3d printing.
 

A friend is an engineer at an small aircraft manufacturer. He recently was moved to a department where he has access to a 3d printer. I recently introduced him to road biking and the last time I saw him he showed me this material and asked if I wanted anything printed with it. His idea was the front fork.

He says it's cheap and stronger than carbon fiber. Felt very light as well. He made it sound like it wasn't a problem to have whatever I want printed up but I just want to owe him 1 favor not a dozen.

So I was wondering if anyone has done anything like this before or has any idea of maybe the most useful thing to have printed. Would seem like a waste to not take advantage of the opportunity.

Yes and a solid cast steel fork would be cheap and strong but its going to be heavy. On something like this you can't divorce the strength from the weight. In my experience with 3d printed parts if its strong then its going to be heavy. If its somewhat light then its going to be like riding on a wet noodle. I would be more apt to make something like custom computer mount or a fancy bottle cage. Definitely not anything that supported my weight and especially not a fork.

Stronger than CF? That seems highly unlikely. Most 3d printers use plastic or resin although some of the high-end printers can print metal. There's a lot of design/engineering for a fork, I'd start with something simpler. Betting you could do a really awesome tool holder or bottle cage.

The real advantage of 3d printing is that you can make things that are custom or would be impossible with conventional manufacturing.

Ya, as a mechanical engineer with some experience in additive manufacturing (AM), I'll chime in that there are some aircraft manufacturers who use AM for production. However, without knowing the material or specific AM process I can't give you much feedback. I can definitely say that there is a reason why bike manufacturers do not use AM for making forks though :). I know of a few pieces (transmission case) that are rather large and carry some load, but I can't think off the top of my head of hearing about any structural suspension pieces that are produced using AM. There might be some precedence, I'm by no means an expert (my expertise is more with structural dynamics and networked sensor arrays), but it doesn't seem like an application that AM would be the best choice. Also, if you don't have any experience with CAD/CAE, and designing a load bearing structural component then you probably should not even be attempting a project like this. Properly designing any structural piece (e.g. front fork) requires material knowledge, structural design to account for both loadings and fatigue limits, and the experience with CAD/CAE software.

It's not just as simple as drawing a fork in a computer program and printing it out.

Yea, thinking smaller is probably a good idea. To the drawing board.

This is the most important part. It's all very well saying this material is stronger/lighter than CF, but you and your friend don't know how it behaves in the unique stress/strain patterns of a bicycle fork. The carbon forks that are on the market now have been honed through 30 years of experimentation to eliminate excess material in places where it isn't needed, thus bringing the weight down. You don't know where these places are in your new material. So to accommodate that, you'll probably have to overdesign your fork by a significant amount. Meaning you'll end up with a much heavier fork, when you could've got a lighter chrome fork for $100 on eBay.


On the other hand, it might be a fun project to work on with him, if you can afford the "printer ink" to do a few dozen different designs before coming up with one that works. DON'T treat this as a way to get a lighter-than-carbon fork on the cheap. Because it isn't.

First of all, that must be some big 3D printer. I guess they are getting to be that size now, but a fork is pretty damn long for many printers.

Second, in a printed part there will be no "orientation" of fibers to strengthen and stiffen the fork in the proper directions. That will make it necessary to add more material to obtain these characteristics and that means lots more weight.

Third, in many 3D systems two plastics are used and the desired part is made out of one plastic while the other plastic is used to fill in the spaces which will need to be hollow in the final part and to support areas of the desired part that need to be built up vertically. The printed fork might look like a solid rectangular block with the fork hidden inside. This second plastic is water soluble and is washed out after the part is printed, leaving just the desired part. I find it hard to believe that it would be easily possible to wash material out of the inside of fork blades and the steerer tube. Would all that material have to be carried along forever?

I wouldn't want to be the one road testing said fork ..

I got wide eyed when he suggested a fork too. He kept calling it a yoke which was funny. But he seemed pretty confident. I really have no need for a fork. But I thought if it ready is stronger and lighter than cf which it may be as it is used in manufacture of these tiny lite aircraft. Then maybe you could end up with something pretty unique. Cutouts or something.

carbon fiber will likely have a higher specific modulus then whatever polymer is being printed

Post a video of the first road tests :)

It could go viral. Then I'm on the today show.

I work in engineering and I just want to warn you that engineers have a bad habit of saying "meh how complicated can it be" and assume they have an understanding of things without actually having an understanding of things. I wouldn't stake my safety on the fact that the guy is an engineer in a completely different field than bicycle manufacturing.

^this.

/endThread

on a 50+mph downhill please.

You should make something like a mount for your phone, light, speedometer or something like that.

Maybe you could replace the seat bag with a little unit that attaches rigidly to the seat rails and is compartmented to hold your CO2 and multitool snugly.

Just don't make a fork, though... for heaven's sake, it's one of the few components on your entire bike that has a good chance of KILLING YOU if it fails!

If he's new to cycling, I don't think he realizes the amount of R&D that goes into designing something like a bike frame.

Best point of all. OP, if you print a front fork, I hope your life insurance is paid up.

Start with a bottle cage.

Well I need a crazy fork, so if he prints you one and you're scared to test it feel free to drop me a PM ;)

Word for word, exactly what I was going to say. Bizarre.

It's easiest to find answers when unencumbered by knowledge or the thought process.

Why not the whole bike??

http://www.youtube.com/watch?v=hmxjLpu2BvY

How would this be better than what exists currently?

Because he'd be making it for himself.