"Very nice sandy beach ... but the sea is really far !". French Aeronavale (Navy) Potez 25 TOE. 1934 "Pink Cruise"

[KevinM]

Looks really good from here Hubert esp. the PE.I think your upper cowling looks pretty good just short nothing that shim stock could not fix the height  look good.

[belugawhaleman]

Truly impressive work Hubert!

[CANicoll]

Wow, I am still in awe of your 3D printing capabilities.  Nice work!

[HubertB]

18 hours ago, KevinM said:

Looks really good from here Hubert esp. the PE.I think your upper cowling looks pretty good just short nothing that shim stock could not fix the height  look good.

 Thank you Kevin, but the difference is really significant, about 2.5 mm, so that's 1/10 of an inch. Of course I could fix this with shim stock and Milliput, but then, what would I have said about the poor design of a kit that would come with this difference ? Because it was poor design from the guy who drew the new part  

And, actuallly, sorting it out at the source, i.e. revising the design was a one-hour affair on the computer this morning ... The new cockpit cover is in the printer right now, with other parts I modified, like the lower cowling ...

Hubert

[HubertB]

18 hours ago, belugawhaleman said:

Truly impressive work Hubert!

 

15 hours ago, CANicoll said:

Wow, I am still in awe of your 3D printing capabilities.  Nice work!

Thanks guys. As for my 3D-printing capabilities, I would argue that a truly capable guy would have avoided the design pitfall that sent the slicer software crashing again and again for four days .... ... Well, you live to learn, don't you ? That's a mistake I will not repeat, now that I'm a smarter a&$$

We'll see tomorrow, when the current print is over, if I have really gained in knowledge. Yesterday's print was not the success I expected, honestly.

Hubert

 

[HubertB]

Where would a man be without Duck Tape ?

I continue working on the assembly of my Potez. Whilst the prining of the new parts is under way, I have started splashing some primer on the cockpit assembly, but frankly, ther is not much to show here.

And I have decided to tackle other bits, like assembling the main wing. Lukgraph has molded the main wing in three parts, a center section and two outer sections. They are molded plain, and therfore quite heavy. A string joint will be needed to esnure the whole wing stays straight over time. I have drilled some 2 mm dia holes in the mating profiles of the three sections, inserted some brass tube of the same dia, and expoxied everything together.

I wanted to make sure my assembly would be straight and true, and remain so whilst the epoxy setlled. This is where I resorted to that ubiquitous saviour of household men, namely Duck Tape 🤣 😂 🤣!

I think my work should be OK. What do you think ?

More when there is more.

HUbert

[HubertB]

 A small update ...

Me and my big mouth 🤣 😂 ... Before boasting about using duct tape, I should have triple checked the alignment of the wing's 3 oarts. When I removed the tape, it was to see that there was a slight vertical mismatch between the center section and the right outer wing .

After careful use of my JLC saw, adn the application of some brute force, I managed to pry apart the two offenders. Now to redo the gluing, with a multiple check of vertical alignment.

Yesterday's printout came OK, but for the hollowed-out landing gear struts. Start again ...

THis is what the Potez looks like with modified parts. The new resin I used, Elegoo's 8K "red clay", came out sharper than the grey resin I used before. Just look at the radios. The difference is small, but noticeable.

and the Potez with the new parts taped in place ...

 

The radiator and lateral cylinder banks are only loosely tape-fitted. The adjustment is in fact perfect.

Happy me . Now about regluing this wing and continuing painting the cockpit...

Hubert

[BlrwestSiR]

Amazing work Hubert. You make designing and printing your own parts look so easy. 

[DocRob]

You put yourself under some pressure with such an ambitious project, Hubert. I really like the results of your printing efforts, albeit the described methods and software usage are just plain Chinese to me. Bummer with the landing gear struts. Finding long drill bits with the needed diameters will be difficult, but maybe you could push a heated steel rod through, especially when there are at least some remains of the projected channels left. As a better guide, you could drill as deep as possible with the bits available. You could also slice the struts and epoxy some rods in.

Cheers Rob

[HubertB]

5 hours ago, DocRob said:

You put yourself under some pressure with such an ambitious project, Hubert. I really like the results of your printing efforts, albeit the described methods and software usage are just plain Chinese to me. Bummer with the landing gear struts. Finding long drill bits with the needed diameters will be difficult, but maybe you could push a heated steel rod through, especially when there are at least some remains of the projected channels left. As a better guide, you could drill as deep as possible with the bits available. You could also slice the struts and epoxy some rods in.

Cheers Rob

Than’s for the comment, Rob. 
To explain the process for everyone :

1) you create a 3D part with a specific software. I am using Alibre Design, but the most commonly used is Fusion 360, which has a fee licence for hobbyists.

2) When the part is designed, you export a printable file. The oldest format is .stl, which results in very  heavy files, and I am now using the .obj format

3) the export file is uploaded in a slicer software. The function of this software is literally to slice your part in a number of layers, which the 3D-printer can then use to print the part. The printer will print each layer in succession, with a UV projection that will polymerise the resin (for an SLA printer such as mine). 
 

4) in the slicing software, you prepare the parts for printing. Basically, you decide of the orientation of the part, and of the supports that need to be added to help « hold » the part during the printing process. The printing takes place from the bottom of the part, up. Only the platform on which the part will be printed is inverted and will progressively lift as the printing goes. The platform is immersed in a vat with the UV-sensitive resin, and the bottom of the vat is clear to allow the UV projection.
To get better results, and avoid visible printing lines, when the human eye is trained to see in two horizontal and one vertical axis, you tilt the part at an angle in the slicing software. The supports can generally be automatically created, but, most of the time, with a bit of experience, you feel where more supports are needed. The worst you can have is either a part insufficiently supported, that will deform, or sometimes detach from the platform. Especially as the lifting of the platform has to fight a suction effect from the viscous resin it is immersed into.

5) when you are happy that you have a printable part, or group of parts, you order the slicing software to slice it. I have set the layer height on my printer at 20 microns, so that means 50 layers per millimeter of vertical height. You end up typically with a print that is going to be made of 5000, 8000, 15000 layers. And each layer takes a few seconds (2.5 for UV exposure, plus the time for the platform to lift a few fractions of a millimeter, and lower again), so that is why typically a print takes a few hours. For me the print runs were between 8 and 13 hours.

6) When the last layer is printed, you have to wash the parts from the uncured resin that still adheres to them - remember the resin is more or less viscous. For most resins, the washing is done in isopropylic alcohol. It takes a few minutes to wash the parts. Before being usable, they then need a « post-cure », which is done by exposing them to UV-light for a few minutes, in a curing machine, or leaving them in the sunshine.

Et voilà !

In the case of the struts where I want a hollow center for the brass rod, inclining them for printing may result in resin « sticking » inside the tube you progressively print. That is why I ended printing them vertically, so that the center hole is aligned vertically layer after layer. Even then, you have to remember that you may have a suction effect that will keep the liquid resin trapped in the middle of the hardened resin part ( like the old magicians’ trick of having a glass of water upside down with a a sheet of paper keeping the water in the glass). So you need to design ventilation holes. All of this is a bit empirical, and the small size of the parts makes the process more complicated, as the size of the holes is limited, when the surface tension of the resin may fight against it flowing easily through the holes …

The resulting resin is very hard. It dan be drilled, sanded, milled, sawn, cut, but I am not sure it will react positively to a heated rod. And of course, I tried slicing the struts in halves in the design, but this is where I ended up with a part that was sending the slicing software into fits …

I am making progress with each new printing trial though. So it is just a matter of time before I get a satisfactory result. But printing a 50 mm long strut vertically takes 10 hours, plus the time redesigning the part, and setting it in a printable way in the slicing software …

Hubert

[PanzerWomble]

.........& I thought getting to grips with my Silhouette machine was 'cutting edge '     😳*

 

 

 

*repeats to self not going down this rabbit hole 

 

 

Bravo to you though Hubert , this will be a build for the books ! 

[HubertB]

14 hours ago, PanzerWomble said:

.........& I thought getting to grips with my Silhouette machine was 'cutting edge '     😳*

 

 

 

*repeats to self not going down this rabbit hole 

 

 

Bravo to you though Hubert , this will be a build for the books ! 

Well, the Silhouette is, literally, all about using "cutting edge technology » .

Just saying …

Hubert

[HubertB]

Who said "Repetition is the mother of skill" ? Once again, my tribulations have proven him (or her) right !

I can now say that I have a number of successful prints of the damned landing gear struts. I launched a new print this morning, with four copies of the struts, two vertical and two at different angles. One vertical print fell off from the plate, but the other three are a success. Before curing them, I did try to get a rod in each strut, along their whole length, and it worked !

"A small step for modelling, but a giant leap for the Potez project". I am in a quotes' mood tonight 😂. More seriously, it means I can envision building a strong and scale-accurate landing gear for the Potez 25 TOE.

Time to celebrate 🥃 🥃 🥃 (after those, forget about using any pointy or sharp tool, and trying to glue teeny weeny PE parts - btw, I was mentioning in another thread my close-to-maniac habit of cleaning the bench at the end of every session. This allowed me to find two really really really tiny PE levers that I thought had flown on an orbit between Mars and Jupiter, among the very few shavings and dust particles on the bench )

Hubert

[BlrwestSiR]

Hubert, thanks for the description of the various steps involved. We recently got a Bambu Labs A1 which is a filament printer. Our youngest has been having fun downloading and printing files that are ready made. Hopefully he gets into the design side of things and he can learn how to make his own stuff.

[KevinM]

I am happy Hubert you finally had success with the prints and yes the red clay has a better presentation.The instruction on the printing I would have to be standing right there as you describe it and perform the magic.I am keeping my eyes on this so await the next installment Sir.

[HubertB]

8 hours ago, KevinM said:

I am happy Hubert you finally had success with the prints and yes the red clay has a better presentation.The instruction on the printing I would have to be standing right there as you describe it and perform the magic.I am keeping my eyes on this so await the next installment Sir.

Thanks a lot Kevin. I am happy to report that I have been able to assemble a reinforced landing gear. With 1.5 mm brass rod for the lower axle, 1.2 dia in the four front V braces and 1 mm in the rear diagonal struts, it is plenty strong, and nothing to compare with the resin-only first model. And it still looks the same, and scale-accurate 

Update pics soon.

Hubert

[Peterpools]

Hubert

Absolutely incredible work and your attention to accuracy is inspiriting.  Of course, I have a bit of a hard time following some of your issues and thanks to the photographs, have a good idea f the work that has gone into the conversion.

 

[Peterpools]

Hubert

Just finished catching up and am completely blown away by the effort, time and knowledge that is required to print at your level. I wish I were a lot younger and would have loved to learn printing but being almost 77, knowing my limits keeps the frustrations and costs down. 

I also was amazed at the difference of the detail and sharpness of the printing between the two resins. 

Of course, your initial question of whether or not we have major reservations on cutting up an expensive model and in today's ages, that seems to be most kits and all the time, as there is always the worry, something will go so very wrong, and the kit then qualifies for the bin.

I've been an OOB builder for decades and it so greatly helps keep my nerves from going into overdrive.

 

[Landlubber Mike]

Those custom printed parts look amazing Hubert!  And thanks for outlining how the process works!

[DocRob]

Good, that the printing of the landing gear worked this time with the reinforcement inserted.
Thank you for the detailed description of your printing process. I may have to look into that myself. It´s not that I´m completely out of the dark, as I produced 3D animations in Lightwave, when I was young. I had a "real" 486 processor by this time and rendering the results took weeks. I learned to design 3D objects then, but there was no need for accuracy, it only had to look good.

Cheers Rob