|This is a bottom view of the fixture made for holding the enclosure tube
while routing its ends.
An 8" dia opening in the table allowed the router bit to clear while routing the outside of the tube.
Spacers kept the tube approximately centered in the opening, and sandpaper strips kept it from sliding down.
|An 18"+ length of 6", Schedule 40, PVC pipe [McM 48925K25]
was cut off with a portable circular saw.
The pipe was supported in the slot of a B&D Workmate stand, and rotated while cutting.
|With the fixture on its side, the tube was positioned so the upper
end was slightly above the table surface.
The tube was held in position with a band clamp, and the fixture mounted upright in the Workmate.
|The inside and outside of the tube end were routed using a 1/4"
radius round-over bit.
Since the wall thickness of the tube was less than a 1/2", the profile of the tube end formed a "Gothic arch" rather than a semicircle, somewhat below the table surface. This will actually help in making a good seal with the faceplate gasket.
|Using the mfg's markings as a guide, a line was drawn parallel to the axis of the tube. Then a paper band guide was used to establish a 2nd line on the opposite side of the tube and two lines for the mounting holes of the retainers|
|Holes were drilled and tapped for #4-40 machine screws to mount the latches and the retainers.|
|Tapping #4-40 and #6-32 holes was made easier with an adapter that allowed an electric screwdriver to be used.|
|Holes were drilled with a step drill...|
|..and then tapped for 1/4" pipe threads to accept the barbed fittings for the motor wiring and Spare-Air connection.|
|Two retainers were cut from door jamb weather stripping. The rubber portion on each end was trimmed long and plugged with a #6-32 roundhead machine screws to facilitate sliding the chassis into place.|
|Each retainer was then mounted in the tube with four #4-40 x 3/8" pan head machine screws|
|Four pieces of aluminum angle (1/2" x 1/2") were cut to length, and then drilled in the corners.|
|Pop-rivets (1/8" x 1/4") were then used to attach the frame pieces together.|
|The corners were trimmed on the end pieces so they wouldn't interfere with the tube, and threaded standoffs mounted to act as bumpers. The long bumpers in the front provide a clear space for the video camera to be mounted. Thread protectors on the bumpers prevent them from scratching the faceplates.|
|The chassis frame is shown here with the retainers holding it firmly in place. In the finished unit, the electronic PCBs, battery, camera, etc. will be mounted on this frame which can be easily slid out for service.|
|Rubber tension latches [Southco 37-10-051-20] are mounted with stainless steel #4-40, 3/8", Phillips, pan head, machine screws in tapped thru-holes diametrically opposed on the PVC tube.|
|Each faceplate is held in place by two tension latches which are easy to attach and release for access to the ROV internals.|
|A pressure test was run with face plates and gaskets mounted on
each end of the tube.
The unit easily held 28" of vacuum without any grease or other sealant on the gaskets. However it would not support appreciable internal pressure.
|Straight and 90° Nylon barbed fittings were installed for the motor wiring and the Spare-Air connection.|
|A ROVing Otter decal was placed on each side of the tube near the front of the finished unit.|