Build Guide: The Sensor Frame

Building the Sensor and its Support Structure

 Unpack and assemble your IR sensor frame.  Be careful to follow all of the manufacturer instructions for assembly, paying particular attention to the pins or ribbon cables between the sides of the sensor edge pieces.  These can easily break or tear so make sure everything is lined up properly and you don’t force it!

Once the frame is fully assembled and all screws are tightened, lay it flat until we have supports built for it.  These are not at all rigid on their own, so even though it is fully assembled, until it is mounted on something, it can easily twist and then electronic connection points (pins or ribbon cables) can get tweaked.  Measure the length and width of the frame (be sure it is square by matching your two diagonal measurements so you get an accurate length and width).  The sensor I used is 7ft 2-15/16in x 4ft 1-3/4in.  Also measure how wide just one "bar" piece of the sensor is (in other words, how big is the bezel when assembled).  For me, this was just less than 1in.

Next, we will make a frame out of the 1x2s and 1x3s to hold the touch frame rigid.  To do this, “stack” a 1x2 on top of a 1x3, line of up an edge and screw it in place along the length.  This should give you basically one solid board with a notch cut out of it, the notch being one inch wide (If your touch frame bezel measurement is bigger than this, you will need to offset the 1x2 and 1x3 to make sure the notch is wide enough. You do not want any part of the sensor overhanging the 1x3).  We will make four of these, then form a frame out of these wooden boards so that the “notch” forms an inset shelf for the IR touch frame to sit in all the way around.  Again, be sure the notch is wide enough that the IR touch frame will inset fully.  The sensor should be fully covered by the wood, not sticking out at all, to protect it from wayward arrows.  Below is a cross section of what we are going for:

Cross section of the frame that supports the IR touch sensor

Once you have 4 of these notched boards,  you will cut them to length and screw on the flat angle braces to affix the corners together. If you want to get fancy, you could use a miter saw to cut these at 45 degree angles, but I found that just doing straight cut butt joints made for a nice “pass through” for the IR frame’s USB cord.  If you choose straight cuts like me, cut 2 at 7ft 15/16in (matching the long side of the sensor minus 2 inches for the sensor to inset into the notch) and 2 at 4ft 4-3/4in (adding 3 inches to the short side of the sensor for the width of the 1x2s). Essentially we are cutting the stacked boards so that the 1x2s frame the touch sensor all the way around with the 1x3 serving as a backing board.  The inner measurements of the 1x2s should therefore equal the outer measurement of the IR touch frame.

Diagram of both sides of the wooden frame that holds the sensor

 

Next, do a dry fit of the IR touch frame into the notch of the wooden frame just constructed.  The IR frame should fit snugly and should not protrude into the center of the rectangle at all.  The entire sensor should be protected by the wooden frame.  If things do not fit, trim the boards or adjust the position of the corner angle brackets as needed.

The IR frame should fit snugly in the inset notch of the wooden frame.

Once the IR frame fits into the wooden frame notch perfectly, cut the heavy duty velcro into 6” strips and space evenly around the inset of the boards and the IR frame.  Velcro the frame inside the notch of the wooden frame.

 

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