Not the hobby I expected :)

mein gott! soldering these 328p chips in is NOT easy. I managed to blow the crystal and a cap off the board whilst de-soldering the bust one, don't mind the xtal blowing off cause that needed changing anyway but the cap was a pain to get back on :P

I also had to remove the ISP header because I was melting it.

Installing the new one (harvested from an arduino nano) was a JOY i got top and bottom pins in fine, but the sides were neatly off by one half pin. uuuuurrrgh :)

Anyhoo, It's booting, flashed with 3.8.8, and the radio doesn't work. That's also had the crystal removed with it's pads.

No worries, got an rfm22b in the post. This is a joy, it's great to have a broken one I don't have to care about to learn these techniques on. I'm super happy that it's booting.

cat wrote:mein gott! soldering these 328p chips in is NOT easy. I managed to blow the crystal and a cap off the board whilst de-soldering the bust one, don't mind the xtal blowing off cause that needed changing anyway but the cap was a pain to get back on :P

I also had to remove the ISP header because I was melting it.

Installing the new one (harvested from an arduino nano) was a JOY i got top and bottom pins in fine, but the sides were neatly off by one half pin. uuuuurrrgh :)

Anyhoo, It's booting, flashed with 3.8.8, and the radio doesn't work. That's also had the crystal removed with it's pads.

No worries, got an rfm22b in the post. This is a joy, it's great to have a broken one I don't have to care about to learn these techniques on. I'm super happy that it's booting.

well done getting it booting, replacing the 22b will be easy compared to the 328.

geofrancis wrote:
well done getting it booting, replacing the 22b will be easy compared to the 328.

The thing I find hard about the daughter boards is the vast gobs of solder UNDER the pads. Wicking all that out is not a skill I am good at. I think I might need some of that gooey flux that come in a syringe to get it all to flow well into my solder wick.

Whilst we're here, what diameter should I be looking at for NiTi wire for bespoke antenna?

cat wrote:

geofrancis wrote:
well done getting it booting, replacing the 22b will be easy compared to the 328.

The thing I find hard about the daughter boards is the vast gobs of solder UNDER the pads. Wicking all that out is not a skill I am good at. I think I might need some of that gooey flux that come in a syringe to get it all to flow well into my solder wick.

Whilst we're here, what diameter should I be looking at for NiTi wire for bespoke antenna?

hot air soldering is much better for removing parts like that as you can heat it all at the same time.

Well it arrived and was glued in in a gap between work meetings.

And it bound right up!


I've checked it against a Tx in my radio and it wiggles a servo on all channels \0/

Thanks again for these radios, I'm astonished that I've now got a couple of spares AND the confidence to repair them, and consider building my own in the future.

The tiniest heat shrink I had wasn't tiny enough so I had to wait for some new stuff to arrive but it did and it has and this little guy is 166mm from the end of the sma connector (which I assume to be shielding it) to the end of the wire.



I'm not sure how to terminate the end to seal it and stop it poking eyes out or grounding out on 'anything else' but a blob of hot glue seems the most probable easy solution.

I made sure it connected to the Rx board with my multimeter and tested it out with my radio. It works!
At some point I may get a nanovna and test it properly but I'm a bit skint atm. (don't have telemetry so can't try the rssi)

I think that's radio 'done' for a bit. I need to get back to failing at building my WTC so I can actually attempt to SINK!

I'm quite high on solvents but I can still see this MASSIVE GAP between the non-parallel sides of this sub.





I'm not sure if that will close up when cylinder support ribs go in and I'll hold off modifying till I have that stuff sorted out, but what advice would you have for closing that gap if it remains later?

In positive news I've actually started *building* the model. In saddening news I've ordered a pre-built WTC because I want to get on with sinking. I WILL still build my own, but I think I stand to learn a bunch of stuff from experiencing some pond activities for myself. I still know almost nothing about building driveline seals and etc. I would love to have this first submarine in a pond next summer. This is my target.

I am in the middle of building the Seawolf myself. Magnets and bulkheads might help. The hull is pretty thin styrene. Keep going and there is no shame in buying a premade WTC.

It's really a hubristic climb down from 'PPFT it's just a TUBE with some STUFF IN. I CAN MAKE THAT FOR PENNIES; WATCH ME' to 'um, it's a bit tricky isn't it?'.

I'm pretty excited about going sinking for real now and I have many years left to make more subs and more tubes.

I also need to remember that I have to learn to DRIVE the sub.

You are right, it's very easy to forget that.
When you first sail a scratch built model it is too easy to interpret a "driver error" as a "design error".
You need to learn to drive (fly?) any sub.

I just recently added a R&R model engineering WTC to my collection in order to finish my Bronco type XXIII in enough time to take it to the regatta next month.  sometimes it just makes sense not to build the entire WTC... and its also an opportunity to see how someone else "did it".

tsenecal wrote:I just recently added a R&R model engineering WTC to my collection in order to finish my Bronco type XXIII in enough time to take it to the regatta next month.  sometimes it just makes sense not to build the entire WTC...   and its also an opportunity to see how someone else "did it".

Yes it's always easier to build something yourself when you have a working version as reference, especially if it's your first build. My first sub is a failed build from another first time builder, so most of the work has been trying to fix mistakes I never made, luckily there are experts here to answer questions!

I am a bit confused about what I'm buying, it has a snorkel with a check valve in it, I was going to build my own pressurising system with a bladder, so my 'air' would stay in the tube. If I'm venting my air up a snorkel, then how do I ever surface, or do I have to NEVER go below conning depth?

The alternative is on pump out to go to negative pressures but yet positive displacement volume, perhaps it will come with instructions, lol. This gas science and density is obviously beyond me.

with the check valve, that will allow air to leave the wtc while filling the bag with water, keeping internal pressure in the wtc stable, even below snorkel depth.

so... you will have negative pressure in the system while emptying the bag, until the snorkel is above water level, then wtc pressure will equalize.

this allows you to keep pressure changes in the wtc to a minimum, but still allows you to become positively bouyant while submerged, with a minimum of mechanical/electrical components.

if you segregate the ballast tank from the rest of the wtc, like the OTW and R&R designs, then you will only be changing the pressure in the ballast tank itself, and not the whole wtc.

So, I have a quite beautiful WTC in hand now, but I'm looking quizzically at the rear end of this boat.
The instructions warn us that the rear end is tight and now I have the parts I can see what is meant by this.

It seems that the magnetic closure is to keep our hull halves together at the nose, but nothing at the rear save for the small lip where the midsection will JUST slip under the tail section.

Whilst this is the most obvious way to achieve this, i can't help wonder whether gluing the top half of the hull together in one piece and razor sawing the top much closer to the control surfaces to get significantly better access, a new locking ridge can surely be created by cementing some styrene to the now sawn top.

Am I mad to consider this, will I lose my mind in the saw kerf panel gap and in shattered plastic?

I toddled down to my local boat club but there was absolutely no one there on a glorious Sunday. So I went to my second nearest boat club that turned out to be amazing, had a building full of people working on projects, a cafe, a dog, parking, and another human who does sinking boats! I’m stunned. Sadly they won’t let me join because renewals are in November and they don’t think it’s sensible to take a years fee for two month’s membership.
I’m allowed to go as a guest though which is super kind of them.
Can’t be too long now till my first post about a lost submarine :)

cat wrote:I toddled down to my local boat club but there was absolutely no one there on a glorious Sunday. So I went to my second nearest boat club that turned out to be amazing, had a building full of people working on projects, a cafe, a dog, parking, and another human who does sinking boats! I’m stunned. Sadly they won’t let me join because renewals are in November and they don’t think it’s sensible to take a years fee for two month’s membership.
I’m allowed to go as a guest though which is super kind of them.
Can’t be too long now till my first post about a lost submarine :)

I know some people in Livingston with boats. il ask then where they go.

Really nice that you have found a potential club with humans in residence. (I won't ask about the age profile!)

I "disliked" your earlier post ( a rare event) but you may regret cutting into it without giving it a few days thought.

dissenting opinions are often the most valuable! :)

I'm thinking i can probably drill holes without gluing up first, the parts register really well so i can tape them up really good, then i can set up the innards pre-glueup.

All mistakes are learnings, and if i get a hole in the wrong place I can just fill the plastic back in and re-drill.

What’s that creamy white plastic everyone loves making end caps out of? The stuff that’s very machinable, I mean.

I use smooth-on.

specifically Smooth-Cast ONYX slow

it isn't white, it is black

it has much higher shore hardness and tensile strength.  it doesn't distort under pressure.

Thanks. Does one buy that pre cast? Or cast parts from fluid and then machine to tolerance?

I cast my own parts using that. basically my endcaps, it is an open face single part mold, so the outside face is machined down to flat on a lathe, and then the o-ring groove is also cut into the side wall... each o-ring groove is cut as a separate step to ensure that it is a perfect fit for the polycarbonate tube it is destinited to fit into.

i use the smooth-on "mold-max 30" rubber for making the molds.

Well, everything went a little on hold because I accidentally bought a tiny lathe, which obviously is a whole project in its own right.

Updates on subs in due course, I hope.

Sunday has been a very good day.

The lathe was a VERY good deal given that it included the machine and a lot of tooling, jacobs chuck, micrometer, dial gauge, knurling whatsit and so forth for small numbers of money.

It has had a malady in its life, it took a hit some-when sufficient to grenade its 3 jaw chuck (it arrived with an independent 4 jaw, which I am happy about)

This event had left the mildest 'tight spot' in the 'work area' and there was some anxiety about potential damage to the ways. Happily I located this tight spot to a burr on the rack which the carriage drives along and 5 mins work with a small file has restored the tooth profile to the rack (which could be replaced for £30) and the lathe is now smooth.

Long story short, my end cap anxiety is behind me so long as I can work out enough of this machine to create reliable o-ring grooves :)

One thing that's been holding me back on the sub front is the very very kind supply of the tiny receivers, 4 outputs and much more suited to the narrow confines of small subs than the 8 channel ones.

I got the transmitter to agree to send the 3 position switch in lieu of channel 4 but was left with a servo on channel 1 which jittered and acted oddly. I assumed some mixer function was getting in the way and was angry that I had removed channel 4.

It's taken FAR FAR too long for it to dawn on me that I needed to reprogram the rx via the tx to disable RSSI on channel 1 of the RX. My servo was dying in the maelstrom of channels 5-16 yelling digitals, lol.

These things solved, it's back to carving out plastic to get propellers into my banana shaped hull, sob.