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Author Topic: Finally geting somewhere  (Read 2857 times)

dave parker

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Finally geting somewhere
« on: January 16, 2020, 09:12:48 AM »

Well after numerous false starts, distractions, and finally getting my hobby workshop set up, I have made a start on my first springer (first model boat full stop).
See pics below but please make any comments or point out if done wrong?

I do have some questions…
Firstly, can someone explain the principle of how the nuts and washers work on the shaft? They are both lose at moment but do I tighten them? Leaves a bit of slack? Or something else?
Secondly, on the rudder post there is a flat plastic disc at bottom to seal against the hull. My hull isn’t flat so what do I do there?
Also, on the picture you can see that the rudder isn’t pushed right up tight against the underside of the hull. There is a gap.  Is this ok or do I have to push the rudder as far up as it will go tight against the hull?
Thanks












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raflaunches

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Re: Finally geting somewhere
« Reply #1 on: January 16, 2020, 12:01:01 PM »

Hi Dave


Good start so far.


Regarding the shaft nuts and washers, you need the shaft to be free running but not too much play backwards and forwards. The nuts are primarily used for locking the prop in to the shaft and the coupling on to the shaft. The washers I believe are called thrust washers as they allow the rotary movement to push against.


The rudder looks okay at the height itís currently sitting at, you ideally want the prop wash to flow over the whole rudder to get the best manoeuvrability from a standard rudder.


Regarding the flat disc on your rudder post and how it sits- it look like youíve given yourself a good size block for the rudder post to pass through. Using a drill or a file just change the curved area of hull to flatten it until your rudder post sits upright. You can then seal it with a bit of epoxy or filler.


Hope this helps, Iím sure other members will give their advice too. :-))
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dave parker

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Re: Finally geting somewhere
« Reply #2 on: January 16, 2020, 12:09:39 PM »

Hi raflaunches


Many thanks for your help, all makes sense to me


If I have one nut tight to the prop and one nut right to the coupling there is a good amount of play between the shaft and the tube... {:-{
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raflaunches

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Re: Finally geting somewhere
« Reply #3 on: January 16, 2020, 12:27:28 PM »

Hi Dave


Iíve just had a closer look at your picture of the prop shaft and the prop itself. By looks of things your threaded portion of your prop shaft is too long for the amount of thread inside your prop. You may have to cut off the excess threaded section to allow your prop to sit closer to the prop shaft tube. Failing that Iíve used washers to take up the slack.


Nick
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Colin Bishop

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Re: Finally geting somewhere
« Reply #4 on: January 16, 2020, 12:30:37 PM »

A locking collar can also come in useful at the inboard end depending on the setup.

https://www.cornwallmodelboats.co.uk/acatalog/Prop_Shaft_Locking_Collars.html

Colin
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dave parker

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Re: Finally geting somewhere
« Reply #5 on: January 16, 2020, 12:36:05 PM »

So this fills in the gaps and stops the rudder from being able to slip out ?



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Colin Bishop

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Re: Finally geting somewhere
« Reply #6 on: January 16, 2020, 02:01:41 PM »

Have a look at this:

https://www.modelboats.co.uk/news/article/drivelines/27166

It is an article by Glynn Guest on the Model Boats Website which was written for the 2011 Special Issue that I edited. It tells you pretty much all you want to know about the principles of installing running gear in model boats.

An example drawing is shown below.

Colin

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SailorGreg

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Re: Finally geting somewhere
« Reply #7 on: January 16, 2020, 05:34:38 PM »

At the risk of repeating some of what has already been said, can I offer the following -

Prop shaft - first, make sure the threaded section is only just long enough for the prop and a locking nut - you don't want a threaded piece running in the end bearing as it will cause wear and might leak.  Cut off any excess with a hacksaw, then file the rough edges off (and leave a nut on the thread when you cut, so it can be wound off to clear the thread).  Wind a nut down to the bottom of the thread, then screw the prop on as far as you can.  Then (Very Important) tighten the nut hard against the propeller.  Put a washer on the shaft, then slide the shaft into the tube (having added a slug of waterproof grease as you have no oiler on the tube you show).  Then slip a washer on the inboard end of the shaft, then the locking collar that Colin Bishop pointed you to.  Tighten the collar so that there is a barely perceptible movement fore and aft of the shaft, then spin it a few times to make sure it runs freely. It is the locking collar that takes the thrust when you are in reverse.  Then you can add the universal joint between the shaft and the motor.  The UJ should not be subject to any forward or backward forces, all those are taken on the prop shaft tube.

Rudder - it doesn't matter too much if the rudder isn't right up to the hull (although some purists might point out that it works most efficiently when it is), but I suggest you cut off the collar that is supposed to seat on the hull and leave the end of the tube sitting below the hull at the distance you want the rudder to be.  You will have to dispense with the nut that would normally be used to fasten the tube and employ a healthy dollop of epoxy adhesive to glue the threaded portion into the block it passes through.  This will be perfectly watertight, and will stop the rudder riding up if there is a gap between it and the tube.

Hope that all makes sense.  Good luck with your build.

Greg

Capt Podge

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Re: Finally geting somewhere
« Reply #8 on: January 16, 2020, 05:48:56 PM »

That's a great write up Greg - can I just add to that, use the same grease in the rudder tube as well...  :-)

... oh, and make sure that no epoxy gets inside the tubes either.

Regards,
Ray.
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dave parker

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Re: Finally geting somewhere
« Reply #9 on: January 16, 2020, 06:07:07 PM »

Thanks Greg that is a fantastic write up!


Makes super sense of the prop shaft, it’s been niggling me for a long time!!! I didn’t even think of shortening the threaded part :-))



I like the idea of bonding the plastic rudder tube further down to locate the rudder where I want it.


Like you say as long as it’s fixed solid using the epoxy, even top and bottom, it’s going  to work fine!!!



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dave parker

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Re: Finally geting somewhere
« Reply #10 on: January 16, 2020, 06:09:26 PM »

Thanks Colin


Is this article available in print anywhere for future reference??
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Colin Bishop

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Re: Finally geting somewhere
« Reply #11 on: January 16, 2020, 06:37:56 PM »

Only if you can find a copy of the printed issue frome sites such as this:

http://magazineexchange.co.uk/cw/model-boats-magazine-summer-2011-issue.html

If you PM me with your email I think I may have a pdf version.

Colin
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dave parker

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Re: Finally geting somewhere
« Reply #12 on: January 16, 2020, 06:58:03 PM »

Thanks Colin


PM sent
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Colin Bishop

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Re: Finally geting somewhere
« Reply #13 on: January 16, 2020, 07:05:59 PM »

Article sent!

Colin
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dave parker

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Re: Finally geting somewhere
« Reply #14 on: January 19, 2020, 02:56:31 PM »

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dave parker

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Re: Finally geting somewhere
« Reply #15 on: January 19, 2020, 03:08:28 PM »

Try again




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Capt Podge

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Re: Finally geting somewhere
« Reply #16 on: January 19, 2020, 04:11:11 PM »

Yep, that's come up crystal clear  :-))


Regards,
Ray.
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dave parker

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Re: Finally geting somewhere
« Reply #17 on: January 19, 2020, 04:14:55 PM »

Excellent
Need more practice posting pics


Anyways, I am making progress with my first build!
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Capt Podge

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Re: Finally geting somewhere
« Reply #18 on: January 19, 2020, 04:20:52 PM »

I am making progress with my first build!


Very neat looking job you're doing as well - I like it  O0


Regards,
Ray.
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dave parker

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Re: Finally geting somewhere
« Reply #19 on: January 19, 2020, 04:27:08 PM »

Thankyou
Not as today as photos make it look but itís something to start from
Filler is a wonderful thing, or will be when I get to that stage
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dave parker

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Re: Finally geting somewhere
« Reply #20 on: January 19, 2020, 07:17:44 PM »

Few more from today....












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Taranis

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Re: Finally geting somewhere
« Reply #21 on: January 19, 2020, 07:21:52 PM »

Tidy Dave  :-)
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dave parker

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Re: Finally geting somewhere
« Reply #22 on: January 20, 2020, 01:13:31 PM »

Few questions if that's ok..

1   when fitting a skeg do I just bond it to the outside of the hull? do I need to pin it through the hull???

it will be blended in with filler once dried

2  On the skeg, I am intending on using a triangle of timber above and below the shaft tube, then a full piece either side, sealing in the tube.
But... what would you recommend to use to fill the gaps between the shaft tube and the first timber pieces before covering with the last parts?

3   can anyone recommend a filler to use to iron out all the dings and splits etc in the plywood  and blending prior to paint? I thought about using the household poly filler but it dries very hard and often you can end up sanding through the surrounding wood rather than the filler.

4   can anyone recommend some sanding sealer here in the UK.  I need to invest in some and would like to get some that I know will do the job

5   How important is it to have a lubrication tube added to the shaft tube?  Mine hasn't got one, I have never soldered before and so would like to avoid is possible but not to the detriment of my model



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Capt Podge

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Re: Finally geting somewhere
« Reply #23 on: January 20, 2020, 01:55:15 PM »

Ref question 5 - found this on Cornwall Model Boats (other suppliers available)


https://www.cornwallmodelboats.co.uk/cgi-bin/sh000001.pl?WD=oil%20clamp&PN=Graupner%2dPropshaft%2dOiler%2dfor%2d4mm%2dPropshaft%2dTube%2dG2997_4%2ehtml#SID=438

Also, other sizes available :-))


Regards,
Ray.
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dave parker

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Re: Finally geting somewhere
« Reply #24 on: January 20, 2020, 02:10:39 PM »

Thanks captain Podge


I assume this just clamps round it then you drill through??
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