A lot of my time spent in the shop is on mechanic work, but I also do a far amount of welding. Today I made a hitch for a snowmobile sled. This is a very common welding job for me. I seem to make a few every winter. Unfortunately I forgot to take a picture of the hitch.
I did take a photo of my home made "fish mouth" marking tool. When you weld two tubes (or pipes) together you need to cut a "fish mouth" into one of them to make them fit together. There are several different commercially manufactured machines for cutting these notches, but they are all rather expensive or require a selection of cutters matched to your tubing size.
Over the years I have found that it is easy to cut these notches with an angle grinders if you have the tube marked properly. The tricky part is marking the tube.
This photo shows the tube being marked on top. My marking gauge can be adjusted to a wide range of tubing sizes and can also mark tubes that intersect at different angles. Once the tube is marked I use one angle grinder with a .045 cutoff wheel to take the big chunks out and then another grinder with a regular wheel to trim down to the line. With a little practice it only takes a few minutes for each tube.
Hopefully next time I'll remember to get some photos of the notches and the welding.