Hi-Speed Ergonomics - The ergonomics relevant for Direct fastening tools

Abstract

Direct Fastening tools are popular for quick fastenings in concrete and steel by propelling the nail with gun powder, gas or electricity. Because of this the users hand needs to absorb a shock caused by the recoil when a setting is performed. The link between the recoil and its effect on the user is essentially unexplored. This makes it hard to design an optimum handle for a direct fastening tool to enable the user to be as precise as possible for the least amount of discomfort. By not knowing what parameters that are relevant for comfort and control it´s hard to interpret the results between different handle designs. The increased focus on vibrations and more ergonomic tools from the customer’s side makes it more important to investigate this topic. The standards that are in place today do not take shocks into account.
The goal of this Thesis was to create a recipe for the design of handheld direct fastening tools handles. A recipe makes it possible to optimize the design of the handles since it enables the development of one handle for each different usage pattern. To create such a recipe a basic understanding of the tools are needed. There is much more research conducted on tools that continuously vibrate and knowing the difference about what happens to the body is therefore important. After acquiring this, the tools could be tested by investigating the pressure pattern inside the hands, user testing of preferences, comfort and control and also by measuring the tool properties such as the weight and balance of the tools.
The results from these tests were the foundation for the cookbook recipe for the design of the handles for handheld Direct Fastening tools. It was found that one has a lot of design freedom, some forces required for use of the tools was too high and the precision was not affected by different handle designs. It was also shown that the optimum handle for a Direct Fastening tool is not the same as for other tools. The recipe was then verified by testing the developed concepts in the same way as the existing tools. The changes in the concepts were focused on the main handle, secondary handle, transition between the main and secondary handle and the trigger.
The cookbook recipe was verified and confirmed with few exceptions. The trigger should be optimized, the main handle cross sections should be adapted to provide more contact surface for the hands. The cross-sections do not need major modifications. The shape and angle of the secondary handle needs to be optimized.
The results also points toward that some of the forces required for use needs to be lowered. It is also shown that the design of the handles does not affect the accuracy and the strain. By distributing the recoil pressure better inside the hand a non-discomforting pressure level could be reached without lowering the recoil.
As a first step the Thesis lets us know what is important for understanding Hi-Speed Ergonomics. Further studies can be more niched and should be focused on further testing of the pressure patterns, setting angle accuracy and optimizing the nozzle.

Popular Abstract

Direct fastening tools are very popular for quick fastenings in concrete and steel. The tool shoots the nail in the material with great force. This creates a recoil that has unknown effects on the user. How can the handles of this tool be designed to maximize the control and comfort of the user?
A direct fastening tool sets a nail by propelling it with gun powder, gas or electricity. Because of this the users hand needs to absorb a shock caused by the recoil when a setting is made. The link between the recoil and its effect on the user is essentially unexplored. Because of this it´s hard to design the perfect handle for a direct fastening tool to enable the user to be as precise as possible for the least amount of discomfort. By not knowing what is relevant for the comfort and the control it´s hard to interpret the results between different handle designs.
The increased focus on reducing vibrations and more ergonomic tools in general from the customer’s side makes this even more important to investigate. The standards that are in place today do not take shocks into account. The slow development of these standards has resulted in that many big construction companies have started to develop there on internal guidelines to protect their employees.
The goal of this Thesis was to create a cookbook recipe for the design of the handles on the handheld direct fastening tools. With such a recipe it is possible to optimize the design of the handles, since it enables the development of one handle for each different usage pattern. To create such a recipe a basic understanding of the tools and their properties is needed. There is much more research conducted on tools that continuously vibrate and knowing the difference about what happens to the body is therefore important. There is also a need to investigate the pressure pattern inside the hands, user testing of preferences, comfort and control.
The results from these tests were the foundation for the cookbook recipe for the design of the handles for handheld Direct Fastening tools. It was found that one has a lot of design freedom, some forces required for use of the tools was too high and the precision was not affected by different handle designs. It was also shown that the optimum handle for a Direct Fastening tool is not the same as for other power tools. The recipe was then verified by testing new concepts of handles in the same way as the existing tools. The changes in the concepts were focused on the main handle, secondary handle, transition between the main and secondary handle and the trigger.
The cookbook recipe was verified and confirmed with few exceptions. The trigger should be optimized, the main handle cross sections should be adapted to provide more contact surface for the hands. The cross-sections do not need major modifications. The shape and angle of the secondary handle needs to be optimized.
The results also points toward that some of the forces needed for use, such as the trigger force, needs to be lowered. One can also see that the design of the handles does not affect the accuracy and the strain. By distributing the recoil pressure better inside the hand a non-discomforting pressure level could be reached without lowering the recoil.
As a first step into the topic this Thesis lets us know what is important for understanding Hi-Speed Ergonomics. Further studies can be more niched and should be focused on further testing of the pressure patterns, setting angle accuracy and optimizing the nozzle.

• author: Bengtsson, Philip
• supervisor: Gerd Johansson
• organization: Ergonomics and Aerosol Technology; Innovation
• course: MMK920 20151
• year: 2015
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Hi-Speed Ergonomics, Direct Fastening tools, vibrations, recoil, handle
• report number: LUTMDN/TMKT 15/5541 SE
• language: English
• id: 8052972
• date added to LUP: 2015-10-08 09:20:10
• date last changed: 2015-10-08 09:20:10