I know Clecos,I have them. I have never seen any designed for "Butt-welding". They are used by drilling an 1/8" hole thru two or more pieces of metal like when lap welding. I also have some Cleco "clamp" style ones that are like a plier and squeezes the metal together. I have never seen any for "Butt-welding" and would like to give them a try if I can get them.
The debate on Butt vs Lap welds goes on and on. I think it is just like what quality of paint to buy, it depends on the subject and the talent of the guy doing the work. I'll be darn if I am going to butt weld the a patch panel on some old working dump truck. I would lap weld (likely with a flange) and down the road. Like wise, if I am talking to a guy with limited welding and body work expereance, I am going to tell him to lap weld it. Butt welds "can" take a LOT more skill to do. So it is not a black and white answer.
