Problem Statement 

The purpose of a Bench Vise is to securely hold work pieces while performing operations on them such as cutting, grinding or even just clamping to allow glue to dry.

Assumptions about the Problem

• The lead screw will actuate the vise jaw to move the table in and out
• We will use a safety factor of 18, and a max load of 1000 lbf.
• We will be using a grade 2 ¾-6 Acme threaded rod, mild steel, Tensile strength of 53,000 psi

• The base of the vise will be a cast steel A-36 

Thought Process Throughout Design

When a lead screw is considered, a lot has come to mind, from scissor jacks to window regulators to CNC milling machines, however given this is should be a simple project a bench vise was thought to give multiple components but not have too simple of a design. After some research it was decided to run a ¾-6 acme threaded rod into a pull block as this would give the maximum strength with minimal compromise and fewer parts than using a separate nut block. The materials chosen were mild steel and cast steel, the mild steel would be the threaded rod while the cast steel would be the body of the vise. The friction Coefficient for the two steels is .40 unlubricated, this was found using the resources Dr. Fagan provided, link at the bottom of the page. After being in the construction industry it is apparent machinery is used well beyond the recommended safety limits, which is why a safety factor of 18 was assigned. The choice of a lead screw instead of ball leads is because vises typically are used in very dirty environments and the simplicity factor of a lead vs ball helps the price point and manufacturability. 

Resources:

https://www.mcmaster.com/lead-screws

https://www.designworldonline.com/how-to-correctly-apply-lead-screws/

https://www.engineeringtoolbox.com/friction-coefficients-d_778.html

Dr. Terence Fagan’s- MEGR 2156 class

https://clubtechnical.com/lead-screw

Machinery Handbook 31^st edition Pg (2054-2059)

Partner

Walker Bond 

https://uncc.instructure.com/eportfolios/2270/Home

Design Sketches Below