Landracing Forum
Tech Information => Technical Discussion => Topic started by: willieworld on February 06, 2010, 12:50:34 AM
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JD mentioned in another thread that z-ed frames ( rectangular ) were also butt welded---i discovered this method way back hope it helps someone-----the first Z is how i usually see it done --the second one i think is better it has more weld area --- both angles in both examples are the same---the tubing is 2 X 4 .120 wall --------------well judge for yourself --------willie buchta
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more pics
willie buchta
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I agree Willie. If one was to plate the end of the square cut tube before putting it in the joint you'd probably have the ultimate in strength you could achieve without using internal or external plates.
Pete
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With either method of cuts, would external plates be advised or required for tech inspection ?
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It would probably depend on the organization and the inspectors. I've always used gusset plates on that type of structure whether it be on race cars of various types or on trailers.
Pete
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Just for "extra strength" I would use diamond shaped gusset plates, or some sort of gusset plate.
Here is an example.
(http://i261.photobucket.com/albums/ii43/cajunkid5690/IMG_0393.jpg)
Charles
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O K you two this is for you---i dont like plates on the outside they always seem to get in the way later ---so i did a plate on the inside --its pretty simple and the pics will probably explain it better than me---i know i only did one side and if you wanted you could do both sides---just remember if you dont have the welding skills but have a welder do the fab work tack it all together and get a good welder (weldor) to weld it together happy motoring willie buchta
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a few more pics
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You continue to do nice work Willie. :-D :-D :cheers: :cheers:
Pete
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Question for all????
I like the idea of th plate being on the inside, however is it as strong as one that is welded on the surface? I see a surface welded plate being stronger due to the complete edges being welded versus 8 spot welds.
Scott
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Question for all????
I like the idea of th plate being on the inside, however is it as strong as one that is welded on the surface? I see a surface welded plate being stronger due to the complete edges being welded versus 8 spot welds.
Scott
Generally not and mostly for the reason you suspect. But it is stronger than no plate.
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scott in the first example the tubes are cut at a 22 1/2 degree angle which will make a 45 degree bend angle---with 2 X 4 X .120 tube a butt weld should be enough ( especially with a full role cage tied in ) if it isnt then perhaps your welding skills need some work---the second example is the same overall angle 45 degrees --the tubes are cut different one is 90 degrees the other is an L cut---in the first example to weld it together will need 12 inches of weld in the second example it will take 16 inches of weld thats 30 precent more--even without the extra weld the 90 L is much stronger ---the third example inside plates is probably overkill --- everyone should be the judge for there own safety regardless of what tech wants ---and those are rosette welds not spot welds and if done properly will probably hold everything together by themselves ---next time you are under your truck take a close look at where the axle tubes connect to the center section---just my 2 ยข cant wait to see your new frame---------------willie buchta
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here is one more option then im on to the diamond outside plate then the piece of railroad track LOL ---this is just a piece cut from a piece of 2 by 2 X .120 scrap ---thanks everyone willie buchta
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Nice.
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I like Willie's method of cutting and fitting the rectangular tube together, but to add strenght to this joint in bending the addition of either internal or external plates on what is the "web" section of the beam is not very effective. It does strengthen the beam considerabily for side loads but we are usually more concerned with the vertical bending loads and I would think that the best method would be the addition of a diamond shaped doubler plate added to the top of the tube and spanning the weld joint. This increases the moment of inertia thru the joint which makes much stronger. The addition of the side plates also increases the moment of inertia of the section but not nearly as much as a plate on the top. The addition of the lower gusset also does a great job of increasing the moment of inertia of the tube thru the joint and this gusset along with the addition of a diamond shape plate spaning the top weld joint would easily make the tube joint many times stronger than the tube itself.
Rex
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rex i used to build stretch wheelbase trucks and with a dump bed pivoting off the back of the frame an overload would bend the frame--the cure was to stitch weld a strap along the top of the frame from the cab to the end of the frame no more problem---in the last few posts i was trying to show how to keep the frame strong yet not make it look like an old dump truck frame --hope i gave someone out there a something to think about ----you are right though sometimes strongest isnt always the nicest looking--willie buchta
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Willie, Keep the posts up. They are very informative. Tony :cheers: