Thread Tools
This thread is privately moderated by sundogz, who may elect to delete unwanted replies.
Jul 06, 2018, 01:59 PM
Registered User
I think Mark is using a similar coupling on his board...maybe he could chip in in this ..if not I will email him and ask how he is going on..he does have some power going through his board setup.
Sign up now
to remove ads between posts
Jul 06, 2018, 02:09 PM
Registered User
Kayaker's Avatar
When a jet sucks half air, half water it runs very ‘out of balance’ so I use good bearings and don’t try for perfect balance.
Jul 06, 2018, 05:06 PM
Registered User
Yup I did get slippage on the coupling when it was new and shiny,,
I lightly dusted the end of the prop shaft with a Dremel with a new drum sander,
I do have to nip them up tight but no slippage,,,
using extra grub screws is just cheating !!! lol,,
Jul 06, 2018, 05:55 PM
Registered User
Quote:
Originally Posted by sundogz
Yes, a spacer is a good solution if your motor shaft is too long. PLA at 100% fill would be best for that. Of course if you are building the drive it is better to shorten the impeller shaft instead.
I'm running a 6mm spacer in the 35mm drive. I have equal amounts of shaft in the coupler that way, and didn't have to grind up the housing for it to fit.
Jul 17, 2018, 04:50 AM
Registered User

The build starts


Ok so I have most of the pieces, including the hull now, to start my 45mm build. I ordered 3 impellers from shapeways but 2 arrived the same so I will order more to do testing. I have a TP 4060 930kv on the way. It is a 40in hull but nice and lite. Lots of room for gear and telemetry etc.
Jul 17, 2018, 06:21 AM
Registered User

Impeller size


Guys can anyone tell me the length of the 50mm vs the 60mm impeller, while the files I uploaded to shapeways for these two impellers have different names they seem to be the same dimensions when I check the order details. Unfortunately my laptop HD died since i downloaded all the files so I cant check what i had, only what the shapeways order states.

Also anyone found a good aluminium print option for the impellers yet?
Jul 17, 2018, 07:09 AM
Registered User
unusual_rc's Avatar
Quote:
Originally Posted by Jezza43
Guys can anyone tell me the length of the 50mm vs the 60mm impeller, while the files I uploaded to shapeways for these two impellers have different names they seem to be the same dimensions when I check the order details. Unfortunately my laptop HD died since i downloaded all the files so I cant check what i had, only what the shapeways order states.

Also anyone found a good aluminium print option for the impellers yet?
Total length of the hub of the first version of the 45mm impeller:

50mm pitch: 36mm
60mm pitch: 41mm

Maybe you should wait for the new impeller I am designing (it is finished, Sundogz will soon test this new set-up)
It will incorporate a metal printed drive-dog, and fixed length impeller hubs with different pitches.
I also will add the pitch on the hub as an emboss.
Jul 17, 2018, 09:51 AM
Platinum Card Member
sundogz's Avatar
Thread OP
Yes, I've posted the drive dog/impellers on page 51 - post 754 in these pages. It will make it much easier to install the impeller on the shaft (than the roll pin method), and you only need one shaft for all the impeller sizes. I have ordered the 65mm version and will be posting the details of fit as soon as I get them in my hands.
Jul 17, 2018, 12:13 PM
Registered User
Kayaker's Avatar
Sundogz, is there a special technique to threading into a Shapeways mettle impeller or drive dog?

I just got a mettle impeller from Shapeways and I am ready to drill and thread for a set screw. When I have tried to use a thread tap to make threads in Shapeways sintered Nylon the Nylon comes out in chunks so is not fused together very well. I forced threads in with a screw instead and this worked. If the mettle is not well fused together the tap may do the same thing, break out chunks. I don’t think I can force threads into their mettle.
Jul 17, 2018, 12:37 PM
Platinum Card Member
sundogz's Avatar
Thread OP
If you chose the bronze/stainless just work slowly. Be sure to drill the hole to the appropriate size for the tap, as the printed hole is undersized - meant to be a pilot hole. Go slowly with the tap, in one turn, and back out to clean the hole and over again until it's through. Be sure to use oil when cutting threads.

But aluminum, according to Shapeways it is like a solid block of aluminum after manufacture and easily tapped. I chose this for the drive dog since it uses a lot less material than for an impeller. The 65mm drive dog in aluminum costs $79, stainless was $43. I had a feeling the aluminum would be stronger than the stainless and I wanted the strongest choice for the larger pump.
Last edited by sundogz; Jul 17, 2018 at 02:30 PM. Reason: fixed the second paragraph
Jul 18, 2018, 05:44 AM
Registered User

Impeller size


Ok thanks for that looks like I have 1x 40mm and 2x 50mm nylon impellers.

Agree if I get aluminium ones done I should do the dog drive version.

I will start building up the boat and keep you guys posted.
Jul 19, 2018, 01:49 AM
Registered User
unusual_rc's Avatar
That is the difficult part with these metal printed materials: are they as strong as the solid material after printing, or not?
Stainless steel is much tougher and a minimum of twice as strong as the average aluminium alloy.
Still I think the alumium will do for a 45mm and 65mm drive dog.
Jul 19, 2018, 08:18 AM
Platinum Card Member
sundogz's Avatar
Thread OP
Quote:
Originally Posted by unusual_rc
That is the difficult part with these metal printed materials: are they as strong as the solid material after printing, or not?
Stainless steel is much tougher and a minimum of twice as strong as the average aluminium alloy.
Still I think the alumium will do for a 45mm and 65mm drive dog.
They are not. Shapeways informs that the stainless/bronze is "printed using a binder jetting process and is later infused with bronze, creating a material that is 60% steel and 40% bronze. It is strong enough for metal parts like bottle openers and dice, but is not recommended for industrial load bearing applications".

Whereas they state for aluminum: "is a light and strong material recommended for functional parts requiring high strength, stiffness, low weight and high accuracy. Its printed using a process called Selective Laser Melting. (It) also has great corrosion resistance, making it an ideal material for outdoor applications, and high electrical and thermal conductivity. It can also be machined, milled and tapped."
Jul 19, 2018, 12:18 PM
Registered User
Kayaker's Avatar
Quote:
Originally Posted by Jezza43
... if I get aluminium ones done should I do the dog drive version?
I hope to have finished testing impellers in a couple of days and I will post some numbers. I think this will tell us if the Shapeways Nylon impellers need thicker blades, or is it better to upgrade to mettle and have thinner blades and more thrust with higher useable RPM.
Last edited by Kayaker; Jul 19, 2018 at 01:16 PM.
Jul 19, 2018, 02:29 PM
Registered User
unusual_rc's Avatar
Quote:
Originally Posted by sundogz
They are not. Shapeways informs that the stainless/bronze is "printed using a binder jetting process and is later infused with bronze, creating a material that is 60% steel and 40% bronze. It is strong enough for metal parts like bottle openers and dice, but is not recommended for industrial load bearing applications".

Whereas they state for aluminum: "is a light and strong material recommended for functional parts requiring high strength, stiffness, low weight and high accuracy. Its printed using a process called Selective Laser Melting. (It) also has great corrosion resistance, making it an ideal material for outdoor applications, and high electrical and thermal conductivity. It can also be machined, milled and tapped."
Aluminium has a much lower melting temperature than steel, so it is easier to melt. And melting creates a perfect bonding.

Looking forward to hear about the aluminium drive-dog you ordered soon!


Quick Reply
Message:

Thread Tools