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stuffing tubes - 4/6/2008 1:13:09 AM   
hammondcrazy


 

Posts: 4
Joined: 4/6/2008
From: huron, SD, USA
Status: offline 		Hello I am building a non scale rc submarine. I have the designs all done as far as the hull and framing. I need to know what you guys use to seal the motor shaft from water entering the sub. can you all help me? Thanks Mike.
       Post #: 1

RE: stuffing tubes - 4/6/2008 2:27:27 AM   
CrunchyFrog



Posts: 465
Joined: 6/10/2005
From: austin, TX, USA
Status: offline 		A really common way of doing it, simpler than building a stuffing box, is to have your prop shaft a solid metal rod--and then jacket it with a short section of hollow rod, the next size up, around the point where the prop shaft exits the watertight cylinder.

I use 1/8" solid rod for the prop shaft (standard size for r/c boats), and a half-inch of 5/32" hollow rod to seal it.

That said, I should say I'm drydocked for the last couple of weeks because my propshaft seal that had held up great for quite a few sessions suddenly decided to leak like a faucet.

Then there's such a thing as a stuffing box--a simple enough thing you find them on Wal-Mart subs, though my homebuild can't have one--it's basically a pot of thick grease, Vaseline or the like, that your prop shaft runs through. The hole in each end is fitted with tight tolerance to your prop shaft; the water presses on the water-exposed side of the grease, deforming it; it will push fine droplets of grease into your watertight cylinder as your shaft spins--but Vaseline, unlike liquid, won't flood your boat.

D & E Miniatures in Virginia or Mike's Sub Works (Texas?) might sell a stuffing tube/box.Subworks seals



< Message edited by CrunchyFrog -- 4/6/2008 3:31:10 AM >

(in reply to hammondcrazy)
       Post #: 2

RE: stuffing tubes - 4/6/2008 3:48:42 AM   
hammondcrazy


 

Posts: 4
Joined: 4/6/2008
From: huron, SD, USA
Status: offline 		Thanks. Mikes Sub Works is the place. I may just buy the Albacore. The price is right and i have TONS of rc radio equipment. I may get that and then build my own. I didn't think that RC subs were that affordable. I can be in the water in no time. Thank you so much for your help!!!!!! Mike.

(in reply to CrunchyFrog)
       Post #: 3

RE: stuffing tubes - 4/7/2008 7:02:40 PM   
CrunchyFrog



Posts: 465
Joined: 6/10/2005
From: austin, TX, USA
Status: offline 		Best of luck to you ! I think it would be awesome to have a model based on USS Albacore. I knew a sub vet whose engines the USS Albacore had inherited, when his sub (Tang, SS 563) got an upgrade.

By the way, anybody else want to share their method of sealing their prop shaft? I don't try to align my prop shaft down to the milimeter; that might be what I someday have to do, if I want to have zero leakage every time.

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       Post #: 4

RE: stuffing tubes - 4/14/2008 2:46:41 PM   
petn7


 

Posts: 137
Joined: 5/25/2004
From: City, PA, USA
Status: offline 		I would not recommend suffing boxes to seal propeller shafts on submarines. They might work for a few minutes, then they basically become a screen door on a submarine.

Caswell Plating sells 1/8" and 3/16" shaft seals. I've bought them for my sub, but they're only installed and have not been tested, so I can't give a personal review yet.

I could be wrong, but SubTech 1/8" pushrod seals work well as propeller shaft seals.

< Message edited by petn7 -- 4/14/2008 2:48:48 PM >

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       Post #: 5

RE: stuffing tubes - 4/14/2008 8:00:34 PM   
CrunchyFrog



Posts: 465
Joined: 6/10/2005
From: austin, TX, USA
Status: offline 		I think I know what you mean by "screen door." The looser your tolerance, in a sleeve the quicker the sealing goop bonds to shaft or sleeve and gives water a place to enter.

What''s the difference between shaft seal by Caswell, and a stuffing box?

Is a stuffing tube just a solid rod with a hollow-rod sleeve, with grease in between?

(in reply to petn7)
       Post #: 6

RE: stuffing tubes - 4/14/2008 11:01:29 PM   
petn7


 

Posts: 137
Joined: 5/25/2004
From: City, PA, USA
Status: offline
quote:

ORIGINAL: CrunchyFrog

I think I know what you mean by "screen door." The looser your tolerance, in a sleeve the quicker the sealing goop bonds to shaft or sleeve and gives water a place to enter.

What''''s the difference between shaft seal by Caswell, and a stuffing box?

Is a stuffing tube just a solid rod with a hollow-rod sleeve, with grease in between?


That's how I've always thought of stuffing seals.

Caswell (actually they just distribute Merriman''s products) and SubTech seals are actually special types of "o-rings" encased in brass, resin or some other material.


< Message edited by petn7 -- 4/14/2008 11:02:09 PM >

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RE: stuffing tubes - 4/15/2008 8:49:38 PM   
cyclops2


 

Posts: 1821
Joined: 12/23/2005
From: Frenchtown, NJ, USA
Status: offline 		My "sub" shaft is 1/4" SS in a brass tube/. I have a flanged, sealed, end bearing taking the foward prop thrust. There is a 1/4 " space, than a sealed bearing in the tube. That 1/4" space is packed with Vasaline. It has never allowed any water into the rest of the stuffing tube.
The boat sits for hours in the water.
No rusting or leaks. Everything is Brass or SS.

This is the " sub" shaft boat.

Attachments
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< Message edited by cyclops2 -- 4/15/2008 8:52:04 PM >

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RE: stuffing tubes - 4/26/2008 6:20:08 PM   
CrunchyFrog



Posts: 465
Joined: 6/10/2005
From: austin, TX, USA
Status: offline 		I'll probably give that system a try. I may have to resize my prop shaft and related parts. Maybe in time for the fall sub season. Thanks for the post! Got any pictures of the bearing?

< Message edited by CrunchyFrog -- 4/27/2008 12:33:36 AM >

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       Post #: 9

RE: stuffing tubes - 4/26/2008 10:18:21 PM   
cyclops2


 

Posts: 1821
Joined: 12/23/2005
From: Frenchtown, NJ, USA
Status: offline

Still not allowed to upload pictures.

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RE: stuffing tubes - 4/27/2008 12:36:13 AM   
CrunchyFrog



Posts: 465
Joined: 6/10/2005
From: austin, TX, USA
Status: offline 		What are those three dimensions I see quoted for bearings? I saw packages yesterday that had numbers like 3 x 5 x 3.5 mm or so describing the bearings.

(in reply to cyclops2)
       Post #: 11

RE: stuffing tubes - 4/27/2008 2:47:30 AM   
cyclops2


 

Posts: 1821
Joined: 12/23/2005
From: Frenchtown, NJ, USA
Status: offline

The 3 = ID......5 = OD.......3.5 = width

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