A Do-It-Yourself Turning Target System

by Edwin C. Hall (February 2002 - updated 22 August 2002)

Note: The ** NEW ** Do-it-Yourself Turning Target System is recommended instead of this older version. Although the newer one doesn't include building it on a tripod, it does allow for mounting it on one if desired. The newer one is less expensive and simpler to construct.



Individual tripod setup

Background

I've designed a home made style turning target system which can be used for a single target or can be designed into a multiple target system.  I build both on this framework.  The unit is powered by a 12 volt 4 AH sealed lead acid rechargeable battery which will last for several hours of use.  The system draws its short bursts of current (up to ~4A) only during the actual turning phases, a minimal amount (<100mA - depends on the relay used) while faced and none during edge time.

The heart of the turning system is a windshield wiper motor.  The particular one used for this project is described as a 2000-2001 Saturn L motor.  Other types may work, but this one started turning up at surplus places for around twenty dollars.  This type of motor has good torque and an integral switching system which can be used to limit the travel in one direction.  Therefore, only one more switch is needed to limit it in the other direction.  I found that for this alternate direction I also needed to provide a stop due to the inertia of the motor (and target).  The integral limiter stops the motor by reversing the polarity of the windings, but I didn't want to get that detailed in my construction of the other limit point.  In the present design there is a relay which controls the direction of travel, the integral limiter for face position, and the added switch and bump stop for the edge position.  The target does have a "bobble" at the end of its swing, but it turns in a relatively quick fashion and the "bobble" ends pretty soon.  The turning time is well less than a second, but is dependent on the weight of the target or system of targets.

This target system was designed to be faced by a momentary contact device such as a switch or relay.  Such a signal is provided by my Rangebox, a command playback and switching controller powered by a 9-volt battery.

I have built several of these, and decided to place this information into the public domain so others can build them.  If I can provide a means for someone to afford a turning system, then I'm happy to have published this page.  If help or more information is needed, contact me (15 Lakeview Ave, Tupper Lake, NY 12986).

A list of materials I use is at the end along with some source information.  Many of the parts are common type items found at many hardware stores, but some are from other places.  For some of the "others," I've also provided part numbers.

Of course, no printed instructions can be free of a safety reminder these days.  Due to the inability of me to be by your side through this, you will need to assume all risk involved with the construction and/or use of this system.  This includes, but is not limited to, the use of all tools involved.

Updates

Feel free to provide feedback on how this project has worked.  I will try to change it if better parts appear or techniques evolve.  I have reviewed this document countless times, but there is no guarantee of accuracy.  If an error is found, I will attempt to immediately get the correction out.  Please feel free to send me comments.

Construction

In an attempt to avoid confusion, I will refer to the motor and housing in the following manner:

Orientation of the motor unit

Orient the motor assembly such that it is sitting in front of you with the shaft at the upper right.  This should place the motor horizontally to the lower left as in the picture.  Where the black motor cover meets the grey housing, two wires emerge and travel to the back of the connector on the bottom of the housing.  The mounting hole just above these wires will be referenced as #1.  Moving clockwise, the next mounting hole is #2 and the last one is #3.  The connections on the bottom of the unit will be referenced by the numbers given on the connector housing.  In case you get a motor which has different markings, this can be a key: A=53b, B=53a, C=53e, D=31b and E=53.  A-E will be from the left looking into the connector with it on the bottom and the shaft pointing upward.  The lever arm mounted on the shaft will be referred to as the arm.  This arm has a "hitch" type ball on the end.  Its orientation at this point will not be important.

Holes drilled in the washers will be numbered to match with the numbering of the motor housing holes to start out.  Subsequent holes made through the washers will be numbered as they are mentioned as referenced in the picture of the three washers.  The large washers will be identified as W1, W2 and W3.

The three washers

Steps to Construction - Working With the Motor and Washers

Moving to the Bracket

Some of the Wiring

Some Testing and Setting of the Stop Position

Assembling the Main Section

Note: At this point you can mount the unit to an existing structure and use it as a stationary system for multiple targets.  Simply use a 3/8"-16 bolt as the center post and connect whatever hardware will turn the targets.  I recommend using a bearing with the bolt to relieve any sideways pressure on the bolt.  In my multiple setup I have a smaller washer on top of washer W3 with a bearing mounted just under that top washer.  In the illustration the board acts as the copper collar/tripod separator.  To hold the bearing toward the top, if your support structure doesn't perform this task, you can use a coil spring around the bolt.  Most hardware stores have a spring selection.  For my local range where I use this setup, I built two swing arms mounted at the side walls.  Each has three targets.  This allows us to swing the turning targets out of the way when not in use.

Working With the Tripod

Connecting Up the Battery

Building the Target Frame

Making a Connecting Cable

Final Testing

Tools and Materials List:

Parts List: (Source and P/N of part)

Note: Some of the parts I used for this project came from All Electronics.  I am in no way affiliated with them other than being a customer.  There are several other sources for many of these parts or similar.  I provided this list with All Electronic part numbers solely for your information.  Feel free to use alternate vendors.  For items without part numbers, these should be readily available from hardware stores.


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