You can can connect two pieces of screwed rod with a hex connector. If needed use locking nuts (or jam nuts) with threaded rod (screwed rod) to prevent them from loosening due to vibration or movement, often by using two nuts tightened against each other (a double-nut method) or by using specialised nuts like nylon insert (Nyloc) or flanged nuts, creating a secure, vibration-resistant connection, vital in automotive, machinery, or structural uses where safety is key. Like and Follow for more fix

Folding Hex Key Set, 7-Key, Metric Sizes - 70582 | Klein Tools

Pro Folding Hex Key Set, 11-Key, SAE Sizes - 70550 | Klein Tools