HMS Instant.

[optima21]

as some of you may be aware Im building a tiny steam engine and steam plant for a small model boat.

https://www.mig-welding.co.uk/forum/threads/small-steam-engine-for-a-model-boat.98238/

so rather than make a mess of making the model and fitting the engine and then seeing if it needs modifying I decided that it would be better to make a simple model boat to try the engine and steam plant out on. I then decided that I'd see if I could make it out of thin sheet metal (0.9mm zintec). last weekend someone lent me a plan of HMS Instant which as simple as you can get. I jsut hope its not too heavy and doesn't sink, but its the first sheet metal work I've done this year so I could do with the practice. I'll only be making the hull though as I think a metal superstructure might give me issues with getting a signal to the radio control receiver.

so here is the plan I've started off with and it was reduced to 3/4 of the size to be of similar size to the boat Im making.

as the hull has a flat bottom, flat sides and a flat too, it is simple as it gets. I thought I'd have rounded edges to the bottom of the hull, so the hull bottom is slightly wider than the deck to allow the metal to be formed

so the edges of the hull floor was tipped over using a bead roller

which creates plenty of distortion as the metal has to go somewhere, so to get it roughly flat some of the excess metal in the lip was removed using a shrinker. most of the reshaping was done using hammers and dollies while clamping it to large chunk of metal

and not so far off.

 

[tom2207]

very tidy

 

[optima21]

and after a bit more shaping of the edges of the bottom of the hull with the deck on top of it to show the fit

then using a marking gauge to level top of the bottom of the hull, and then filing to the scribed line

then creating the kink at the back of the hull, with a tack to hold it in place, and a bot of hammering required to open the gap up again and maintain the correct angle

then marking out the hull sides, I was wondering how I was going to do this for a while, but as they are at right angles to the hull bottom a a few clamps and wooden blocks are all that are required, and scribe around the top of the hull base

and then a few tacks with the mig

and one side tacked up

and the other side and back tacked in place, with the front seam welded with the mig

 

[Bullet2012]

Need a mug for a sense of scale please .

 

[optima21]

Need a mug for a sense of scale please .

there you go,

 

[optima21]

On Sunday I ground the tacks back

and tig welded it all together

and as you can see I'm needing a bit of practice as this is the first welding I've done this year. I then went along to the model boat club to see if it would float which it did and I used a tin of custard as ballast the roughly replicate the weight of a steam plant and engine and radio control gear, and it was a bit low in the water, but it didn't sink and the welding was watertight, so its not a bad start. so no-one had to go magnet fishing for it.

when I got home I got the kit out of the boat I want as the finished model (and this is the test mule for), and weighed it. allowing for wastage I'm thinking the wooden hull would weigh about 400 grams, and the metal hull is currently 630 grams. I still need to weld the top on the hull and some other bits.

so a couple of options that I've thought about are :-

1) buy a cheap metal shelving unit to use the steel to make a new hull with as its likely to be 0.5 or 0.6mm thick (I've used 0.9)mm

2) drill big holes in it and coat both sides of the hull with strong waterproof tape.

but before I do anything else on it, I need to practice my tig welding, as the fillet welds in 0.9mm are not looking good.

ohh and HMS Instant, what a name, as they used to say on the old food adverts "Instant ???????, just add water", makes perfect sense with a boat.

 

[RichardM]

If it's just a mock-up to test function, drill holes and then brown cellulose tape on the outside to seal it.

 

[optima21]

as usual with me things seem to go slower and slower, but more progress has been made, and sorry about the poor quality of the TIG welding, think this would be much easier with mig, but at some stage you need to try and do things outside your comefort zone, and the thin metal doesn't exactly make things easier. with the tight space I needed to use a short backcap for the first time and none of the ones Ive got will tighten the collet up enough, so a bit of clearance was found by using a lathe

and then a tube was welded in place to hold the propeller tube its 6mm o/d and 4mm i/d

then it was suggested that I put some polystyrene blocks at the front and back to stop it sinking, but a metal plate (bulkhead) is roughly the same weight as the polystyrene, so I thought I'd tack a plate in place and then seal it with silicone sealer later. the back one was done first with a mounting for the servo for the rudder.

and badly tacked in place

its just to tight spacewise for me and you guys that manage to TIG in these areas and get decent welds, Im impressed with that. MIG tacks would have been so much easier. and the back part of the deck welded in place. the fillets were much better on the practice welds though

and the front bulkhead tacked in place

and the front part of the deck welded in place, once sealed there will be less chance of it sinking that there was with the titanic.

I ended up using pulse to do the outside joint without any filler, so far its been the only bit that looks anything like it should, then back to the lathe to make some studs to weld into the bottom of the hull to hold a plate fro mounting the radio gear and steam plant etc. if only TIG welding was as easy as using a lathe

 

[Screwdriver]

Of course if you had a model of the superstructure, it could be 3d printed just go give it that "look".

Some of the earlier destroyer class vessels had seriously impressive topweight just to look seriously impressive. Made from magnesium alloy unfortunately as we all know. Still, they did look amazingly aggressive.

 

[optima21]

seems like most things I do, its not instant

I decided that as I planned on using different power sources in it , either electric of steam, the easiest option would be to mount them on a metal plate, which also also made it easier for aligning the mounting studs before welding them in place.

and the studs welded in place, stainless steel to steel, without 309 rods, but I think it'll be fine

and a bit of lightening of the bulkheads with a burr in a die grinder, think it would have been easier before welding it in place

and then welding the sides of the deck on top. at this stage I changed the clear screen on my welding helmet at stopped using a cheater lens, it made a massive difference to what I could see, so here's a top of the deck being tacked in place at 60amps and and autogenous outside joint, using pulse, 60a peak, 30% on time and off time minimum current. still not brilliant but Im happy with it,

and marking the keel out, it takes time to get the fit right, I ended up filing it a bit at a time

and holding it to tack it in place, using crocodile clips and some metal offcuts

and the completed keel on the hull

ohh is looking a bit heavy, so I'd like to grind about 200 grams off it to stop it being like a submarine, but at least the bulkheads will stop it sinking, I know that 640 grams will let it ride high enough in the water (I think I'll have to learn the technical names for these bits.

before I started this HMS instant I thought it would be unlikely that I would get the steam powered river launch finished this year but thought I needed to get a model finished this year.... so then had a look on youtube and found a small model of a trawler converted to radio control

and a small landing craft

and here they are with the steam launch, although Im not going to be doing the builds on here apart from some small bits of metalwork, and both of the plastic kits have been in production for 50 years.

 

[optima21]

so then it was time to paint the hull, with this being a boat I think using Jotun 87 would have been appropriate, but instead I chose to use Lechler 29107 epoxy primer as its thinner than the Jotun. the inside was brush painted, and the outside was sprayed on

before I try this with a steam engine, I think I need to try it out with an electric motor to test propellers and propeller shaft assemblies. I'll being using a single cell lipo battery for the radio control, so was looking at using a 3v motor with a speed of 5,000 to 8,000 rpm, so ended up buying 3 different motors from 3 diffrent suppliers in the uk off ebay that matched the specification, but when they arrived their speeds were between 18,000 and 40,000 rpm off 3.7v, no no use for me and were sent back..... if you're that specific about what you're selling, make sure thats what you're selling......and you wonder if the 200 other people who bought from then had the same issues as me. anyway I bought direct from china and they were spot on what I think i want

https://www.ebay.co.uk/itm/254603349836

now I could just but a prop shaft and tube for a couple of pounds, but it seems to me that they are poor quality and to stop them from leaking water into the hull they just fill them with grease. the propeller shaft Im using is 2mm diameter stainless steel, and the outer tube is 4mm diameter. my choice of bearing is phosphor bronze and use an O ring at the propeller end to work as a seal, as lip seals that small arn't generally available. For a 1mm section O ring used as a rotary dynamic seal is recommended that the O ring is compressed between 0.2mm and 0.3mm. As I wont have any real pressure, I decided to compress the O ring by 0.1mm to reduce the amount of wasted power by reducing the friction. also it it looks like an O ring can be used as dymanic rotary seal at upto 600ft per minute, so since at 5000rpm I'll be doing less than 100ft peer minute, I think I'll be ok.

and here is a prop shaft, prop tube and a couple of bearing blanks to be loctited into the tube before being bored, and the O ring

and machining the groove for the o ring to sit in, and just for scale the tube is 4mm O/D, the bore for the bearing in 2mm, the 4mm o/d O ring goes though a hole 3mm dia and sits in a groove 3.8mm diameter.

and then to test to see if this prop tube would work without using too much power I needed to try it. so I machined a piece of nylon tube to connect the motor to the propshaft, if you've drilled nylon, you'll know that the hole closes up, so I thought I'd take advantage of this, and it seemed to work well. here I am turning the diameter using a tool with high rake in reverse, with a 2mm metal rod in the bore to stop it flexing.

and then its time to do some testing (unlike the cowboys selling motors on ebay)

the propeller Im using is 20mm diameter and is cut down from a 30mm one bought off ebay, but I'll be making my own eventually. and the propeller is on the inside of the jug, this is after a couple of hours running and the batteries voltage had gone down to 3.0v, so the motor was still running at over 4000rpm. so it looks like it'll be ok for running for a fair while. when the prop shaft was taken apart the o ring was dry apart from the oil that was used to lubricate it when it was assembled. So at this stage I think I'd call that a success.

at this time I was thinking about how to mount the motor in the hull so that it aligns correctly with the prop shaft and after a while I decided that you could just clamp the motor to the end of the prop shaft tube ( and remove the bearing from the motor end of the tube).

 

[optima21]

so now its time to make a small adaptor to fit the motor to the prop shaft.

a block of aluminium was squared off and holes for locating on the motor bearing and prop tube and screw holes were drilled

the sided were then milled out to create the flange for the mounting to screw to the motor (the other side had already been done)

and then a recess was cut so that position of the nylon coupling could be adjusted if required, thats a 2mm dia cutter, but seems massive compared to the one milling a human hair

and then after cutting the mounting to length, the slot was cut to clamp it onto the propeller tube

and the components that make up the driveline (of is that propulsion system).

and I'm pretty happy with how well this little mounting worked out, as I thought aligning the prop shaft and motor was going to be a big issue

and fitted in the boat, with the added bonus of how easy it is to fit the motor in place

 

[optima21]

and the final installment, as its not a forum about radio controlled boats, but I think I can get away with a bit of welding and making parts

now I'd sorted the propulsion, it'll help if the boat can steer too. I could have welded a tube through the back of the hull and put the rudder though that. Instead I decided to make a bracket to screw to the back of the hull and put the spindle for the rudder through that.

first of all squaring up a block of aluminium with a flycutter

then a bit of weight reduction and mounting holes, this was taller than necessary but was done like this so it could be held in the vice

and then it was turned over and the height reduced

and I decided to make the rudder out of nylon just because when you drill it the hole closes up, so can be a push fit in a stainless steel shaft, here trying to drill a 2mm dia hole in a 3mm nylon plate

and the I needed steering arm for the rudder to loctite to the shaft, so this was made from brass, milling and drilling first

and then turning the boss on a spigot

and the parts of the steering

and the assembled steering and propulsion systems. One thing about the way they have been made is that they are easy to take apart and re-assemble, because if you cant remove the rudder, you cant change the propeller

and then I needed a battery holder and place to keep the speed controller and receiver. this was the first time that Ive used sheet styrene and think I'll be using it more as its easy to work with and is solvent welded together. the round tube is just some conduit that the stainless steel rod that the propeller shaft was delivered in. it was required to stick the receiver ariel to, as there is alot of metal in this boat and radio waves dont go though it too easily

and out on the water, and its just coincidence that it looks like there is a funnel on it.

to that's the mule done, ready for when I design and build my steam engine, it also has the motor and single cell lipo and propulsion system that I'll be using when converting the model kits to radio control. its goes at a very fast walking pace which for something this size (or smaller) on the water will be fine, and for that its worth doing this testing. I was thinking about painting this in dazzle camoflage, but in the grey I've used, its hard enough to see on the water.

 

[Brad93]

Depth the boat rides in the water is the draught/draft.

 

[selectedgrub]

Mad skills.

 

[tom2207]

great read , well done

 

[Exuptoy]

Amazing once again.

 

[optima21]

thanks for you kind comments guys, the machining wasn't toobad, wish I could do the welding to same standard as some of you guys on here and have the vision of the creative people like selectedgrub.

I wasn't going to update this, but today I finished the radio control conversion for the Revell Trawler, which has the same radio control components and motor from HMS instant, but a smaller servo.

and a closer look, showing from left to right, the single cell lipo battery that will give over 2 hours running, which plugs into the speed controller on the end of the battery holder and on the right in the radio control receiver and the red power connector to the motor.

and at the other end of the hull, we have from left to right, the motor, the smaller servo and the arm that operates the rubber on the right. The way this has been done means that all the parts to make this a working model can easily be removed if I decide to modify it later. Im pleased with how simple the install looks, and the deck will be held on place with magnets.

and the propeller and rudder arrangement. the propeller is 18mm diameter which is 2mm smaller than HMS instant. the rudder is once again made from nylon which is "press fitted" (using hand pressure) onto a stainless steel shaft.

 

[Parm]

The master of ultimate attention to detail

 

[optima21]

The master of ultimate attention to detail

well I keep things simple..... on the other hand look at what the germans are doing.

these models are 1/87 scale, just look at the tiny boat being "operated" from the big boat which is less than 40cm long. I'd like to know how they do these kinds of model

https://www.ebay.co.uk/itm/353053710165