I had a 12" x 54" bed on my craftsmen lathe. It's a newer model so it has the 1/2" thick ways. Had a job come in last month that needed a longer bed lathe. Looked like a money making deal so I picked up another bed on ebay and fastened both beds together and made a 8' lead screw for it. Was a real job to get everything lined up but works great. Had to set up three vices on my mill to hold the acme thread so as to cut the key way. If you cut just a little deeper than the thread everything should be fine.