Propeller Gaurd

sthone · Post by **sthone** » Thu Jan 22, 2015 7:18 pm

OMG

that is awesome... we'll be here when it's done.

-Steve

Spotopolis · Post by **Spotopolis** » Fri Jan 23, 2015 2:45 am

You may already be aware of this carbon-fiber PLA already, but I thought I'd point it out.

I haven't tried anything exotic myself, but I saw this carbon-fiber PLA filament the other day at proto-pasta.com. They claim it prints much like PLA and it's much stronger than ABS and PLA in terms of stiffness and flexibility, but the impact is lower. They have a chart comparing the characteristics in their FAQ section.

I wonder if making your structure with even thinner elements and/or less infill with this stuff would pay off in terms of weight, but I'm not sure it would be worth it if they snap upon impact due to a crash. I would think the added rigidity and flexibility might help in that regard, but I'm no engineer.

Apparently, it is tough on nozzles so it might be a good idea to get a spare or two, and I wonder if bumping up the nozzle size would equate to less wear along with faster prints.

They have some interesting filaments and I'd love to experiment with them, but for now ABS and PLA are cutting it for me. Besides, I have a roll of PET+ waiting for me to play with it.

pyronaught · Post by **pyronaught** » Fri Jan 23, 2015 4:50 am

I was not aware of the carbon fiber PLA. It sounds interesting, but it's expensive at $72/Kg and doesn't have any benefits for the blade guard application. It actually weighs more than plain ABS, so you don't get the light weight advantage of real carbon fiber. My ABS has a measured density of .976 g/cc, whereas the carbon fiber PLA is 1.24 g/cc according to their MSDS data. I actually don't want something brittle for the fan guard since it is subject to smacking the ground. I would rather have something that flexes but doesn't break. If the carbon fiber filament were very light weight then I'd use it for other things on the blimp, but without the weight advantage of real carbon fiber it just really has nothing to offer on making parts for an airship.

Thanks for pointing it out though, I have not looked much at exotic filaments.

pyronaught · Post by **pyronaught** » Fri Feb 27, 2015 3:32 am

Just an update on the blimp project here. The motor mount swivel is done, complete with home-made balsa core carbon fiber composite bracket. The rest is all printed parts, except for the plastic gears and fiberglass rods. This same exact design would work pretty good as the rotating base for making a servo driven desktop robot arm.

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: motor_mount2.jpg (411.05 KiB) Viewed 10359 times

jimc · Post by **jimc** » Fri Feb 27, 2015 3:46 am

Nice! How did you do the balsa core? Hand lay it, vacuum bag it?

pyronaught · Post by **pyronaught** » Fri Feb 27, 2015 4:40 am

jimc wrote:Nice! How did you do the balsa core? Hand lay it, vacuum bag it?

Vacuum bagged it. That's what the pump project was for a few weeks back. It turned out pretty good for my first attempt, but I'm still trying to find the ideal release agent. Wax tends to repel the epoxy and leave gaps on the gloss side, while PVA leaves brush marks so that the finish isn't as glossy as the wax method. I'm going to try spraying PVA on next time. PVA on top of wax releases a lot easier compared with just PVA only, but then you get the same problem with the wax repelling the PVA just like it did the epoxy. I know the wax method can be made to work because I see guys using it on youtube, I just don't know how they are solving the problem of the epoxy beading up and leaving bald spots.

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pyronaught · Post by **pyronaught** » Fri Mar 13, 2015 3:37 am

I got the whole motor pod done and working now. 19 hours total print time for 16 different pieces that are printed in three groups. The yaw axis has 180 degrees of motion while the pitch axis has about 120 since the back side of the mounting bracket won't allow it to go all the way around 180. Thrust from this on full throttle is 850g with a current draw of 11 amps, which was kind of surprising. I would expect higher current draw for that amount of thrust. Two of these on the blimp is really going to give it a lot of push.

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: motor_pod_parts.jpg (453.58 KiB) Viewed 10306 times

: arm_servo_hack.jpg (384.59 KiB) Viewed 10306 times

sthone · Post by **sthone** » Fri Mar 13, 2015 7:10 pm

Yay Updates! It's looking real good. That's a very cool setup. Keep up the great work.

-Steve

dklassen · Post by **dklassen** » Sun Mar 15, 2015 3:19 pm

Looking really good. I had some R/C Blimp experience back in the day but nothing so nice.

pyronaught · Post by **pyronaught** » Sun Mar 15, 2015 7:31 pm

dklassen wrote:Looking really good. I had some R/C Blimp experience back in the day but nothing so nice.

Nice. Did you build that from scratch or buy it? It looks like an indoor type blimp.

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