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Old 05-19-2010, 08:53 AM   #1 (permalink)

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Default What size tube for my buggy?

I am collecting parts and tools for a new build. Single seat 80- 100 HP. A friend has loaned me a JD-2 bender with 1.75" die. I am considering buying a 1.5" die and using .065 tube (not DOM). I will TIG all my welds and will get good tight joints first. Is this going to be strong enough? What is the best size x thickness for weight / strength? Assuming enough bracing in critical areas.
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Old 05-19-2010, 12:58 PM   #2 (permalink)

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Default Re: What size tube for my buggy?

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Originally Posted by Duane View Post
I am collecting parts and tools for a new build. Single seat 80- 100 HP. A friend has loaned me a JD-2 bender with 1.75" die. I am considering buying a 1.5" die and using .065 tube (not DOM). I will TIG all my welds and will get good tight joints first. Is this going to be strong enough? What is the best size x thickness for weight / strength? Assuming enough bracing in critical areas.
Seems like 065 is a little thin for a high horsepower/high speed capable buggy. If you are not using DOM, why not go up at least to 095 and be safer. I would also think .120 on the main hoop as a minimum for durability and safety. Thats sort of the direction I am going on my first build and have not found any hard fast numbers published, so I am taking the stuff that I can find, and adding one size in thickness to offset my lack of knowledge and welding skills. Just my .02, and you wont gain too much weight if you do it that way.

Last edited by Rbeckett; 05-19-2010 at 01:01 PM.. Reason: After thought
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Old 05-19-2010, 04:31 PM   #3 (permalink)

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Default Re: What size tube for my buggy?

1.5 x .065 would certainly be sufficient for a single seat buggy, as long as you don't have huge unsupported spans of tubing and have proper triangulation. I could see using .095 for the main roll hoop and lower frame cross members just to increase strength and dent resistance in those areas. The only other issue is that it may be tricky to bend 1.5 x .065 in a tight radius without it kinking a little, but as I haven't actually done it I can't say for sure.

Most of my buggy is 1.25 x .058 chromoly and it is 70 hp and I'm not worried about it lacking in the safety department, but it's also somewhat small (Honda Pilot size). I did add gussets to the roll cage corners just to spread the load in those areas and prevent failures of the heat affected zone. But if I ever build another one, I would increase the tubing size.
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Old 05-19-2010, 05:03 PM   #4 (permalink)

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Default Re: What size tube for my buggy?

i totally agree with Rbeckett
IMHO .065 mild steel is denting and crushing very easy .... keep in mind tubing is only strong as long as it is uniform; dent it and it will fail right there.
mounting high stressed tabs (like engine, suspension, ...) to a .065" tube is very difficult... you need tabs with large webbing to spread the stress-load over a wide area...

i personally think 1.75 x .095 (DOM) is the best compromise between strength vs weight vs joint/welding area (for a fullsize buggy)....
for a mini/midi i would use 1.5 x .095 for the cage with 1.5 x .120 lower main rails and 1 x .095 for webbing... preferable DOM for its higher strength and uniform.
you could do some of the webbing with .083 ... but IMHO the weight saving is minimal ... and welding same wall thickness tubing to each other is a lot easier if your a novice welder
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Old 05-19-2010, 06:06 PM   #5 (permalink)

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Default Re: What size tube for my buggy?

Why not use the 1.75 Die and save yourself a few bucks from the beginning? You didn't say what the Cl of the die is, but that might play into what thickness tubing you use also......
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Old 05-19-2010, 06:10 PM   #6 (permalink)

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Default Re: What size tube for my buggy?

Thanks, you guys. My supplier tells me that DOM in small orders is a least double the price of mild steel tube. This buggy will be a toy for mountain property I have access to. It has lots of graded dirt roads with no traffic. I don't see it going over 40 mph there. So the .095/.120 mild steel seems a good choice for me. My welding skills are good as I was certified in the 80's for all position MIG and stick. Check out the album I posted in my profile page. That project was so much fun to build that I must go bigger and faster. Soon I will post a thread about motor choices for torque in low end.
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Old 05-19-2010, 06:18 PM   #7 (permalink)

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Default Re: What size tube for my buggy?

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Why not use the 1.75 Die and save yourself a few bucks from the beginning? You didn't say what the Cl of the die is, but that might play into what thickness tubing you use also......
Yeah that is an option. The 1.75" just seems so big in a mini buggy frame of 120" x 48" or less. The guy that loaned me the bender used it for rock crawler stuff.
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