I agree with the taking up a mentor. It will allow you to learn what is safe on a lathe, as well as help in understanding the limitations of the lathe. The motor may be able to turn it, but you are wearing the bearings out in the motor. Putting strain on the spindle like that may not break it today, but it will break eventually. It could be on a large piece or a small piece. Misdesigned buildings do not fail typically when the building is built, but later on after it has been straied for a while. Take the advice from the people here.