Tube frame: round or square?
Logistics Pro
Joined: Jan 2002
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From: GANS
I'd use 2x6x1/4" or 2x8x1/4" square tubing for the frame rails. IMHO, tube sucks for the frame itself.. it you look at a good many moonbuggies, they use like 3-5' square tube for the motor mount and passenger space, then tube the rest off..
Senior User
Joined: Oct 2004
Posts: 198
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From: Auburn, OH
Ok, I just checked some numbers. 2"x.12 tube frame is going to bend 2x easier than C6x8.2 (2x4x1/4) in the narrow dirrection and 37x easier in the wide dirrection. but it is 3.38x lighter per unit length. This is if both were of the same material. Now, the round tubing is going to resist twisting better. This also means you can shape it better. The general Idea to building a frame isn't to get one strong peice though. The strongest frame is going to be lighter pieces separated by a distance by tied together well. The roll cage on most baja cars is part of the frame and helps to keep the car from buckling. Ok, I just realized I'm rambling and it's been a long day. I'm going to stop trying to think.
Posting Guru
Joined: Mar 2003
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Read and learn
http://www.pirate4x4.com/tech/billav...0/index1a.html
Fyi, I just bought a production tube chassis. I was thinking of going with HREW(welded seam) but dom was only 200 more for the whole thing and twice as strong in every facet. It should be noted that moly is roughly twice as strong as dom. Pipe is for plumbing and square tube is to hold up your mailbox.
http://www.pirate4x4.com/tech/billav...0/index1a.html
Fyi, I just bought a production tube chassis. I was thinking of going with HREW(welded seam) but dom was only 200 more for the whole thing and twice as strong in every facet. It should be noted that moly is roughly twice as strong as dom. Pipe is for plumbing and square tube is to hold up your mailbox.
Posting Guru
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Originally Posted by bremen242
I'd use 2x6x1/4" or 2x8x1/4" square tubing for the frame rails. IMHO, tube sucks for the frame itself.. it you look at a good many moonbuggies, they use like 3-5' square tube for the motor mount and passenger space, then tube the rest off..
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
> He already has a Miller 251 ... So I am pretty sure these are just as good
> of tools that Nascar would use.
I believe both NASCAR and the NHRA have rules that state that roll cages can not be ARC or MIG welded. I downloaded the rule book from one of those assoc. to read about two years ago and was surprised to see MIG welding excluded. I imagine the rules have not changed that much.
That pretty much leaves something such as TIG welding which costs much more then most of us would be willing to spend. Plus, we do not have machines to X-Ray or flux our welds like a NASCAR shop does.
So that machine (Miller 251) would be no good for NASCAR/NHRA roll cages or a frame since in many classes the roll cage and frame are the same.
So, I stick by this :
I dare to say that a guy welding a NASCAR vehicle has better experience, tools, and materials then any of us could hope to have in our vehicles.
So for us, we have to over build to compensate for our lack of experience, tools, AND money.
> of tools that Nascar would use.
I believe both NASCAR and the NHRA have rules that state that roll cages can not be ARC or MIG welded. I downloaded the rule book from one of those assoc. to read about two years ago and was surprised to see MIG welding excluded. I imagine the rules have not changed that much.
That pretty much leaves something such as TIG welding which costs much more then most of us would be willing to spend. Plus, we do not have machines to X-Ray or flux our welds like a NASCAR shop does.
So that machine (Miller 251) would be no good for NASCAR/NHRA roll cages or a frame since in many classes the roll cage and frame are the same.
So, I stick by this :
I dare to say that a guy welding a NASCAR vehicle has better experience, tools, and materials then any of us could hope to have in our vehicles.
So for us, we have to over build to compensate for our lack of experience, tools, AND money.
Elder User
Joined: Sep 2000
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From: Bay area
http://www.irwindalespeedway.com/sit...pertrucks.html
spend the better part of a hour tonight trying to find something in stone from nascar's website and thier site sucks. NHRA I did not look into very much. This was as close as I could come to finding anything about nascar's actual regulations.
(g) Roll Bars:
(1) Spec part required: full tubular chassis, STI part number: 0303.
(2) Roll cage must be constructed of tubing, 1-3/4 inch x .095 inch minimum.
(3) A minimum of four (4) door bars is required on the both the left and right sides of the truck. All door bars except the bottom door bar must extend into the door skin and be convex. The bottom bar may be straight with a minimum of (3) convex door bars required on each side of truck. The door bars must have a minimum of six (6) vertical supports per side with two (2) equally spaced between each door bar.
(4) The driver’s side door bars must be plated with a steel plate of not less than 1/8-inch material. The minimum size for this plate shall be 24 inches in height and 32 inches in length. The plate may be a single plate or several plates cut and welded into the door bar gaps.
(5) All trucks with steel covering over inside door bars on driver’s side must be padded.
(6) All joints and connections must be welded. It is recommended that welds be certified. Welds should be made by MIG, TIG, or arc welding.
(7) All areas of roll cage near driver and within his/her reach must be padded with approved padding.
(8) It is recommended that the area behind the driver’s seat be plated with 1/8 inch or thicker steel.
(1) Spec part required: full tubular chassis, STI part number: 0303.
(2) Roll cage must be constructed of tubing, 1-3/4 inch x .095 inch minimum.
(3) A minimum of four (4) door bars is required on the both the left and right sides of the truck. All door bars except the bottom door bar must extend into the door skin and be convex. The bottom bar may be straight with a minimum of (3) convex door bars required on each side of truck. The door bars must have a minimum of six (6) vertical supports per side with two (2) equally spaced between each door bar.
(4) The driver’s side door bars must be plated with a steel plate of not less than 1/8-inch material. The minimum size for this plate shall be 24 inches in height and 32 inches in length. The plate may be a single plate or several plates cut and welded into the door bar gaps.
(5) All trucks with steel covering over inside door bars on driver’s side must be padded.
(6) All joints and connections must be welded. It is recommended that welds be certified. Welds should be made by MIG, TIG, or arc welding.
(7) All areas of roll cage near driver and within his/her reach must be padded with approved padding.
(8) It is recommended that the area behind the driver’s seat be plated with 1/8 inch or thicker steel.
spend the better part of a hour tonight trying to find something in stone from nascar's website and thier site sucks. NHRA I did not look into very much. This was as close as I could come to finding anything about nascar's actual regulations.
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Post Fiend
Joined: Dec 2003
Posts: 6,658
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From: "Islander"
Mig,Tig, depends
Rebocardo, around the country many people have a Tig of Mig welder in their garage. You don't have to be a production or frame shop to fabricate a safe legal NHRA frame. I enjoy welding and fab work at home in the shop, a personal satisfaction thing. With a Miller Synchrowave 350, Millermatic 251, lathe and Bridgeport mill i can fabricate many things and i'm not a professional, just a serious hobby nut. Carl.....o&o>........
Logistics Pro
Joined: Jan 2002
Posts: 3,739
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From: GANS
Originally Posted by cwb
Like whose for instance? I think you are looking at tubed chassis on frame. Campbell and Nelson both run moonbuggies with tubed frames.
BTW,
I think the welding confusion comes from if you have chromoly tubing. I think it states that if you use chromoly you have to TIG it.
Posting Guru
Joined: Mar 2003
Posts: 1,311
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From: Quispamsis, N.B, Canada
Square is stronger than round I've heard. At least on Monster Garage they are always using square tubing for strength, and on trucks stacey used square tubing for some cross member peices. Maybe round is strong but it can dent and buckle faster.
Post Fiend
Joined: Sep 2000
Posts: 8,238
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From: Oregon
Originally Posted by moose94
Square is stronger than round I've heard. At least on Monster Garage they are always using square tubing for strength, and on trucks stacey used square tubing for some cross member peices. Maybe round is strong but it can dent and buckle faster.
Lead Driver
Joined: May 2000
Posts: 9,236
Likes: 12
From: Senoia, GA
Originally Posted by Beemer Nut
Rebocardo, around the country many people have a Tig of Mig welder in their garage. You don't have to be a production or frame shop to fabricate a safe legal NHRA frame. I enjoy welding and fab work at home in the shop, a personal satisfaction thing. With a Miller Synchrowave 350, Millermatic 251, lathe and Bridgeport mill i can fabricate many things and i'm not a professional, just a serious hobby nut. Carl.....o&o>........
you have a synchrowave AND a millermatic? geez...i am coming over there to play
.....got any plasmas or other fun play toys?-cutts-
Hotshot
Joined: Dec 2003
Posts: 18,423
Likes: 9
From: iowa
Originally Posted by proeliator
This is why you don't learn fabrication from television. As I mentioned in the second post, given the same materials and dimensions, round tube is stronger than square. Fact, period, end of discussion. For most people, myself included, square stock is easier to fabricate with though, just like 'Stang mentioned.