield. It takes a machine with pretty good output to run dualshield. You are looking at machines typically in the 250 amp or better category, not smaller home hobby machines. 200 amp class machines are borderline at best with dualshield..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Flux Core wire (Not Dual Core) on smaller welders (<200amp) for anything structural is the only way to go if you have to use a smaller welder.  I assume you're welding outdoors so there's a very good chance your shielding gas is never truly doing a good job of protecting the weld.    Not one person is going to see these welds once your project is done.  I suggest you watch a good 5-10 mins of FluxCore welding videos each time before you weld to train your eye to see what the "puddle" and edges of the metal look like with a good weld, that way you'll have a mental image fresh as you pull down your hood.  Oh... and don't forget to set up your polarity correctly!!  If you can't get good penetration, then it's time to step up to a better welder, simple as that.Good luckLast edited by Capstone; 03-25-2016 at 08:04 AM.
Reply:Looks to be 5" channel?  Too small for the clear span.The fishplate is too short.  It should be around 3x the channel depth before the taper starts. For 5" channel....it should be around 15" long, then tapered....something like 23-24" OAL.  Don't cut fishplates to a point, square/round the tips.The splice doesn't have a coverplate on the flanges.  Your flanges do the work, not the web.The weight distribution is wrong.  Your tongue weight is too high.  Should be about 15% of empty weight/gross weightSplice is too close to the max deflection point on the clearspan.  Because of the fishplate, (and the coverplate you forgot), this is a very rigid area.  The splice is precisely plonked down in an area that needs to flex.Just my opinion, and probably at odds with a lot of other folks.Lose the wire welder, and pick up a stick machine for this kind of stuff."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Did a quick static beam analysis for ya.7000GVW trailer will possibly encounter a point load (in the middle of the beam).  The load is distributed between the two frame rails, thus each rail might encounter a 3500# load.MIDPOINT LOAD ON A 14' BEAM C5 6.7More realistically.......the load will hopefully be distributed along the length of the beam.DISTRIBUTED LOAD ON A 14' BEAM C5 6.7I've left the gooseneck out of the equation, mainly because it's different material.  The thinner section is what we're focusing on.  Not a perfect model, but gives an indication of the dynamics.  Speaking of dynamics.......this is A STATIC LOAD, not a live load, such as is encountered when rolling over a road.  Impacts increase the load factors"Any day above ground is a good day"http://www.farmersamm.com/
Reply:When we add the gooseneck, the equation changes.  It gets worse.Although the gooseneck is built out of (thicker?) material, I'm using C5 properties for the entire length of around 19'POINT LOAD, 19 FOOT BEAM, C5 6.7DISTRIBUTED LOAD, 19 FOOT BEAM, C5 6.7Obviously, you're not gonna change it at this point, but it does give you some intuition as to its weakness.  This should be a guide as to how to load it.  Keep the weight close to the trailer axles."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammWhen we add the gooseneck, the equation changes.  It gets worse.Although the gooseneck is built out of (thicker?) material, I'm using C5 properties for the entire length of around 19'POINT LOAD, 19 FOOT BEAM, C5 6.7DISTRIBUTED LOAD, 19 FOOT BEAM, C5 6.7Obviously, you're not gonna change it at this point, but it does give you some intuition as to its weakness.  This should be a guide as to how to load it.  Keep the weight close to the trailer axles.
Reply:C6 would bring you down to a 22K bending stress.  C7 would bring you down to a 16K bending stress.  I dunno if C7 is available in that neck of the woods.  We jump to 8 from 6 around here.C7 would be ideal."Bridging" as you, and the OP, should be aware,,,,,is actually a truss/strongback arrangement.  For this application, I don' t believe it's viable unless the existing channel has diaphrams installed inside the open "C" to keep the flange from possibly rolling in on itself.  As drawn, the "bridging" isn't workable because it has to rest on a surface that's resistant to axial twist.  Channel isn't resistant to twist under a truss load as drawn.You could do the strongback, with the diaphrams, but it's a lot of welding.Easiest method, other than cutting out the 5" channel, and replacing it with deeper channel, is to simply add a piece of 3" channel underneath the existing channel, with blocking to keep it from buckling.  Blocking doesn't have to be some BS full width crap, just has to be 45 degree angle gussets tied to the existing crossmembers.Just in passing......C6 would have been fine if the axles were further forward to reduce the clear span.  Providing we're still talking a 7000GVW trailer.  Not something loaded to the modified axle capacity."Any day above ground is a good day"http://www.farmersamm.com/
Reply:I've never seen a bridged trailer with anything to keep the channel from rolling and since he already has full height crossmembers to keep the channel from rolling I don't see the need. The 3" channel under would work too as long as it is held vertical. No reason at this point and for his intended use to change out materials now tho.Last edited by welderj; 03-25-2016 at 05:59 PM.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw