Jigs are commonly used in industry to speed production of repeated assemblies, and there is no reason why you shouldn’t be using them in your own shop to make your life easier too.
Now one of the key things whenever you are undertaking a project is to assess the tolerances required – I think that’s becoming less of a factor in industry with computer controlled equipment, but if you shop is like mine – pretty manual, then tolerances are a key factor. Keep that in mind when you produce the jigs. In this case I’m welding up parts for an iron and oak shelf for my brother and sister in law. It has to be square but doesn’t need to be super precise – so a quickly put together jig made from scraps of plywood is just the think to make the repeat assemblies quickly and accurately.
While there are six T’s those are fitted into two larger leg assemblies – while there isn’t a whole lot of repeatably required with only two assemblies quickly assembling a jig to ensure that the parts get put together and are square and in the right spots is well worth the ten minutes it took to screw the plywood pieces together. The end result is that the leg assemblies were identical – and I ended up saving a lot of time and cursing because they made holding the elements in the correct space without having to double and triple check.
Now, wooden jigs for welding are not necessarily long lasting given wood deteriorates when heated to a temperature that will melt metal. Sure, but you probably aren’t turning out hundreds of assemblies so this is a bit irrelevant, and the speed, ease and low cost offered by using wood more than offset the limited life-cycle of flammable jigs.
So, next time you have a welding job consider using jigs in your setup if it’s appropriate.