Jeff has a craftsman lathe. Virtually impossible to have a holder on the backside. He is pretty much limited to the front side. Mikey has educated me on the forces involved and how everything flexes that makes parting on a craftsman lathe difficult. To have any chance of success you need your setup as rigid as possible with a properly sharpened blade exactly on center.
When parting on the front side the carriage, cross slide and compound all want to lift on the outside and press down at the work. This flexing is what causes the blade to go below center line and into the work resulting in the work riding over the top of the blade. There are gooseneck tool holders designed to compensate for this flexing
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I bought some but they were too big to use on my lathe. So I have not used them and can not attest to how well they work. I have seen pictures online of gooseneck tool holders for a QCTP. I have thought about making one.
Jeff you just have to keep experimenting until you get a setup that works for you.