roedj

Dave,

I have no intention of starting any kind of fight here nor flame war. All I want is hard information.

My concern with your stuffing box is that water from the outside will be driven into the stuffing box, emulsifying the grease, thereby reducing its density (thickness) and allow it to squirt out the other end into your WTC.

You say that does not happen. OK, great.

1) So, specifically, please tell me what kind of "marine grease" do you use. I really want to know its brand name and part number if there is one.

2) Also, is there a reason you used stainless steel shafts instead of copper or brass?

OK. No fight, no hostility from anyone.

Thanks for your time,

Dan

junglelord

I am interested in using it on my Enterprise Aircraft carrier, so I am interested in the low price and hardware store self items.
Thanks

Skip Asay

"My concern with your stuffing box is that water from the outside will be driven into the stuffing box, emulsifying the grease, thereby reducing its density (thickness) and allow it to squirt out the other end into your WTC."

Just the fact that it is not "hard" will allow the outside water pressure to force it past the bearings/bushings.

"2) Also, is there a reason you used stainless steel shafts instead of copper or brass?"

Oilite bronze is much harder than brass so the brass shaft will wear very quickly. On top of that, a long SS shaft is much less prone to bending than either copper or brass. And last but not least, SS shafts are usually ground which means that if it's supposed to be 1/8" it will measure .125" its whole length. You certainly can't say that about brass and copper.

Skip Asay

junglelord

The rubber boot, that is on his system, is on my Robbe Seawolf, minus the grease, and they do not leak...I am a newbie, but I think the rubber boot makes the seal...just a thought based on my Seawolf, which has no grease, just an endcap with a port, I drilled, put in the pushrod, put it through the boot and it has not leaked yet.
Mind you I only go about 8-10 feet deep.

Also my Seawolf propshaft is only waterproof due to grease, mind you, it is a long shaft and so a lot of grease.
None is spitting into my WTC. It did leak water from my propshaft into the WTC, till I installed a grease nipple and packed it properly.
I did not put in a grease nipple initially. It would need to be retrived in about 45min due to the slow leak at the prop shaft.
I had put grease on it, when I first installed it, but I never got it into the water until two or three years after that.
I also did not put on enough grease to seal, as I did not understand at the time, the purpose of the grease.

This is my experience....not a speck of cereal, milage may vary.

roedj

Junglelord,

I'm not clear on the rubber boot. I see them on the control surfaces push rods but I'm interested in the stuffing box for the prop shaft. Tell me more, please, about the stuffing box on your Robbe Seawolf. Or perhaps I've misunderstood and there's no stuffing box on the prop shaft on the Seawolf just an ordinary "O" ring type bushing.

Dan

junglelord

There is no rubber O ring on the Robbe Seawolf.
I think it works like a stuffing box, as when I did not have it greased properly it leaked water.
I put on a grease nipple, pumped it full, and now no leaks.
I am a newbie, but that is my experience with my Seawolf.
It is about 12 inches long, mind you. So thats a lot of packing, and no, it does not spit grease.

Concerning Aqua's, I thought he had a rubber boot on his shaft, my mistake.

AQUASUB

Hi Dan

The 2 oilite bearings that I have ben useing for years now are from   SmallParts .com they come in many dimentions and types but in general the the ones that have a lip or outer flange are the best ,in 3/16th iner diamiter, the stainless steel Centerless ground and polished  precition shaft is also the best way to go and will seal and last for many years .

I garantee it persopnaly. It will not leak water nor spit out alot of grease.

The grease can be marine bearing packing grease or believe it or not regular black bearing grease,the light brown stuff is too sticky and can cause some friction.

I simply cut the K and S tube to the desired lenght it can be from 3/4in long to 4ft if desired thats the beuty of this simlpe method ,any size can be made in any diamiter even in metric MM.Just order the desired bushings.

Shafts can even be ordered with a desired thread on one end.

The Shaft must be a centerless prescition ground type which are used in fine instruments and don't cost much more than the standard SS shaft.

I gring the ends at the desried ares to acomodate a set screw or screws.



Now to asemble the tube onece cut must have no burs so that the bushing fits inside of it to the flange ,the tube must be as close fitting as is possible to the bushing and K and S makes them just take your bushing to the store and fit it.

Take one bushing and either GOOP it carefully to the tube ,naturaly the uoter part of the bushing not the shafts bushing.

Let it dry  for an hour and then fill some gease in the tube with with a syringe ,thats right a syringe will push the grease right in,usualy about 50% is enough.

Glue on the secund bushing ,after you have clened any grease from the opening of the tube.

Insert the shaft that has been cut then had the end corner edge rounded a bit so that the shaft will slide into the bushing and not get stuck.

Once the shaft  emerges from the other end rotate the shaft to be sure that it is freethen  let the assembly dry on a flat serface.

If the shaft is too long or needs more flats exetra it can be added ,even if the tube is to long or short simply pull the bushings or one bushing apart and redo the above.


Its simple and cheap yet uses the best materials available and I garantee it will not laek for long time of marine use,high speed or not.

No rubber seal to fail and they do at the wrong time.

I also have the Seawolf she was my first sub and she went very very deep in Lke Tahoe and never laeked a drop,her stuffing box has the same graese it did then,no need for those niples if you use the right materials ,that is the difference ,many makers use inferior material with lousy tolerarances and hence they wear out or leak in short order,Robbe makes a good stuffing box ,but grease is super important not only for lubrication but for sealing out water.

Now one might think that the water will emusify the grease and get in,it might happen with the lose tolerance bushings as more water can get under the bushings lose fit.
In use there might be some minor grease expelled but that will stop in a runn or two as the grease stabalizes and lubes the bushings also normal thermal expantion can cuse some minor extrution but will also stop in a few runs.
I think my boxes are lapped naturaly as they wear and simply hold up exeptionaly well,I mean well because think about it my ballast sytem makes a vacume inside of the casing  and if I had bad stuffing boxes I would have a leak and a nasty one!
Such is not the case or as I said before I would have dumped this hobby a long time ago.

The stuffing box that I use is that important  ,it works never fails and is super inexpensive ,made to any custom fit and its one of my secrets to a good running sub and now you can make it as well.
I garantee IT.
See diagram of install...I can give exact bushing  part numbers exetra.


Dave Amur Sub Yard 

AQUASUB

Stuffing Box Details

AQUASUB

As one inserts the shaft grease will be extruded from the other end ,don't mind that its just excess.

AQUASUB

No boot on shaft only on the servo rod and they are another easy method ,will show how to make as well.

roedj

Dave,

Yes, please, show us your design for sealing servo rods.

Dan

AQUASUB

Here is the methodI use .

The bellows can be from Robbe or a smaller and just as good but alot cheaper on Ebay ,look up bellow seals and there chould be a vendor in China,there like 4 bucks for 14 bellws ,man what a deal ,these are great bellows ,ther strong and last a long time used with RC boats.

Once you get them get the K and S tube that fits them snugly not to lose or tight,there will plenty of clearance for the servo to rod to travel without binding,thats the beuty of the bellows seal,no binding and no intrution of grit into a O ring seal and there is no binding ,friction to drainthe power from the servos ,very important thingwhen one realized that just how much the 2 servos are used or on my casings 3the forward dive plains servo also has its bellows seal.

On subs that i havebuilt some 6 years ago the bellow seals are still perfectly sea worthy.

Just be sure to ocationaly check them for cracks and pressure check with soapy water or emersed in water.

These realy hold up well and are easy to install are a snap to replace and best of all super inexpensive quality product.


If you have more questionsI am more than happy to help.

dave amur Sub Yard

Home to thedeepest divingRC Subs !!!

AQUASUB

The installed Diagram and the bellows I use,the smaller ones from Germany are not Robbe and are not as flexable nor have enogh travel and are more expensive,go with the ones in the green picture.

Notice that the stainless rod is sauldered to a brass cleives used on air craft by Sullivan and are the large ones,the rod vertualy screws into the cleives then sauldered.

Skip Asay

Here is a method of sealing propshafts that I've been using for many years with just a drop of oil added about twice a season. Note that this method can use either "O" rings or cup seals, which is what I personally prefer. And I've never had one leak and there's certainly no messy grease to contend with, either. Also note that this can be used for pushrod seals as well.

I've been using these seals in my now 30 year old Type XXIII and have never had one leak or go bad in any way. Also, when I had SubTech, I sold literally thousands without any problems (not counting those guys who didn't know about reading the destructions)! And I've never had a servo go bad, either.

OOPS! I left out the important part. Since the seal is incorporated within, it's not a good idea to use Goop to hold the bushings in place. But that's easily attended to - just take a punch and LIGHTLY dimple the brass tube right over the bushing. BUT MAKE SURE THERE"S A SHAFT INSTALLED. Without that, you'll end up deforming the bushing. With a shaft, everything stays just fine.

Skip Asay

AQUASUB

That looks exactly what I used before but don't now because the O ring would eventualy fail as it is free spinning and just lack of lube would also cause the bushings to fail as well.
I used to use 2 O rings and grease but also found that not necessary as only good bushings and shaft with the above grease did the trick so well that I still build them that way.
Grease might be a bit mesy but if delivered properly and handled well the clean up is very minimal and the benifits far outwaigh any little mess.
Useing a light oil in a marine prop shaft aplication is just going to fail as the light oil is easily displaced or disolved in water and made worse in warm weather.
As for a servo rod seal ,again servos have a arck of travel and are not linear unless you order that type ,they will bind the bushings as the servo moves from center to extream left or right limiting there travel,not good and the greatly added friction will cause the servo to fail prematurely and draw more power than necessary also not good,so why go threw all trhat hassle to end up with a diffective set up?A simple bellow seal performs far better for a fraction of the price.

I would never even consider that aplication it would be asking for a leak.

Dave Amur Sub Yard

roedj

With that I'd like to close this thread unless someone has something else to add. I'd like to thank Dave and Skip for sharing their approaches to a common submariner's problem - keeping the water out.

Dan

Noibla

The bellows can be found at bicycle shops. they are used on brake systems

AQUASUB

l supose it could be used ,mine are just 4 bucks for 14 bellows and there a good quality product.

Dave