FWD Lag Screws & T-Nuts

Machine thread on one end and wood screw thread on the other. The wood screw is usually driven into the timber by locknutting the machine thread and using a spanner to turn into the work piece. 

Then you have an exposed machine thread for attaching premanent or temporary items to your timber basework. One way of doing this is using t-nuts with the matching size machine thread. Capture the t-nut into the other work piece against the direction of pull on the timber surfaces and then thread together for a strong, snug joint.