Some months back, before I decided to focus this project on learning composite construction techniques, I ran across images of a frame made by Robot Bike Co.
They bonded pre-made filament-wound carbon composite tubes into DMLS printed titanium lugs. This had also been accomplished by Bastion and Metier.
Cool concept. One exciting benefit was, if done correctly, the method could eliminate external jig requirements altogether. Conceivably your lugs would fit your tubes with enough accuracy to simply glue the frame structure together: the lugs are the jig.
Simple enough process:
CAD lugs > print lugs > ream important diameters > precision cut tubes to length > glue together
Teets, right? And the light bulb went off:
Me got CAD.
Me use DMLS.
Me can buy tubes.
Me make one!
So I designed this:
This was a quick concept test design which provided for the Rocky Mountain Element pivot locations. Tube sizes were COTS items off RockWest Composite's online inventory (here). The general size of the frame and pivots were correct, but the surfacing and important fits were not detailed out. This was done to simply generate a rough idea of how much cash would be necessary to construct a bicycle frame in this manner.
5 basic printed parts: head tube, bottom bracket, top tube to seat tube clam-shell set, and a shock mount.
The head tube and bottom bracket lugs would essentially be hollow with internal ribbing for the tube junctions to help transition the stress from the tube to the lug body.
Quoted it...
$300 in tubes. No biggie.
$50 in adhesives and applicators. Can do.
Then DMLS part quote came in...
I was prepared for a few grand. I would probably even pay as much $10k. Which is, admittedly, fugging stupid expensive for a bike frame. But little compares to the satisfaction from riding a frame of your own design and construction. However...
The DMLS parts for the front triangle quoted out over $20,000
Nope, this frame construction was just not feasible for my budget. So I pivoted the project. It was then that the project became less about making a carbon bike frame, and more about learning the composite construction processes themselves.
They bonded pre-made filament-wound carbon composite tubes into DMLS printed titanium lugs. This had also been accomplished by Bastion and Metier.
Cool concept. One exciting benefit was, if done correctly, the method could eliminate external jig requirements altogether. Conceivably your lugs would fit your tubes with enough accuracy to simply glue the frame structure together: the lugs are the jig.
Simple enough process:
CAD lugs > print lugs > ream important diameters > precision cut tubes to length > glue together
Teets, right? And the light bulb went off:
Me got CAD.
Me use DMLS.
Me can buy tubes.
Me make one!
So I designed this:
5 basic printed parts: head tube, bottom bracket, top tube to seat tube clam-shell set, and a shock mount.
The head tube and bottom bracket lugs would essentially be hollow with internal ribbing for the tube junctions to help transition the stress from the tube to the lug body.
Quoted it...
$300 in tubes. No biggie.
$50 in adhesives and applicators. Can do.
Then DMLS part quote came in...
I was prepared for a few grand. I would probably even pay as much $10k. Which is, admittedly, fugging stupid expensive for a bike frame. But little compares to the satisfaction from riding a frame of your own design and construction. However...
The DMLS parts for the front triangle quoted out over $20,000
Nope, this frame construction was just not feasible for my budget. So I pivoted the project. It was then that the project became less about making a carbon bike frame, and more about learning the composite construction processes themselves.
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