Pro­fes­sor Ham­mer

Shap­ing Curved Run­ning Boards: There are sev­eral ap­proaches for curl­ing the edges

Street Rodder - - Contents - Ron Covell

QI’m mak­ing new curved run­ning boards for my ’35 Ford project from 18-gauge steel, and I’m con­sid­er­ing my op­tions for do­ing the shap­ing. I was think­ing about screw­ing two 2x12 boards to­gether, cut­ting the curved edge with a band­saw, then us­ing a grinder to shape the edge ra­dius, and ham­mer­form­ing my metal over the wood. That would take care of the top, but I’m not sure how to shape the sides. I was think­ing I could make the ra­dius on the top edge with my Pull­max, and then get the curve by us­ing a shrinker and stretcher.

I’m think­ing of us­ing wooden ham­mer­forms so both sides would match per­fectly. I could do the form­ing in ei­ther a bead roller or the Pull­max, but I’m con­cerned about get­ting the arch ex­actly the same on both sides. It would be easy to see any dis­crep­ancy if you stand in front of the ve­hi­cle, look­ing at both run­ning boards. Am I over­think­ing this? DonOliver

Via the Internet

A With the right dies on your Pull­max, you can curl the edge of both straight and curved pieces, so I don’t think you need to make wooden ham­mer­forms (although that ap­proach could cer­tainly work). If you cut an ac­cu­rate curve in the flat metal blanks and fol­low that edge with a guide on your Pull­max tool­ing, you can cre­ate a 45-de­gree curl with very good pre­ci­sion.

I have used “Round­ingOver” dies on a bead­ing ma­chine to make run­ning boards, and that works very well. The prin­ci­ple is the same as us­ing Pull­max dies—you make a 45-de­gree curl on the top piece and a 45-de­gree curl on the side piece, and weld the curled edges to­gether.

It would help to put the front-to-back curve in the top pieces be­fore curl­ing the edges, but even if you formed them flat it wouldn’t take much work to get them into the right shape af­ter the edge was formed. When you tack the side piece to the top, each piece helps to hold the other in the cor­rect shape.

Q I am a cer­ti­fied weld­ing in­spec­tor, and I was a welder for 30 years. Af­ter read­ing your ar­ti­cle on weld poros­ity, thought I might pass my ex­pe­ri­ence along to you. Usu­ally poros­ity is caused by dirty ma­te­rial, which could in­clude weld­ing rods, tung­sten, or weld­ing wire. If it’s windy or your gas pres­sure is not high enough that can cause prob­lems, too. Usu­ally you can grind out the poros­ity and weld again, as long as you go deep enough. On sheet­metal that can be tricky, as

I’m sure you know. One thing you can do is use a cop­per backup bar. That helps ab­sorb the heat and pre­vent burn-through. I hope this will be help­ful to your read­ers. LouHickam, AWSCWI Via the Internet

A Thanks for the tips, Lou. I al­ways ap­pre­ci­ate it when a trained pro­fes­sional chimes in on this col­umn and I can share their knowl­edge with our read­ers. My ex­pe­ri­ence is that cop­per backup bars can be very help­ful on flat metal, such as when do­ing chas­sis work or patch­ing pickup beds. I’ve found it to be much more chal­leng­ing to use a backup bar when you’re do­ing body­work, where the metal most al­ways has some cur­va­ture. If there is even a tiny gap be­tween the metal you’re weld­ing and the backup bar, you lose most of the bar’s ben­e­fit as a heat-sink, and the big­ger the gap, the less ef­fec­tive it is for pre­vent­ing burn-through.

✦Mak­ing a curved run­ning board can be a chal­leng­ing project. This month we’ll dis­cuss sev­eral op­tions for do­ing this type of work.

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