Hope there are a few welders reading tonight…
I am in the process of building a camper that will sit on the flatbed of an F350. I came up with the shape of the camper (very much a traditional flatbed camper with cabover). A smart (paid) engineer designed the aluminum frame to achieve the desired shape. A professional (paid) welder is now welding the frame for about $8,000 (material and labor). I provided a cut sheet of all 120 members (length, cut angles, etc.). I just visited the welder to approve the assembly before he welds all of the joints (it is currently tacked together).
I am not a welder! I fully accept that I have zero knowledge about welding. But I am an engineer at work, have two engineering degrees, and design/build machines during the day. The assembly had a few noticeable areas that caused me concern and I’d like to ask the forum for advice. The frame is made of aluminum square tubing. I do not know which alloy. The welder has encountered a series of small problems that seem to be cascading into a few larger problems. Here are my concerns (see pics):
I’ll never see the welds after I skin the exterior and interior so it’s important the welds be reliable.
Many thanks and virtual beers for your thoughts.
Ben




I am in the process of building a camper that will sit on the flatbed of an F350. I came up with the shape of the camper (very much a traditional flatbed camper with cabover). A smart (paid) engineer designed the aluminum frame to achieve the desired shape. A professional (paid) welder is now welding the frame for about $8,000 (material and labor). I provided a cut sheet of all 120 members (length, cut angles, etc.). I just visited the welder to approve the assembly before he welds all of the joints (it is currently tacked together).
I am not a welder! I fully accept that I have zero knowledge about welding. But I am an engineer at work, have two engineering degrees, and design/build machines during the day. The assembly had a few noticeable areas that caused me concern and I’d like to ask the forum for advice. The frame is made of aluminum square tubing. I do not know which alloy. The welder has encountered a series of small problems that seem to be cascading into a few larger problems. Here are my concerns (see pics):
- Some of the gaps of the joints are 3/8”. These joints will be structural. Can these joints be filled and be as strong as if the members were cut to the correct length?
- Some bar stock and tubes were cut too short. His fix was to weld the shorter pieces end-to-end. Acceptable or not?
- The longest straight section of the camper is 12 feet. The maximum deflection of this straight section is 1.5” on one side (bowed out) and 0.25” on the other side (bowed in). Aside from the asymmetry that must be fixed. What is a reasonable maximum allowable deflection in a straight plane? He already tried to straighten the frame with a jack and said it bent several inches in the right direction.
- The design diagrams indicated 2x1 tubing in certain areas. The welder ordered the wrong material so instead is using two 1x1s. It’s heavier but will this be as strong? Lead to other problems? Acceptable?
I’ll never see the welds after I skin the exterior and interior so it’s important the welds be reliable.
Many thanks and virtual beers for your thoughts.
Ben



