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Oct 16, 2021, 12:39 AM
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Thread OP
Too many holes... It's better for me to use the four , because the rings are sealed in place they don't move when the black screws are removed. So can we go back to just four holes at 45 degrees? Please.
8 is overkill, just means more work when you need to change , Also if I am right the black screws are bigger so easier to fit. Let's not over complicate the job.
Last edited by returntohome; Oct 16, 2021 at 12:50 AM.
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Oct 16, 2021, 10:00 AM
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unusual_rc's Avatar
Yes, I know not everyone likes Swiss cheese

You are right, structural integrity is less with so many holes. The material is plastic, do some rigidity is welcome!

I will make a 4 and 8 holes version of this file, as soon as I have time to sit behind my workstation. Will cost less than a minute each.
So 3 versions of the STL will be available soon.
To be continued!
Oct 16, 2021, 11:18 PM
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Thanks, I checked and the 8 little screws are only 2mm. The four black screws are 2.5mm so easier to handle. Did you have to buy your drawing program? Are there any good free programs? I like the way it's presented on the pdf complete with 3d view.
Oct 17, 2021, 03:44 AM
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unusual_rc's Avatar

3 final STL files


Quote:
Originally Posted by returntohome
Thanks, I checked and the 8 little screws are only 2mm. The four black screws are 2.5mm so easier to handle
I kept al dimensions as version 0.3, I only removed holes in these attached files.
Always check the files for the correct hole pattern (visual) before you print them, or send them to SW or Sculpteo.
Not on the pdf (forgot), the LE AoA is 15, a lot less than the original!

Quote:
Originally Posted by returntohome
I like the way it's presented on the pdf complete with 3d view.
The pdf drawing is made using the 3D model. However there is some degree of labour necessary to make it appear as is.
The industry is heading for "paperless" 3D files, which is called MBD (Model Based Definition).
That saves time, however 2D views with dimensions are in my opinion of vital importance for understanding.

The pdf shows 12 holes, the 3D files have them in or excluded as the name indicates.

Quote:
Originally Posted by returntohome
Did you have to buy your drawing program?
I have been a freelance machine-designer for over 12 years. I bought SolidWorks for that reason, and still have the license (although I cannot upgrade to the newer version anymore in the future).
There is a free copy available of SolidWorks for home use.

In a nutshell these are the most common 3D CAD programs used in the machine industry (not aerospace of automotive):

- SolidWorks (Dassault, industry standard)
- Inventor (Autodesk)
- Solid Edge (Siemens)

Out of all these packages I would rate the learning curve from easy to difficult: SolidWorks, Solid Edge, Inventor.
The word "easy" does not fit well I am afraid. All programs require some time and practice to get used to.
https://student-version.com/solidworks-student-version/ (scroll down and read first)

I do not have much experience with free CAD programs, although I have seen a few.
My recommendation would be to have a look at Fusion 360 from Autodesk. It is completely free to use, and I see it being used in our hobby more and more.
https://www.autodesk.com/products/fusion-360/personal

A lot of resources are available online for Fusion, among other a lot on youtube.
Again except some learning curve.

However it is great for viewing and converting 3D files to start with.
Last edited by unusual_rc; Oct 17, 2021 at 05:51 AM.
Oct 18, 2021, 01:56 PM
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Thread OP
Thanks for the files, I will test the sundogz version, maybe next Sunday, meanwhile I will print yours.
The photo was taken at the show, no prize this year!😥
Oct 18, 2021, 02:01 PM
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Thread OP
I am printing a hull for the ringo, to see if it works better, no back on it so I can get in to add nuts to the bolts.
Oct 19, 2021, 12:49 AM
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unusual_rc's Avatar
Quote:
Originally Posted by returntohome
Thanks for the files, I will test the sundogz version, maybe next Sunday, meanwhile I will print yours.
The photo was taken at the show, no prize this year!😥
Now I have the interface dimensions, it might be possible to make enhanced iterations in the future for the TFL29.
Let us know about the progress and your findings!

If you print flange on bed, it is not necessary that the stator vanes run all the way to the end.
That is only done to make printing exit nozzle on the bed possible, to make edges on the flange possible (like our FJD has)
Oct 19, 2021, 12:47 PM
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Thread OP
Looks nice in two tone, but that was due to the grey filament kept snapping, so got fed up and went back to blue. The grey is the same make , but could it be old stock? Every so often it's brittle enough to snap.
Stator vanes , it seems to me they should be curved all the way to the end , not a lot just enough to get a straight flow. On my spy cam video you can still see a spiralling flow.
Oct 19, 2021, 02:00 PM
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unusual_rc's Avatar
Are you sure the grey PLA is from the same brand and type as the blue?
Production date should be on the package, you might check both dates!

Concerning the stator vanes. Real scale axial jet drives, as the Thrasher and the Swash/Jettec drives all feature short vanes.
Hydrodynamics dictate the longer the surface a fluid has to flow along, the higher the chance turbulence will occur, causing non-linear increased drag!

So these long vanes running from the beginning to the end are a true compromise for FDM 3D printing exit nozzle up. If you order at shapeways like Denis, you are not restricted to this necessity.

I made these stator vanes straight, with a very modest fillet of 15 (AoA) on the leading edge. For sure this will give less drag.
In the event there will be a spiral visible again (rotating the correct direction this time), we know somewhere in between this and the previous angle will be right in the ball-park!

I have not found any calculation or directions how to predict this angle, or that a progressive AoA like Grael's exit nozzles is necessary on such a small scale.

I clocked 42kmh this weekend with the 45mm FJD with 4 straight stator vanes.
My previous tests showed between the 40 and 15 designs a mayor difference in top speed and current draw.

That is a 45mm diameter impeller with a 18mm hub. A lot bigger than the TFL 29.

There is also a correlation between pitch of the impeller and the angle of the stator vanes.

I am hoping to come with some new designs this winter, among other a two part stator so the blades can be a lot shorter.
Oct 24, 2021, 01:38 AM
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Thread OP
Quote:
Originally Posted by returntohome
Stator vanes , it seems to me they should be curved all the way to the end , not a lot just enough to get a straight flow. On my spy cam video you can still see a spiralling flow.
It seems I am not the only one to think of curved stator blades, I found this , beautiful curved blades with the main twist at the end of the blade not at the beginning.
Oct 24, 2021, 01:55 AM
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Thread OP
The blades are separate from the housing
Oct 24, 2021, 07:32 AM
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unusual_rc's Avatar
Quote:
Originally Posted by returntohome
It seems I am not the only one to think of curved stator blades, I found this , beautiful curved blades with the main twist at the end of the blade not at the beginning.
Both aero-dynamics as fluid-dynamics agree with you.
If you want to create lift (you are if you want to "bend" a flow of gas or fluid) a curve is more efficient than a flat part.

The metal milled part you show here has a foil profile, which is creating a lot of lift at the cost of a lot of drag.

Creating a foil shape for you to 3D print is not difficult.
However I am sure this example will give a swirl the opposite way.

Indeed the purpose of the stator-vanes is cancelling out the rotation the water-column gets from the impeller.

We noticed a rotational swirl out of the nozzle to with our FJD project.
The first design stator had a long flat vane with a leading edge curve of 40.
(picture of exact design attached)
In despite the length of the flat section of the stator-vane, a rotation counter-opposite the rotation direction of the impeller was visible!
Although I already had a gut feeling this angle was too large, I was amazed by this phenomenon.
How is it possible that the water channelled through a straight canal still has so much rotational energy to "fly out" the wrong direction?

Creating a separate piece for 3D printing of the hub with stator-vanes is also not difficult, and makes more complex shapes possible
However this one looks a bit too much.

Is there any footage of someone running this drive?
Oct 27, 2021, 12:54 PM
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Thread OP
So sorry to say Sundogz version made no difference at all. I can try the next one , but i dont hold out much hope.
Oct 27, 2021, 01:55 PM
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unusual_rc's Avatar
Quote:
Originally Posted by returntohome
So sorry to say Sundogz version made no difference at all. I can try the next one , but i dont hold out much hope.
Lost in translation a bit. "Sundogz" version is the one I changed for you, or the one posted a while back ago by Sundogz?

I am constantly progressing to make the FJD 45mm more efficient. I am currently working on a 6 to 7 short vaned, curved bladed stator-housing design. FDM printing is a limitation here, so I am looking for ways to make it work. It is unavoidable to assemble it out of two or even three parts. All for efficiency

Denis_BE was also planning to test this nozzle I made you on the same pump if I am not mistaken. However autumn is not the best time for testing.
You might want to wait for his test report?
Oct 28, 2021, 12:51 AM
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Thread OP
It was the one Sundogz did a while back. I can try the one you have done with the reduced angle.


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