Build Guide: Mounting the Sensor Assembly

Mounting the Sensor Assembly to the Backstop

Next, we will make another conduit frame to support the wooden frame/IR touch sensor.  To do this, we’ll cut two more full-height upright lengths, only slightly shorter than the uprights for the backstop since we will be orienting the T connector the other way.  As mentioned previously, a connector adds 1-3/4in so we’ll need to subtract 3-1/2in (a connector on each side) from our previous upright length of 6ft 2in (if you altered the plans for the backstop previously, be sure to make compatible alterations here too), giving a cut length of 5ft 10-1/2in. We will use these uprights to suspend the sensor assembly in front of the backstop.

We will then cut two more pieces of EMT to span the distance between these new uprights such that they are the same width of the sensor itself.  We previously measured the width of the sensor at 7ft 2-15/16in (again alter this as necessary if your sensor is a different size).  These will also have connectors oriented on them such that they add 1-3/4in on each size so that means we should cut these at 6ft 11-7/16in.

Next, lay the sensor frame flat with the sensor facing the ground.  Working on top of the wooden frame, connect the newly cut EMT so that the uprights we just cut align with the left and right edges of the sensor (overhanging the top and bottom of the wooden frame) and the cross pieces connect the two uprights together and themselves align with the top and bottom of the sensor.

Laying out the conduit so it aligns with the wooden sensor frame

Before you tighten all of the T connector bolts all of the way, be sure you have things lined up exactly in front of the sensor. It is very important to get it lined up as this is another layer of protection for your sensor, the conduit will deflect arrows away.  Also be sure that the upright pieces are lined up so that the same measurement protrudes from the wooden part of the frame, both sides, top and bottom (center it).  Then tighten all of the T connector bolts.

Use the single hole EMT straps to attach the EMT to the wooden frame.  This doesn’t have to be exact, but I recommend spacing these about 2 feet apart all the way around the wooden frame.  Below is the same cross section as before, shown mounted with the straps.

Cross section of the wooden frame mounted to EMT conduit

Next, cut 4 pieces of EMT at 1ft (If you shoot particularly fast cut at 15 inches if you have the material) from the scrap from other cuts (do not cut from the remaining full lengths).  Lay the backstop flat with the nicer side of the tarp facing up.  Carefully place the sensor assembly on top of the tarp and center.  Attach the 1ft conduit pieces, one on each corner, facing straight up, aligned with the sensor assembly uprights.  When these line up with all four uprights, tighten them down so they do not slip.

Lifting one corner of the sensor assembly up from the backstop at a time, use a T connector to connect the sensor assembly upright to the 1ft conduit piece pointing straight up. After all four corners have been attached, the sensor assembly should be suspended above the backstop as shown.

Suspended sensor assembly in front of backstop

At this point, you can use the end plugs from Makerpipe to plug up any open ends of the conduit to give it a more finished look.
 
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