I know it stands for "Drawn Over Mandrel" but I have always wondered how they do it. If it's extruded how can they keep the bore size within 5 thou. or so?
I don't think it's welded because there is no visible seam......
Interviewed as Plant Manager of a brand-new DOM factory - right near where my ancestor is buried - first settler. 1760's Jane Lew, WBGVA. about.... f**k me... 1974? forty-six years ago?
Our History
It for damned sure IS "welded". From flat sheet. Slit and formed. FAST!
That's the whole POINT!
Just waaaay faster and better than Old Bill over at the local steelyard runs his arc!
And yes, you can find the seam. If you know HOW to "look". Cheap import shite, there is even a blue-black heat line, outside, RUDE f**king raggedy-burr.. on the inside. Some shapes, similar process, (check Big Box squares) yah may draw THROUGH a mandrel (die..) or rollers as final-final rather than just OVER one. Whatever keeps the cost down ... and still
sells ... for cheap office furniture legs and the like.
Jane Lew, WBGVA plant, Pittsburgh Tube, early 1970's "Made in USA"? No such crap. Serious nice goods!
Being used for stuff like HEAVY tandem-axle stone and coal-truck suspension trunnions, printing-press rollers.... So it hadda be right consistent and straight as well as strong.
Yah pay for what yah get..