How do your motor bearings hold up on your motors, mine get noisy after short usage


#1

Hi All

The bearings on my motors seem to get very noisy after a few dives. I am trying to understand why they seem to fail so early. When I was first testing the ROV in my neighbors pool the motors seem to become very noisy a short time afterwards, so I thought they were just cheap bearings. I bought new bearings and replaced them all before going to Little Hawk Lake on my first open water dives. The bearings seem to hold up even after about 8-10 dives with no issues. When I came home and put the ROV back in my neighbors pool for the kids to play with I noticed a few days later that one motor developed very noisy bearings. I am now thinking the the chemicals used in their pool may be the cause of the bearings failure and I think Bromine is one of the chemicals used.Has anyone else had premature bearing failures and under what conditions? How have they help up in Salt water dives? I did use a Teflon spray on all the motors to repel the water.


#2

Mine are also very noisy and I have never been in salt water and I have all so been using Teflon spray before each dive. Mine are looking rusty. See attached. I have not changed them, never thought about doing it.

John

1225-motorbearingleft.jpg (166 KB) 1226-motorbearingright.jpg (133 KB)

#3

Mine were noisy even before I had the ROV in the water the first time. I blamed the mechanical stress during removing/inserting the motor shafts several times during the ROV assembly for it. Sure they are the cheapest bearings you can imagine if you look at the price for the motors. What else can you expect? But I still think it was right to chose these motors for low cost replacement.
-Stefan


#4

Thanks for your input John & Stefan I just wanted to make sure it was not just me. After seeing John's pictures mine look better than new :) the poor old fish that have to listen to all this noise.

The project that Ben McCandless is working on, putting the motors in a tube with mineral oil is looking very promising.


#5

Hi John your motor enclosures caught my attention. I was going to order up new motors, the same as those used in the OpenROV project but was pondering how I should mount them. Could you post a few more pictures of these and one showing how you mounted it to the side of your ROV. As you can see I have a mount on the side of the tube to which I attach the duct fans, these duct fans are about 94mm in Diameter and now that I have gone to the 65mm props I would like to streamline the Motor enclosures. thanks



#6

I just screwed them on with 6-32 brass screws, nothing special. This weekend I am going to print a new set with a few changes.

John

1220-motormountfront.JPG (148 KB) 1221-motormountside.JPG (106 KB) 1222-motormountiso.JPG (139 KB)

#7

I like where you are going with this. I have been looking at these: http://www.ebay.com/itm/130844768893?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

but there is no motor mount and a way to attach them to the ROV. Is it very difficult to design these and what software do you use. I might give it a try although I do not have access to a printer but maybe I could look around to see if there is anyone who might have one or maybe check with the community college. I noticed that the motor mount could be made smaller and might help with reverse so the water does not have as much surface area to hit, maybe even put a point on the motor mount arms much like a spear head so the water flows around them.

great work!!


#8

I have answered my own question by downloading Sketchup Make software. seems be very easy to use once you play with it a bit unless someone knows of a better software package to use.


#9

Sorry I didn't reply. Sketchup is a good program and the price is right. I have been using Autodesk Inventor, which is pricey. There is a add on for Sketchup which allows you to bring in STL files and it is free. Also you can always upgrade to Sketchup Pro. I have used Sketchup but find Inventor more accurate.

I was planning on printing new motor mounts this weekend but my 3D printer is giving me problems (it is plugged up). I made the new version motor mount a little longer and opened up the end where the motor mounts for better water flow. If I ever get new ones printed you could have the old ones.

1217-OpenROV_Dev_Horizontal_Motor_Mountv3a.pdf (119 KB) 1218-OpenROV_Dev_Horizontal_Motor_Mountv3c.pdf (144 KB)

#10

Hi John thank for your reply and photo's. I like your creative design and Ideas great work. Thanks for your offer on your old ones but I am now doing my own design and will look for a printer in my area that might be able to print them. I need 4 because I have 2 vertical motors. This is fun designing these and I will have to look to see if AutoCad has STL functionality because I would prefer to use it over Sketchup Make just because of accuracy and I am use to using it.


#11

Hi John

I have created a design for my thruster and wanted your opinion to see if this could be made using a 3D printer. I do not have any experience with 3D printing and I know you have, so any comments you have would be welcome.

Regards

Dave



#12

I like the looks! If you build this with the largest ring face down (prop side against the build platform) you need to use a lot of support material to hold up where the motor fastens (center platform). If you flip it over so the motor back face is down on the platform you then need to use support material to hold up the outside ring. My 3D printer can not build in open air it needs support to hold the material it is putting out.So it will build a platform to support the open area. This can be build it will just use a lot of support material. When I made mine the motor side was down on the build platform and it was flat against it. Using very little support material. Hope that makes sense? The printer specifies how much of an angle it can go with out support material.


#13

Thanks John yes that does make sense having to use support material. I will put some thought into to that to figure out the best way to do it. But I think you are right starting from the largest face down. and building it up from there,


#14

Hi again John

Hope those bearings work well for you, please let me know how they hold up after you get them installed. I came up with a different design after your comments on the 1st thruster. I think this will print much better and it will be a smaller profile because of the way I am going to mount the prop to the shaft of the motor. I am planning to have the bottom of the motor mount sit on the 3D printer plate and then build it up from there. I do have some curves on the bottom and was not sure if the 3D printer can do that. Please give me your comments and any changes that you might do to improve on this design.



#15

Your 2nd design looks good and should be able to built with little problems.

On the bearings I have pulled the 3 motors apart. Two of the motors the front bearings were in really bad shape and I have not been able to get the outside bearing races out of the motor housing. When I pulled the shaft with magnets off, the balls fell out and the inside race stayed with the shaft. Ugh!

I had order the bearings and they came, but did not realize that there is 2 different size bearings and I had ordered only the back bearings. You need for the back a bearing 8mm OD, 3mm ID, 4mm high and the front bearing is 7mm OD, 3mm ID, 3mm high. So now I am waiting for the front bearings to come.

Any idea how to get the outside race out of the motor? There is no lip to catch on to tap it out.

1210-motorbearings.jpg (232 KB)

#16

Hi John

I am very sorry about miss leading you on the bearing sizes. I did not notice the different sizes until you pointed it out. I would have ordered only one set when I went to do so, Thank you for pointing that out.

As for the outer bearings race no coming out, that happened on my larger motor and I ended up using a set of pliers that opened rather than closed when you squeeze them, the tips were small enough to fit into the ring and I was able to just pull it out very easy. The other method I read on was someone using a soldering iron to heat up the motor mount then the bearing fell out.using both methods in you case may work.


#17

PS: If you would like to reduce your cost on the bearings I would be interested in buying some of the extra ones form you. I have 6 Motors to do. Let me know if interested.

Regards

Dave


#18

Hi John

How did the Stainless & Ceramic bearings you ordered work out for you and were you able to get the old bearing rings out that you were having problems with.

Regards

Dave


#19

I installed the new bearings and the motors don't rattle anymore. One of the motors I could not get the outside race out, so I replaced the motor. On the new motor I changed the bearings also. So now all 3 motors have the ceramic bearings. I have only had it in the water once since changing the bearing and I had a leak in the electronics housing.

I have reprinted my motor housings ("ears"). I made them lighter, longer and with a natural color. The leak I mentioned above was from adding more wires so I can light up my "ears"

John


#20

Great to hear they are working well, I was reading this article and thought about your ears and wings http://hackaday.com/2013/02/26/giving-3d-printed-parts-a-shiny-smooth-finish/ I was wondering if you did anything like this to smooth out your 3D parts. I have yet to find anyone in my area that has a 3D printer so I am still on hold to get my motor mounts printed.