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Jun 24, 2019, 05:28 AM
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Given your workmanship so far, I'm sure it will look superb!

What did you decide about the propeller? The 'standard' EeZeBilt tinplate prop is probably a bit too small to get the best out of modern motors and batteries. The power you will want also depends on where you want to run it. of course. A big lake will require more power and control authority than a small pond.

One point that I note on the web site is the tendency of the high bow to catch the wind - more important on a free running boat than a controlled one, of course, but still an argument for decent power to maintain control.
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Jun 25, 2019, 05:07 AM
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Originally Posted by dodgy
What did you decide about the propeller? The 'standard' EeZeBilt tinplate prop is probably a bit too small to get the best out of modern motors and batteries.
I haven't yet. I was going to try a cut down aircraft/drone prop reamed out for a push fit on the shaft. But I was also going to have a go at a tinplate version from your instructions when I get the soldering gear out. I have to make the rudder too, I'm just waiting for some 0.5mm brass sheet to arrive. I've only done electrical soldering in the past but I have a pencil torch. Will electrical solder and flux be ok or should I get some plumbers stuff?
Jun 25, 2019, 06:37 AM
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I was going to try a cut down aircraft/drone prop reamed out for a push fit on the shaft.

I recall that earlier you said that you wanted to make a 'real' model boat - but every model has its particular characteristics, and EeZeBilts are no different. Many modellers would not think of them as 'real' boat modelling - they are optimised for simple rapid construction for a beginner, and are usually much smaller than a typical lake model.

This causes difficulties for the fittings and running gear - you have limited choice, and in some cases none at all. Props are a prime example. Someone with a 36" boat and 4mm prop-shaft has plenty of choices - EeZeBuilders have this - https://hobby.uk.com/prop-shaft-30mm-229mm.html

I have two concerns about your aircraft prop - would the hub be too large, and would a push-fit stay on under acceleration? Water can produce quite a drag - much more than air, and sudden speed changes or reverses put quite a torque on the prop.

The tinplate prop can be made out of material from a stout tin can - note that it really does depend on the brass hub being soldered well in place to let it resist the torque. Quite big props can be made like this - here is the Beaver fittings page : http://eezebilt.tk/bevfit1.pdf

Will electrical solder and flux be ok or should I get some plumbers stuff?

Soldering! Ah, THERE is a topic guaranteed to bring in comments from everyone!

I use electrical solder and plumber's 'active' flux for all my soldering - running gear and fittings, and I have had no problems yet. My electrical solder is very old, so it's probably not lead-free.
Plumber's solder will be lead free and available in big chunks - electrical solder will be available in thinner gauges (easier for small EeZeBilts) and may or may not be lead-free. I don't think there is a great difference in strength between them.

To assist lead-free solder flow in dirty conditions, plumbers use an acid 'active' flux. I find this to be brilliant stuff - you hardly need to clean surfaces, you can smear the flux where you want the solder to go and it will wet just that area beautifully. I don't use it much on electrical connections, but when I do I haven't found that it corrodes the wire badly. Clean it off after use, of course...

With this flux I have found that a 25W iron does most of the soldering I need, and holding an item in a gas hob does the rest! A pencil torch is sophistication for me...

The real difference in strength is between 'soft' solder and silver soldering or brazing. For 'real' model boat running gear like rudders or props strong joints are essential, but the stresses on EeZeBilts are sufficiently low for soft solder to be fine in the vast majority of cases.
Jun 26, 2019, 06:28 AM
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Got quite a bit more done but not much has changed visually. I've sealed the cabin with sealer, sanded, doped and then covered the external surfaces in white esaki tissue. This will be painted white. I've made the cabin roofs and sanded them accurately, then stained them so that they can be glued straight on after painting. The doghouse screen will have to be added between the roofs as per instructions. The reason for doing things in this odd sequence is that the window glazing needs to be done before the roofs go on in my opinion - it would be possible but tricky to access after the roofs go on.

The brass sheet arrived this morning but the flippin Ebay seller has sent 0.7mm instead of 0.5mm (whcich I already had ) It's hefty stuff and distorts when cutting with tin snips but I'll see what I can do with it.
Last edited by slowmatch; Jun 26, 2019 at 06:36 AM.
Jun 26, 2019, 08:57 AM
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This is the slow bit of EeZeBuilding - sealing and painting!

Have you mounted the prop-shaft and motor yet? I tend to make the hole for the prop-tube oversize - then assemble a 1/8" shaft right through the motor (I tend to use small brushless, which are easy to take the shaft off) and mount the whole item as a rigid fitting. I then fill in the gap around the prop-shaft with epoxy, and change the shaft for a prop and a coupling.

I have been looking around at what props are available for small sizes, and I see that there are properly moulded Chinese Ready-to-Run props which are push-fit for 2mm. here are some - a bit big, but they can be sanded down. I suspect that getting the pitch right on a tinplate one will be tricky, and it might be better to use a ready made?

https://www.ebay.co.uk/sch/i.html?_f...peller&_sop=15
Jul 03, 2019, 07:00 AM
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I've managed to convert a plastic aircraft prop successfully - albeit untested as yet.

It was a 65mm King Kong drone prop, very common for small brushed motors. It's pretty thin and so perhaps fragile but hopefully not going to strike anything in operation anyway. The normal 8.5mm motor shaft is 0.8mm so I drilled it though and reamed it out for a very tight push fit (actually hammering the shaft in!) The blades are cut down to 7/8" diameter. Also shown is a thicker GWS 3x2" prop with wider blades that might be worth a try.

I'm also tempted to laminate a thin ply rudder which may be easier than getting organised for soldering at the moment. I'm going for the 9V MFA RE-140/1 motor on 2 cell Lipo so the power won't be excessive. (There's room to add a bigger motor if I need to.)

Jon
Jul 04, 2019, 09:19 AM
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Impressive! I think you have just discovered how to produce a close match for the later Keil Kraft plastic prop! Please can I use these pictures on the web site?
Jul 04, 2019, 09:52 AM
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Sure no problem It is as yet untested obviously....
Jul 12, 2019, 06:54 AM
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I've made some progress with the Mermaid. Painting the cabin sides has gone ok. Next step is to add the glazing.

I've had a bit of a mare with soldering for the rudder - really struggling to get the solder to stick where I want it to so something is wrong with my method. I think I will just laminate a wooden rudder to a piano wire rudder post. The good news is that there is room for the rudder post to be in the main cabin (I thought it would need to be through the 'stern locker' compartment) so I can access it easier. I've added the rudder tube and supported it with a few bits of scrap balsa.

The forward keel and transom have now been added and the sides sanded for planking. The transom is a little short so sanding into the chine plate was necessary. I think I may get the radio/motor installation done before planking so as to have easy access.

The last few pics show progress so far. I'm considering doing planking lines on the deck with raw balsa - the light wood isn't too far off for rubbed teak.
Jul 12, 2019, 09:01 AM
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"...I've had a bit of a mare with soldering for the rudder - really struggling to get the solder to stick where I want it to so something is wrong with my method...."

It's well worth getting a foolproof technique for constructional soft soldering - it's such a useful way to join thin metal.

Two things are necessary (apart from the materials and solder!). Adequate heat and cleanliness.

Adequate heat is generally provided by a gas flame - it can be hard to get good contact with a soldering iron, though not impossible.

Cleanliness is usually achieved by cleaning with emery paper. But I have found that plumbers 'active' flux (an acid flux) is a magic alternative. You don't need to clean if you use it - just paint a little of the paste where you want the solder to go and it works perfectly. I can't recommend the product highly enough, and always use it when making soldered parts. Something like this: https://www.toolstation.com/fernoxpo...CABEgLOL_D_BwE

Easiest to draw lines on the deck before assembly, of course...
Jul 26, 2019, 10:33 AM
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Thanks for the tip - I was usung normal paste (not acid) so maybe I will try plumbers paste. I have done a ply rudder now with balsa outer laminations as the pics show - but I still need to do the servo arm.


Quote:
Originally Posted by dodgy
Easiest to draw lines on the deck before assembly, of course...
Thanks - yeah I should have thought of this I did consider printing them on tissue ( a method more common in aircraft modelling maybe.)
Aug 09, 2019, 03:17 AM
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This is nice looking little boat. I like your craftsmanship, good job.
With it's lack of compound curves, I'm thinking Sintra might be a good material to use in some places for it's waterproofness (is this a real word?) and smooth texture.
Is this on the Marinecraft website?
Aug 11, 2019, 04:58 AM
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Quote:
Originally Posted by babblefish
This is nice looking little boat. I like your craftsmanship, good job.
With it's lack of compound curves, I'm thinking Sintra might be a good material to use in some places for it's waterproofness (is this a real word?) and smooth texture.
Is this on the Marinecraft website?
This is a Keil Kraft EeZeBilt model - a 'pocket-money' kit (14" long) sold in the UK in the 1950s to about 1980. It would not have been radio controlled then!

Plans for it, and the whole range, and some modern designs using the same technique, can be found on the EeZeBilt website at http://eezebilt.tk That's part of the same group as the Marinecraft website http://marinecraft.tk ...
Aug 12, 2019, 04:29 AM
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Quote:
Originally Posted by babblefish
This is nice looking little boat. I like your craftsmanship, good job.
Thanks


Quote:
Originally Posted by dodgy
It would not have been radio controlled then!
Does anyone still do 'free running' boats? I make timers for free flight electric aircraft - they give an time adjustable motor run for electric motors. It would be quite possible to design a similar thing for a boat It might be a nice simple solution for the small Eeze-Bilt range...
Aug 12, 2019, 12:42 PM
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They still race tethered boats - look up 'on the wire'...

A timer might be useful - though simply stopping the motor run is of less value to a boat which may be in the middle of a lake...

One trick used in the 1940s was to mount a cam on a slow-moving clockwork mechanism, and attach this to the rudder. That let you pre-define a course....


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