Motorized Rivet Dispenser


Requested Project

This is an adaptation of the rivet dispenser completed by Russ Schuchmann in Feb 2003 for Ann at Options.  The adaptation requested would automate the turning of the wheel so that a person operating a switch could participate in the process.

Design Notes

Motorized Rivet Dispenser

The design of the motorized rivet dispenser is based on the manually operated rivet dispenser completed under the Rivet Dispenser project entered on 10/16/2002.  Please refer to that design for parts not directly related to the drive mechanism. The link to the manual rivet dispenser design is listed in the Addition Information section below.

In the motorized version, the rivet-containing-drum is driven by a rubber belt having a round cross section about .275 in. in diameter (available from True Value Hardware, E-30563 for use in many upright vacuum cleaners).  A semicircular groove having a diameter of .25? is machined in the wooden bearing that supports the drum to serve as a pulley for the belt.  The belt is driven by a 4.8 rpm 115VAC gearhead motor of the type commonly used in appliance timers. The motor specifications give the rated power as 1/50 HP.

This timing motor is available from the Surplus Center, 1015 West ?O? Street, P.O. Box 82209, Lincoln, NE 68501-2209.  Phone 402-474-4055.  The web site for the Surplus Center is http://www.surpluscenter.com.  The motor is a Timetech, Inc Catalog # S430.1.  The Surplus Center item number is #5-1274.  The cost of each motor is $3.99.

The motor as supplied must be modified before use.  The synchronous motors commonly used will start in either direction and if a specified direction is required, they must be constrained to permit rotation in only one direction.  This is usually accomplished by a dog mechanism which pivots about the gearshaft driven by the motor pinion gear.  The motor shaft comes fitted with a nylon cog piece that engages the dog when the motor attempts to start in the wrong direction.  However, the dog is not supplied in this particular motor as apparently the intended application was not sensitive to the direction of rotation.  Consequently this dog piece must be fabricated from a piece of nylon and installed in the motor.  Photographs of this piece and the location in the motor are included on the website for this project.  The output shaft of the gear motor should rotate CW when facing the shaft.

The pulley attached to the gear motor is 2? in diameter and like the drum bearing has a semicircle groove .25? in diameter machined in the outer circumference to accept the belt.  This pulley was made of 3/8? phenolic sheet material.

The timing motor is mounted to the heavy metal ?L? bracket that supports the drum and a ?? diameter hole is bored in the bracket to allow the shaft to pass through and the bearing to nest in the hole. Two 6-32x3/8? screws are used to mount the motor.  Mounting holes in the bracket are threaded to accept the screws.  The motor mounting position is chosen to properly tension the drive belt.

The timing motor bearing is not designed to handle the side load imposed by the belt tension.  Also, the shaft of the motor is too short to mount the pulley.  Consequently an adapter shaft must be made to slip over the motor shaft (where it is secured to a flat on the motor shaft by a set screw) and then extend through the pulley to engage an outer support bearing that shares the belt side load with the motor bearing.  The pulley must be secured to this shaft extension and in the first model this was done by capturing the pulley between a flange on one side and a 5/16-24 lock nut on the other.  In addition a pin through the extension shaft nests in a slot in the pulley to prevent rotation between the shaft and the pulley.  Drawings entered on the web site show an alternate method that should be easier to construct where there is a 1? diameter flange on the shaft extension to which the pulley is secured with three machine screws.

The timer motor should be connected to the electrical supply with a 3-wire cord where the 3rd wire is a ground.  The ground wire should be securely fastened to the drum support ?L? bracket.  The hot and neutral wires should be terminated with insulated crimp-on female spade terminals and mated to the male spade lugs provided on the motor.  

A shield, constructed from a heavy aluminum bread pan, prevents finger contact with the drive mechanism and the electrical connections.  This shield is shown in the web site drawings.  It has a 3 point mount consisting of two tabs secured to the base board by screws and a bolt that engages a long connecting nut that extends from the drum support shaft. Mechanical restraint for the electrical cord is provided by a plastic clamp grommet that mounts in a ? in. hole in the side of the shield.  

It is intended that the motorized rivet dispenser be used with an Ablenet timer box that will accept a control switch and energize the motor for an appropriate time to deliver the desired quantity of rivets after each activation of the switch.  Please note that the Ablenet box must accept switch inputs and provide a switched 120VAC outlet for the motor drive.

Pictures of the completed assembly are shown on the web site along with mechanical drawings.

RCRV designer is Russell Schuchmann, and was requested by Options of Linn County--Wayne Clayton. The project was begun Sep 10, 2003 and completed Dec 11, 2003.

    


Additional Information:

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Construction description
Motor drive drawings
Manual dispenser drawings
Manual rivet dispenser project

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