DOM Vs. HREW

[rebelce]

I am building up a XO/GR and have came to the point where I would like your technical input.   My question is simply, roll cage material, HREW Vs. DOM.  It's my understanding that they are both 1020 steel. Differing only that DOM is work hardened in the process of being drawn into it's final dimensions. Out here on the east coast 1 5/8" X .120 DOM is $9.80 a foot while 1.66 X .140 HREW is 2 bucks.  For that, I could easily add another hoop or two to the cage.  Is DOM mandatory?  Does it matter if the OVERALL strength of the cage is the same?

[Harold Bettes]

The DOM tubing is typically ERW tubing that is drawn over a mandrel and the flash removed internally by the mandrel and the outside by specs. Most ERW has the outside flash removed as well.

IF the alloy is the same, (typically 1020 to 1026), then the mechanical strength is the same. C1018 and C1020 are the most common ERW tubing materials. The DOM stuff doesn't gain you any strength. I sincerely doubt that seamless tubing of the same dimensions and material is of any advantage either when used in cage type construction.

The mechanical strength of C1020 material should be an ultimate yield of 60-65ksi.

IF you use the rulebook as a guidebook for minimums, you will fare well.

At least that is my story and I will stick to it.

Regards to All,
HB2

[Dean Los Angeles]

The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing.

The cold-drawing process creates a uniform, precision product with substantially improved tolerances, surface finish and tensile strength, increased hardness and good machinability. In this process, the tube is cleaned and annealed, and one end of each length is squeezed to a point so it can be gripped by the drawing mechanism. The tube is then drawn through one or more dies and over mandrels (see drawing). This reduces the diameter of the tube and thins its walls to the required dimensions in a controlled fashion to provide the qualities desired in the finished product. Metallurgically, drawing improves the tube's concentricity, tensile strength, hardness and machinability. Close dimensional accuracy is achieved through tight control of both outside and inside diameters.

1020 DOM has a yield strength of 70 ksi and a tensile strength of 60 ksi. 1020 hot rolled has a yield strength 30 ksi and tensile strength 55 ksi.

If you are paying $9.80 a foot for 1020 DOM you need another supplier. Somewhere about half of that, maybe less.

[rebelce]

I've only found one place that would even talk to me about DOM and it was over towards Boston. They had to have it shipped in, hence the price. With only a 5 ksi difference in tensile strength, maybe letting it deform and take some of the shock might be a good thing!

[hitz]

I've only found one place that would even talk to me about DOM and it was over towards Boston. They had to have it shipped in, hence the price. With only a 5 ksi difference in tensile strength, maybe letting it deform and take some of the shock might be a good thing!

  Not if it's the cage around your body!

  Harv

[JackD]

You would do well to call one of the advertisers in the rule book that is in the business of building roll cages and such for LSR.
They will be happy to discuss the materials that are best suited to your needs and abilities.
 At least one of the major material suppliers is nationwide and the builders  can also direct you to a source that is best for your location.
Support those that know what you and they are doing.
 

[bearingburner]

I'm in Western Mass. and just bought 1 1/2 X.120DOM tubing for less than 1/2 the price you were given. I get mine from  street rod/stock car builder. Buy in mill length about 20ft and save cutting charge. I know when I buy flat or angle at a steel shop they charge $6.00 to cut.

[rebelce]

Could you send me their web site or phone #?  I'm just north of Hartford and a little drive, now that the sun is out, would be a good thing!

[RICK]

 I build a few cages a year and keep a couple hundred feet in stock. $9.80 a foot sounds more like 4130, or chrome-moly price. DOM; 1020/1026 1 5/8 x.125 is $4.10 and x.134 is $4.50 afoot. If i buy a 100 foot the price goes down to about $4.00. ERW;  1 5/8x.125 or .134 about $2.30 or $1.90 100 ft. The more I buy the cheaper it gets. And just like gas, the price changes every day, and always seems to be creaping up.
 They are suppose to be the same alloy, but it seems to me that the DOM is just cleaner and welds better. I recomend DOM to all my clients, some choose to try and save a few bucks and go ERW. I would only use 4130 on a drag or race car where weight is a major concern. It work hardens/softens, and needs to be TIG welded.
  I'm in the St. Louis area. I buy most my steel supplys from Shapiro( 1-800-833-1259), Warrenton Steel for rectanglar tube, and Tublar Steel supply, for orders of 1,000 ft. or more.
  Get out the phone book and call them all and ask for $$$. Be sure to tell them how much you need.
Then you need to find a way to bend it and notch it.
 If you still have the phone book out, you might look up fabricators/race car builders. It may be cheaper and quicker.

  Good luck,   RICK