MetallicaJunkie

got pics of a lobster boat?

wayne d

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I have a few that I have found online and different threads.

blizard05

The motor shafts are 5m, prop shafts are 4m

wayne d

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Cool, looking at shafts and stuffing boxs now.

blizard05

Just checke my motors,only have them with 1/8 shafts. Have 3 Send your EM, will send pics of boat Larry

wayne d

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Good morning Larry
Not sure what you meant by the last post.

blizard05

Don't you ever sleep? The output shafts on motors are 1/8 not 5m Larry

wayne d

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I work midnights for the local sheriffs dept. I sleep during the day. Matter if fact I just got home.

wayne d

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So I'll need a coupler from 1/8 to 4mm.
Glad I didn't order a shaft last night.

blizard05

Wayne, 1/8=.1250=3.11750 mm Asfar as real lobster boats go,I live 10 min from about 50 of them,in Plymouth harbor,on Cape Cod bay (pics on the way to you) Larry

rblubaugh

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Good morning Wayne,

Good to see Larry tuning in to the thread, he was a real help to Fred during his build.

I was about to tell you no way on that 775, only 10 turns and too much current and RPM's. Any way I see Larry is coming up with some motors for you.


Bob

wayne d

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Hey guys
Both of you have Been a tremendous help and I would not have made it this far so quickly.
Larry sent me some pictures this morning of his boats and would like me to post them. I'll get them on here shortly.
Now that I got the motor situation worked out I'll look around for a couple of ESC's, that shouldn't be to hard. Seems eBay has a lot of that stuff.
I plan on ordering the stuffing boxes, shafts and most of the wood tonight.
Then I'll start cutting some wood as soon as that is delivered.

That all for now, stay tuned.

wayne d

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As promised, Here is a couple shots of Larry's boat.

wayne d

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Any comments on these couplers.
I can get any of these from Harbor Models in 3.2mm (1/8) x 4mm.
I leaning towards the red one.

rblubaugh

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Wayne,

I prefer the universal joint, the one in the middle. That one's a double universal, a single universal works just as well as long as you have everything in alignment.

BTW, with a double 4mm coupler you can use a 1/4 to 5/16" long piece of 5/32" brass tubing with a slot filed about 1/8" from one end for the set screw to give you a 1/8" by 4mm coupler. Once the set screw is tightened it is mechanically sound.

Bob

wayne d

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Evening Bob
I had the same thoughts about the coupler but ordered the red one.
My thought was that I wil be able to adjust the former or motor to line up straight. At least thats my thought. if for some reason that does not work out, I'll order the other one.

The good news is progress is being made.
All the shafts, couplers and wood have been ordered. Progress is always good.
hopefully I'll be cutting some formers out by next week.
Of course I'll be posting the pictures and progress as I go. Looking at the plans for a couple of days it looks like it will be a fairly quick build. As always the part that take the most time is when you reach the finishing stage.

Stay tuned, as soon as the wood arrives I'll get busy.

wayne d

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Hey guys,
What ESC's should I be looking for?
I'm looking at Traxxas right now but really have no idea about any of them.
Do I need to be looking for a certain voltage?

blizard05

Wayne you have a email on a coupler, you can use any esc with a high turn motor.Look for one that will take 7-12 cells,reverse would be nice. I run 2- 7 cell packs in pra Larry

blizard05

They are ok for low rpm,won't last long with a higher rpm. I would use a Graupner flex coupler #grp 3344 1/8-4mm, I used a 5mm-4mm on my boat. Check out www off shore electrics for them Larry

wayne d

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Thanks Larry
I'll order one tonight.
I was looking at the Traxxas XL5 ESC,
Seems to be plentiful, would that work?

blizard05

Any of the traxxas esc will work,take a look at the nautica. Will send motors out Mon. $5,000 shipping-discount of $4,992= $8.00 Larry

wayne d

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Thanks I will.

wayne d

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Man I like that kind of discount. LOL

Apismelifera

Choice #1. The dogbone coupler shown on the left is basically a double universal joint and coupler combination. Double universals tolerate parallel misalignment, singles do not. All universals tolerate angular misalignment, to a degree. Obviously the better your shaft alignment is the better. If you buy the 1/8" version the ends can be drilled out to what ever shaft size you have, within reason. These are OK for small to moderate size scale boats.

Choice #2. The black one in the middle is another example of a double universal joint, coupler combination. Make sure you order it with the right size bushings in the ends. They are molded in and therefore not changeable. Measure you shafts before you order. You can get these in either both ends the same shaft size or different. Good for moderate to larger scale boats.

Choice #3. The Red one. These are made so the the splined bushing that goes in the end and can tolerate a small amount of end play along the length of the part. The bushings also come in different sizes, you order the two size end bushings you need and the universal. Presto you're there. You can also get a double spline connector, allowing you to put two of the red universals together. Some places sell the bushings with an internal spacer that allows you to use the same bushings for two different shaft sizes. IE: A 5MM bushing supplied with a 5MM OD x 4MM ID spacer. Put the spacer in to the bushing and you can now use a 4MM shaft without wobble or excess vibration. Good for moderate to larger scale boats.

Choice #1 & #3. Because of the built in end play will, if you set your propeller shaft up correctly, keep propeller thrust from reaching the motor bearings. You should have a thrust washer on each end of the propeller stuffing tube so that prop thrust is only coupled into the prop tube, not the motor bearings. Motors are not designed to handle radial load only axial load.

Choice #2. This is a hard coupler (it transmits fore and aft propeller thrust). This WILL transmit radial load (prop thrust) from the prop shaft into the motor. This decreases the life the motor bearings.

With a hard coupling you need to be especially careful of the gap at each end of the prop shaft. The space between thrust washer and propeller, also between thrust washer and prop shaft coupler. There is only one gap. The gap changes location when you change direction. When going forward the propeller is pushing against the aft end of the stuffing tube. The gap now wants to be at the forward end of the prop shaft, just behind the coupling. And it moves to the opposite end when in reverse. If the total amount of gap is smaller that the radial slop in the motor you're good to go. This can be a hard adjustment to get right.

I wouldn't use any of those couplers for a go fast boat, or one with an Internal Combustion engine in it.

For a scale boat I would use the red one (my personal preference) and set it up a tiny bit loose so that the gap in the shaft is smaller than the gap in the coupler. That way when the shaft moves fore/aft it's not transmitting any prop thrust to the motor. Either #1 or #3 will work like that.

wayne d

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Thanks John for all the information.
At this point, I need all I can get.

I ordered the red ones and the one pictured below. I figure one the of two should work.