Hi!
Has any of you ever encountered a stripped set screw on a T200 ?
Sadly the hex key stripped the set screw on the first attempt.
Any idea how to remove it ?
Thanks
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Iāve been struggling with one of these too!
I found the lug screw doesnt seem to take a metric sized key which is probably what caused it to round off. Normally I would use a screw removal tool where you drill a small hole and reverse screw a removal tool bit. Havent been able to do this so far because of the difficulty accessing the lug screw and being stainless steel it is very hard to drill.
Iām thinking I will have to get a hardened drill bit and completely drill out the entire lug screw. This will destroy the thread in the collar as well so both would need to be replaced.
Not sure there is any other way but be pleased to hear any ideas (and the correct hex key size!).
PS A tip for drilling 316 stainless steel is to use a low speed and squirt water on the hole you are trying to drill. Keeping it cool saves your drill bit dulling and reduces the heat which just makes the metal you are trying to drill even harder.
Thanks for the reply, @BillyBudd . Itās reassuring to know Iām not the only one encountering this problem.
I considered your suggestion of using a drill press with a hardened drill bit, but I see it as a last resort. Drilling 316 stainless steel is quite challenging, and Iām worried it might compromise the original stator balance.
By the way, itās possible that the material is 304 stainless steel instead of 316, as it seems more prone to rust ?
In the last 24 hours, Iāve tried removing the set screw by gluing the hex key to it with cyanoacrylate glue and letting it cure for 24 hours, but without success. The set screw is too rounded off. I managed to apply a bit of torque, but as soon as I reached a few Nm, the glue bond between the set screw and the hex key broke. 
Next, I plan to try using a Torx key instead of a hex key.
Itās quite frustrating to be unable to use the BR2 because of a $1.50 problem.
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Hi @Lyra, sorry to hear youāre having issues with one of our products.
If you havenāt already Iād recommend filling out our āproduct problemā form (which thereās a link to from the āResourcesā at the top of the forum), to get some help from Blue Robotics support, and potentially a replacement or refund of one of our components thatās not working as expected.
Youāre of course welcome to post about this kind of problem on the forum to discuss with the community, but the official support we provide here is focused around finding the causes of unknown issues, digging into software specifics, understanding marine robotics principles, and helping with custom integrations 
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I feel your pain @Lyra but not sure there is any other way than drilling but keen to see if your methods will work. Even 316 SS can show surface rust and that part of the motor is susceptible which tends to lock up the lug screw. I think its because its difficult to flush/wash?
I think the worst that will happen is the lug screw and the locking ring will need replacing. but the key to drilling SS is to constantly flush with water while drilling. You need to keep the drill and hole as cool as possible and the drill on a low speed. Its suprisingly easy to drill SS when using this method.
I had a few like that on some older M200s - I think simply flushing motors with fresh water after use in salt water isnt enough as clearly salt can still get trapped here over time. Another salt trap exists in the M200 mounting frame itself around the metal thread inserts. When these become salt/rust siezed you cannot remove the motor without destroying the mounting frame. I think the solution is to occaisionally dissemble the entire motor, clean and apply some anti corrosion grease like CorrosionX?
EDIT- actually dont do this as petroleum products will damage the plastic parts of the motor housing (see thread).
Similarly some stators can be susceptible to rust an so should be regularly cleaned as well. Iāve also noticed some scratches on the motor spindles presumably caused by the lug screws in the part you show becoming loose. So seems important to check this occaisionally and re-installed with loctight to prevent this from happening as might contribute to the issue you illustrate.
Another related maintenance issue relates to something @tony-white once referred to as āheat-cyclingā. I think this refers to the repeated stess on plastic components caused by fluctuations in environmental temperature. This can cause the M200 mounts to crack (usually fine hair cracks) around the metal screws as the screws expand in heat and cool when placed in water. Solution would be to avoid leaving the ROV in the sun for any period (as advised) and store in a cool place with a constant temperature (eg. not in a periodically heated room). Also overtightening any screws (as advised) might increase the likelihood this will happen.
Try use a left hand twist drill bit. That way it tries to bring the fastner out the whole time your drilling. With any luck should cut down your efforts.
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Absolutely 
Thats the best way to remove a stripped screw. Main issue is getting a left-handed drill bit (and left-handed removal tool) into the lug screw as is not easily accessible on the assembled T200 motor.
I found that this may not be neccesary though if you first use a more expensive hex key (eg. Wera brand) to remove. Taking care to insert fully I have removed even a totally rust-siezed lug screw so long as you applied some anti-corrosion lubricant like WD40 first (but see this thread for precautions using WD40 on/near plastic).
Once the lug screw has been stripped though the only option is to drill/remove but this is not easy and have destroyed two T200 motor mounts trying.
Certainly wise to check these regularly particularly if youāve made my noob mistake and assumed a swimming pool is good for a fresh water flush - nope!
Very true. I understand there are space constraints. I have 20 plus years of horror stories myself with small set screws, just isnāt much tool surface area contact for strength no matter the tool brand, however a quality set of Allens is key no pun intended. Making sure the hex hole has no impacted crud to take away from the tools insert depth is very important aswell. The small sizes especially you have one good shot at extraction before disaster and thats it. This being a critical component that rotor shaft end sure looks like a great place for a snap ring to top the assembly off and backup that lock collar if the screw does happen to backoff. Seen a post of such an event. That to happen once at depth is a hundred times to many in my book. Could have been very costly as you owners are quite aware im sure.
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