Is 3d printing a bike possible?
 

Quick disclaimer, I am a complete newbie.
I've been looking into building my own frame, which as you know comes with a set of daunting logistics. Looking to dumb things down a bit I came up with this idea to 3d print the bike. After a little more research I found that people do actually 3d print lugs. I then found this website https://i.materialise.com/3d-printin...rials/titanium that allows you to upload 3d designs and print them. These designs can be 9.8 by 9.8 inches, which should be more than enough for a lug. My question is, would this be a viable method for making a lug? Also, assuming this is possible, how would you keep the frame together? welding? brazing? (preferably a begginer friendly method).
Thanks
Also here are the Mechanical Properties of the printed Titanium.

Tensile Strength min. 930
Ultimate tensile strength ASTM E 8M 1140 MPa
Yield strength (Rp 0.2 %) min. 860 MPa
Elongation at Break 13 - 15%
E- modulus 104 - 124 GPa
Impact Strenght 7 - 15 J
Young’s modulus 111 GPa
Charpy V-notch toughness ASTM E23 10 - 11.5 J
Hardness Rockwell C 308 – 332 HV5

Whole frames have been printed, and I think they may have printed whole bikes, the parts moved but were not serious bikes, the printed frame though, was in three pieces and real.

Lugs are brazed to other parts to make a bike. I don't know of any way to braze Ti. You can weld it to more ti, but if you wanted to do that, you might as well weld a ti bike, which is a fair distance down the road from being a beginner project.

You could probably print lugs in Ti, and glue them to carbon tubing (well any tubing for that mater). You need a lot of overlap though. Old popular mechanics issues have short articles one bike built that way using Al, or carbon.

To help you get where you want to go, it would be helpful to know the whys behind all these questions: Why do you want to build; what is it you need a custom bike for; why are you trying to re-invent the thing that holds the wheels together (there are good reasons for all of this, but you may be headed off in the wrong direction). We live in a world where it is pretty easy to get a whole custom Ti bike from china for what not too much printing or cnc costs.

First off, there are no shortcuts. Everything comes at a cost. If you absolutely have to build a bike and don't want to gain any skill, maybe bamboo is the way to go. Lots of info about that. Or maybe we'll be reading about you and your 3d printed bike sometime in the future.

people print parts of bikes. Some are doing it just because they can, a few are doing a nice job of using the properties of the technique. Parts that don't have a thick section are probably not good candidates for printing. Just about the only thing I liked about the carbon-3d printed hybrid bike was how small the envelope was for the print, less than a 1 foot cube. Those bikes have carbon tubes glued into the lugs. Buying carbon tubes is an entirely different subject.

You could weld to these parts, but if you were good enough at welding to do that, you could certainly build a frame without any 3d printed parts

Commercial 3D printing is incredibly expensive. There are no home 3D printers for metal. So you will be charged for the amount of metal consumed, plus the amount of metal used in the envelop size, and the run time of the machine. Printing a part layer by layer takes many hours. Standard shop rates is about $140 or so an hour. So an 8 hour print is $1000 in labor. Each lug would probably cost $500 or more.

So can it be done, yes. Is it feasible, no.

the possibility of 3D printing an investment, to make something like the Cast Kirk magnesium I beam frame

1987 Kirk precision magnesium road bike | Classic Cycle Bainbridge Island Kitsap County

and burning out the investment and Then Pouring in Molten Metal Is possible .

@fietsbob thanks for the link , that is very interesting!

I thought one of the more home practical things a guy did was 3d print lug molds out of plastic, it think he made a thread here. He then molded carbon lugs in the plastic molds. I forget whether this actually helped in any particularly useful way compared to just tying stuff together with tow. If you read up on the bamboo bikes, but substituted carbon tubes and Al elements, and knit it together with carbon tow, you could make a high end bike with little of the nonsense involved in steel. Steel is great, but the heat distortion is a major nightmare relative to the gear you need to have, like taps. There are Chinese carbon tube suppliers on ebay that compare well on cost, but it may not be bike grade stuff.

To my knowledge, there are no metal 3d printers capable of printing a full scale frame. Lugs and maybe a tube, sure. Full frame, no way. There are plastic printers capable of very large scale objects (furniture sized).

Ti honeycomb type lugs could probably be easily bonded to stock CF tubing, so it's definitely feasible. The advantage of a honeycomb is that it would have significantly more surface area for bonding and likely more robust than a conventional bonded lug.

As mentioned above, 3d printing costs for metals are astronomical. Metal 3d printers are almost exclusively used for R&D type activities where the cost is folded into an overall R&D program. There are a few places using 3D metal printing for production, namely medical and aerospace (jet engines). If you happen to have access to a metal 3d printer, then it's totally feasible to print your own lugs...

Calfee does this when they don't have a aluminum mold already made.

I thought Calfee's molds were aluminum husks/shells that had a silicone insert in them. By altering the silicone insert, different geometries can be accommodated using one set of aluminum molds.

You might want to read this when it comes to 3D printing with metals
https://3dprintingindustry.com/news/...-part-1-44130/

Spencer is also featured here, with some other links on 3D printed projects at the bottom of the article
3D Printed Titanium Seatmast Topper Coming from Designer Spencer Wright - Bikerumor

Sorry, that's Parlee that uses the silicone insert in aluminum mold technique.

There are tons of ways to use 3D printing making molds and tooling. We do it in my industry all the time. There's potential to make plastic parts in small quantities but in large quantities it's faster and cheaper to injection mold. Metal works best when worked and heat treated. It's hard to do that with 3D printing. We still use a lot of forgings that are NC milled or lathed to final shape. NC machines are used to lay carbon fiber tow for pressure vessels and other things, but it doesn't quite fit the image of "3D printing" you might have in your head.

You can silver braze Ti if you have the proper set up for it. One of my predecessors held the patent for vacuum brazing Ti those who know will know this as the Pino-Behr project. As for 3D printing a frame my students son just finished and internship with I think GE he was interning on a huge 3D printer that printed with steel powder.
Paul