RC10Talk - The Net's Largest Vintage R/C Community

hugger19 wrote:any coupon codes that work for this month of nov??? need to order some parts

this this this

just a side note, one of my coworkers says that if you empty your cart for a few days then add stuff you want and let it sit there, they will eventually send you a 10% off coupon.

cool ill give it a try

I've been under the impression that the main purpose of a 3D printer is for prototyping. That is in order to see if a part/design will work before making it out of the proper material for the given application. I imagine that's why the parts from these 'rapid prototyping machines' aren't as strong as they weren't intended for final production run manufacturing. Maybe the most expensive and technologically advanced ones do a better job of this?

As has been noted, there have been some quality issues with my Shapeways parts as well. I've gotten some that were perfect and quite durable. Sometimes they even look off. I've had inconsistencies with hinge pin holes. On some you have to drill them out slightly. On others they are oversized. There are certain parts that I make where the quality difference doesn't matter such as the diff mount for the Raborn Invencer. For arms, you bet it matters. Unfortunately price is a function of Shapeways costs to make them. I add so little markup to each part that it isn't based on that. I make about $1.50 on a pair of arms so I'm not doing it for the income!

I too am looking for alternatives. From some of the parts that I've gotten, I have faith that 3D printing is a viable method to use. Unfortunately the finished product has as much to do with who made it, at what speed, heat range, and orientation, as it does with the actual material properties.

Here's a nice paper that looked at post-processing methods of increasing the strength of Nylon SLS parts, they tried annealing the samples for different times at different temperatures as well as infusing them with Thompson's waterseal and superglue.

Their results showed about a 57% increase in (impact) strength with annealing at 183 C for 3 hours, but the parts distorted since they were only 1 degree below the melt temperature. At 180 C (3 hrs) they saw about a 42% increase in strength, which still seems pretty significant. That having been said, you would need a pretty accurate oven to heat them to 180 C as going just a few degrees higher would melt the part, and going lower the effect drops off pretty quickly.

As for infusing parts, believe it or not they saw more benefit from Thompson's than superglue. But even the Thompson's only made about a 14% improvement in strength. Superglue showed little to no improvement, which was surprising to me.

You can see the paper here --> http://sffsymposium.engr.utexas.edu/Manuscripts/2003/2003-57-Zarringhalam.pdf

I have some pretty accurate ovens at work, I may actually try annealing some parts at 180 and see what happens. I may also try picking up some Thompson's

I got a set of my longer arms printed through i.materialize to compare to Shapeways. Not only are they printed in the exact same orientation, they are completely identical. I can't tell them apart from my Shapeways parts in any way. I wonder if the actual printers are contracted by Shapeways and i.materialize and are in fact the same ones?

I'd be curious to see if someone has some sort of measuring device, that they could put the arms in, and push on them until they break. Then do this with a real Associated arm and see what the difference is. Because as of yet I haven't seen any real comparisons done.

Or maybe I should buy a set myself, and run them on my RC10T Buggy, since I tend to break the rear hinge pin mounts....which are now aluminum, so the next thing to break will be arms. Do they make RC10T rear arms?

one thing that paper touched on and I think could be pretty indicative of differences between the two vendors is the part placement and build orientation affecting the ultimate strength of the part. Since you can essentially build the part from any direction and probably many at a time on the sintering bed, maybe only certain parts would exhibit a weakness, and it would be a random distribution of who gets shipped a 'weak' part out of a batch.

Yeah, I wonder if you can specify a build direction in shapeways, as the part designer. I know with other rapid prototyping vendors I've used for work you can specify it. I'll look into it, but I don't remember seeing it as an option.

If you look at the forums on both Shapeways and I.materialise sites you can see there is a big need for print orientation control among designers.
I agree, it would be nice.
If I understand right Shapeways is looking for a safe way to save print orientation in their system. They need to be sure system is not changing orientation in some point of process. It's on their todo-list. This was posted on forum not a month ago...

Shapeways and now i.materialize have been printing my arms all standing up. They are clearly trying to cram lots of items onto a print bed at once. I want them printed lying down flat. Shapeways states somewhere on their site that the person loading the file has no control over print orientation. A part lying down, besides having the print grain run the length of the arm, will also have a more evenly heated part across all layers, strengthening the part.

Well, hopefully soon they will let us specify it.

Here in France, I ve had more luck on European parts from Shapeways which feel and act very good.
If anyone wants to source from Shapeways Europe, i d be happy to help.

On a pure geometry to geometry basis, a printed part is not going to be as strong as a molded part. My longer arms were designed to look just like the factory arms but slightly longer. They hold up decently but on hard modern tracks at the speeds that many people run, they will break before a stock arm will. I do have a set of rear arms that I call "racers". I haven't done the fronts yet. They don't look stock but are much beefier. They are noticeably more rigid and less prone to failure. Shapeways also seems to print them lying down.

The reality is that any design needs to be based around the material it is being made from. If we want to copy something that already exists, we need to understand that due to material properties it'll be weaker. 3D printing is perfectly viable for runners and racers if those parts being made takes the material into account and is designed accordingly. For shelf queens, it doesn't really matter.

I have read this thread and i am a little worried because i plan to build a 91 stealth using shapway 3d printed items, and on there site you can choose race or replica, implying that the race version can hold up to today's level off racing, is this not the case because if i cant race it i don't think i will build it.