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