Is anyone else having the problem that the plastic of the shroud is cracking around the mounting section of the shroud. It seems to have been caused by use over time (we’ve been using these thrusters for 6 months) and there is cracking all around the plastic on both thrusters. Since the beginning I’ve been worried about over tightening the bolts but I suppose the repeated mounting/dismounting is the problem.
Could we get replacements for the shrouds as I’m worried they are going to fall apart.
It is not my design, but I am going to say that based on using PEM nuts etc. that you will end up with cracking in that area shown in your photos. The issue here revolves around torque specification or lack of one. Since the material is plastic and that they are held captive … you can’t apply a lot of force when you are mounting the items or you are going to stress the plastic. If it doesn’t crack it then, vibration etc. is going to help contribute to the problem with long term use. It is just a fact of life.
Interesting - I’ve never seen one crack like that. We see hairline cracks right around the threaded inserts occasionally, but never through the entire nozzle. What screws did you use to attach the thruster and how tight did you tighten them? If the screws were too long they will push directly on the plastic as you tighten, which could cause this.
Please email me and we can see what we can do about getting a replacement sent out to you.
While this is an old topic, I’ve just found identical cracking in all six thruster shrouds on my BROV2. The ROV has been in storage for about 6 months and I didn’t notice any issues while in use before then. Very strange. . .
Make sure you use the provided attachment brace instead of directly bolting the thrusters to your craft. I think our repeated attaching and removing of the thruster using its built-in metal inserts put stress on the surrounding plastic which could have been avoided.
Then again, I wonder if the torque applied from repeatedly screwing the thruster in place compares with the torque/ force from the thruster being used.
Was the ROV stored indoors? Was it subjected to violent launches? I’ve repeatedly launched the BROV2 from 10 to 15 feet up (into water) and have not seen any cracking on thrusters…
Did you ever found out what may have caused this? I was about to prepare our university’s ROV for its first sea dive and started to notice these cracks on all of the 6 motor nozzles.
The one in the pictures is the most damaged one. I thought it might have something to do with the water in our university’s tank, maybe the maintainnance chemicals (it’s just NaCl as far as i know). However when I was about to replace it, I found out that the new one had also these cracks (pictures below)
The ROV has been stored indoors, in a closed room. This room has an AC/ Heater which is used when needed during some seasons throughout the year, neither the ROV nor the replacement parts are close to the AC/Heater output. The replacement part has always been contained in its package cylinder.
Finally, this ROV and its parts were purchased in 2019 through a distribuitor which no longer sells BlueRobotics parts. We also own a BlueROV1 with T100 thrusters, these seem made of a different plastic (it feels different when touching it), and these have not developed any crack.
I hope you can help me figure out what may have caused this so it doesn’t happen again and if there is a way to negotiate a replacement.
This is an expected/known issue. A number of years ago, we were using an injection mold supplier that started playing games/being lazy with the part quality, and were plagued with cracking nozzles and cores for a while. We swapped to a new supplier, and the problem hasn’t come up since.
I can tell this is one of those, due to the glossy part finish. The newer parts since that have a matte finish.
However, the second lead cause of crashing like this is exposure to thread lock. Any thread lock coming in contact with polycarbonate will absolutely destroy it very quickly, sometime customers accidentally use it on thrusters.
Original response
That damage looks like failure from some kind of impact, perhaps repeatedly, which would likely be made worse by stress-concentrations from over-tightening of screws. There’s also some possibility that the testing tank water chemically brittled the plastic - it’s generally a good idea to rinse anything that’s been in salt-water or other chemicals with fresh water after each dive.
That’s very odd, and sounds like either damage during shipping, being stored with weight on top, or maybe significant repeated expansion/contraction from temperature cycles (which seems somewhat unlikely).
Very interesting, I wonder if they could be a ‘copy’ product made from a different plastic.
Hopefully my comments are some indication on what might have happened, and helpful in what kind of things to avoid in future. I’d suggest you contact our support team (support@bluerobotics.com) with a link to your comment here to discuss replacement. They’ll want to know which supplier the thrusters were bought from and when, and might be interested in getting sent some of the broken ones so we can try to determine exactly what went wrong and things that would cause it
Thanks for the update, I will contact support then. I am 99% sure that these were not exposed to thread lock, specially the one that was just taken out of its package, but they surely were exposed to the silicone grease used in the O-rings (I don’t know if this has something to do).
I forgot to mention that the dome retaining flange also had these cracks, and it seems to be made of the same shiny plastic as the nozzles.
We purchased 2 more BlueROV kits from another distributor that arrived last week. I just checked and the nozzles that arrived have, in fact, the matte finish you mentioned.
