Question for the metal guys

Stang

Stang

Member
#1
#1
Starting to think about trying our hand at another custom frame.

Would the following be something that could be used for forks and a frame? I was thinking 1" x .125.

https://www.discountsteel.com/index.cfm/go/main.itemDisplay/itemID/90

It's probably been asked, but I'm feeling lazy with the search button. What are some other recommended materials as far as alloys or types of tubing.

Also, any recommended site to order from online. I found 2 mentioned already in the forums, Discount Steel and Online Metals.
 
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ogygopsis

ogygopsis

#2
#2
Stang....most minibikes use 7/8" x .083 in a mild steel like 1018....it welds up easily and is nice to work with....look for something called DOM....stands for Drawn Over Mandrel....which means it does not have a seam on the inside and is smooth on the inside....the two sources you cited are good....but living in Michigan you should have tons of local places from which to choose....if you're looking for lightweight and strong then 4130 chromoly works well....however, a quick check of the price will cure you of that idea....hope this helps...Ogy.
 
Stang

Stang

Member
#3
#3
yea we got some steel, not sure which alloy it was, from some local metal place, but it was a pretty high price for a small amount.

Is there an aluminum that would be good for a frame or would the strength needed require a very high priced aluminum?
 
N

nORMAN tINKER

New Member
#4
#4
My company sells 1026 dom for 2.88 per ft. That is a .875 x .095 wall. Our 4130 1" x .065 wall goes for 3.50 per ft.. The 4130 is overkill if you ask me. 1018/1026 Dom or Seamless is fine for your application. We don't carry alluminum but I know it trumps steel by a longshot. Good Luck.
 
Oldsalt

Oldsalt

Well-Known Member
#5
#5
Typicaly there's no advantage in useing 4130 for that sort of project. There are numerous reasons for this besides cost. Have seen a few frames in aluminum. Years ago I put one together. If it's your first frame stick with something like .875 [7/8] O.D. steel tube.
 
Stang

Stang

Member
#6
#6
It will be the second, I like to do things that are some what unique or not the norm :)

What aluminum did you use for your old frame?
 
Oldsalt

Oldsalt

Well-Known Member
#7
#7
Stang said:
It will be the second, I like to do things that are some what unique or not the norm :)

What aluminum did you use for your old frame?
Click to expand...
At the time I was working [late 60s] as a welder/fitter for Fruehauf which made a lot of aluminum gas rigs. I highgraded [read stole] all the material so I couldn't tell what the stuff was. Be aware there is more BS and withch craft sited in the selection of weldable grade aluminum than in any other material. Almost any weldable aluminum [which is vertually anything you might find] is OK to use with little or no advantage over another grade that some dumb magazine says is the trick stuff. Within an ace, it's all just straight aluminum. Used a Gilera 202 cc motorcycle engine. The frame had to be made in two pieces, a right and left side that bolted together at the steering head. That was the only way a mini bike sized frame [Taco proportions] could accomodate the wet sump engine. The fuel tank was on the bars. The Delorto carb was higher than the seat. [Ya learned to avoid scooting too far forward on the seat]. I used aluminum only because it looked cool and was really cheap. The 5 or so pounds that was saved in frame weight would have been easier to accomplish by not drinking Pepsi Cola for a month. There ended up being a problem. The mini was built for hard blacktop. I sold it to a ridgerunner [fully aware it was a drag bike] that promply went out in a field and practiced his jumps. The practice sesson was seriously shortened when the aluminum forks failed in a catistropic manner and he fractured his hip. I didn't get to see it. Hopefully he still doesn't still walk with a limp. Stick with steel.
 
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steven Durham

steven Durham

#9
#9
When you go the aluminum route you best know a lot about each type, some do not take to bending very well and then the welding process is more of a specialty and usually more costly.
As for 4130 leave it to the Indy car circuit even N.A.S.C.A.R. does not use it in their frames. I have some 4130 in stock 1 inch .095 and I cant find a justifiable use for it over the normal DOM 1020 .
Steve :scooter:
 
Oldsalt

Oldsalt

Well-Known Member
#10
#10
Just realized I have a picture of an aluminum framed mini. At the Bonneville Speedweek there seems to be an unofficial competition on who has the coolest mini for use as a pit bike. The closest mini in the picture shows how nice an aluminum frame can look. Beautiful design and execution! Remember most of these guys build or work on land speed cars and motocycles. They're all nuts and highly talented.
 
ogygopsis

ogygopsis

#12
#12
GTO said:
Hey, whats wrong with the seemed steel tubing?
Click to expand...
Hey Gote....I did not say there was anything "wrong" with seamed tubing but there are occasions when you'd like to telescope two pieces of tubing in order to strengthen a frame where a crack has occurred. It's the method of repair required by the FAA for repairs to chromoly tube aircraft frames. Impossible to do when there is a seam inside the tubing. Secondly, when tubing has been Drawn Over Mandrel the ID, OD, and Walls are all uniform in dimension and that can't be a bad thing: can it?....Ogy
 
B

briggsscooter

New Member
#15
#15
"4130 chromoly works well.."

Definetely dont want to buy chromoly unless your familiar with its properties and how to weld it. Chromoly usually needs to be preheated before welding or else microscopic stress cracks can occur and spread.
 
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