steel grade

[alga]

Originally Posted by mark

You would think that the book lists a certain type of steel for a reason, if it didnt matter the book would probably say that you could use either.

But it doesn't! The book just says "Rectangular hollow sections: 25 x 25 mm square 16swg" (page 30), then it goes on suggesting having a look in the offcut piles of fab shops, and you can't be sure of the grade of steel you find in the skip! The recommendation to use ERW appeared on this forum, as these tubes are cleaner and more precise.

All I could get here in Lithuania was black tubes, albeit of the correct thickness (1.5 nominal, about 1.7 measured). I got a habit of using cotton gloves when handling steel. I went over each length with an emery sponge and a rag, wiping off the occasional surface rust and the loose black oxides. Then on it was quite workable. On the upside, the square section tubes for the whole chassis cost me only 33 quid!