1325's First 3D Printed Gear!

[K519_1325]

We were recently sponsored by Robo3D, a new company that makes 3D Printers. They have provided our team with a 3D Printer that we used today to make our first gear that we used for our shooter.
The gear did not last too long but it held up surprisingly well. This is a first iteration and we plan to make it a lot better.

[SenorZ]

Our team found 3D printed parts to be good for low stress custom parts. We used gears connected to a potentiometer on our shooter. 3 competitions and no failure.
Anything with shearing stress probably wont survive long.

[geomapguy]

Originally Posted by SenorZ

Our team found 3D printed parts to be good for low stress custom parts. We used gears connected to a potentiometer on our shooter. 3 competitions and no failure.
Anything with shearing stress probably wont survive long.

Do you have a picture??

[SenorZ]

Here are a couple of pics from our 2013 robot. The gears were on the robot through 3 competitions (2 regionals and Championships)
I'm pretty sure the cam for the shooter was put on at our second regional to replace one that didn't work well at our first regional.

In both cases, no breakage because they were not under high stress.

https://plus.google.com/photos/10807...1/albums/posts

[K519_1325]

Originally Posted by SenorZ

In both cases, no breakage because they were not under high stress.

Without a doubt the parts we print are going to be used in minimal stress situations. Just out of curiosity, what plastics do teams use to print? Our printer can only print PLA components.

[yash101]

Most printers support either PLA or ABS or both. However, there are some more expensive ones that support different materials, sometimes as strong as Aluminum!

We print in ABS

[Chris_Ely]

Originally Posted by yash101

Most printers support either PLA or ABS or both. However, there are some more expensive ones that support different materials, sometimes as strong as Aluminum!

We print in ABS

What are you basing this on? What printable polymer is as "strong as Aluminum"? My high school just got a $40,000 printer that prints ABS. According to the spec sheet, that has tensile strength of 37MPa. By comparison, my Materials Science textbook says that Aluminum has a tensile strength of 90MPa. Please provide support for your claims.

[LittleRed]

Originally Posted by luckof13

What are you basing this on? What printable polymer is as "strong as Aluminum"? My high school just got a $40,000 printer that prints ABS. According to the spec sheet, that has tensile strength of 37MPa. By comparison, my Materials Science textbook says that Aluminum has a tensile strength of 90MPa. Please provide support for your claims.

It isn't quite the strength of aluminum, but ULTEM has a tensile strength of 71.6MPa.

[pfreivald]

How about steel?

[Chris_Ely]

Originally Posted by LittleRed

It isn't quite the strength of aluminum, but ULTEM has a tensile strength of 71.6MPa.

True, but printers capable of printing that cost much more than most schools can afford. Although, I know there is at least one team (blanking on the number) that uses this with great success.

How about steel?

I did see this a few days ago. Once the technology is improved upon, it looks like it could be very promising.

[seg9585]

$40k to print ABS? They probably purchased an Objet or similar that best uses FDM or Polyjet to much higher res and precision. You can probably get much cleaner tolerances with that printer compared to a Makerbot, Reprap, Cube, desktop printer but obviously at high cost.

Anyway we tried to print hubs last year but the motors tore them apart very quickly. Larger gears may work just fine as long as the gears dont have to absorb large loads (for example in a drive train, holding up robot weight on a large arm, etc). 3D printed gears would work just find for conveyors and the like, but pulleys would work even better.

The other issue is ABS and especially PLA tend to melt and warp if you attempted to drill a hole in them post-printing, so make sure the shaft size is correct the first time. Quick hint: on my Rep2 I increase the desired shaft bore diameter by 0.05in because the plastic tends to expand. Drilling out a larger bore will melt the plastic.

I recommend you test some of the print parameters and see what lasts the longest. For example, try adding additional shells and infill ratios, consider reducing your Z layer height, and even try printing in different orientations (vertical vs horizontal, etc).

[seg9585]

Oh, and regarding material: PLA and ABS is generally the most common but you can also print in nylon. This is good for timing belts since it's bendable:

http://eric.segonline.net/2013/3dprints/timingbelt2.jpg

I haven't tried the Makerbot "Flexible PLA" yet, but I'm looking forward to testing it out!

Then there's always LAYWOOD, which apparently smells and looks like wood:
http://www.fabberworld.com/Laywood-D...3-00:::10.html

[Brandon Holley]

Originally Posted by seg9585

$40k to print ABS? They probably purchased an Objet or similar that best uses FDM or Polyjet to much higher res and precision. You can probably get much cleaner tolerances with that printer compared to a Makerbot, Reprap, Cube, desktop printer but obviously at high cost.

...

The other issue is ABS and especially PLA tend to melt and warp if you attempted to drill a hole in them post-printing, so make sure the shaft size is correct the first time. Quick hint: on my Rep2 I increase the desired shaft bore diameter by 0.05in because the plastic tends to expand. Drilling out a larger bore will melt the plastic.

Objets are quite pricey. The one we have at work was well north of 200k. 40k sounds right about in the Fortus 250 or Dimension range as far as price goes.


I've had no problem drilling out ABS printed parts in the past. I actually drilled a bunch of holes out today. FDM printed parts (particularly ABS parts) are actually really good at secondary operations such as drilling, pressing in brass inserts, and sanding. They often hold up much better than Objet or SLA'd parts.

-Brando

[Chris_Ely]

Originally Posted by seg9585

$40k to print ABS? They probably purchased an Objet or similar that best uses FDM or Polyjet to much higher res and precision. You can probably get much cleaner tolerances with that printer compared to a Makerbot, Reprap, Cube, desktop printer but obviously at high cost.

I believe the model is a Dimension1200se, but I don't know for sure. I don't know much about the printer since I graduated after it was purchased.

[geomapguy]

Originally Posted by luckof13

team (blanking on the number)

Maybe the team that partnered with Oak Ridge Lab