Melted firewall

[CPJ]

New guy here, built and finally managed to fly (without crashing ) a Tiny Trainer. One issue I have noticed is that my 3d printed firewall seemed to have gotten a bit... "melty" . Noticed that tonight when preparing to rebuild the power pod for the 7 or 8th time. (slow, stubborn learner)
The motor is obviously getting hot, I noticed that after about 7-8 minutes that I flew. Not sure how hot they are supposed to get, Im new to the hobby. But Im assuming mine was too hot. Ive lawn darted the plane a few times, but nothing other than the pod seemed damaged. Attached are the pics of my electronics, everything is supposed to be rated to work with each other.
Thoughts? I really like the 3d printed firewalls, they are quick and easy to make. I just tell my robot to make more.

 

[Arcfyre]

The only reason the motor would be getting hot would be if you are putting a propeller on it that's too big or has too much pitch.

That motor should be happy with something between 6x3 and 6x5

 

[CPJ]

It’s a 6x3. While running it was at cruising speed , for all but the last few seconds when I pinned the throttle to see what it would do. What it did was shook things loose. 🤣

 

[kdobson83]

The only reason the motor would be getting hot would be if you are putting a propeller on it that's too big or has too much pitch.

That motor should be happy with something between 6x3 and 6x5

New guy here, built and finally managed to fly (without crashing ) a Tiny Trainer. One issue I have noticed is that my 3d printed firewall seemed to have gotten a bit... "melty" . Noticed that tonight when preparing to rebuild the power pod for the 7 or 8th time. (slow, stubborn learner)
The motor is obviously getting hot, I noticed that after about 7-8 minutes that I flew. Not sure how hot they are supposed to get, Im new to the hobby. But Im assuming mine was too hot. Ive lawn darted the plane a few times, but nothing other than the pod seemed damaged. Attached are the pics of my electronics, everything is supposed to be rated to work with each other.
Thoughts? I really like the 3d printed firewalls, they are quick and easy to make. I just tell my robot to make more.

What size prop are you using? Even a 6x45 on 3s can make it hot. And what plastic are you using? PLA? Try printing using ABS. It has a higher melting temp. I use ABS for my firewalls after I had a PLA one get soft on me. ABS is a bit harder to print tho. You really need a heated bed, and much higher bed/nozzle temps. I use a Ender 3 printer and have to print at Max temps for bed/nozzle on a glass plate. I use Aussie hair spray to help it stick too.
Anyway, check your prop size, use a 6045 or a 6030. I use 5x4x3 on my mini guinea and arrow with 1806s and it does nice.

 

[sprzout]

I've never had a 3D printed firewall melt like that...If it's hot, something's wrong. Since you're running a 6x3, that sounds right, but if it's shaking things loose, you might need to check that the prop is balanced. That could cause it to get overworked and definitely cause short life...

 

[CPJ]

I've never had a 3D printed firewall melt like that...If it's hot, something's wrong. Since you're running a 6x3, that sounds right, but if it's shaking things loose, you might need to check that the prop is balanced. That could cause it to get overworked and definitely cause short life...

I shall google prop balancing. Wouldn’t surprise me if it’s hosed, it’s taken a beating. Looks ok on the surface, but maybe not.

 

[CPJ]

What size prop are you using? Even a 6x45 on 3s can make it hot. And what plastic are you using? PLA? Try printing using ABS. It has a higher melting temp. I use ABS for my firewalls after I had a PLA one get soft on me. ABS is a bit harder to print tho. You really need a heated bed, and much higher bed/nozzle temps. I use a Ender 3 printer and have to print at Max temps for bed/nozzle on a glass plate. I use Aussie hair spray to help it stick too.
Anyway, check your prop size, use a 6045 or a 6030. I use 5x4x3 on my mini guinea and arrow with 1806s and it does nice.

I too, have an Ender3. I’ll make PLA work, or, I’ll whip up something in aluminum on my mill or use plywood. Nothing I do as of now warrants ABS, or the challenges that go with it. I just think for whatever reason my motor is way too hot.

 

[CPJ]

Well, I ordered a new motor and a few more props, it was worth the $20 to have spares anyway. And, one never knows when a new plane needs to be built.
The motor feels "notchy" when I spin it. Not horrible, but with no experience and nothing to compare it with, I cant say if its good or bad.
Thanks for the help so far. This seems to be a pretty cool place.

 

[kilroy07]

Nothing I do as of now warrants ABS, or the challenges that go with it.

What build surface do you have? PETG is pretty forgiving (and has a higher glass point than PLA) but if you have a PEI build surface I wouldn't even attempt it! (It'll fuse and ruin your PEI plate.)

Edit; But I agree with others, I would first look into the cause of the motor getting that hot!

 

[CPJ]

What build surface do you have? PETG is pretty forgiving (and has a higher glass point than PLA) but if you have a PEI build surface I wouldn't even attempt it! (It'll fuse and ruin your PEI plate.)

Edit; But I agree with others, I would first look into the cause of the motor getting that hot!

Whichever surface that came with the Ender 3. I havent done anything to it other than a filament guide. Its worked very well, especially considering the price. Its main uses have been storage boxes and organizers for my tool box.

 

[kilroy07]

Whichever surface that came with the Ender 3. I havent done anything to it other than a filament guide. Its worked very well, especially considering the price. Its main uses have been storage boxes and organizers for my tool box.

That will work fine (I have an Ender 3 as well... among others.)

 

[FDS]

I have never had a PLA firewall melt.

 

[CarolineTyler]

+1 for PETG - strong as it's less brittle than PLA, less suspectable to such melting and much easier to print than nylon or ABS.

 

[TEAJR66]

Here are a couple suggestions.

Try a 5x3 prop (balanced will help).

Use longer mounting bolts and place a couple washers between the motor and the firewall (be careful about bolt length and the windings in the motor. Do not make contact).

I’ve melted a few 3D printed firewalls. Sometimes motors get hot. It’s what they do.

 

[CPJ]

Here are a couple suggestions.

Try a 5x3 prop (balanced will help).

Use longer mounting bolts and place a couple washers between the motor and the firewall (be careful about bolt length and the windings in the motor. Do not make contact).

I’ve melted a few 3D printed firewalls. Sometimes motors get hot. It’s what they do.

I had to cut down all the mounting screws that came with the motor as they were WAY too long. The washers would be easy enough to make on the lathe out of some aluminum. May help sink some of the heat without adding much weight.

 

[quorneng]

I fear all aluminium washers would do would be conduct the heat into the bulkhead. Fibre washers would be better.

It would still be useful to measure the current the motor is taking (Watt meter) to see if it is within the motor's specification.
If it is then a lack of cooling airflow may be the problem.

 

[CPJ]

I fear all aluminium washers would do would be conduct the heat into the bulkhead. Fibre washers would be better.

It would still be useful to measure the current the motor is taking (Watt meter) to see if it is within the motor's specification.
If it is then a lack of cooling airflow may be the problem.

Fair point on the aluminum. I wondered about airflow, but, there’s.......a lot of air flowing, right behind the prop. Maybe it’s a dead zone. Who knows? I’ll have the new motor by the end of the week hopefully and I’ll get it swapped and try again.
Side note, ever order “just a couple things” then a few hours later think of all kinds of stuff you could have ordered for hardly any extra shipping? 😬

 

[kilroy07]

Side note, ever order “just a couple things” then a few hours later think of all kinds of stuff you could have ordered for hardly any extra shipping?

Yup, pretty much every time!

 

[quorneng]

If an out runner brushless is in the 'open' the very rotation of the bell usually causes an air flow through the windings sufficient to prevent over heating - unless the motor is being asked to draw more amps than it is designed to take. i.e its over propped.

An example
28 mm diam bell, pusher 10 x 4.2 prop. 375W (measured). Printed PLA motor mount.

Just gets warm. Flown regularly now 2 years old.

 

[Dante]

Have you checked that the hole in the center of the firewall is not rubbing on the c clip? I have seen another instance somewhere on youtube where the c clip wasn't spinning with the shaft and was rubbing against the shaft creating heat. Now I drill the holes extra big