internal and external screw threads


	Internal and External Screw Threads
	External screw threads are synonymous with worms but operate with internal screw threads to change rotational movement into lateral (axial) movement. It is a more positive motion than a rack and pinion drive but it has its limitations. Our maximum external screw thread diameter is 250mm (10 inches) and maximum pitch 20MOD (1.25DP, 2.5 inches circular pitch). We can also cut maximum 200mm (7.87 inches) diameter * 3m (118 inches) long. The maximum number of starts 20. Our maximum internal screw thread diameter is 200mm (8 inches) * 200mm (8 inches) long and maximum number of starts 8. The maximum pitch 12mm (0.5 inches circular pitch)


	Hewitt & Topham Limited, Dyneley Road, Greenbank Business Park, Blackburn BB1 3AB United Kingdom Tel: +44 (0) 1254 679222 Fax : +44 (0) 1254 680534 Email: sales@hewitt-topham.co.uk