The production of Acme and lead screws is a complex procedure that requires several steps that must be done with complete precision. The specific thread pattern of the Acme screw allows for easy movement of the Acme nut along the thread pattern without any catching or wedging as the nut moves along the length of the thread.
The Difference
While the Acme screw falls under the general category of the trapezoidal thread form, it is different. The typical trapezoidal thread form has a 30-degree thread angle while the Acme thread is set at 29 degrees. This is measured at the top of each thread and between the next thread up or down the shaft.
It is important to realize this 29-degree thread remains the same regardless of the diameter. In addition, the thread height is half of that of the pitch and the top and bottom or the crest and valley of the thread are flat, not rounded or pointed in shape.
This specific thread shape is important, as it allows the thread to carry additional weight over other shapes. Both standard and split nuts can be used on this type of thread form. The split nut will open along the length to allow the nut to be placed on the bolt. It also provides the option to move the nut into position up or down the length of the thread without having to turn it into place.
Considerations
When choosing Acme screws options, it is important to choose a manufacturer offering precision machining and production options, particularly when the order calls for customized components.
It is important to know the class of Acme screws you required as well as the diameter and length. Additionally, these screws can be configured with either a right or left-hand thread as well as single or multiple thread leads.
