Here are a few of my favorite insert tool bits for the lathe:
The first two on the left are shop made using 3/8" 1018 steel. Nothing special except that I like to put an insert on each end of the tool blank. With that config I can turn to a shoulder either left or right depending on the tool and then just remove and replace the tool holder on the 90 degree side of the tool post (parallel with bed) and the same tool (opposite end) will face the end of the part that is being turned.
The pair in the middle are purchased tool holders for small triangular inserts but I machined the blank end to handle an insert also. This converts it to my kind of tool that cuts from both sides of the QCTP.
The pair on the right is another set of shop made tools. They are also 1018 3/8 steel with small square inserts for facing and chamfering on the back end.
The tool at the top was too large for my lathe but it works fine now. The last two pictures show this tool in better detail. It is commercial in manufacture but I milled it down to 1/2" thick so it would fit my tool post. Probably too large for my little lathe but great for roughing. I will grind the inserts with little to no nose radius and just re-grind it when it breaks. Great for removing scale on hot rolled steel.