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Old Nov 06, 2005, 01:57 AM
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Treetop's Avatar
Tucker, Georgia, United States
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Couple of probably dumb newbie questions.

So, I ordered a book by "Dynamite" Payson, but I don't think is has RC info, (maybe I will be surprised).

After reading some of the threads, I have been left wondering about keeping the electrics dry.

Is the "stuffing box" something that prevents water from rising up the drive shaft, or is there some other method that prevents this? Grease?

I notice there are both waterproof and non waterproof ESCs available, how does one protect the non-waterproof ESC without causing it to get too hot?

Thanks for your patience, tt.
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Old Nov 06, 2005, 06:13 AM
Useful Idiot
Asturias, Spain
Joined Mar 2001
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TT, I think keeping water completely out of a boat is utopia. Packing the stuffing box with grease is not really an option in view of the added resistance. It's really a question of using a light oil regularly and cleaning, drying and re-lubing between runs.
On the question of watercooling esc's, your posting here, ather than on electic racing makes me think that you're not thinking of pushing your motor and electronics so hard as to make it necessary. The simplest way is to use a rubber balloons or "similar" to hold the esc and receiver and to mount both higher in the hull. Esc's sold for boats are usually splasproof. Car or aeroplane ones are another matter.
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Old Nov 06, 2005, 05:22 PM
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Monterey Bay California
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Treetop, we need a book review! This one is a classic and I'm thinking about buying it myself- I am particularly interested in the drawings of the Grand Banks Fishing Schooner- do they look adequate to build from in the book, if enlarged?

If I'm not mistaken, RGinCanada's excellent Sardine Carrier is based on one of the boats in this book. Http://www.rcgroups.com/forums/showt...rdine+Carrier+

A 'bread and butter' hull build is on my short list, looks like big fun!

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Old Nov 06, 2005, 06:02 PM
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McAlester
Joined Nov 2004
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'T.T.',
Just like in a full sized boat, the stuffing box keeps MOST of the water out of the hull. Depending on the type of 'grease' used, it generally works as well as oil or whatever. Sort of depends on temperature too, to some extent.
Water proofing the electronics isn't as big a job as it might seem. The first thing is to not put them where water can't get on them, right? Then, limit the water that can get into the boat. There are a number of ways to do that. Mounting the ESC high in the hull (superstructure maybe?) is one way. There are others, only limited by your imagination (within reason that is).
- 'Doc

PS - Don't worry about "dumb newbie questions". Very few of us were born knowing all this stuff...
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Old Nov 06, 2005, 07:39 PM
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FWIW, I've heard A LOT of dumb answers in my time, but NEVER a dumb question! If you don't ask, you may never find the answer.
PAT
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Old Nov 07, 2005, 12:20 AM
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Tucker, Georgia, United States
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Thanks for all the friendly replies, sounds like mostly using common sense.

Aerominded, the book I ordered (used from half.com) was "Boat Modeling the easy way: A scratchbuilders guide. I might get the other one later, (Boat Modeling with Dynamite Payson).

From the website:

Quote:
There's a classic Gloucester lobster boat, a Maine tug boat, two sardine carriers, a turn-of-the-century day cruiser, a Friendship sloop, a torpedo-stern launch, a Gloucester fishing schooner, and a plank-on-edge English cutter

http://www.instantboats.com/books.htm
Haven't received it yet. Our local library (where I used to work) has a grand total of one book on ship modeling. I'll have to talk to my old boss about maybe getting a couple of Payson's books.

Does anyone know of a link to a picture of a stuffing box? Maybe I have seen one on the forum and just didn't recognise it. Thanks again, tt.
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Old Nov 07, 2005, 01:04 AM
Useful Idiot
Asturias, Spain
Joined Mar 2001
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There's nothing over technical about a stuffing box; usually a length of brass tube with an i/d an 1/8" approx more than the drive shaft o/d and the gap filled by a bronze bushing at either end (long shafts might need an intermediate bushing). Improvements can be ball-bearings in place of plain bushings, lubrication nipple etc.
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Old Nov 07, 2005, 04:32 AM
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Kitchener Ontario Canada
Joined Jan 2005
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Here's some pictures of stuffing tube's,The top one is home made and the bottom one is a Graupner unit that I have'nt solderd the oiling tube on to yet
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Old Nov 07, 2005, 05:18 AM
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Tucker, Georgia, United States
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Very interesting. I am beginning to see the light, thanks guys. tt
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Old Nov 07, 2005, 09:42 AM
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Newburgh New York
Joined May 2005
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there is a builder of converted plastic models that uses Q tips as his stuffing tubes.
they work fine. please remember, the models are of the 1/125 to 1/350 scale.
skip
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Old Nov 07, 2005, 12:19 PM
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PDX, OR
Joined Dec 2002
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I usually build my own stuffing tubes.

Start with the shaft size you are using, and build up some KS brass tubing into your stuffing tube. Solder the small pieces into each end of the tube. Run the tube out the bottom of your hull, and epoxy it in place. Fill that with a little (not to much) white bearing grease, and you are ready to run the propeller/drive shaft.

Quote:
The longer explanation...
Take your prop shaft to the hardware store.
(Or pick up a 1/8" or 5/32" brass rod at the hardware store for the prop shaft.)
Ask to see the K&S brass tubing.

Put the first tube that fits, - over your propeller shaft.
Put the second tube that fits, - over the first tube, and the propeller shaft.
Put the third tube that fits, - over the second tube and over all three.

Buy a tubing cutter
You will need solder and a soldering iron also.

When you get home, take the three tubes off the shaft.

From the smallest tube cut two 1/8th inch long pieces off.
Clean the inside edge out with an X-acto knife till the two pieces slide smoothly over the propeller shaft.

Cut two 1/4 inch pieces off the next larger tube.
Again clean the inside edgest so that the little 1/8th inch long pieces of the smallest tube will slide in.

Cut the third and largest tube to a length that will run from the motor, out through the hull and to the propeller. This should somewhat shorter than your propeller shaft.

Solder the two small pieces of tube flush with the end of the largest tube.
When finished, that tube will then have a small bearing at each end, for minimum friction, and can hold grease inside to keep water from getting into the boat.


Or build a stuffing box.
A " Stuffing Box" is actually a four sided box built on the bottom of the hull around where the shaft exits the ship. The shaft passes through the front of the box, down through the center, and out the bottom of the hull. The box is then stuffed with grease(white Lithium grease), and then a lid is placed, or cemented on top. The grease prevents, or slows the water from penetrating the hull.

(Note)
Too much grease in either the stuffing tube or box can actually cause a lot of friction and prevent the prop shaft from turning.
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Last edited by Umi_Ryuzuki; Nov 07, 2005 at 12:30 PM.
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Old Nov 07, 2005, 04:34 PM
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Madison, MS
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Hi Umi, As usual, an excellent job of explaining the purpose of and how-to-make stuffing tubes. Now, could you please explain for me when thrust washers are necessary and how to make them. Is one necessary when using electric power (say about a 550-size motor) to turn an inch-and-a-half three-bladed propeller, or are they only needed with gas or nitro powered engines. If one is needed, what material is used? A not-too-local hobby shop guy had some, but they were the wrong size. Any help here would be greatly appreciated.
Bill
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Old Nov 07, 2005, 10:06 PM
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Quote:
Now, could you please explain for me when thrust washers are necessary and how to make them.
Not really,...

A washer between the end to the stuffing tube and the propeller always seemed logical to me. The first thought being to reduce friction. Later, upon some consideration, it occured to me, "Just what is the propeller pushing against to drive the boat?" I usually allow a little play forward and back when mounting the universal joints between the motor and shaft. So would it be ok to let the forward force translate through the prop shaft and against the motor itself?
Probably not.
Ideally forward would apply force at the end of the stuffing tube, bracing struts, or keel, and reverse would pull the u-joint back against the same.

Electric motors that I have disassembled don't have much in the way of thrust bearing other than a fixed washer against the armature. So if there is some good place for the propeller to translate forward thrust to the boat, it would be at the end of the stuffing tube that is firmly mounted to the hull and/or typically further braced with one to two struts. So whether it is an actual "thrust bearing, or a washer between the propeller and stuffing tube. Such a bearing can only increase the life of your motor.
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Old Nov 07, 2005, 11:37 PM
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Madison, MS
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Umi, This is very helpful information; thank you.
Bill
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Old Nov 07, 2005, 11:52 PM
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Tucker, Georgia, United States
Joined Feb 2004
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Thanks Umi, terrific info and nice support drawings. I am assuming that when you use a stuffing box, there is no stuffing tube, just the bare shaft penetrating the hull, possibly supported elsewhere if needed.

Thanks again, tt.

-------

Wingnut, the Qtips, are you talking about the ones with the plastic stick?
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