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[DJW]

Rudders finished.




Couple of air bubbles in the silver solder. But not bad enough to do it again... just irritating...

Meant to shoot the rudders against a ruler. But forgot...  the tube used on the rudder stocks is 10mm OD.
Leading edge profile.

And trailing edge.

Blades are 60mm in length,  40mm deep and 4mm thick on 5mm shafts.
Regards to all..!
David.

[Capt Podge]

Congratulations on a fantastic job, they are real beauties, it's a shame they'll have to go into the wet stuff!


Cheers,
Ray.

[DJW]

Haha... They may spend their time on the lake underwater and unseen, but you and I will know they're there and that they're very shiny...! 

[DJW]

Couple of hours shaping the P bracket struts today.

Some aggressive filing then finer grit sanding discs. Final polish will wait for after the soldering.

Shape is now about right I think.

Next step is the more tricky silver solder job. Joining the skegs to the bearings.
So this is what it should look like, if I don't melt them...

Will post the results...
David.

[DJW]

Evening All

P Brackets are ready...!

I was a bit worried about how this would go, but very pleased with the results.

Made up a jig to hold skeg and bearing hub in position:

That's a firebrick btw, not MDF...

Managed to keep the silver solder in the joint in the main...



And the cleaned up versions:










Maybe a tad more buffing up, otherwise good to go.

Props will be drilled and tapped for a grubscrew rather than use a nut on the shaft.  (This was recommended by UKMike and has worked really well. (As in it looks good and I haven't lost a prop on the 1/10th yet...)

Going to start working my way up the shafts now to the motor mounts.  So thrust collars, couplings and so on.

Hope the updates are of interest.
Best regards to all.
David.

[Capt Podge]

Hope the updates are of interest.
Best regards to all.
David.

Definitely of interest David!
... and quite inspiring as well... Once again, a beautiful result. 


Aye,
Ray.

[Ralph]

Haven't commented before, but I'm really enjoying your build. The electronics are way over my head but the quality of what you are doing is superb.


Ralph

[DJW]

Thanks for the feedback and encouraging comments chaps.


Been looking at the top end of the prop shafts and how they're going to connect to the motor mounts. I've got most of it figured out with 3D printed prototype parts, so it's now time for the brass and aluminium components to be created.



Prop tubes are 10mm brass, so am making up a brass header that will contain a bearing race plus seal plus oiling tube and be finished with a 35mm diameter flange that will connect to the thrust block.(Still in black plastic in the above picture)


I've been scratching my head re how to get the flanges accurate as I don't really have the tooling to do it. I'm trying with 3D printed dies that hold the flange plates and have guide holes in precise locations required. And it seems to work...





And when flipped over



Then tapped out for M4



That's one of the flanges for top of a shaft. It'll be silver soldered after a bit more machining. Then ready to move on to the thrust block.


Quite pleased with that approach as it should keep all the flanges accurate.


Work in progress..!
David.

[DJW]

More progress...

Bit more machining of the top end of the prop shaft ready to take its flange.


And some machining of the flange itself so its an interference fit (small hammer required to seat it..)


So its ready to silver solder


This shows the seat for the 11mm od ball race and 15mm od seal, and shows an apparent gap where the flange joins...  I put a bit of a chamfer on the end so there's somewhere for the silver solder to go, its actually a tight push fit...


Here's the ball race inserted


And the seal over the bearing (this build method will keep all parts available in future for maintenance / replacement if required)


And here's the result after some silver soldering and facing on the lathe


Foreground of the pic above shows start of the thrust bearing assembly, thrust will be passed to the solid part of the motor mount, not the motor which will be isolated on bobbin mounts.

And finally for today, I've got the aluminium bar stock in the lathe that will hopefully become the thrust block between the top of the prop shaft and the motor mount.  3D printed version shown alongside, that's what I'm aiming for...



We shall see.  Next exciting episode (maybe) tomorrow...
Best regards to all
David.
 

[Nordlys]

You seem to have made a very gallant attempt to drill the flanges accurately! That kind of accuracy usually needs the dividing head as you indicate.
That's where a lot of projects for me go adrift with just a bench pillar drill and centre punch!
N

[DJW]

Hi N
Agreed re the problems marking out then centre punch then pillar drill. That's been an issue for me too. This is most ambitious machining attempted by me in a while...  Test with the 3d guides will be to see if they are consistent enough in terms of correct line up when holes are transferred to metal. I plan to print a new guide for each flange to avoid any wear in the holes building up to a problem.
A cnc setup would be nice....  But not sure the wife would agree. 🤔
Best regards
David.

[DJW]

Didn't have much time today, but promised an update. Some progress with initial machining of the aluminium bar for the thrust collar.



It's then a 10mm drill all the way through, and a boring bar to take out most of the length to 16mm id.  The flange at the left of the pic above will be left at 10mm, this is where the 15mm od thrust bearing will be seated.


Will then cut at the left flange and mill out to expose the shaft and give access to the thrust collar for adjustments and face that left flange. That's the motor mount end.





That's now tomorrow's task.  Then we'll see if the flanges line up OK...


Regards to all
David.

[DJW]

First thrust collar machined...


This is the thrust bearing that will take reverse thrust.



And this is the forward bearing.



Milling out the access slot.



And comparison with the 3d printed version.



And the assembly so far.



And this is where the thrust collar will transfer that thrust to the motor mount.






Coming along...
Best regards to all.
David.

[Mark T]

Thats some pretty amazing engineering going on there.  A great build that just gets better as it evolves 

[DJW]

Thanks Mark. I suspect that like you I need to know that I've done my very best with the build, so, I try.


Not much progress this week, just a few hours today. But good news is that the flanges are lining up. This is current state of play...





Also now drilled at the motor mount end. And with thrust bearing in place.





And the whole assembly.





It's pretty rigid and I think fit for the power of the motors.


Now have to make the second one, but should be easier as it will be a copy.


Regards to all.
David.

[Capt Podge]

I've just been playing catch-up on your updates David and I must say that I am in absolute awe of your abilities - you're showing just what can be achieved with attention to detail. Really appreciate your updates. 


Ray.

[T888]

Hi David,

Nice bit of engineering,  like you I enjoy making my own running gear, just a question how do you plan on lubricating the shafts ?

[DJW]

Hi Ray and Dave


All I can say is that having set out to build a 1/5 Aquarama I think I have to pull out all the stops to do it justice. And I've made my life just that little more difficult by wanting to suppress unwanted brushless sounds as far as possible. And add a boatload (pun intended..!) of electronic toys. Don't know how long it's all going to take... or cost...
But I am enjoying the build process, that's the main thing..!
@Dave. I've yet to add an oiling tube on the shaft tube. I'm planning to add it on that top brass collar that holds the top bearing and seal. There is an issue with this as I've found on the 1/10 build, there's a large deck assembly immediately above that collar. So maybe still add the tube there but add a feed tube in a more convenient location and link with some pipe. Then I use a syringe to force in a few ml of lube before each outing.
I'm using what I've heard is the Ron Dean mix, vasalene, WD40 and 3 in 1 oil in roughly equal parts on the 1/10 Aquarama. Seems to work very well and that's using the same seals as the current build. I add a drop of same mix to the 'other' side of the shaft seal near the motors every now and then just to stop the seal getting dry.
I was reading on the forum that some are using olive oil. I'd like to do that from an eco point of view, but have also ready mixed reports. Until I'm more convinced I'll stick with the current mixture.


Best regards
David.

[Stuw]

Wow....I’m assuming that thrust bearings aren’t needed on smaller scale boats? It becomes an issue due to your scaled up version? Without any is my (someday to be finished) Javelin with brushless motor likely to suffer as the forces are transmitted into the motor?

[DJW]

Morning Stuw
To be honest I don't know what forces the outrunner motors can really take. I do know they're designed to take the pull or push of an aero / drone propeller, but given water is a more 'solid' substance than air, it could create significant loads, instantaneous and sustained...  Maybe there are some folks here who can comment. I'm doing it for a couple of reasons that I can't really quantify, more of a gut feel.
1. I'm using exposed shafts, and I don't want the P brackets to take the force.
2. The motors have the potential to develop around 1,600w / 2.2hp each. I just remember using a 2hp outboard motor and the force it could generate.
3. I'm planning to isolate the motors from the hull by mounting on bobbin mounts, and at the coupling using a suitable three part design.  So this alone means I can't have the thrust from the shaft passed to the motors.  They just have to produce their rotation energy, and not take any forces that would deform the rubber mounts...


In general terms I think the issue of where to take the thrust rises as the motor size and power of that thrust goes up.  On full length prop tubes I think its conventional to use a thrust washer (maybe a teflon washer between a couple of ss washers) at the prop end to help take and transmit the thrust to the prop tube.  So it's not all passed up to the motor.  Then its down to setting up the shaft to not place too much thrust at the coupling end.


As always just my opinion.  A very interesting point and I'd be interested in other folks views.
(Then there's always the fact that I like using the lathe...)
Best regards
David.

[ChrisF]

Yes, David, we all know it's because you like to introduce a nice bit of engineering!   


But seriously can't really argue with anything you are saying with the main points being that in this build you are isolating the motors and also that the forces on the P bracket could be considerable. Ok they could be reduced/eliminated by using a collar at the end of the prop tube just outside of the hull with washers as you have said for full length prop tubes but its nowhere as elegant a solution and you have the space.


So no Stuw, it won't be a problem with your Javelin or similar sized craft and the locknut and thrush washer approach at the prop end and a collar at the motor end is a tried and tested solution. Even if some thrust is applied to the motor by not setting up correctly the motor should still last for ages.


Chris

[JimG]

There's much less worry about thrust being applied to the motor bearings with a brushless motor. The old brushed motors normally use a plain bearing so any thrust is applied to the face of the bearing and any lack of lubrication will create drag and wear the bearing surface. Brushless motors use ball bearings and they are designed so that the load is on the bearing center which rotates with the shaft so no wear from this. The actual load is on the balls running on the hardened outers and as they are normally a sealed bearing they are well lubricated. As you say these motors are generally sold for aircraft use where the load is on an e-clip on the shaft at the rear of the motor running on the rear bearing. In a boat the load is normally in the opposite direction where it is the rear of the rotating case pushing on the internal bearing. In both cases the bearings can take the load easily without problems.Not too sure why you need to isolate the motors as they should be well balanced and vibration free when running.
Jim

[Stuw]

Morning Stuw
To be honest I don't know what forces the outrunner motors can really take. I do know they're designed to take the pull or push of an aero / drone propeller, but given water is a more 'solid' substance than air, it could create significant loads, instantaneous and sustained...  Maybe there are some folks here who can comment. I'm doing it for a couple of reasons that I can't really quantify, more of a gut feel.
1. I'm using exposed shafts, and I don't want the P brackets to take the force.
2. The motors have the potential to develop around 1,600w / 2.2hp each. I just remember using a 2hp outboard motor and the force it could generate.
3. I'm planning to isolate the motors from the hull by mounting on bobbin mounts, and at the coupling using a suitable three part design.  So this alone means I can't have the thrust from the shaft passed to the motors.  They just have to produce their rotation energy, and not take any forces that would deform the rubber mounts...


In general terms I think the issue of where to take the thrust rises as the motor size and power of that thrust goes up.  On full length prop tubes I think its conventional to use a thrust washer (maybe a teflon washer between a couple of ss washers) at the prop end to help take and transmit the thrust to the prop tube.  So it's not all passed up to the motor.  Then its down to setting up the shaft to not place too much thrust at the coupling end.


As always just my opinion.  A very interesting point and I'd be interested in other folks views.
(Then there's always the fact that I like using the lathe...)
Best regards
David.

Hi David. That all makes sense to me. I understand now that you want to avoid loading the P brackets and the shear scale of your boat warrants some serious use of the lathe I reckon 


Although it’s not something I’ve done, I also see the need to solve the issue as you’re mounting the motor on bobbins. To be honest I had thought of doing that with mine but couldn’t get my head around avoiding the motor being pushed around! By using the bobbins I take it one of your aims is to eliminate noise being transmitted and magnified through the hull so that you can have a deeper V8 sound generated?


Thanks again for the detailed explanation. I follow with interest and awe...

[DJW]

Morning Chaps


@Jim. Thanks for the feedback re the bearings, good to know. I agree that these brushless motors are well balanced and precision pieces of engineering, so no mechanically generated 'vibrations' to speak of.  Having said that... I really don't like the high pitched whine that these systems give off, and that's what I'm trying to address...  (The following might be rubbish, but it's what I understand right now...)
I think the whine comes from the pulsing of power into the coils of the pole pairs.  My motors are 14 pole, so seven pairs, each shaft rotation needs 7 'jolts' of volts (and amps..), so to speak, so this is not really totally smooth delivery of power.  Its 7 kicks per shaft rotation.  I'm using FrSky Neuron ESCs that can use sine wave delivery of that power, so smoother than usual...  But the issue then remains if one attaches this 'pulse generator' or as we're calling them 'brushless motors', to a sounding box, or as we're calling them, hulls, we get a very effective speaker resonating at whatever frequency (or harmonic that we can hear) is being generated by the motors...
Maybe the ESCs are adding to the party too as they're busy generating these pulses...   (Just like a mains transformer will hum)


So, I'm isolating and containing the ESCs.  And doing my best to isolate the motors.


@Stuw. I have the same concerns about the bobbins allowing too much movement, that really would not be good.  So, this is the initial test arrangement, standard 20mm bobbins x 4 on the prototype 3D printed mount:





It's pretty firm, but could be better, so I've added some cups (below) that are a tight fit around the bobbins.  At the moment just in PLA plastic from a 3D printer.  And they really make the mounts more rigid and resistant to the effects of torque by constraining their movement, while still isolating the motor from the mount and hull with rubber...





The idea is that the cups can be made shorter or longer to arrive at a solution that works.


Whether it will all work...  I don't know but it's fun to try.


My 1/10th Aquarama is noticeably quieter than many other similar brushless systems, so I'm planning to use similar techniques, and go further in the quest to have a quiet boat..!


And yes, I'd rather just hear the water coming off the hull, or the V8 sound system..!


Best regards
David.

[DJW]

By the way...  I now have two of the thrust blocks ready to go.  That makes the props to the couplings for both shafts reasonably complete.








Motor mounts next...


David.