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Guide 4 - Motor Mounting

You are making great progress and are about halfway done with your build.

  • Author: OpenROV
  • Time estimate: 1 hour
  • Difficulty: Moderate

You will gain more soldering experience while connecting all of the motors.

Edit Step 1 Propellers  ¶ 

Image 1/1:

Edit Step 1 Propellers  ¶ 

  • Use a razor blade or hobby knife to remove excess plastic from the propellers.

2 Edit Step 2  ¶ 

Image 1/3: Using a set of pliers, hold stationary the locknut (with the nylon insert) and rotate the motor bell to thread the nut until it protrudes out the other side. Image 2/3: Take off the nut, then put it back on backwards, nylon side first. Thread it down as shown in image 3. Image 3/3: Take off the nut, then put it back on backwards, nylon side first. Thread it down as shown in image 3.

2 Edit Step 2  ¶ 

  • Remove the existing nuts and washers from the threaded rod on all three motor bells.

  • Using a set of pliers, hold stationary the locknut (with the nylon insert) and rotate the motor bell to thread the nut until it protrudes out the other side.

  • Take off the nut, then put it back on backwards, nylon side first. Thread it down as shown in image 3.

2 Edit Step 3  ¶ 

Image 1/1: The edges of the propeller can be very sharp. Please use caution and use a cloth or gloves if you are worried about getting cut.

2 Edit Step 3  ¶ 

  • While holding the bell with one hand and the propeller in the other hand, thread the propeller onto the threaded shaft.

  • The edges of the propeller can be very sharp. Please use caution and use a cloth or gloves if you are worried about getting cut.

  • Tighten the propeller very snugly.

  • There should be a gap between the locknut and the propeller.

Edit Step 4  ¶ 

Image 1/3: Tighten this very snugly. Image 2/3: You should still be able to remove the propeller if needed, but it should not rotate freely. Image 3/3: If you are concerned about the propeller coming loose, repeat this process until tight.

Edit Step 4  ¶ 

  • Back the locknut up against the propeller while holding the bell in one hand.

  • Tighten this very snugly.

  • You should still be able to remove the propeller if needed, but it should not rotate freely.

  • If you are concerned about the propeller coming loose, repeat this process until tight.

  • Do this to all your motors and props.

  • Threadlocking compounds can be used to further ensure that the propeller will not come unscrewed during operation. This would be recommended for long deployments or usage in harsh environments.

2 Edit Step 5 Wiring Harness  ¶ 

Image 1/3: Place end cap to port side of structure. This will help you measure out the length of wire. Image 2/3: Locate and separate the bright green and striped bright green/black wires. These will be for the starboard battery tube. Wrap the rest of the wires with the black cable wrap and around the frame. Image 3/3: The ROV is upside down in this image.

2 Edit Step 5 Wiring Harness  ¶ 

  • With the 1/2" wire sleeve, begin wrapping the wires starting at the end cap. Do not wrap entire length just yet!! You'll need to pull two wires out first and it will be easier to organize wires while they are out of the sleeve.

  • Place end cap to port side of structure. This will help you measure out the length of wire.

  • Locate and separate the bright green and striped bright green/black wires. These will be for the starboard battery tube. Wrap the rest of the wires with the black cable wrap and around the frame.

  • The ROV is upside down in this image.

Edit Step 6  ¶ 

Image 1/3: Make sure the green and black/green wires are sticking out on top. Image 2/3: Zip tie the bundles together by threading the zip tie through the slits on the acrylic piece. Image 3/3: Zip tie the bundles together by threading the zip tie through the slits on the acrylic piece.

Edit Step 6  ¶ 

  • Now that you have the length of the wires to the notch, have the bundle travel along the structure as shown in image 2.

  • Make sure the green and black/green wires are sticking out on top.

  • Zip tie the bundles together by threading the zip tie through the slits on the acrylic piece.

Edit Step 7  ¶ 

Image 1/3: Solid green (3 wires) Image 2/3: Grey wires with stripes (4 wires) Image 3/3: Solid blue (3 wires)

Edit Step 7  ¶ 

  • Have the wire bundle go over the middle acrylic piece. As you wrap it over take out wires in respective order.

    • Solid green (3 wires)

    • Grey wires with stripes (4 wires)

    • Solid blue (3 wires)

    • Solid yellow (2 wires)

    • Solid red (3 wires)

  • On the other side, pull out the orange and black/orange wires. This will be for the port side battery tube and will stick out of the wire wrap similar to starboard side battery tube wires on top of the acrylic.

  • The 6 gray auxiliary wires will continue past where the orange and black/orange exit the sleeve.

Edit Step 8  ¶ 

Image 1/2: Cut the wires and sleeve where you estimate they reach the base. Image 2/2: Cut the wires and sleeve where you estimate they reach the base.

Edit Step 8  ¶ 

  • For the gray wires and sleeve, wrap up the rest of the wires all the way and measure out the length as it wraps over vertical structure and down to the base.

  • Cut the wires and sleeve where you estimate they reach the base.

1 Edit Step 9  ¶ 

Image 1/3: Cut six lengths of heat shrink and put at the ends of the grey wires. Image 2/3: With a heat gun, heat up the heat shrink. Image 3/3: Do this for all grey wires.

1 Edit Step 9  ¶ 

  • Pull the six gray wires out of the sleeve.

  • Cut six lengths of heat shrink and put at the ends of the grey wires.

  • With a heat gun, heat up the heat shrink.

  • Do this for all grey wires.

  • When using a heat gun be careful as these wires will get hot.

  • The heatshrink has an adhesive on the inside that will provides a waterproof layer between the wires and the water.

  • Re-wrap the six gray wires into the sleeve after the heatshrink cools.

Edit Step 10  ¶ 

Image 1/3: Cut the excess zip-tie on both ends. Image 2/3: Cut the excess zip-tie on both ends. Image 3/3: Cut the excess zip-tie on both ends.

Edit Step 10  ¶ 

  • With a zip tie, tie the sleeve and wires to the acrylic structure.

  • Cut the excess zip-tie on both ends.

4 Edit Step 11  ¶ 

Image 1/3: Using the same process apply heat shrink to the end to waterproof the ends of these wires. Image 2/3: Tuck them back into the sleeve when complete. Image 3/3: Tuck them back into the sleeve when complete.

4 Edit Step 11  ¶ 

  • Cut the 4 I2C wires (the grey wires with the colored stripes) about 6 cm from where they come out of the base of the sleeve.

  • Using the same process apply heat shrink to the end to waterproof the ends of these wires.

  • Tuck them back into the sleeve when complete.

Edit Step 12  ¶ 

Image 1/3: Green - starboard motor Image 2/3: Blue - vertical motor Image 3/3: Red - port motor

Edit Step 12  ¶ 

  • Now to solder on and mount the motors. The colored wires refer to a specific propeller. Match up the propellers with their respective wires designated in the images.

    • Green - starboard motor

    • Blue - vertical motor

    • Red - port motor

  • The frame is upside down right now.

Edit Step 13  ¶ 

Image 1/2: The first type has writing on the insulation and is sealed on the inside. No further preparation work is needed. '''Skip to step 17.''' Image 2/2: The second type has no writing on the insulation and is not sealed on the inside. There are a few preparation steps that must be completed in order to ensure a waterproof connection.

Edit Step 13  ¶ 

  • There are two different types of insulation on the motors.

  • The first type has writing on the insulation and is sealed on the inside. No further preparation work is needed. Skip to step 17.

  • The second type has no writing on the insulation and is not sealed on the inside. There are a few preparation steps that must be completed in order to ensure a waterproof connection.

Edit Step 14  ¶ 

Image 1/3: Image 2/3: Image 3/3:

Edit Step 14  ¶ 

  • Using your fingernails you can remove the insulation a little at a time. You need to remove enough to expose the enamel (as seen in the next step).

Edit Step 15  ¶ 

Image 1/1: Bare wire (dull copper). Also not safe from water.

Edit Step 15  ¶ 

  • Copper wire tinned with solder (silver in color). Not safe from water.

  • Bare wire (dull copper). Also not safe from water.

  • Enamel coated wire (shiny, wet-looking copper). Safe from water.

Edit Step 16  ¶ 

Image 1/3: Image 2/3: Image 3/3:

Edit Step 16  ¶ 

  • Once you can see the enamel, use flush cutters to cut some of the tinned wire. Do not cut off all the tinned wire. Some must be exposed to solder the wires onto.

Edit Step 17 Starboard Motor (Green Wires)  ¶ 

Image 1/3: You want a length/location that you will be able to tuck the wires back into the sleeve '''AND''' avoid getting caught in the propeller '''AND''' not rub against the motor bell when it runs. Image 2/3: Cut the wires at the desired location and strip the ends. Image 3/3: Slide a strip of heat shrink on each leg of the motor. '''REMEMBER TO MATCH THE CORRECT PROPELLER TO THE CORRECT SIDE'''.

Edit Step 17 Starboard Motor (Green Wires)  ¶ 

  • Starting with the starboard side, measure out where you should cut the green wires to solder the motor on.

  • You want a length/location that you will be able to tuck the wires back into the sleeve AND avoid getting caught in the propeller AND not rub against the motor bell when it runs.

  • Cut the wires at the desired location and strip the ends.

  • Slide a strip of heat shrink on each leg of the motor. REMEMBER TO MATCH THE CORRECT PROPELLER TO THE CORRECT SIDE.

Edit Step 18  ¶ 

Image 1/3: Slide the heat shrink over the solder joints and use a heat gun on all 3 joints. Make sure it is entirely heated on all sides to ensure the adhesive is melted inside the heat shrink and encapsulating the joint. Image 2/3: '''If you had to make the modifications to your motor insulation make sure that the heatshrink completely covers all the bare wire. The enameled wire will be protected against seawater, but the bare wire or the soldered area should be completely covered by completely melted heatshrink.''' Image 3/3: When soldering it is recommended that you wear safety glasses and have air circulation in the room you are working.

Edit Step 18  ¶ 

  • Solder motor wires to the 3 green wires. The order of the three wires from the motor to the 3 green wires does not matter.

  • Slide the heat shrink over the solder joints and use a heat gun on all 3 joints. Make sure it is entirely heated on all sides to ensure the adhesive is melted inside the heat shrink and encapsulating the joint.

  • If you had to make the modifications to your motor insulation make sure that the heatshrink completely covers all the bare wire. The enameled wire will be protected against seawater, but the bare wire or the soldered area should be completely covered by completely melted heatshrink.

  • When soldering it is recommended that you wear safety glasses and have air circulation in the room you are working.

Edit Step 19  ¶ 

Image 1/3: Place in the flange and tighten screws to mount motor. Image 2/3: Place in the flange and tighten screws to mount motor. Image 3/3: Place in the flange and tighten screws to mount motor.

Edit Step 19  ¶ 

  • Tuck the wires into the sleeve.

  • Place in the flange and tighten screws to mount motor.

Edit Step 20 Vertical Motor (Blue Wires)  ¶ 

Image 1/3: Estimate the length of the wires along the blue wires. Image 2/3: Cut blue wires at estimated length. Strip the ends. Image 3/3: Cut blue wires at estimated length. Strip the ends.

Edit Step 20 Vertical Motor (Blue Wires)  ¶ 

  • Place the vertical motor in the flange. Have the wires curl over the side as shown in image 1.

  • Estimate the length of the wires along the blue wires.

  • Cut blue wires at estimated length. Strip the ends.

Edit Step 21  ¶ 

Image 1/2: Solder on the motor wires to the blue wires. Image 2/2: Use the heat gun to heat up the heat shrink over the solder joints.

Edit Step 21  ¶ 

  • Slide heat shrink on the motor wires.

  • Solder on the motor wires to the blue wires.

  • Use the heat gun to heat up the heat shrink over the solder joints.

Edit Step 22  ¶ 

Image 1/1:

Edit Step 22  ¶ 

  • Tuck the blue wires into the sleeve.

Edit Step 23  ¶ 

Image 1/1:

Edit Step 23  ¶ 

  • Attach the motor to the flange and screw down the screws to hold the motor in place.

Edit Step 24 Port Motor (Red Wires)  ¶ 

Image 1/3: Cut at the estimated length marker. Image 2/3: Slide heat shrink on the motor wires. Image 3/3: Slide heat shrink on the motor wires.

Edit Step 24 Port Motor (Red Wires)  ¶ 

  • Place port motor in flange and estimate red wire length.

  • Cut at the estimated length marker.

  • Slide heat shrink on the motor wires.

Edit Step 25  ¶ 

Image 1/2: Heat gun the heat shrink on the solder joints. Image 2/2: Heat gun the heat shrink on the solder joints.

Edit Step 25  ¶ 

  • Solder on motor wires to red wires.

  • Heat gun the heat shrink on the solder joints.

Edit Step 26  ¶ 

Image 1/2: Image 2/2:

Edit Step 26  ¶ 

  • Tuck the wires into the sleeve.

Edit Step 27  ¶ 

Image 1/1:

Edit Step 27  ¶ 

  • Attach motor to flange and tighten the screws to mount the motor.

Edit Step 28  ¶ 

Image 1/2: Spin the motors with your fingers and ensure that it isn't rubbing against any wires, or the sleeve. Image 2/2: Spin the motors with your fingers and ensure that it isn't rubbing against any wires, or the sleeve.

Edit Step 28  ¶ 

  • Put zip ties to hold down the wire sleeve away from the motor bells. Do it for both sides.

  • Spin the motors with your fingers and ensure that it isn't rubbing against any wires, or the sleeve.

Edit Step 29  ¶ 

Image 1/1:

Edit Step 29  ¶ 

  • Continue your build by progressing to Guide 5.

You're Done!

11 Comments

I cannot get the locknut on the motor screw mounted upside down for the life of me. I've tried as much as I can think of and the screw just won't fit down the top of the nylock. Please help!

Mason Hall - Reply

Nevermind, I got it. Make sure you spin the bell, not the mounter! Derp.

Mason Hall -

According to the BOM the motor shaft is M3 threated and the propeller nut is M4. How does it fit together?

Eugen - Reply

You are correct, the stock propeller has an M4 thread. We have worked with the manufacturer and when they are making the propellers for us they press in an M3 nut instead of an M4. The propellers that come in the kits and that we sell in our store are all M3 so the connection works.

OpenROV -

I think it would be worthwhile to add a note here saying to label the ends of the 6 grey auxiliary wires with their trace number (sorry I don't know the proper nomenclature - new to all this) - eg. TP-20, TP-25, etc. I'm adding an external servo and although it's not a big deal to cut open the waterproof shrink tubing and use a multimeter to label the wires, it would have saved shrink tubing and a step or two to label it in the beginning.

Kimi - Reply

by trace I think I meant test point or pin number

Kimi -

If you dont have a heat gun, a camping rocket stove works fine if you are careful and wrap the rest of things (motor for example with something). Tried the normal electric cooking stove, that works fine as well but it gets complicated for heat shrinks close to the motor on soldered pieces. Be sure to do a trial run on the discarded pieces of wire first.

sankar subramanian - Reply

If you purchased the optional IMU/depth sensor it will be connected to the four gray/striped wires. You might strongly consider leaving them untucked from the sleeve and not covered with heat shrink. Otherwise you will have to dig them out of the sleeve and cut-off the heat shrink during IMU installation. If you don't install the IMU be sure to heat shrink and stow the wires in the sleeve.

Chris McCann - Reply

Chris - Thanks for the great comment. You are completely correct! We did go back and forth about whether or not to include these words of wisdom in the directions. Ultimately, we have the directions the way they are because not everyone purchases as IMU and we do not want those wires to accidentally be left exposed to the water. Also people get really excited to get their ROVs in the water (completely understandable) and can forget to put the IMU on before the first water test. We do recognize that it is a few minutes of extra work, but we believe that in the long run it will protect a few ROVs from failure. Please continue to post other build comments that can help others!

OpenROV -

Ahaha wish i read that sooner.

Grace - Reply

So, when do I attach my IMU?

Jerry Fiddler -