Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Working Vessels => Topic started by: bfgstew on January 06, 2017, 05:26:14 pm
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After several hours on AutoCad and several more 3D modelling, a few quid spent at Shapeways mh parts for my thruster have arrived. It is purely proof of concept at the moment and am not going to get into rights and wrongs etc etc, i would lkke just to share my idea with the Mayhem collective. If it works, great, i shall sell it and make my fortune and retire to the sunny Canary islands if it fails, so what, i had a go.
Right, it has a little 2212 1000kv brushless outrunner motor at the heart of it, took original shaft out and fitted a longer one to accept 2 props.
The motor is mounted in a split case, sealed and then fittdd into the pump case, in theory the area of the inlet is the same as the body so there should be no loss or increase in pressure/flow.
30mm inlet, 2 29mm dia thruster props from Raboesch, length as it is 120mm, a bit long but as its proof of concept we need not worry too much about this at the moment.
Have got a bit of work to do first getting the motor to fit in casing, nothing major and can be tweaked in AutoCad for next version!!!!
So i shall start in earnest and post next stage when props come from Germany.
Any thoughts or ideas please feel free to indulge me.
Regards
Stewart
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Stewart - Wow - this looks amazing.
Will be very interested in following your progress with this.
One goal of mine for 2017 is to dabble/get into 3D printing even if it's using an external service like Shapeways.
C-3PO
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looks great . What sort of size is it
john
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As it stands at the moment, 120mm long 50mm wide and 55mm high, inlet is 30mm dia. This will be reduced in the future if all goes well.
Main concerns at this moment are flex of motor shaft with those 29mm dia brass props, may have to go to plastic?
Durability of motor if water ingress into motor chamber (i know brushless can run submèrged).
Durability of 3D printed material (strong and flexible from shapeways), how long it can stand flow and pressure of water, different from just sitting in it?
As i say, early days and mainly proof of concept, but thanks for showing an interest in my little project.
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It great to see some one trying new ides .
john
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First job is to make sure the motor fits in the housing, a bit on the tight side so some slight fetting to one of the faces to give slight clearance so the can of the motor rotates freely, then some very careful fettling on the cable ducting. 2 x 3mm cap heads hold the motor to the housing and 6 tiny self tappers to squeeze it all together. Some grease will need applying around the shafts and bearings then a thin smear of silicone sealant to seal it off. Cant do owt now until seals arrive on Monday from Germany.
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Hi stew. looks a great project, are you purchasing the two props the same side ( 2x left or 2x right ) ?
John
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They are off the twin prop Raboesch unit. They do a 5 bladed prop as well.
These types of props are just a skewed blade so can run both directions with no change in performance.
Raboesch catalague worth downloading, got some serious brasswork for sale!!!!!!!!!!
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Hi Stew. Was just a mention because if they were handed props they would work against one another.
Regards
John
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Ok I have built my thruster unit, had a bit of a hiccup as the prop bore is 4mm but the motor shaft is 1/8".........had to do a bit of machining to sort out.
Pictures should tell the story.
All thats left to do is power it up and see how it performs, should get that done at weekend.
Regards
Stewart
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That is fantastic 👍 It looks like something very expensive that's been shop bought. Lovely job Stew and great lateral think with the motor too
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Thanks Mark, the idea has been bouncing about for a while now after seeing the Dutch and German master builders make their own thrusters but have always hated the noise of the gear drives, so came up with this idea. It may work, it may not, obviously i am hoping it will because i can see potential in the market for this, not just as a bow/stern thruster but maybe for subs, springers and other craft. Will have to see how trials go first...........👍
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Now that IS nice. :-))
Len.
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Agreed! ..."but will it blend?" {-)
Andy
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Ok, got everthing together and made a dummy hull out of a washing up bowl, glued to 30mm stub pipes in and fitted thruster inbetween with some flexi pipe as joints, filled sink up and plopped it in with 2 SLA batteries to act as ballast. Sat for half an hour and no leaks, a good start. So connected electrics up and away it went, fair bit of thrust from it so just transferring it for a bath tub test, will try and get a video of it but difficult as there is just me here at the moment.
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Not bad for first go even if I say so myself.......and yes it does shred!!!!!!!!
It did tend to cavitate slightly when it was against the side of the bath but this was due to it tipping slightly allowing the inlet to rise up and with the force it goes was sucking air in. This will push anything and am pleased with the outcome. I have another motor on the way as want to make a few adjustments here and there but all in all very happy with it.
Any one want to buy one?
Sorry about poor quality of the video but think you can see how well it runs.
https://youtu.be/GuP78muwnII (https://youtu.be/GuP78muwnII)
Regards
Stewart
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Hi
That looks good . Looks like it has some power
John
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Very impressive performance.
I didn't expect quite that much thrust.
:-))
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The motor is 1000Kv and on 12v so a bit spritely. New motor is down to 800Kv and may run it on 7.2v.
But it certainly does have plenty of thrust, more than my baths spa nozzles!!!!!!!!!
I did find a few places water had seeped through so going to have a rethink on the casing design but nothing major.
Thanks for the comments
Stewart
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Perhaps you can create a slot for some "O" rings at the shafts.
:-)
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Well it does look like water is ingressing past the G rings, think the problem is because the casing is in 2 halves the alignment of the shaft to the bore and therefore the G ring is out very slightly. Looks like I need to design some form of canister/tube that the motor can be seated and aligned accurately along its axis. Also there may be some flexing in the shaft, at 1/8" and flying around at 12000 rpm I dont blame it. So, new motor at lower Kv and bigger shaft, smaller battery 7.2v, cannister design for motor housing, 'O' rings for shaft seals plus 2 outer bearings in housing to take out any flexing.
Should keep me busy for a few days!!!!
Thanks so far guys
Stewart
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now that you will be using 4mm shafts, use these instead of o-rings on the shaft seals:
http://www.engel-modellbau.eu/catalog/product_info.php?cPath=37_256&products_id=539 (http://www.engel-modellbau.eu/catalog/product_info.php?cPath=37_256&products_id=539)
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now that you will be using 4mm shafts, use these instead of o-rings on the shaft seals:
http://www.engel-modellbau.eu/catalog/product_info.php?cPath=37_256&products_id=539 (http://www.engel-modellbau.eu/catalog/product_info.php?cPath=37_256&products_id=539)
They look very similar to the 'Valve stem oil seals' used in the motor trade. :-)
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It is the one I am going to use.
Always known these as lip seals. The spring is the key to these, keeping uniform pressure on the shaft.
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Very nice work. All credit to you for giving it a shot and getting something that works.
Nice job.
I know you having teething problems. But I am sure it is nothing you can't overcome. Just look at how far you got so far.
Keep.up the great work
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BFG, when you have sorted the leakage, i will be in line to buy at least 2, what sort of price are you paying shapeway?
Mark
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Hi Mark, at the moment I am on version 5 of the pump body. I keep finding slight flaws and areas I can improve on, the latest is adding guide veins at both inlet/outlets. Also trying to keep the price down on manafacturing costs is another reason to keep adjusting the design, the original version cost over £80 from shapeway, I have it now down to just over £60 but that may have to change if this version doesn't stand up to full power testing.
I am in the middle of purchasing my own 3D printer so I may be able to bring the price down even more once I work out how to use it and how well the PLA or ABS stand up to tests.
I should have version 5 submitted for pre print report by the end of today and if all goes well and funds allow I shall have this printed up so can test with the newer motor and sealing arrangement.
So to be realistic, I cant really give a price just yet, but I really do hope I can knock these out, fully built for under £100 bearing in mind the cost of quality brushless motors and Raboesch props this may not be possible........Let's see how the development goes and take it a step at a time. Thanks for showing an interest in my attempts and is heartening that someone is willing to pay for it, just hope I can succeed.
Regards
Stewart
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HI Stewart, R&D costs money and heartache, all is well till it fails somewhere else, thats development at its best/worst!!!! i will pay for good gear, look at the price of Raboesch bow thrusters, you are not far out in pricing yours.
Keep up the good work
Regards
Mark
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Use cheaper Brushed Motors and Plastic Props.
Len.
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Use cheaper Brushed Motors and Plastic Props.
Len.
I think the idea is to develope a
Product that is quality and will
be durable.
Cheap components won't last the distance.
Ned
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The idea is to put out a quality product that will last (hopefully). Plastic props have crossed my mind also 3D printed props, but at the moment I shall keep it as a quality item until such time when I am on the deck of my super yacht, I shall do a cheapo version...... :-)) :-)) :-)) :-)) :-))
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Finally finished the design on the pump body and cap and now well within a fairly decent price at Shapeways.
My only concern now is the actual motor casing design, I have a slight nagging feeling in the back of my head that is going to leak, so I am going to continue with a newer design before I commit to getting this printed up, a shame really as I was making inroads and was looking forward to another bath tub test session!!!!
Some more thoughts on this design for use on a model boat is instead of the normal installation at the bow end going across the beam of the ship, because of it width (100mm), it could be installed midships and plumbed in with hose pipe to the outlet nozzles installed in the bowor stern. Outlet is 30mm dia, if need a smaller outlet simply print up a reducing bush and use 20mm dia pipe. May have a bash at drawing that up so you can decipher my Heath Robinson ramblings............. {:-{ {:-{ {:-{ {:-{ Oh well, some more hours burning the midnight oil.
Thanks for looking and putting up with my ideas!
Regards
Stewart
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Hi Stewart, 2 thoughts, 1, what about an Oring seal round the case, and, 2 the outlet tube size with a collar, 20mm or 30mm would work for most models.
Heath Robinson has been responsible for some great products, dont put your efforts down, you have come a long way in a short time!!!!
Mark
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Will the motor need maintenance Stew?? If not can it just be glued/moulded in place??
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Cheers guys for your input, much appreciated.
I think I may have come up with a simple solution for sealing the two halves of the body together that will work. The only thing now that can fail is the shaft seals on either end, so to overcome that I think I may need to fill the body with an oil, this not only insulates/lubricates the motor it acts as a pressure barrier against ingress of water. I seem to remember years ago we trialed an oil filled submersible pump and it worked, so I shall go down this route. Just need to sit in front of the PC now and study the 3D images and see if it is doable, if it is doable, will people want this type of maintenance/installation............ {:-{
The joys of developing a crazy idea into something of use...... :-)) :-)) :-))
Cheers guys, keep you posted.
Stewart