I don't want to do it but I am going to start looking for a chuck for my lathe. I am new to this and don't know what the differences are. My lathe max length is 18" so i don't want one of the big thick chuks expense is also an issuei I saw a good deal on ebay almost bought them the realized it wa just add on jaws. I would go used if I could get a set that was not worn out.