Mini Chopper Frame Material

[chancer]

I will be building this cart for my kids and I want it to be safe. Firemanjim says PIPE may cause death and damage! The DIY kart plan page mentions using pipe and explains the differences. Rocketkart says above "I just use standard black pipe for my gokart frames. The Machinest@large seems to know about pipe.
Any one have a bad or tragic experience using black pipe on a gokart frame? No offense Jim I have heard somewhere long ago NOT to use pipe, but it seems to come up a lot on this site so I am about to assume it is ok.

Thanks for this site! it is very helpful and inspiring, this is a new hobby for my Family.

 

[OzFab]

Cutting and mitering works well; as long as the wall thickness of your material is "in the range" and you add gussets where necessary you shouldn't have any problems.

Although, Square tube makes it much easier... Just saying

Now, how to fish mouth/ miter round tubing; I'm going to have to admit defeat here and ask one of the others to link the sticky that's somewhere on the site for the tube mitering calculator, the one where you input the dia. of your tube and the angle, and it hands you a printer ready template that you just print, cut out, wrap around your tube (w/ tape) and grind the profile in with an angle grinder.

Here it is

 

[machinist@large]

Wait a minute; I've done that and had no problems!!!!

Pipe is for mechanical transfer of a product. Tubing is for structural strength. DONT build a frame out of black pipe like from home depot (hardware store). It will BREAK when subjected to severe shock or impact. Tubing is designed for the stresses ..... it wil bend,but stay intact, where the black pipe will break and cause damage,death.....
For a chopper frame, use 1&1/4" x .100-.125" steel tube (welded seam is just fine!) for the backbone. For the down leg parts (engine cradle) , 1"x.09" tube...... make your design. Put it on paper how the bends will be. The radius and everything. Then go to a muffler shop and get them to bend the pieces for ya..... If you can, draw out a full scale print so you can actually check shape of parts while you're at the shop.....

Hold up there a second; black pipe is structural, and a great many people, such as my self and my family, as well as many of the other small farms around us (the one left anyways) have built a great many high strength products for our farms using it. I'd provide pictures, but when Dad got out of raising beef, he answered an ad looking for livestock equipment and go good money for the whole lot.

Quality black pipe has identical structural properties as tubing of identical cross section and wall thickness. The only reason it's more of a pain to spec out for this is because the jump from one schedule rating to the next is so big; schedule 80 is almost 3 times the thickness of schedule 40. When the power company for the nearest town decided to remove from service the three oldest diesel gen-sets they had, the company that pulled them out and moved them to their new owners used schedule 80, 120, and 160 pipe up to 10" in diameter to fabricate most of the custom lifting equipment they needed to do the job.

Would black pipe be my first choice for building a kart? Probably not. Will it work just fine if done properly? H*LL yes!!! We've even had a member successfully build a kart out of schedule 40 PVC for crying out loud; the plastic version has way less structural strength that the steel version. Just because you may have never used it doesn't mean it won't work.

Sorry to all about this turning into a rant; it's just that it lights my fuze when I see someone telling someone else that something can't be done when I and many others have done so, and quite successfully at that.

 

[firemanjim]

Hold up there a second; black pipe is structural, and a great many people, such as my self and my family, as well as many of the other small farms around us (the one left anyways) have built a great many high strength products for our farms using it. I'd provide pictures, but when Dad got out of raising beef, he answered an ad looking for livestock equipment and go good money for the whole lot.

Quality black pipe has identical structural properties as tubing of identical cross section and wall thickness. The only reason it's more of a pain to spec out for this is because the jump from one schedule rating to the next is so big; schedule 80 is almost 3 times the thickness of schedule 40. When the power company for the nearest town decided to remove from service the three oldest diesel gen-sets they had, the company that pulled them out and moved them to their new owners used schedule 80, 120, and 160 pipe up to 10" in diameter to fabricate most of the custom lifting equipment they needed to do the job.

Would black pipe be my first choice for building a kart? Probably not. Will it work just fine if done properly? H*LL yes!!! We've even had a member successfully build a kart out of schedule 40 PVC for crying out loud; the plastic version has way less structural strength that the steel version. Just because you may have never used it doesn't mean it won't work.

Sorry to all about this turning into a rant; it's just that it lights my fuze when I see someone telling someone else that something can't be done when I and many others have done so, and quite successfully at that.

Whooaaa...... I never said I DONT use it..... I do not suggest it to build a chopper frame.... That was the original question. I wouldnt want the op to buy n cut a buch of black pipe and then her(?) welding teacher laughs n shrugs his shoulders..... Jesse James uses steel tubing, NOT black pipe from the hardware stores.....
With all that being said, if you look at my build (kart called kricket), you will see that I used 3/4" black pipe for a few short braces. The bumper and all other round stock is .100" wall steel tube. There is a place for everything......

 

[WeldingWoman]

I am happy to report that I have put the order in for my material and will be picking it up tomorrow. Twenty-four feet of round welded steel tubing, 1" with .083 walls. I had to do some real hard thinking over round vs. square tubing, but ended up choosing round for the aesthetics. I will probably hate myself later for that...

Thank you again to everyone who gave me feedback, I really appreciate it! Hope you all don't mind more questions...as I am sure I will come up with many as soon as I begin this fab process.

 

[firemanjim]

Make sure you post some pics..... we LOVE pics.....

 

[OzFab]

I had to do some real hard thinking over round vs. square tubing, but ended up choosing round for the aesthetics. I will probably hate myself later for that...

That's entirely likely, especially since you don't have tube bending equipment. Just as round angles (bends) don't look quite right on square tube, square angles (mitre joins) on round tube look even worse... IMO

Thank you again to everyone who gave me feedback, I really appreciate it! Hope you all don't mind more questions...as I am sure I will come up with many as soon as I begin this fab process.

I thought that's why we were here

Make sure you post some pics..... we LOVE pics.....

That too...

 

[freakincage]

Check out this site for some help with your project. It is for full size choppers, but the plans can easily be scaled down by 3/4 or 1/2. There are many how to's and FREE plans as well (including building a budget bender and frames). I am using this guys site for quite a bit of my build. http://www.chopperhandbook.com

 

[Scout]

A word of warning, don't use a pipe bender (like harbor freight sells) to bend tube. It won't work well.

 

[firemanjim]

A word of warning, don't use a pipe bender (like harbor freight sells) to bend tube. It won't work well.

Mine works pretty good, and from harbour freight. Just need to know how to use it and know how to measure the lengths right so your bend starts and stops at the right places......