Adjustable Height Computer Table

Revision for “Adjustable Height Computer Table” created on August 20, 2014 @ 18:55:56

Title
Adjustable Height Computer Table
Content
<h2>Adjustable Height Computer Table</h2> <h4><em>Students: Michael Murphy, Barry Hampton, Cynthia Wilson</em> <em>Client Coordinators: Dr. Gary Edwards, United Cerebral Palsy of Birmingham</em></h4> &nbsp; An adjustable keyboard computer table was requested for the Fullen House, a group home for adults with cerebral palsy in Birmingham.  The existing computer table could not accommodate varying wheelchair heights and the keyboard was fixed in a stationary flat position.  In addition, the monitor was stationary and could not accommodate patients with various problems with eyesight.  The present design allows the table to translate vertically for wheelchair height adjustment, while the keyboard pivots in order to allow for the patients’ ease of use.  These movements are electronically controllable by the clients via large buttons.  Also, the monitor is manually adjustable to slide on the tabletop to a position where the monitor face is flush with the edge of the keyboard. <h3>TECHNICAL DESCRIPTION</h3> &nbsp; The tabletop consists of ¾ in. plywood with an applied veneer laminate (84 in. x 30 in.). The wood panels are cut from ½ in. oak plywood and stained to produce a pleasing appearance.  Foam is applied to the edges of the keyboard tray to soften the table edges.  The table lift mechanism consists of two AC linear actuators with a tubing guidance system housed in C-channel sections. The 18” stroke linear actuators are centered and secured via pin attachments inside the 6” A36 steel C-channel bolted underneath and below the table. ASTM A500 steel square tubing guidance system under the table consists of four telescoping sections of tubing under the four corners of the table.  The A36 C-channel and angle were selected to meet ASME Specification SA-36. The tubing is welded (AWS Specification E7018) to the inside of the C-channels that also house the linear actuators.  Each telescoping section consists of 2 square tubes, one smaller tube with a 2 1/2” OD and one larger tube with a 3” ID.  These telescoping tubes are greased appropriately to ensure smooth sliding during table lifting.  The actuators and guidance system are concealed inside two telescoping wood panels, one of which was stationary while the outer panel extends as the table was raised.  These panels are guided using ball bearing drawer slides between them. The keyboard pivot consists of a “universally sized” keyboard housing to hold the keyboard with a Velcro patch to secure the keyboard in the housing made from A36 steel plate. A third linear actuator is connected to the keyboard housing and flat bar via pin attachments, such that, when retracted the keyboard would begin in the flat position (180°), while the fully extended length would pivot the keyboard to a maximum angle of 80°.  The keyboard housing pivots about its center axis. “Jelly bean” buttons control the table height and keyboard pivot adjustments, attached to the tabletop via Locline flexible neck rods. The monitor slide/support mechanism consists of two 2 x 4-in. pieces of pine, bolted to the tabletop with two additional pieces offset at a 2-in. height and connected to the support pieces using 20” heavy duty full extension zinc-plated carbon steel slides.  These slides are rated to carry 115 lb./slide at the fully retracted and fully extended positions.  The oak wood platform for the monitor is bolted to the top 2 x 4-in. pine support beams.  The extension slides allows the monitor to move up to 12” past the tabletop,flush with the keyboard edge.  The total cost of this device, illustrated in Figure 29, was $1,463. <a href="http://www.rectech.org/wp-content/uploads/2014/08/29-adjustable-height-computer-table1.jpg" target="_blank"><img class="alignleft size-thumbnail wp-image-747" src="http://www.rectech.org/wp-content/uploads/2014/08/29-adjustable-height-computer-table1-150x150.jpg" alt="29 - adjustable height computer table" width="150" height="150" /></a> <em>Figure 4.  Close-up view of adjustable computer table, showing adjustable, inclined keyboard tray, sliding monitor stand and jelly-bean control buttons.</em>
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August 20, 2014 @ 18:55:56 Fred Gilbert
August 20, 2014 @ 18:55:40 Fred Gilbert
August 20, 2014 @ 18:55:30 Fred Gilbert