Author Topic: Print to Ride  (Read 21093 times)

PonoBill

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Re: Print to Ride
« Reply #60 on: January 08, 2023, 02:15:40 PM »
I've used just typical glassing epoxy to seal the surface of 3D prints. It works about as well as hot coat usually works, which means some pinholes remain. I tried kind of a modified WEST treatment (Wood Epoxy Saturation Technique), Let's call it PEST (Plastic Expoxy..., I coated the part with a heavy hot coat of epoxy with medium fast hardener and stuck it in my vacuum pot. Drew a vacuum on it and watched the bubbles come through the surface. When I held the vacuum at about 15 inches of mercury the bubbles stopped and I let air in. The idea is to have air pressure shove the epoxy into the porous surface. It works--sort of. The surface got a fairly dry. I let it kick and then stuck the part in water. It took up a lot less water than it does untreated, but it wasn't perfect. I did it again and did a second hot coat over it, and that one was completely waterproof. It's a bit of fucking around, and I don't have anything big enough to do a wing, though I could certainly weld up a suitable chamber out of heavy steel pipe, plug one end, and weld a removable flange on one end--or maybe glue something up out of heavy plexiglass tube (which gave me a flashback to the Wilson Cloud Chamber science project I did when I was 14. Fuck, that's 62 years ago--depressing). Load it like an autoclave.  The Faux Drive nosecone in the middle of the picture is PC-CF with both PEST and a hotcoat. I added a through-bolt after coating because I had a problem with some of the nose cones splitting when I tightened them onto the mast (the clearance between the mast and the cone was too tight). The orange drive base attached to a motor is PETG with just PEST. It sucks a tiny bit of water--added about 3 grams after soaking overnight. The cone on the right is PC-CF with no treatment.

If left untreated, these parts suck up water like EPS, though when you take them out of the water it slowly dribbles out and will dry completely with no weight gain after a few days of drying. It probably wouldn't dry as completely with saltwater since the salt and minerals left behind are hygroscopic.

Yikes, I looked up what 3 feet of 8"X .250" plexiglass tube would cost and it's about 900 bucks.
« Last Edit: January 08, 2023, 02:38:24 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #61 on: January 08, 2023, 06:59:07 PM »
So this is kind of interesting given my current struggles with attaching spline rails to the dat to spline-generated airfoils. I'll figure it out eventually, but here's a quick and dirty workaround. A wing design from winghopper that I whipped up in a few seconds and stuck the shroud and mast onto. Kind of cool. I might have problems slicing it up into printable chunks and adding in the holes for the stiffening rods, but maybe not.

« Last Edit: January 08, 2023, 07:02:11 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #62 on: January 09, 2023, 12:46:43 AM »
So this is kind of interesting given my current struggles with attaching spline rails to the dat to spline-generated airfoils. I'll figure it out eventually

Sorry Bill, I thought I had posted this before!  The key thing is that order that I mentioned by phone.  It is super critical that you go in that order and there are like 30 quirky little things that need to happen.  The rails have to be fully functional and the original foil profiles need to be completely moveable in (both in all 3 dimensions) and getting there is super specific.  Have you picked up that your view angle will allow or disallow certain options (yes, the angle at which you are viewing from!)?  In your design what points on the profiles are you attaching to?

PonoBill

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Re: Print to Ride
« Reply #63 on: January 10, 2023, 10:27:50 PM »
This has driven me nuts, but I can finally loft a wing between two foils and have rails work. This shouldn't have been so hard. I've determined that running Airfoil Dat To Spline optimizer makes it much more certain that rails, especially splined rails, will be attached to the foil shapes.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #64 on: January 12, 2023, 10:18:04 AM »
Rod placement is going to be tricky, especially with anhedral or foil profile changes. This center body is Eppler E837, a symmetrical hydrofoil profile, the wing section translates to Eppler 818 with no anhedral. Just the reduction in chord (which scales down all dimensions) and the camber of the 818 has the rod toward the trailing edge waving around in space.
« Last Edit: January 12, 2023, 10:20:32 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #65 on: January 12, 2023, 10:34:03 AM »
Damn, even moving the rod a bunch left a notch, and it's going to get worse as the chord decreases
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #66 on: January 12, 2023, 12:41:30 PM »
Damn, even moving the rod a bunch left a notch, and it's going to get worse as the chord decreases

Have you contoured your cavities to match the wings shape or angled them in?  level and straight won't work for long.  What diameter tubing are you using?  You can vary tube diameters as needed or change shape.  You should order a bunch of carbon products to feel how stiff this stuff is at each diameter or dimension.  You may be greater than required. 

PonoBill

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Re: Print to Ride
« Reply #67 on: January 12, 2023, 08:36:49 PM »
So how are you making curved holes? I guess I'd try something with the shell feature. I was trying 5mm for the tube size. I think it might be worthwhile to use the tubes close to the centerline and print-in reinforcement when/if a straight tube becomes impractical. I'm not sure how to convince a slicer to make some solid ribs, but there has to be a way. 

For any tapered wing, as the chord decreases the lift (and therefore the force applied) further outboard of the wings decreases. We'll probably have to break a lot of stuff to really understand what the limitations of Print to Ride actually are.

On the bright side, even with a fair amount of experience with 3D printing, I'm surprised at how strong these parts are. I printed the center section shown above today and then tried to destroy it. I didn't do anything to strengthen the part and it took my weight with no indication of flex. That will be a bit different with longer sections, but I think we can make some fairly strong wings this way.

If nothing else I'm learning a lot.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #68 on: January 13, 2023, 01:37:38 AM »
Hi Bill,

I see a few things.  There is a lot of disparity between your two profiles.  You are going from 16.1% at 36.9 to 9.4% at 33.  Those are unconventional numbers at both ends for front wings.  It is going to be harder (but possible) to join there.  It will be much easier to join after the transition.  The 9.4 percent combined with the extreme contours of the main profile are going to add challenges.  If those holes are 5 mm then you are looking about 1 cm or a touch over for max thickness at 6 to 8 inches off of the root.  That is very thin.  The thinnest foil I have here is 2.4 cm at that same spot, and those carry their thickness much further out in both directions.  Also when existing foils are using a symmetrical thicker profile at the root, it is exactly matching the main profile for the top half.  The bottom is a mirror of the top.  That leaves an even top contour for the whole span.  That would also make joining (even with thicker rods) much easier)

To contour the cavities, you can use the guide sketches for your lofting as paths but 5mm tubing essentially has no usable flex.  It is going to fight you at joining for any curves.

I am not suggesting that you follow convention or modify your design to make it easy.  I dig it!  The whole point is exploration and "what if?"  That is where the fun lies.  If we want what already exists we can buy it.  There are a ton of great options. 

This PA-CF is super stiff and light and all of the carbon samples I have here are surprising as well.  I have had to completely rework what I had planned because we are dealing with so much more stiffness than I had conceived.

My Bambu has been running nonstop and I have done a silly amount of models, protos, tools, and refinements.

I have been making tools (jigs) to help me cut the notches, etc for interlocking and aligning the carbon parts with accuracy.  I also spent a few hours talking to various bonding solution mfg's and have a bunch of samples coming to test the adhesives which they are suggesting for our specific plastic to CF for this use.

The tail wing and fuselage are going to be complete this week.  I mean the products and the process which I can use on any wings going forward.  The weight savings, strength and drag reduction / streamlining have me very stoked.

This is a great project which involves all of my favorite things :).
« Last Edit: January 13, 2023, 03:25:12 AM by Admin »

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Re: Print to Ride
« Reply #69 on: January 13, 2023, 08:20:56 AM »
I have all of the diameters correct now for a super snug fit on both fuse plugs and all wing connection rods.  This image shows all four 4mm connection rods in place on one side.  I determined that printed fuse plugs are so stiff and strong at this dimension that stock carbon rods won't add anything.  These printed plugs (pictured in fuse) will not bend or twist at all.  This fuse in the pic is 17.5 inches which will exactly equal the length of an Axis "Standard" (their longest except for the windsurfing one) when added to the extra length that occurs my front foil.  The whole Axis range is 8 inches length difference (from silly short advance to the standard) so the total range of carbon tube length in my system would be 9.5 inches to 17.5 inches to match that range (as an example).  At those lengths the flex of the tube and plugs is non-existent.  I supported the plugs only with 2x4's and bounced my entire 170 lbs on the center of the carbon tube,  It noticed no flex.  If carbon could yawn, it would have.  It is really crazy.  In the image I lightly sanded two of the 3 pieces, again just seeing how that will best be done.  This product sands beautifully so my next tests will be full assembly when the adhesives arrive.  I haven't notched the fuse yet in this image.  Oh, and the fuse, the 450 tail wing (all pieces, both plugs and all rods) weigh 7.4 ounces :).

Weird to be working from the ass forward but I needed to understand my fuse and connections to see what would be needed on the front wing.  I will start on that next week.
« Last Edit: January 13, 2023, 08:39:08 AM by Admin »

PonoBill

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Re: Print to Ride
« Reply #70 on: January 13, 2023, 09:24:58 AM »
Hi Bill,

I see a few things.  There is a lot of disparity between your two profiles.  You are going from 16.1% at 36.9 to 9.4% at 33.  Those are unconventional numbers at both ends for front wings.  It is going to be harder (but possible) to join there.  It will be much easier to join after the transition.  The 9.4 percent combined with the extreme contours of the main profile are going to add challenges.  If those holes are 5 mm then you are looking about 1 cm or a touch over for max thickness at 6 to 8 inches off of the root.  That is very thin.  The thinnest foil I have here is 2.4 cm at that same spot, and those carry their thickness much further out in both directions.  Also when existing foils are using a symmetrical thicker profile at the root, it is exactly matching the main profile for the top half.  The bottom is a mirror of the top.  That leaves an even top contour for the whole span.  That would also make joining (even with thicker rods) much easier)

To contour the cavities, you can use the guide sketches for your lofting as paths but 5mm tubing essentially has no usable flex.  It is going to fight you at joining for any curves.

I am not suggesting that you follow convention or modify your design to make it easy.  I dig it!  The whole point is exploration and "what if?"  That is where the fun lies.  If we want what already exists we can buy it.  There are a ton of great options. 

This PA-CF is super stiff and light and all of the carbon samples I have here are surprising as well.  I have had to completely rework what I had planned because we are dealing with so much more stiffness than I had conceived.

My Bambu has been running nonstop and I have done a silly amount of models, protos, tools, and refinements.

I have been making tools (jigs) to help me cut the notches, etc for interlocking and aligning the carbon parts with accuracy.  I also spent a few hours talking to various bonding solution mfg's and have a bunch of samples coming to test the adhesives which they are suggesting for our specific plastic to CF for this use.

The tail wing and fuselage are going to be complete this week.  I mean the products and the process which I can use on any wings going forward.  The weight savings, strength and drag reduction / streamlining have me very stoked.

This is a great project which involves all of my favorite things :).

Thanks for the suggestions. Yes, the transition in the first wing section is extreme. The symmetrical foil section is fundamentally the fuselage, and there is no reason to continue it to the first section of the wing. I can make the transition from E837 to whatever foil the first section of the wing is in the first chord shift from the center section of what I've been calling the wing root to the chord transition bit. This stuff is hard to describe, it reads like I'm discussing music theory. Since the center section is essentially the fuselage. I think I need the thickness of that chubby 837 foil to fully support the mast. These printers are amazing. Not only are the parts strong, but they're also beautiful. My Prusa and modified Ender 3s don't do prints like this. The crunchy bits on the edge of the part is from my testing. I bolted it to the leg of my workbench with a piece of angled aluminum to step on. That's all that 230 pounds did to it.

I originally envisioned carbon rods extending almost the full length of the wing. That's clearly not going to happen. I have lots of carbon rods and stuff here leftover from RC airplane and quadcopter building. Even a 5mm rod will only bend slightly. I think shorter sections to reinforce joints is a more reasonable direction. 
« Last Edit: January 13, 2023, 09:30:22 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

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Re: Print to Ride
« Reply #71 on: January 13, 2023, 11:50:34 PM »
I'm not sure how to convince a slicer to make some solid ribs, but there has to be a way. 

I am planning to do this in the file.  Basically define the shapes of the internal ribs (or voids that define the ribs, if that is how you think of it) and then cut the voids from the body.   Then just make sure that the slicer is set to print support on the plate only (so it will not fill your voids) and you have ribs to taste (which just made me hungry).  Here is a ski/snowboard vise that we produce and sell under one of our brands.  The ribbing is external on this one (and it is obviously molded for volume production)  but this is how it was done and the same applies internally.

« Last Edit: January 14, 2023, 04:49:08 AM by Admin »

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Re: Print to Ride
« Reply #72 on: January 14, 2023, 02:32:42 AM »
Here is an image of the fuse guides which will print on both wings as well as the disposable collar jig (I suppose) tool I made to notch the carbon tube to match.  It just gets taped in place with painters tape and then the cuts are made with a 35000 rpm Dremel cutting disc.  Super clean and accurate notches, without splinters or fragments.  I am using my trusty Park tool for carbon steer tubes which is almost 30 years old from when we were bike shop owners.  That is still the best and easiest (30 seconds) way to cut carbon tube perfectly straight.


 

« Last Edit: January 14, 2023, 02:53:13 AM by Admin »

PonoBill

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Re: Print to Ride
« Reply #73 on: January 14, 2023, 01:09:00 PM »
I'm thinking a rib structure that is printed at 100% and then the rest of the voids are printed at something around 50% or less. Doing 100% infill for the full size of a wing would be heavy and use a lot of filament. Or maybe just what I did for the blue part above which was to print the walls at about 3.3mm (I think I used 5 layers) which made both the skin of the wing and the walls of the tubing holes well reinforced. If you look closely you can see that the first and last hole walls are connected to the skin.

This is the scrunched side. I screwed the other side to my workbench with sheet metal screws, then made a step with a piece of aluminum and three long 5mm screws. I fully expected the part to break or at least tear out the screws on the bench side or rip through the holes. But nothing happened other than a little crunch on the bottom edge and maybe a little separation of the face from the wing surface toward the trailing edge, though that might just be a printing artifact. This is just PLA. I'm amazed. It seems the key to strong parts with 3D printing is not necessarily the material but the structure.
« Last Edit: January 14, 2023, 01:20:50 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Print to Ride
« Reply #74 on: January 15, 2023, 09:46:18 AM »
I printed the wing root fuselage last night. seeing the physical parts illustrates refinements I need to make, but I like the progression.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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