Cabinet

The cabinet is the box, made of T-slotted frames and panels, that holds all the components of the training rig. It also works as a sound-insulated space in which the mice perform the tasks. The control module and the other modules' components are placed on one side of the cabinet, and the projector at the back.

Training mini VR rig cabinet.

Sound-absorbing sheet preparation

We use 75% sound-absorbing sheets with adhesive backing, glued to the inside of all the cabinet panels. They help isolate the rig from lab noise; nevertheless, the room should be quiet and dark while the animals are training.

Cut cardboard templates for cutting the foam for each panel, according to the following table.

Panel	Size in inches
Front doors	19" x 9 1/2"
Back doors	9 3/8" x 9 3/8"
Sides	19" x 24 3/8"
Top	24 1/2" x 22 3/8"
Bottom back	7 11/16" x 22 3/8"

Place the sound-absorbing sheet foam side up, put the template on top of it and trace around its edges with a black marker.

Then place a pair of profiles on top to keep the sheet flat. Place a long ruler (or any thin, flat edge; I used a DIN rail) along the marked edges and apply a good amount of pressure, then cut the sheet along the marked lines with a sharp X-Acto knife. It took us two passes to cut all the way through.

TIP

Change the X-Acto blade often; a good sign that it needs changing is when it no longer cuts smoothly and sometimes gets stuck.

Cabinet assembly

We use 1.5" x 1.5" T-slotted profiles to build the cabinet frame and 1/4" black Haircell ABS (smooth side up) for the panels. Our supplier is the Knotts Company, an authorized 80/20 distributor; we sent them the drawings for a quote. You can also buy the pieces described in the drawings from other suppliers, but that will require adjustments and drilling a lot of holes. Assemble the cabinet following the steps below.

1. We start building the cabinet from the bottom up. Slide a pair of bottom plate holders (80/20 2425) into a 24.5" long profile. Make sure the top part of the holder is at the same height as the top part of the profile, as shown in the picture below. Repeat the process with another 24.5" long profile.

2. Insert a standard end fastener into both ends of the 24.5" long profiles with the bottom plate holders and of a pair of 22.5" long profiles. First insert the fastener into one of the slots and screw it in loosely, then repeat with the other end, making sure the fastener faces the same direction. Do this for both ends of all 4 profiles.

3. Arrange the profiles in a square, making sure that the profiles with the plate holders are facing each other to the left and right, and in the correct position (top part of the holder must be at the same height as the top part of the profile); and the 22.5" long profiles are facing each other at the back and front. Use the 22.05" long profile with holes at 1.5" from the ends to join the front part, and use the 22.05" long profile with holes at 1.5" from both ends and a hole at 11.675" from the top down to join the back part of the rig. Insert the profiles from the top down and tighten the screws through the holes.

4. Place the aluminum bottom plate on top of the frame and slide the bottom plate holders so that they line up with the plate holes. If the holes don't match in the lateral position, you can unscrew the holders just enough for them to reach the holes. Use 5/16-18 x 0.625" long screws to fasten the bottom plate to the holders.

TIP

If you are working on a raised table, you can push the structure over the edge just enough to see the bottom and line up the holders with the holes, then turn the structure around and repeat.

TIP

Use a permanent marker to draw two straight lines on top of the bottom plate, using the grooves at the sides as shown below. They will be extremely useful for the projection calibration.

5. Cut 8.2" off the top base of the drawer slider, then use 1/4"-20 x 1/2" long low-profile screws to install the 26" long steel base-mount drawer sliders. Screw the latch holder to the latch holder adapter with M4x0.7 mm, 8 mm long screws, then use 1/4"-20 x 11/16" flat head screws to attach the latch holder with the adapter to the bottom plate.

6. Install the structure to hold the projector at the back of the rig. Set the height of the structure to 3 15/16" from a flat surface to the top of the profile.

TIP

You can install the projector bottom plate before measuring to make it easier to set the height.

7. To install the back panel of the rig, first make the hole for the projection to go through: 2 3/4" from the top of the panel and centered horizontally (11 5/8" from the side). We recommend drilling a small pilot hole first and then using a 1" drill bit or hole saw.

Install the soundproofing foam, then cut the hole in the foam.

TIP

To install the soundproofing foam, first clean the smooth surface of the panel with 70% ethanol and let it dry. Then peel back just a small portion of the protective liner from the adhesive side of the sound-absorbing sheet, as shown below.

Center the sheet on the panel and stick down the uncovered portion by pressing along the sheet from the top down.

Peel back another small-to-medium portion of the liner and press it onto the panel from the top down. Repeat until the whole sound-absorbing sheet is stuck to the panel.

Finally, slide the panel down into the T-slotted profiles at the back of the rig, slide a 22.5" profile (with its fasteners already attached) down until it reaches the panel, and tighten the screws through the holes in the side profiles.

8. For the left panel, first cut out of the sound-absorbing sheet the square where the air supply adapter will be attached, then stick the sheet to the panel and cut the hole for the cables and hoses (as in the previous step). Install both side panels first, then arrange two 24.5" long profiles and two 22.5" long profiles, with fasteners loosely screwed in, around the four sides of the top panel and lower them onto the structure. Tighten the screws once the structure is in place.

TIP

Sometimes the top panel and profiles don't fit properly. If you have trouble fitting them, loosen the screws at the bottom of the four corners and the middle screws at the back of the frame so you can push the top structure down. Once the top structure is in place, tighten all the screws.

9. Assemble each door by first building a U-shaped frame. For the front doors, screw a 9.65" long profile at the bottom to a pair of 22.05" long profiles; for the back doors, build the U shape from 9.65" long profiles. Then slide in the panels with the sound-absorbing sheet already in place. After that, screw a 9.65" long profile across the top of both front and back doors. Finally, insert the joining strip along the outer edges of the doors.

10. Insert the joining strip around all the panels of the cabinet.

11. Install the DIN rails by screwing 4 DIN rail mounting adapters into the profile using a T-slotted framing drop-in nut, 1/4"-20 thread size. We buy a 2 m long steel DIN rail and cut two 27.5" pieces. Then attach the first DIN rail to its pair of mounting adapters and repeat the process for the other rail.

TIP

Before placing the top DIN rail mounting adapter at the back of the rig, slide the middle door hinge down. Alternatively, you could replace the standard framing nut with a 1/4"-20 T-slotted framing drop-in nut to install that door hinge.

12. Install the doors by screwing on the lift-off hinges; each door needs a pair, one at the top and one at the bottom. Finally, install the lock using a 1/4"-20 screw and 1/4"-20 T-slotted framing drop-in nut.