retics4me
New member
If I use 2x4 can I get away with using 11 gauge? 3/16 Would be overkill dont you think?
Another frame Material question
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EnglishBob
Well-known member
.120 is the size i use
Bob
Bob
Not to HIJACK, just curious, but does anyone know of a listing on the net (or otherwise) of general square tube load, strength, and deflection ratings? Seems like something like that would be very helpful on a site like this. May save someone some serious headaches down the road.
Thunder1
Well-known member
I'm not an engineer but maybe your looking for something similar to this site? This is a private company's website but maybe it will give some general ideas?
http://www.onlinemetals.com/steelguide.cfm
I believe that the ASTM provides the standard for the different types of steel available?
Bonehead would likely know a whole lot more about this than me.
Any thoughts Bonehead?
Anyway, I hope this helps,
Thunder1
http://www.onlinemetals.com/steelguide.cfm
I believe that the ASTM provides the standard for the different types of steel available?
Bonehead would likely know a whole lot more about this than me.
Any thoughts Bonehead?
Anyway, I hope this helps,
Thunder1
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moronthethrottle
Cross Member
AISC Steel Construction
It just so happens I'm sitting around a bunch of engineers with books full of funny letters, numbers & such. Unfortunately, the Ninth Edition (or green version as they call it) only goes down to 3/16" for 4x2 & 3x2 tubing. The Z value is deflection, which is what we are probably most interested in.
4x2x3/16 the Y-Y axis (4") of the tube Z = 1.52 in.3 section modulus
3x2x3/16 the Y-Y axis (3") of the tube Z = 1.18 in.3 section modulus
No, I'm not 100% sure what that means either
, but you asked!
There has to be another book around here with 11 gage/.1196 to compare to. Maybe I'll put a call in to a couple of structural engineers. The only way to answer questions of required strength is to know what length the tube is, other forces acting on (like what a FEA study can show) and other specifics. I don't want to copy the page out of the book for copyright infringement purposes, but I could throw together an excel sheet with some info on it to help clear things up a bit. Look for somthing tomorrow, if you're interested.
OK Bonehead...now that everyone is thoroughly confused, you can bat clean-up.
It just so happens I'm sitting around a bunch of engineers with books full of funny letters, numbers & such. Unfortunately, the Ninth Edition (or green version as they call it) only goes down to 3/16" for 4x2 & 3x2 tubing. The Z value is deflection, which is what we are probably most interested in.
4x2x3/16 the Y-Y axis (4") of the tube Z = 1.52 in.3 section modulus
3x2x3/16 the Y-Y axis (3") of the tube Z = 1.18 in.3 section modulus
No, I'm not 100% sure what that means either
, but you asked!There has to be another book around here with 11 gage/.1196 to compare to. Maybe I'll put a call in to a couple of structural engineers. The only way to answer questions of required strength is to know what length the tube is, other forces acting on (like what a FEA study can show) and other specifics. I don't want to copy the page out of the book for copyright infringement purposes, but I could throw together an excel sheet with some info on it to help clear things up a bit. Look for somthing tomorrow, if you're interested.
OK Bonehead...now that everyone is thoroughly confused, you can bat clean-up.
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Bonehead
Skull Master
Hey, I am not an engineer. I am what they call a shade tree engineer. I used to build bridges years ago and was up on I beam info. That info left unused has long since been forgotten. However, I would not use 11 ga. 3/16 is not overkill. 10 gauge is just under 3/16ths, but then again, it depends on what engine, tranny, and body are going on this. Also wheel base, and frame design. The loads on a bounce centered between the wheel base could be enough to rip the tubing. Usually next to a weld for a crossmember. Inside where it is hard to see until it gets bad enough to sag into the train tracks you are crossing. ouch!
The shade tree engineer always says, " more is better", "over build, and you will never worry about it."
I have a little book around here somewhere, I'll see if I can find some numbers.
The shade tree engineer always says, " more is better", "over build, and you will never worry about it."
I have a little book around here somewhere, I'll see if I can find some numbers.
Gearhead10
Well-known member
Moronthethrottle and I were discusing this at Christmas. I am wanting to build a frame for the IH out of tube but was wonderin about all that info also. I really like 2x3 tubing 3/16 wall and I've seen alot of 2x4 tubing used as frame material. We were talkin about the flex issue, wall thickness, k-members and gussets in the frame. We used to build stock car chassis together so there is alot of knowlege there. To build a frame from scratch takes a litte bit of knowlege of the material your gonna use and to make it safe .
moronthethrottle
Cross Member
Deflection of tubing
Bonehead, you hit the nail on the head. Your background serves you well. I used to weld on conveyor truss frames with a guy who was a certified bridge welder. Valuable experience! Now I am in the engineering side of bulk material handling conveyors for aggregate, coal, etc., but am also not an engineer.
As far as actual tubing strength-below are some numbers that are much simpler to understand. I have used 2000 lbs as a point loading for the tube, keep in mind that our vehicles will probably have only 1000 lbs max dead load on each frame rail. I used 2000 to compensate for some of the live load that will be applied by engine torque, road vibration, etc. actual loads may indeed by higher with severe bouncing and other stresses that we are all capable of putting on a frame!
A 3x2x3/16" rect tube that is 96" long will deflect .427" @ 2000# load; or .2135" @ 1000# load (half).
A 4x2x3/16" rect tube that is 96" long will deflect .205" @ 2000# load; or .1025" @ 1000# load (half).
That being said, let's clear up some assumptions...if the tube is shorter, the deflection will be less. The "American Institute of Steel Construction" handbook does not give "I" values for 11 gage, so I am not able to show the difference in deflection between the two. Let's look at it another way, a racing rule of thumb that we lived by was that for 10 lbs of weight it took another 1 hp to make up the difference. If that is true and 16' of 4x2x3/16 = 110 lbs, vs. 16' of 3x2x11gage = 60 lbs, then we need only 5hp to make up for the 50 additional pounds of weight. From what I've seen here, we are all capable of producing enough horsepower!!
Ultimately, "when in doubt, build it stout" is the safest way to protect you and your investment.
Another rule of thumb that I thought might be valuable to some of you-when cutting away a portion of structural material, it is necessary to replace that material with an equivalant amount of area. Example: if you cut away 1" x 1" you need to weld a 1" x 1" piece of the same thickness material around the cutout to compensate for the loss of strength.
Sorry this is such a long post, but I've seen my share of wrecked street cars, race cars and conveyors that have hit the ground to want to warn y'all that safety should always come first!
If you have any other specific engineering related questions, shoot them my way and I can have my group of engineers give some sort of answer. Also, thanks Namboo-my Indian engineer for doing the calculations shown above!!
Bonehead, you hit the nail on the head. Your background serves you well. I used to weld on conveyor truss frames with a guy who was a certified bridge welder. Valuable experience! Now I am in the engineering side of bulk material handling conveyors for aggregate, coal, etc., but am also not an engineer.
As far as actual tubing strength-below are some numbers that are much simpler to understand. I have used 2000 lbs as a point loading for the tube, keep in mind that our vehicles will probably have only 1000 lbs max dead load on each frame rail. I used 2000 to compensate for some of the live load that will be applied by engine torque, road vibration, etc. actual loads may indeed by higher with severe bouncing and other stresses that we are all capable of putting on a frame!
A 3x2x3/16" rect tube that is 96" long will deflect .427" @ 2000# load; or .2135" @ 1000# load (half).
A 4x2x3/16" rect tube that is 96" long will deflect .205" @ 2000# load; or .1025" @ 1000# load (half).
That being said, let's clear up some assumptions...if the tube is shorter, the deflection will be less. The "American Institute of Steel Construction" handbook does not give "I" values for 11 gage, so I am not able to show the difference in deflection between the two. Let's look at it another way, a racing rule of thumb that we lived by was that for 10 lbs of weight it took another 1 hp to make up the difference. If that is true and 16' of 4x2x3/16 = 110 lbs, vs. 16' of 3x2x11gage = 60 lbs, then we need only 5hp to make up for the 50 additional pounds of weight. From what I've seen here, we are all capable of producing enough horsepower!!
Ultimately, "when in doubt, build it stout" is the safest way to protect you and your investment.
Another rule of thumb that I thought might be valuable to some of you-when cutting away a portion of structural material, it is necessary to replace that material with an equivalant amount of area. Example: if you cut away 1" x 1" you need to weld a 1" x 1" piece of the same thickness material around the cutout to compensate for the loss of strength.
Sorry this is such a long post, but I've seen my share of wrecked street cars, race cars and conveyors that have hit the ground to want to warn y'all that safety should always come first!
If you have any other specific engineering related questions, shoot them my way and I can have my group of engineers give some sort of answer. Also, thanks Namboo-my Indian engineer for doing the calculations shown above!!
Bonehead
Skull Master
Good, and interesting info. Thanks.
retics4me
New member
Thanks Guys 2x4 3/16s it is .
Super info Moronthethrottle! That right there says it all as to why 3x2 is not a good choice.
Well, I have one more question if it's not too much trouble. How thick of wall 3x2 would be needed to match (roughly) a 4x2x3/16ths tube?
Well, I have one more question if it's not too much trouble. How thick of wall 3x2 would be needed to match (roughly) a 4x2x3/16ths tube?
moronthethrottle
Cross Member
tubing equivalents
Excellent question Sam...I wanted to post something that would give a fair comparison between the two, but the AISC book only lists 3x2x3/16 and 1/4".
The 3x2x1/4" wall tube has an I value of 2.21 as opposed to 4x2x3/16 @ 3.87. So any further results must be made on assumptions. My Ryerson stock steel catalog lists 3x2x5/16 as a possibility for purchase, but that too is only a 2.5891 I value (according to some nifty AutoCAD tricks). I haven't been able to locate anyone making tubing thicker than that. I can say that 3 1/2" x 2 1/2" x 1/4" is slightly stronger than 4x2x3/16. Also a 3x3x5/16" square tube is nearly as strong as a 4x2x3/16.
Another "properties of steel" note to keep in the back of your head: The tubing we are talking about is A500, that is it has a 50 ksi strength value. Which means that it's tolerance is up to 50,000 pounds per square inch. This is significant when comparing it to "ugly iron" like channel, angle, beam, etc. These structural shapes are only A36, or 36,000 ksi. After running into some troubles (below) we did learn that most structural shapes are actually formed to nearly 50ksi, but the mill certificates will not reflect that as they are only 36,000 tested. Long story shortened, try to avoid channel iron when dealing with structural members that are to be exposed to extreme stresses.
This is what happens to 6x6x5/16 angle when it is over stressed...
Excellent question Sam...I wanted to post something that would give a fair comparison between the two, but the AISC book only lists 3x2x3/16 and 1/4".
The 3x2x1/4" wall tube has an I value of 2.21 as opposed to 4x2x3/16 @ 3.87. So any further results must be made on assumptions. My Ryerson stock steel catalog lists 3x2x5/16 as a possibility for purchase, but that too is only a 2.5891 I value (according to some nifty AutoCAD tricks). I haven't been able to locate anyone making tubing thicker than that. I can say that 3 1/2" x 2 1/2" x 1/4" is slightly stronger than 4x2x3/16. Also a 3x3x5/16" square tube is nearly as strong as a 4x2x3/16.
Another "properties of steel" note to keep in the back of your head: The tubing we are talking about is A500, that is it has a 50 ksi strength value. Which means that it's tolerance is up to 50,000 pounds per square inch. This is significant when comparing it to "ugly iron" like channel, angle, beam, etc. These structural shapes are only A36, or 36,000 ksi. After running into some troubles (below) we did learn that most structural shapes are actually formed to nearly 50ksi, but the mill certificates will not reflect that as they are only 36,000 tested. Long story shortened, try to avoid channel iron when dealing with structural members that are to be exposed to extreme stresses.
This is what happens to 6x6x5/16 angle when it is over stressed...
Based on this I'm going to assume it would take something like a 3/8" wall 3x2 to replace 3/16" 4x2! Bet that would cost ya if you can find it. Might as well run 2 3x2's per side. Either way, it seems like a lot of $ or work just to have a shorter (height) rail.
Thanks again for the excellent info. If anyone asks again about what to use for frame rail, we have a thread to link to.
ratterman
Well-known member
would using 1/4 inch wall 2x4 be way over kill? i bought a new 20 foot piece of it at and auction for 75 dollars. planning on using my 220 volt hobart mig to weld up a frame for my rat out of it.
should i switch to 3/16 to save weight or just use my 1/4 inch wall? this will be my first frame build.
should i switch to 3/16 to save weight or just use my 1/4 inch wall? this will be my first frame build.
moronthethrottle
Cross Member
1/4" is more than required imo, but if you have it, use it. Your 220 Hobart should have no troubles filling a good beveled seam. Don't be afraid to make a double or triple pass weld if you think the groove is too deep-brush out your root pass before laying your second bead. Be mindful of your duty cycle (6:4 on yours I think), you don't want to fry your rectifier!
I personally don't believe that anyone using 11 gage is in any sort of danger of damaging their frame. The unsupported distances are usually pretty short on our rods and it is still stronger than the formed OEM frame. Don't be over-influenced by engineering numbers...I've found that the numbers typically create an over-built situation.
My gut feeling is that a typical rat with only a body & maybe fenders can be safely done out of 3x2x3/16". For a '40's or later truck I would lean toward a 4x2x3/16" frame-they are typically longer and heavier. JMO!! I also believe that personal testimonies on RRR can best attest for tubing member sizing...check around with people who have built a similar model to your project and see how it is holding up.
I personally don't believe that anyone using 11 gage is in any sort of danger of damaging their frame. The unsupported distances are usually pretty short on our rods and it is still stronger than the formed OEM frame. Don't be over-influenced by engineering numbers...I've found that the numbers typically create an over-built situation.
My gut feeling is that a typical rat with only a body & maybe fenders can be safely done out of 3x2x3/16". For a '40's or later truck I would lean toward a 4x2x3/16" frame-they are typically longer and heavier. JMO!! I also believe that personal testimonies on RRR can best attest for tubing member sizing...check around with people who have built a similar model to your project and see how it is holding up.
Here is a testimonial on the bad side. lil bounce in the frame ? In short he used 3x2x3/16 and has deflection and bounce.
goose-em
Well-known member
I guess i will chime in here. I am using .120 x 2 x 4 tube for my chassis. Prior to doing so I designed the chassis in Solid Works and then ran FEA on it. I also calculated the deflection and found that for my chassis this type/size of tube is more than needed with a safety factor of 5.
I am not however using this material for the entire chassis. I am only using it for the rear section behind the cab. I did not run any numbers for the rest of the chassis as I am using a highly modified original.
I would guess that .120 2 x 4 could be used but it would have enough deflection and would cause the car to bounce as stated above.
I am not however using this material for the entire chassis. I am only using it for the rear section behind the cab. I did not run any numbers for the rest of the chassis as I am using a highly modified original.
I would guess that .120 2 x 4 could be used but it would have enough deflection and would cause the car to bounce as stated above.
