[PSUBS-MAILIST] PSUBS manipulator

Wed Sep 23 15:40:13 EDT 2020

Sometimes those outer O-rings are regarded as sacrificial in underwater rotary
shaft applications. They wouldn't see as much muck or get as much wear on a manipulator as they would operating a trim tab on a speeding boat.
Maybe just pack some grease between the two O-rings if possible.
They are great for this application though, being built for a rugged marine use.
For me I am still not sure whether I will go with electric, hydraulic or pneumatic
on the first few joints & then use some open motors for grippers & wrist.
I am wanting a long manipulator to use as a periscope & reach my thrusters.
Alan

> On 24/09/2020, at 6:13 AM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Very interesting. I have a mix of extreme duty and standard duty, but all mine are plastic!
> 
>> On Wed, Sep 23, 2020 at 1:49 PM hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Alec, I have an actuator with a metal end cap.  I think it is the extreme duty model
>> Hank
>> 
>> On Wednesday, September 23, 2020, 6:55:22 AM MDT, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> 
>> Oh, that's a good find Alan, I was unaware of the second O ring. My suggestion would be to remove the outer one if going very deep, or drilling a tiny hole between the two. Else the O-ring would tend to squeeze the shaft at depth, freezing it up or increasing current draw. My impression of these actuators is that the likely failure point is the top cap (the disc-shaped piece that ends the main cylinder). Not that pressure would be a problem, but it's a plastic piece and includes the pivot point of the actuator, so is subject to significant mechanical stress.
>> 
>> 
>> On Tue, Sep 22, 2020 at 8:17 PM Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Thanks Alec & Hank.
>> I found the diagram below that doesn't show any switches.
>> I like the idea of air compensating them, perhaps with an over pressure from
>> a regulator as Cliff is using on his thrusters.
>> The two shaft O-rings are as per the Minnkota, with the outer O-ring doomed
>> to fail when the pressure gets high enough. If there was an overpressure  the 
>> inner O-ring would fail first (hopefully)  leaving the cavity between the two with air.
>> Or is it filled with Greece?
>> Alan
>> <image1.PNG>
>> 
>> 
>>> On 23/09/2020, at 10:49 AM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Hi Alan,
>>> 
>>> I don't think there are any microswitches in these. Nor in fact any sealed components at all that I saw.
>>> 
>>> Best,
>>> Alec
>>> 
>>> On Tue, Sep 22, 2020 at 5:24 PM Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> Alec & Hank,
>>> when I was compensating linear actuators ( a long time ago ) mine had
>>> micro switches in them that stopped the travel.
>>> I am not sure whether the Lenco has them or not!
>>> I was sticking a hot needle through the plastic housing of the micro switch to
>>> help compensate them, as it was pretty well sealed & I feared it would randomly
>>> be switched because of the oil compensation pressure at depth.
>>> Also the brushed motors were sealed. This again may be a problem if the 
>>> compensating oil hasn't fully filled the cavities inside the motor housing &
>>> suddenly experiences pressure as you descend. The small brushed motors
>>> can have what Phil describes as a "herky jerky" action when oil compensated
>>> due to the oil lifting the brushes off as they spin fast.
>>> Mentioning this in case you encounter problems operating them at depth!
>>> Alan
>>> 
>>>> On 4/09/2020, at 9:59 AM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>> 
>>>> Hi friends,
>>>> 
>>>> The PSUBS Community Projects page (http://www.psubs.org/community/projects/ ) now features an "open source manipulator" developed by Hank Pronk and me. This is an intentionally simple manipulator built using only a drill press and an angle grinder, except for a few plastic bushings that were turned on a lathe for expedience. We purposely avoided things like aluminum welding, to keep it's fabrication as accessible as possible. The page contains blueprints, photos, and a bill of materials - but I recommend beginning at the "Start Here" document in the ZIP file. Please don't hesitate to reach out if you have any questions, or if you have any suggested improvements.
>>>> 
>>>> Best,
>>>> Alec
>>>> _______________________________________________
>>>> Personal_Submersibles mailing list
>>>> Personal_Submersibles at psubs.org
>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20200924/49c7b187/attachment.html>