Hi Roger, no worries using the idea, that's why I put it up, as many people have had the same problems I've had with the Chinese stuff,(with planes and boats) As long as your tubing is a good tight push fit it should hang on ok, but if you can fit those really small zip ties, just place the zip locks at 180 deg to each other and they should be fine. You can also experiment with the ties for any fine balance required, -leave them only just tight enough to be able to move them, and move them round alternately 30deg at a time to see if there is an improvement (if it's not way out). If you can get 2 small ties on each end 180deg apart, you have more balancing opportunities. I've balanced 46 diam outrunners like this. You also need to check the shafts, - rolling them on a flat surface with a light behind is a good way to spot any bowing,- doesn't take a lot to cause vibration (gets worse the higher the revs).

You might need to manipulate the silicone a bit on the splines if it's been in a tight coil, as it can cause a small vibration initially,- usually sorts itself out though. You could fill the inside gap up with silicone (or a piece of smaller tubing) which might stop it twisting on hard starts if you have a powerful motor, but it's probably not necessary if you use the thick tube . Cheap as chips to experiment with, and once you have the size, you can cut a bunch of spares for the tool box. Hurts nothing if it breaks. If you hear it squeal just back the throttle off, it will be the silicone slipping (automatic throttle control 😁) Good luck with the experiment.

JB

Hi Rowen, might have been the one I made, using large diameter silicone tube on splined aluminium end pieces I made . You could probably use the Radio Active brand ready made splined ends for the plastic universal joints from CMB and use silicone instead of the plastic coupling. I used the 12mmx6mm automotive tube and made the ends to suit. Works pretty well, although had an accidental failure with a big overload on the coupling (about 40A), while in the test tank, but that was with the ends just pushed in and not zip tied.

Aluminium ends were reamed for a precise fit on the motor and shaft. Most of the usual Chinese universals are useless for high speed, as they have far too much movement all round (the rattling sound you hear in a lot of models). Only really suitable for cars or slower speeds. This one has been run to around 30,000 RPM unloaded. I've put this info in the Hartley cabin jet boat blog. Good thing about a silicone coupling is it has a built in safety release if the prop jambs in weed etc (depending on your motor power and the size of tubing you use) and is cheap and easy to replace. I have a meter of the tube, so lots of replacements in that if necessary.

JB

I hope you have filled out requisition form 1314 and submitted it to the appropriate department for approval Colin? 😂

JB

Great video Phil, shows Grahams set-up very well.👍👍

JB

Sails well Ron, nice job👍👍👍

JB

Great tug and barge combo Ron, really looks the part. Schooner is very nice as well,- looks to be sitting spot on.

JB

Hi PJ, very cheap and easy to do,- plenty of bits on Ali Express. Pic is the type I'm using,- works well with a 1s Lipo.

JB

Perhaps his name was Chris, Ron 😉 (ie Chris's craft)😁 Rare sighting, usually those boats are only seen at shows these days, ( from what I've seen.) I was looking at a boat show on YT (might have been your neck of the woods) where there were all sorts of amazing restored boats like that one, - fins galore, as well as wooden boats.

We had a lot of interesting glass boats here years ago, but most have ended up in the tip. The odd one pops up now and again from a 'barn find'. There is a 70s glass 18 footer I saw for sale for $1100 on a trailer, on my way to the pond the other day, (a lot later style, which would make a nice restoration project (if only I had room for one more LOL.) 10 yrs ago,- maybe. Even these are getting rare now, and very few people building their own any more from plans like they used to.

JB

You're really ripping into it Trev👍 looking good.

JB

Hi Steve, I've managed to reduce the power to about 50% (which is still a lot) after having a play with the TX settings again, (the ESC was not playing ball with the TX settings). All was fine the previous night, but next day when turned on, the throttle was back to the middle again. Changed the end point setting from left to right side (has 120 each way) zero'd everything and changed the ESC from soft start to auto throttle range, and now seem to have the stick back at the bottom, where it should be for a plane ESC.

None of this is a problem with a plain old std 4/6ch, as there is no fancy stuff hidden in a menu to forget about, and ending up having to hunt for when there's an odd problem. This ESC's been in a crash, so may be dodgy,- time will tell.

I'm going to try the coupling again as it was before, but if it slips I'll look at the idea you mentioned (was actually hunting through my spring collection tonight for a suitable tension spring to cut some coils off.) Might have to find some HT wire and wind a special one on the lathe, with small legs to grab with pliers, (like mini radiator hose clips, - very little room to do much). I do have some proper wide ones which came with the tubing, but they are too big. I don't think it will need much to stop it slipping, just needs holding from expanding with use and age,- as silicone does.. If the coupling doesn't work this time, I might even just make a dog clutch, then there definitely won't be a problem, (except maybe noise)😁

JB

Tested the new gear yesterday and it all went well till I was playing with the throttle trims and end points and had an unexpected full power no stop situation which ripped the coupling. Went like a fire hose till it did though, and took a lot of power to break it. I had not cable tied the tube onto the ends which were just pushed in, so it did pretty well to hold up like that. One end still had the spline marks, but the other had skidded then ripped the tube down the middle. Good anti stall safety feature for the motor I think.

Probably withstood around 1/2hp at 25000rpm for about 6 seconds before breaking, so a big improvement on the Mk 2 version. The new motor has a ton of torque and with the new 40/90c 3s 2700mah Hyperion battery is about double the power of the MK2 setup, - 3s 25c 2200mah zippy compact which was a bit tired after 10 yrs for any heavy stuff.

I had trouble with the sound unit not syncing with the throttle, which required allsorts of trimming to get it almost right. I'm using a one way aircraft ESC, but the sound unit works like a fwd-rev ESC and using a fwd- rev ESC, and needs a center point. I think I have got round it now by switching the siamesed throttle lead (with ESC lead) to the Aux hover pitch rotary on the 9X TX. seems to work just as well, but allows the throttle to be returned to full down-full up mode, and the sound controlled separately, which is good, as you can rev the 'motor' without the boat taking off.

Some vids of playing with the setup at idle power, and views of the jet mods in case anyone is wanting to do the same to the cheap jets without a reverse bucket.

https://youtu.be/RgWO96netJ4
https://youtu.be/aSA3AnX0iyY
https://youtu.be/rGPMgO7zvnQ

JB

https://youtu.be/RgWO96netJ4

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https://youtu.be/aSA3AnX0iyY

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https://youtu.be/rGPMgO7zvnQ

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What a classic,-beautiful !

JB

Bet you wished you still had it today Trev !?

JB

Good find Martin, that's one I haven't seen before !

JB

Hi Rick, coming along nicely. Funny how far China has spread, I have exactly the same clamps way down here !

JB

Hi Steve, I was surprised it lasted a couple of runs, as there is a big load on it at full power. The main problem with the silicone I found, (even with the plastic tube reinforcement) is that the torque screws the silicone tube, and makes it climb towards the motor and tries to screw itself into the rear bearing. I put a small collar in front of the bearing, but as you can see by the flare in the plastic tube, it had tried to climb over the collar.

I had the same problem with the high speed brushed motor I started with in the boat, and I made brass tube and washer stops for that, (same in the runabout) but it still did the same if you gave it some stick. Hopefully this one will fix it, and if it does, it might be my std coupling on any future models.

Re the coupling letting go near the bank, that was only half of it. When I went back to the jetty to grab the launching trolley, (bank was too steep to grab the boat) the wind suddenly changed and the boat started to head out into the pond. I raced back and thought, "crap, I'll have to step in and grab it before I need to swim for it" One of those times when the brain says "that's a really dumb idea mate!" but the body says "stuff you, I know better". So in I stepped, shoes and all, into 2ft of water with a slimy clay bottom, and promptly sat on my A888se up to my waist 😂😂😂.

Was up in a flash before I was 100% saturated, but covered in clay and rather damp, (and hoping the residents of the apartments over the pond hadn't seen it and had a stroke laughing, - didn't hear any clapping so might have been lucky) Rescued the boat though, which was the important thing. Luckily I had a few old towels with me and managed to dry off a bit and drain the shoes. I had to wash the clothes and have a shower in disinfectant pretty much when I got home, as you don't know what's in those collection ponds (everything from the roads and land run-off etc).😐

All in all a great day, -what more could you ask for,- a play with the model and a swim on a lovely evening LOL. Probably scared the carp out of the eels.😂 Did manage to complete the vids of the trip to the pond which I'll post once YTd Think I'll have to build a rescue boat.😁

JB

Hi Trev, a similar type of coupling is sold by CMB and others, but are just pressed into plastic universals. There was nothing available in such a short size other than the spiral aluminium connector it came with. They are only meant for 3D printers etc and they have a 'handed' spiral cut which is only good for one direction or light loads (with the spiral, not against it,-which could cause distortion under heavy loads and metal fatigue.

The impeller in the jet is doing about 25,000rpm loaded, so needs to be precise. The holes (4mm+5mm) in the ends are reamed to size (not just drilled like Chinese rubbish) and are a light push fit on both shafts and have no movement. Could still be improved by making them from brass, but I'll see how these hold up first. I should probably cable tie them before giving them too much stress.

JB

Looks and sounds great Trev👍👍

JB

I decided to change the Surpass 3650 3000KV in-runner for an XTeam 3660 2550KV for a bit more torque and try the heavy duty (hopefully) coupling I made on the lathe. The coupling uses 11mm OD x 6mm ID silicone tube and is a 3 piece unit with alloy ends with splined inner diams which are a tight fit in the tubing. The whole coupling is only 25mm long to fit in between the jet unit and motor mount, (not a lot of room for most std couplings.)

The previous experimental coupling was silicone tube with a firm plastic tube pressed on, which lasted for a few previous runs, but the last run shredded it completely, so I thought it was time to try my new MK 3 coupling. After I modified the jet unit, (better impeller and min clearance) the 3000KV motor pulled 30A static, and obviously had a bit of torque to shred the coupling. I like the silicone as you can't damage your motor if something jambs the prop,- it will strip or tear and stop the motor stalling. The smaller tubing obviously has its' limitations,- hence going BIG.

I've run the new coupling up to around 25000rpm with a shaft, and it's very smooth with no vibration. I might add small zip ties to the tubing to grip the splines better.

Forgot to check on the earlier runs, but the thermostatic fans on the motor (2 in the dummy motor and 1 in the battery compartment) worked well on this last run, which was good, and the fans cooled things down quite quickly, (battery gets quite warm). Both use a 30C thermo switch,- the battery one is just taped to the battery.

Another test due when the weather clears up, (rubbish at the moment).

Quick vid before the old coupling let go.
https://www.youtube.com/watch?v=xpAOqwlh9Ok

JB

https://www.youtube.com/watch?v=xpAOqwlh9Ok

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Hi Rowen, thought that might get your interest😁

JB

Hi Martin, the Swedes seem pretty good at navigating narrow waterways at speed, -think they've had a bit of practice since WW2.

JB

Another crossbar clamping option. I tried grinding the sides of the anvils and webs off the tops of the small G clamps to see if they could be utilised in the slots, and now they are a bit easier to use. Handy if you can't find the small vice grips. The small G clamps are probably more common.

JB

I've thought of a better clamping method, so gave it a try last night. Just milled slots in the cross bars to take the small Chinese 5mm wide long nosed vice-grips,- Much easier ! At $5 each these clamps are cheaper and 100x better than most of the plastic rubbish you can buy now. Much more useful !

JB

Hi Graham, if I cut down a few trees and widen the parking area, I might be able to squeeze one in. LOL The guy who owns the 64ft British Power boat HSL here, managed to wiggle it in beside his house while he worked on it, (had to demolish his garage to fit it in though )😂 If you are wondering where the instruments are, it's navigated with an IPad (bit like a Tesla). He bought it in bad shape as its' second reincarnation. Now fully air-conditioned.

JB

Good thinking Trev, I bet most people throw those handy internal 'profiles' away without thinking! ( I still have a bunch from old kit planes) At least it's a good start.👍

JB

Great video of a 90E Swedish combat boat. Water jet powered.

https://www.youtube.com/watch?v=BYc6dMuSqNg

52ft
2x 625 HP Scania DS114 V8
2x Kamewa water jets for 40knts

Impressive,- I want one😁 (you can pick one up for NZ $ 157k at the moment, -one careful lady owner (and a hundred rough Swedish army buggers) Make a good jet model.

JB

JB

https://www.youtube.com/watch?v=BYc6dMuSqNg

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Combat Boat 90E 720p phoneversion closeup. Stridsbåt 90E 720p telefonversion närbild.

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Great job Andy, looks fantastic and sails well, looks well balanced looking at the rudder inputs 👍👍 You'll be happy with that.

JB

Hi Rowen, seemed an unusual choice of model for a ship from the opposite side of the world. I sailed across Cook Strait to Christchurch and back from Picton on her sister ship about 2 yrs later, and you sailed past the wreck as you came into and out of Wellington harbour. Vids Might be of interest. http://maritimeradio.org/in-distress/wahine/1968-salvaging-w...


JB

http://maritimeradio.org/in-distress/wahine/1968-salvaging-wahine/

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Looks great Bill, nothing wrong with that ! Good you are able to be back at it again👍

JB

Looks spot on Steve. I think once you get the rails, all the deck fittings and wheelhouse etc on, it won't look over done. I think it's just that you have a big 'plain' surface to find faults with.

Jb