Some advice on an aluminum project

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Hi all,I was asked to build a pair of aluminum car ramps 10 foot long.  Problem is that I am not sure what thickness aluminum would be adequate for this job.  Can someone that has more aluminum experience than I give me some ideas on this?I was thinking 3/8" angle as the main rails  with inverted pieces for the tread wells as in other designs I've seen.  I did a search on the forum for anyone doing similar projects and came across a thread started by serious_lee back in July of 2012.  In the replies was a pair of hinged designs by farmersamm and markfuga.  I like them because they have the support in the center and will use that design.  That solves the problem of the flexing.My other question has to do with the welding process I will use.  I only have a tig welder for aluminum work.  It would seem to me that a wire feeder would be better suited for this project as there are so many joints to weld.  I fear that my quote would have to be much higher than if I could MIG the project.  Anyone have any thoughts on this?  I would hate to have to price myself out of the project but on the other hand I have to charge for my time.If these were all tig welded what time would you say is reasonable to allow for?  I don't do much aluminum fabrication.  My main bread and butter work with aluminum is in the repair end of things (engine blocks, tranny cases, etc. .and small projects so I don't have a good sense of time fabricating larger projects. Anyone?Thanks for any help,TonyLast edited by therrera; 01-31-2013 at 11:18 AM.Reason: For clarity and for more detail.
Reply:Gonna need a lot more info, about design and intended purpose, before we can help.Ian TannerKawasaki KX450 and many other fine tools
Reply:What kind of weight are you crossing it with? My friend has a set that are used to load his Kubota excavator ~8000lb  They are 8' long and 16" wide each one weighs in at roughly 80lb made from U channel  aluminum that's 3" x 1.5" x 1/4"  ladder style with the crossovers every 6".  These ramps don't even flex under his machine. Unsure of the rating on them thoughKind of like these
Reply:Hi and thanks for the replies.  These ramps would be for a Jeep Wrangler weighing in at about 3600 pounds going up into a trailer that is four foot off the ground.The Kubota tractor ramps sounds like a good design too.  I was worried about them flexing too much and liked the idea of having a support in the center but if that design works I could scratch the center support.Thanks,Tony
Reply:Personally I'd look around online first, I have built aluminum ramps and you can probably buy them cheaper more often than build them for hire.  Part of the reason is the commercial ones sometimes use special extruded shapes and are not limited to regular structural shapes like the average guy.
Reply:personally, I don't like the ramps that require a center support, because you don't know what terrain you'll be loadning and unloading on and you can end up loading or unload off camber. A design that minimizes this (single length) is better for my liking. you need to know how the ramps will be stored (under trailer, under vehicle, hinged on the rear of the trailer, etc.), what the max weight needs to be per ramp is (total weight of the ramp, not what it can hold), and how the buyer wants them designed (folding, center support, etc.).I built steel 8' ramps for my trailer that utilize a bowstring design and was told they should hold 3200 lbs each. They weigh less than 40 lbs each and are 14" wide.http://weldingweb.com/vbb/showthread.php?t=59022&page=2 Picture of the ramps in post #46. Not sure if you'd get that kind of load bearing from Ali ramps.There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:Channel would definitely be better than angle. I'd consider 4" channel to be sure they don't bend. You might be surprised the difference between strength required to span 8 feet compared to 10 feet, with the same material and same load the deflection can actually double. MIG would cut the welding time in half, at least. I'd expect to take 4-6 hours TIG welding all those rungs, depending on the design.Ian TannerKawasaki KX450 and many other fine tools
Reply:Thanks again for your feedback.  Client (potential client) has not gotten back to me on this project but its just a matter of time before I get asked again by someone else.  Now I have a sense of how to go about it.I appreciate the help,Tony
Reply:I think I would start with 4" Aluminum channel minimum as well. I have a guy who wants me to build ramps to get his JD350 Bulldozer into the back of his dumpt truck, truck is pretty high so the ramps need to be at least 10 feet to cut down the angle, probably more. They get heavy quick and i don't know if aluminum will do it, Machine is around 11,000. Thing you should watch if comparing is anything on tracks spreads out the load, cars with tires give you more point loading."Si Vis Pacem Para Bellum"Lincoln Idealarc 250 AC/DCMillermatic 251   Syncrowave 300   30A spoolgunLincoln MP210Hypertherm 45(2) LN 25(2) Lincoln Weldanpower 225 CV(4) SA200   1 short hood    SA250    SAM 400