This instruction set will talk you through all the steps necessary to build and assemble the OpenROV 2.3 structure. Building tasks can be broken down into seven general assembly sections:
(1) Cutting out parts
(2) Heat bending the outer shell
(3) Assembling and gluing the inner structure
(4) Assembling and gluing the end caps
(5) Assembling the battery packs,
(6) Assembling and waterproofing the thrusters
(7) Potting the wire pass throughs in the end caps.
Assembly of the entire OpenROV 2.3 structure can be done over a weekend, and most sections take less then an hour. Listed with each assembly section is a Bill Of Materials (what parts and tools you'll need), general notes for the assembly (what the best working space is, how long it should take, what each part is for, etc), the instruction set itself, and notes on what to do if something goes wrong. We hope that improvements will be made periodically by builders who find tricks and rules of thumb to make the build go more smoothly.
Remember, if you have questions, you can always visit the OpenROV builder's forum at this link
Good luck, and happy building!
**************************1. Cutting Out Parts**********************
Note: although the OpenROV 2.3 design is metric, most stores in the US will only sell acrylic in English units, so we've provided dimensions in inches for this section.
- One 24" x 18" sheet of 1/8" (actually .118") thick translucent blue acrylic.
- One 24" x 12" sheet of 1/8" thick white acrylic
- One 4" OD, 3.75" ID (1/8" wall thickness) by greater then 7in (180mm) long piece of clear cast acrylic tubing (Note, that tube must be CAST rather then extruded, as extruded tubes usually have longitudinal distortion which would interfere with camera image)
- Laser cutter connected to a computer (we use a 24" x 18" Epilog 60W Helix)
- Chop saw
- Masking tape
- 24" x 18" sheet will be used for main OpenROV structural parts and 24" x 12" sheet will be used for end cap components
- Remove backing on side of plastic that will be facing the laser source should be removed to prevent flame
- Assure that outline of ROV parts will be cut as vectors while OpenROV logo and serial number are set to be rastered
- For 60W Epilog Helix laser cutter, settings should be 60% speed at 30% power for raster, and 18% speed at 90% power (5000kHz frequency) for vector
- Focus laser toward top of plastic sheet to assure clear rastering
- Cut out test piece with both raster and vector components in upper left corner of sheet before starting to assure settings and adjustments are correct
- The main parts pattern (cut out from the 24" x 18" sheet) should take about 8 minuets to finish
- The end cap parts parttern (on the 24" x 12" sheet) should take bout 4 minutes
Each OpenROV has a unique serial number. If you plan to laser cut your own OpenROV structure, please request a serial number by sending an email with the subject heading "SERIAL REQUEST" to firstname.lastname@example.org several days before you plan to cut. Once we get your request, we will issue a serial number which will be valid for the next three days. If you don't cut during that time, just let us know and we can reissue you a new number.
1. Remove backing from one side of 24" by 18" acrylic sheet and place on laser cutter platform with backing-less side facing up
2. Focus laser to top surface of sheet
3. Cut out test piece (such ) in upper left hand corner and verify quality
4. At high speed, verify that laser path stays on sheet by running with pointer on and laser off (lid open)
5. Cut out Laser Cut Pattern
6. Inspect all pieces for quality. Whipe clean rastered area with moist rag
7. Repeat steps 4 and 5 for 24" x 12" sheet, but for Endcap pattern
8. Wrap masking tape around acrylic tube so that it's center is about 175mm from one end. Masking tape will hold a mark and also prevent chipping during the cut
9. Mark the masking tape at exactly 175mm from the end of the acrylic tube
10. Use a chop saw to (slowly) cut the acrylic tube at the mark
11. Deburr edges with fine sandpaper when done and remove tape
*********************2. Heat Bending Outer Shell******************
- Shell piece from laser cut parts
- Carpender's square
- Razor blade
- Heat strip bender (we use a Formech FLB500)
- Bending guide
1. Begin heating the strip heater. For the Formech FLB500, a setting of "5" on the heat dial is desired, and should take about 15 minuets to reach full temperature from startup.
2. Prepair a bending guide that will be able to hold the heated acrylic so that it is bent at just less then 90 degrees (perhaps around 87 degreees).
3. Using a razor, etch lines in two places along the length of the shell on the opposite side of the logo (which will eventually be the inside of the shell) as shown. A carpender's square can be used to etch the lines at right angles to the forward and aft edges of the shell. These lines will be used to assure the piece is being bent in precisly the right spot.
4. Remove any additional backing on the shell
5. Make a note of the minuet and second, and place the shell -logo down- onto the heat bender so that one of the etched lines is aligned with the heating element strip heater. The shell should be in roughly the center of the heating area.
6. After 2 minuets has elapst, varify that the plastic is easely bendable over the heating element and carefully lift the shell off the heater from one end. If the shell is not yet flexable, ad time as needed until flexability is achieved. Make note of how long this takes so that the same timeing can be used for the other bend.
7. Immediately after removing the shell from the strip heater, bend it by hand along the etched line (with the line on the inside of the bend), being vary cairful to assure the etched line is co-linear with and in the center of the bend
8. Place the shell on the already prepaired jig and hold until cool (no longer flexable)
9. Repeat steps 3-8 for the other bend line. Be sure to place the shell on the strip heater for the same amount of time as the previous bend or bend radii may be different.
****************(3) Assembling and gluing the inner structure****************
- Tube Braces
- Acrylic cement (we use Weld-On 4)
- Acrylic cement despensing syringe
- Paper towels should be handy
- Low viscosity acrylic cement that is drawn between pieces using the capillary effect is preferable over thicker glues which must be applied directly to each surface
- Always re-cap acrylic cement container immediately after filling syringe to prevent evaporation and spilling
- Glue pieces over several layers of paper towel or other material that will absorb excess glue. A piece of wax paper can be placed under the towels to prevent glue from getting on the table you are using.
- The tabs coming out of the firewall may not align perfectly with the outer shell at first. If this is the case, a file may be used to trim the tabs as necessary.
At this point, description of each step would just be silly, so instead, assembly instructions are shown below Lego-style. Brief written instructions may be added later to help with procedures that are not intuitive- if you have any questions about the assembly, please feel free to list them in the Comments section of this page, and we'll try to address them in this instruction set.