Author Topic: Print to Ride  (Read 21341 times)

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Re: Print to Ride
« Reply #120 on: February 01, 2023, 05:51:25 AM »
Wait, What? 15mm?? How thick is your wing going to be. I'm basing mine on the 999 ART. It's not 15mm thick.

Hiya Bill,

Check that measurement.  Axis uses 16 mm front screws on the ART's that don't poke though so those wings are likely 20-21 mm thick ? for the width of the fuse head at least.  The Axis Red fuse head itself is just under 2.4 cm thick and we know that there is an extra .6 under that for screw attachment depth.  Their heads are 2.5 inches wide.  With that we know that every foil that fits an Axis red fuse is a minimum of 3 cm thickness for about 3 inches of span at the root.  I am thinner than they are at the max dimension and then I drop off quickly from there.  Also, I have no symmetrical section, so my entire span is lift producing (Bernoulli style). Where we are adding max drag we should get the max lift benefit :)
« Last Edit: February 01, 2023, 10:25:57 AM by Admin »

PonoBill

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Re: Print to Ride
« Reply #121 on: February 01, 2023, 01:04:51 PM »
Well, math is cool and all that, but I just directly measured my ART999 and it's 16.5mm thick at max. So I was wrong, it IS more than 15mm thick, but not much thicker.

My wing root section starts off with a symmetrical foil but I've slimmed that down to just the width of the shroud, about 32 mm, and then it transitions to an E818 foil which is decidedly Bernoulli-ish. The symmetrical section gets down to 12mm thick (driven by the chord and the foil profile) about 20mm from the start of the transition. One of the reasons I chose the 818 profile is that it has a similar thickness to the ART999 for the same chord.
« Last Edit: February 01, 2023, 01:09:08 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 #122 on: February 03, 2023, 01:08:42 AM »
Hi Bill,

What schedules and temps have you tried so far for annealing?  I am finding stuff all across the map.  All are very long processes and nothing specific for our PA-CF yet.  Bambu says on their spec that they are annealing for their tests but they give no specifics, only a drying temp.  They give us a crystallization temp of 140 C/284 F so we have that.  I have plenty of parts here to test in the oven and can set any schedule with unlimited timed steps, so the time is really not a factor but...

https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Annealing-Guidelines
https://www.plasticsintl.com/media/wysiwyg/Nylon___Reinforced_Nylon_Annealing.pdf
« Last Edit: February 03, 2023, 03:52:45 AM by Admin »

finbox

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Re: Print to Ride
« Reply #123 on: February 03, 2023, 08:14:56 AM »
I worked in a factory where we had some plastic parts ( I think some type of nylon, injection molded)- We had a post treatment of boiling them in water for a few hours. That added ductility or fracture toughness to the parts.

PonoBill

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Re: Print to Ride
« Reply #124 on: February 03, 2023, 09:32:24 AM »
Boiling in water is kind of a standard method, but the temperature is a little low for nylon. The intent is to hold the part above the crystallization temperature and the gold standard is to encase the parts in plaster while you bake them. Way too much work. I'm stuffing them into sand and baking at 350F for two hours starting with a cold oven. In theory, I could go a little higher, ramp the temperature more slowly, and hold the temp longer, in practice, it works pretty well. The edges get a little blurry at 350. I'm going to try 300 and see if that works better.

In the general 3D printing community it looks like people are using lower temperatures for PA--lower temps held for a long time will actually help for heat resistance and strengthen the part a little bit, but not as much as exceeding the temperature of crystallization. I suspect they use lower temps because they use sparse infill and don't want their parts getting tweaked and collapsing. Sand helps to a surprising degree with minimizing distortion, and solid parts don't collapse.

I suspect there is more going on with 3D print annealing than just molecules getting aligned. The large increase in strength from aligning layers parallel to the direction of forces applied makes it clear that the layers are not completely bonded. Ideally, we'd probably remelt the part and let the layers flow together. Practically, this would result in a puddle of plastic. I suspect there is some improvement in layer bonds at temperatures that don't melt the plastic but encourage migration. For that matter, temperatures are never evenly distributed so microscopically hotter areas might melt and flow.

Whatever the case, I'm seeing a substantial improvement in strength using my primitive and inaccurate testing methods.
« Last Edit: February 03, 2023, 10:13:08 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.

PonoBill

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Re: Print to Ride
« Reply #125 on: February 03, 2023, 09:37:30 AM »
So this only took five tries to get all the dimensions right (particularly bolt locations). I want to test my stabilizer designs on an axis mast and front foil before doing a lot of work building them the way I think they should be designed. So I made an adapter, which will also work for adapting KD tails to Axis and makes a good basis for making shims for axis tails.

Of course, I'm not going to really print these in PLA, and switching to PA-CF is probably going to screw up the bolt-hole locations, but printing in cheap and easy PLA first feels comfy to me. I still struggle a little with PA-CF, the print settings to get nice parts are ridiculously critical.

« Last Edit: February 03, 2023, 09:51:47 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 #126 on: February 04, 2023, 01:18:45 AM »
Boiling in water is kind of a standard method, but the temperature is a little low for nylon. The intent is to hold the part above the crystallization temperature and the gold standard is to encase the parts in plaster while you bake them. Way too much work. I'm stuffing them into sand and baking at 350F for two hours starting with a cold oven. In theory, I could go a little higher, ramp the temperature more slowly, and hold the temp longer, in practice, it works pretty well. The edges get a little blurry at 350. I'm going to try 300 and see if that works better.

In the general 3D printing community it looks like people are using lower temperatures for PA--lower temps held for a long time will actually help for heat resistance and strengthen the part a little bit, but not as much as exceeding the temperature of crystallization. I suspect they use lower temps because they use sparse infill and don't want their parts getting tweaked and collapsing. Sand helps to a surprising degree with minimizing distortion, and solid parts don't collapse.

I suspect there is more going on with 3D print annealing than just molecules getting aligned. The large increase in strength from aligning layers parallel to the direction of forces applied makes it clear that the layers are not completely bonded. Ideally, we'd probably remelt the part and let the layers flow together. Practically, this would result in a puddle of plastic. I suspect there is some improvement in layer bonds at temperatures that don't melt the plastic but encourage migration. For that matter, temperatures are never evenly distributed so microscopically hotter areas might melt and flow.

Whatever the case, I'm seeing a substantial improvement in strength using my primitive and inaccurate testing methods.

I opened a (new) ticket with Bambu and asked on their forum.  It is their product and they need to tell us.  Of course, I completely get why they do not want to, but...

PS, sweet on the adapter!
« Last Edit: February 04, 2023, 01:20:30 AM by Admin »

 


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