Converting small scale plastic model kits to RC

[Andy BrackParticipant @andybrack14125]

I recently built the Revell 1/72 s100 as a radio controlled model. I really enjoyed the process and the resulting boat performs reasonably well on my local lake.

Converting small scale kits to RC is an area of the hobby I can see myself getting into as it isn’t too demanding in terms of time and money. Indeed, I’ve already got my next project lined up – the Revell 1/144 North Sea trawler.

I can source suitable RC gear quite easily. Micro servos, lightweight escs etc are quite easy to come by. I am however struggling with running gear. The prop I used on the s100 is a 20mm diameter and it works fine but ideally I would have gone for something smaller. The rudder I used is a cut down resin one made by Aeronaut. Again this works fine but it seemed a shame to cut up a perfectly good rudder. The smallest diameter prop tube I can find is a 4mm outer diameter one. If I could get hold of smaller I would probably use it.

Does anyone have any suggestions where I could source such items? Alternatively if people have tips and advice about how to make them myself that would be much appreciated.

[Andy BrackParticipant @andybrack14125]

[Colin BishopModerator @colinbishop34627]

Hi Andy,

Welcom to the Forum. 20mm props, 4mm tubes and 2mm shafts are pretty much as small as you can easily get commercially although Deans Marine advertise an 18mm plastic prop.

You could make up your own tube assemblies using suitable brass rod and tube but you would probably end up with something approaching 4mm anyway.

Ali Express advertise 15mm props:

**LINK**

Another source of very small props is children's toys, model RIBs with 'outboard' motors for example.

These very small props are probably not very efficient though and you might be better off sticking with the 20mm type. After all you can't see them when the boat is afloat!

Colin

[Chris FellowsParticipant @chrisfellows72943]

Hi Andy

ModelBoatBits do 3/16 brass prop tubes with 2mm shafts advertised as ideal for plastic model conversions.

Chris

Ignore me, that is over 4mm! They do 20mm M2 brass props though that would be easier to file down than plastic.

Edited By Chris Fellows on 30/06/2022 11:20:09

[Richard SimpsonParticipant @richardsimpson88330]

I think as has been mentioned that 2mm shafts in 4mm tubes are about as small as you are going to get. Beyond that you are going to have to make them yourself.

Having said that probably the only difficult part would be making a couple of bushes for either end of the tube, which should be fairly straightforward for most modellers. I would use rubber tube as a coupling, brass rod for the shaft and brass tube for the tube, all of which is easily obtainable. For the propeller you can try cutting the basic shape out of an aluminium or tin can and then twisting the blades manually when you are happy with the shape. You would then need to come up with a means of securing it to the shaft.

Another thing to consider though is that when you start getting into the realms of models that small they tend to bounce around very unrealistically on the slightest ripple and can look dissapointingly toy like. At least if you stay with a model of a couple of foot long it can still remain fairly stable on the water.

As regards rudders, when I converted a Revell 1/72nd U-Boat to surface running RC I used the kit rudders and was surprised at how manoeuvrable it is on the water.

[Ray Wood 3Participant @raywood3]

Hi Andy,

When I was kid back in the 1960's building Keilcraft balsa boats like Otter & Curlew, the kits were supplied with a shaft and a close fitting brass tube with a turned brass boss and a tin plated prop soft soldered to it bent to a pitch, I don't recall those shafts leaking significantly, I'm sure it would still work as the boats are light displacement so little water pressure, with a drop of oil ?

I'm tempted to to make one to see how it goes

Regards Ray

[Charles OatesParticipant @charlesoates31738]

There's an article on this website about making your own miniature propellers. It's easy and they can perform better than some commercial ones.

https://www.modelboats.co.uk/news/article/miniature-two-blade-propellers/6354

 

Edited By Colin Bishop on 02/07/2022 08:23:57

[Andy BrackParticipant @andybrack14125]

Thanks for all the input guys. Really helpful.

I’ve bought some of the 18mm props from deans marine. I’ll see how I get on with those. I saw that you can get even smaller ones on Ali express so that’s another option. I may well have a go at making my own too.

I’m hoping to get started on the Revell trawler in the next few days.

[Richard SimpsonParticipant @richardsimpson88330]

Andy, These couple of shots were taken at my club in 2008 and I originally thought they are of the Revel Trawler but I've checked and it wasn't.  I'm sure it was a very small kit though.  I'm afraid I have no idea who the owner was but I can ask one or two people who might know.

It shows what a lovely job can be made with a small scale model.

Edited By Richard Simpson on 02/07/2022 09:55:27

[Francis MacnaughtonParticipant @francismacnaughton39461]

I have converted quite a few plastic kits to RC including the Airfix MTB and the RAF Rescue launch and in most cases for a single prop I find that the smallest of the Dean's Marine 3 blade plastic range at 18mm diameter usually works well – you can always trim a mm or so off each blade tip if you need to reduce further. Another option is the set of props provided in some of the earlier Tamiya (and the Academy clone) 1/350th battleships such as the Bismarck which were motorized. These are 15mm diameter and you get a left and right hand pair which fit nicely on 2mm shafts. The Tamiya 1/72nd Perkasa props are also 15mm in diameter and look useable if you can get hold of any.

For prop tubes, the SHG range of 2mm shaft sets are excellent (available via their ebay shop) and the tubes are 4mm in diameter. You might be able to get down to 3.5 mm diameter using thin walled slide fit brass tubing with the bushes made from 1/8th inch plastic tube carefully drilled out to take the shaft.

[Steven S. 1Participant @stevens-1]

A propeller of any size could be modeled in a 3D CAD program and then 3D printed. Here's one that I modeled with Solid Edge for a Springer Tug.

[Richard SimpsonParticipant @richardsimpson88330]

I think Steven that while many of us appreciate the capabilities of 3D printing I still suspect there are very few amongst us who have CAD software and know how to use it as well as having the 3D printer and know how to use it.

There are designers on Shapeways though who will design a specific component although by the time you have paid for international shipping it doesn't always come out cheap.

[Steven S. 1Participant @stevens-1]

Yes, I understand that you wouldn't want to learn CAD modeling and then buy a printer to made a few small parts, but in both my RC airplane and RC boat clubs I am not the only CAD modeller. There are also club members with 3D printers eager to help fellow members with parts.

[Richard SimpsonParticipant @richardsimpson88330]

I think that is where Shapeways very cleverly saw the niche in the market for connecting up designers with potential buyers. The trouble is they are A) Quite expensive and B) Based on the continent so items tend to also cost a lot in shipping and C) difficult to deal with when something goes wrong.

Maybe there is an opening for someone to do something similar but based in the UK.

[Colin BishopModerator @colinbishop34627]

You don't have to go to Shapeways. There are items on the Thingiverse website where you can download deigns for free and print them off on your on machine without the need to learn CAD.

A quick search brought up 'Model Boat Propeller Designer'

**LINK**

Might just be what you need.

Colin

[Colin BishopModerator @colinbishop34627]

Somebody on the Mayhem site has dowloaded the software and is going to try it out.

**LINK**

Colin

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