In reply to dculberson:
No thats just where I keep um.
In reply to dculberson:
No thats just where I keep um.
I got a large quantity of DOM tubing for free once from a dumpster at a military base. They were remodeling the building, and filled the roll off dumpster with the tubing, which had been used for steam heat.
Free, and completely race legal.
kreb wrote:dculberson wrote:I am amazed how many people can't be bothered to learn a little craftsmanship - especially when it's a safety item. I once had a well-respected muffler guy do a sidepipe for me. I had better skills that that guy over the course of my first semester in trade school. This guys been welding for 20 years and can't do a nice job.N Sperlo wrote:You can tell what the welds are made of, though! Boogers!No idea what its made of.
Man, I love circle track racing now-a-days but damn alot of the heaps that show up at the track have some questionable welds. Some of the bubbas out there just cannot weld or just don't care. 
I will second or fifth ERW over DOM for price alone in this application. You just need to pay attention to where you put the seams when you bend and form the cage. Alot of drag cages are made of ERW and they seem to hold up fairly well. For any type of on road race track application the rules are pretty straight forward DOM is the way to go.
Ok... what does ERW stand for? DOM I know is drawn-over-mandrel, but is that synonymous with cold-rolled?
Electric resistance welded. It is seamed tubing.
ditchdigger wrote: Electric resistance welded. It is seamed tubing.
So basic mild steel tubing?
In reply to curtis73:
Yup. The same material as DOM, just not worked to remove the seam.
I want to say that I see a surprising difference bending up between DOM and ERW. I now only use DOM, and Moly if it is a nice car. I was very shocked at how my bender works harder with DOM as compared to ERW. I previously thought I would not notice the difference at all.
I am not saying at all that ERW won't do the job, but knowing that DOM is stronger gives me a piece of mind, and I would say helps with resale, Moly even more.
I always end up going much faster than the car was initially intended to go. I don't want to think about the cage and materials.
Roll Bar & Cages - Frequently Asked Questions
Stolen from the interwebz!
Electric Resistance Welded (ERW) Tube
ERW is the most economical and readily available type of mechanical tuning. It is produced by taking a flat bar of steel and rolling it into a tube shape (picture rolling up a newspaper - but without any overlap) and then welding the seam - by, you guessed it - electric resistance - hence the name. Electric resistance welding is somewhat like a long, continuous spot weld. It's often computer controlled and extremely consistent. ERW is normally SAE 1010 (for wall thickness < 16 ga) or SAE 1020. ERW tube comes in 2 flavours:
Hot Rolled ERW (HREW)
HREW is rolled into a tube at elevated temperatures, usually way above room temperature. This produces a tubing that is more malleable and therefore easier to form but that is also not as strong, is supplied covered with scale, and not as uniform in dimension as cold rolled. It is also quite a bit cheaper than cold rolled.
Cold Rolled ERW (CREW)
CREW is manufactured by a process in which a steel bar is rolled into a tube and the seam welded, usually at room temperature. Compared to hot rolled, CREW is stronger - (greater yield strength) - because of the improvement in the crystal lattice structure from improved grain size, shape, and orientation imparted by being worked at cold (room) temperatures), straighter, has a much smoother and more uniform surface finish, and is made to much tighter, more consistent dimensions. It is the best economical choice for tube work, and because of the better surface finish and tighter dimensional tolerances it is much nicer to work with than HREW.
Drawn Over Mandrel (DOM)
Strong and well-finished DOM is an electric resistance welded tube tested for soundness of weld and drawn through a die and over a mandrel. This process imparts significantly improved mechanical properties to the tube, due to the cold working process. It is considered a high quality tube, and is normally constructed from SAE 1020 or 1026 steel. Note that, technically DOM refers to the process by which the tube is finished after having started as an ERW tube. Technically, DOM is not a type of steel tube, but rather a process. As so often happen though - in common use the term has become accepted to mean a specific type of tubing rather than a process. In this case, when people say "DOM" they normally mean an ERW tube drawn over a mandrel at (close to) room temperature and made from SAE 1020 steel. It is normally drawn to O.D. and I.D. dimensions.
DOM isn't THAT expensive for something that is going to be a welded part of the car's structure and will likely be there until it is crushed. That said, if you need to save the money, ERW is fine for a low speed vehicle IMO, but make sure you put the weld seam on the inside of the bends.
In reply to Giant Purple Snorklewacker:
Great stuff, thanks!
Couple steel suppliers in the 'Burgh area.
http://www.alro.com/Locations/Locations_PT.aspx
http://www.glossersteel.com/
I haven't used them yet but was recommended by local roundy- rounder
When you check with steel suppliers, ask if they have any with surface rust at a reduced price. The rust doesn't hurt the strength and you can clean off easily.
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