One of the problems facing the combine holders in Iran for years has been the thresher cylinder with one piece passing through shaft. The problem has arisen ever since domestic make buckled shaft has been used. Buckle is too much to recover by simple machining. As such, disassembling the cylinder is a breath taking, time consuming and expensive task to do. On the other hand, manual welding in factory to join the thin plates to rather thick tubing cause undercutting. This research was performed to cope with both problems by designing a suitable threshing cylinder for Iran namely the 3 piece cylinder. A tube was installed to carry the plates. The plates unlike similar cylinders are not welded to the tube but bolted to specially designed flanges. The flanges are welded to the tubing instead, which eliminates the undercutting phenomena. The two piece shafts on the sides, the long and the short are joined to the tubing by simple flanges and studs. Putting down the cylinder is as easy as un-screwing 12 bolts and screws. Bolting the plates to the flanges makes the mechanism indispensable. Any damaged plate can be removed for repair or replacement. The similar three piece cylinders are rather disposable type because the flanges are welded the plates. The cylinder was designed successfully. Auto Cad software was used for the design. The vibration consideration and calculations indicated a critical speed way beyond the operating speed to avoid resonance.