@cicliottotubi on IG has some really slick bosses that I have been trying to reverse-engineer. They tagged it 3D printing, but it looks like its machined or welded. I don’t see any layer lines so I don’t think it is 3D printed. They show an un-curved one, which suggests it’s machined, but they show a CAD that is curved, which suggests it’s printed…
In 3D printed stainless, this is like a $4 part. But you could also laser cut the flange, bend it, then braze a boss in. Printed in Ti, its probably a $15 part.
Hey, from what I understood (speak the same language), all the lugs are 3D printed, those bosses I am not sure, they could have been 3D printed at the beginning and then machined.
I think in a post Daniel (Daniel owner of Cicli Ottotubi) explains that he worked on the original boss design to make it look better, I guess he went to town with a file or something. That part is made by Meti (https://www.metireggioemilia.it/) so it’s possible there is a 3D printed one and a machined one, most of the stuff Daniel is doing is one-off so, who knows.
Those are glued and there is a piece of carbon to reinforce the boss inside the tube, so the tube is actually sandwiched between the boss parts.
I put a dab of epoxy on rivnuts. Best of both worlds. I’ve done the same on 30-40 production carbon bikes that have come into shops with loose inserts.
A little back on topic for the seat mast topper, I am planning on using some aero/oval tubing from a race car company I found and I thought it might be a fun challenge to try a seat mast, since I can’t really put a round seat post in an oval seat tube.
So I designed a topper for some seat post hardware that I have a lot of at work. (Perks of working at a bike manufacturer)
My options for seat mast wall thickness are .035 and .049 and the tube is roughly 35mm deep x 27mm wide. I ride hard but that’s gonna be a long seat mast since it would have to be around 720mm long. Any suggestions?
I’ve been working on my own seat mast design and figured I’d try to reinvent the wheel while I’m there.
Here’s my take on a topper that would use the Thomson hardware. To me, that seems the safest bet in terms of long-term sourcing. I need to get some hardware on hand to verify dimensions, but it seems pretty close to their photos.
I’ve been waffling over seat mast diameter - Rock West recommends Ø34.9x1.6mm but I’m tempted by the Ø30.0x1.4mm tubing for compliance and the fact that it could accept 27.2mm seat posts if the topper idea doesn’t work.
I’m also trying to figure out if it makes sense to weld on a longer tube to the topper or just extend the printed piece. Certainly more expensive to print more, but the lack of assembly is appealing.
Oh interesting! I’m still most interested in a supplier that is transparent, super easy to access, and has a track record of not changing designs frequently, I think Thomson still wins in that regard.
A weird thought I had - could you build with a thick-ish 28.6mm seat mast (similar to a steerer tube) and use stem hardware to affix the saddle? Or would that be too much clamping force?
Sure thing! I’ll post the design here when I’ve finished iterating on it and will let you know before I order them. Is there any specific clamp diameter you’d be interested in?
Besides the weight penalty, isn’t the hoop strength of the tube much stronger in the internal direction than the external “crushing” direction? Would a “quill-style” internal seatpost with higher internal force + smaller surface area of contact equal friction generated by an external seatpost that has a lower clamping force but higher surface area?
Here’s yet another idea. This one is for a 27.2mm carbon seat mast and a PMW seat tube topper. I’d worry about the wall thickness on the printed part, it necks down to 0.9mm where it overlaps the tube.
Damn. That’s clever. Love using pre-made parts for unintended uses. What if the overlap went deeper up into the printed part to where there is more material? Looks like there are a few millimetres before the seat clamp hardware.
