Strength is just one component.
Has anyone in the US used the supplier ProtoTi for 316L SLM parts? Craftcloud is recommending them. If you’ve used them I’m curious what the tariff was and what your experience was.
I’m taking the leap into printed parts, hoping for some feedback from those who have some experience. I’m planning on 316L, glass bead blasted, magnetic polished, heat treated. Probably using Protosoon unless anyone has a better recommendation.
My goal is cutting down on fabrication time because I hand cut/file/grind all joints.
Seat Cluster Yoke:
1.7mm walls
31.6 for the seat post - should I make this smaller to allow for reaming to make up for any distortion?
Seat tube/Down tube yoke:
2mm walls
1mm web
Hole for dropper cable - is this a bad idea?
Chainstay yoke:
2mm walls
1mm web
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I know nothing except it looks good
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Looks really nice! I have only done two frames with 316L printed pieces in them so I am not an expert. In my opinion, you can reduce your wall thicknesses by 0.2-0.3mm across the board (webs can stay the same) and that’s still pretty conservative. If you are tigging this I would add maybe a couple more mm of the sleeve where the tubes join, just to give the heat a little more space to go and the overlap offers a little peace of mind. Your post treatment options are wise and everything looks great, but again I’m just an amateur. There are a lot more experienced people on here that I would listen to over me 
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I’m also no expert, but I do know that 3D printing does not like coming to a thin sharp point. I’d revise your design in these areas to either add a radius or adjust the design to limit these thin points. In addition to increasing the overlap on the printed part and the tube like was suggested above. If you want to save money, you can always use an off the shelf seat binder, or weld one on. Printing the seat binder is going to add some cost since the prints are usually quoted by weight. Since it’s a 3D print, you could also just print a small guide for the dropper post into the part. Overall the design looks awesome.
Edit: I think with the heat treating and post processing of many 3D printed metals, it can create a hard surface that can be difficult to work with (tapping, reaming). I have heard it’s really difficult with titanium, but I’m not sure how difficult it is with Stainless.
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Great, I’ll drop it a bit.
I was avoiding the longer sleeve so I would have more adjustment wiggle room in the overall geometry. I didn’t think about heat, that makes sense.
Makes sense, I’ll get rid of the sharps.
My original plan was to copy @Daniel_Y’s top tube yoke, but after pricing the parts, it’s barely more cost to print the whole thing compared to buying the seat tube collar and binders and printing the yoke.
For reference the part cost quotes from Protosoon (these will go down a bit when I reduce wall thickness)
:
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Nice, looks good. Also as for your seat tube, I’ve never printed one so I haven’t had to ream one but I have done several bearing seats and pivot holes and I I have just gone 0.3mm undersized on the diameters and have had good luck. However I am machining all those on a mill with a reamer or boring bar. I haven’t done any by hand but I assume it would be a similar experience. I know the holes are not perfectly round without the machining.
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I only have one piece of 3D modelling advice: use fillets based on “chord length” instead of a normal constant radius. It will look even nicer and is better at avoiding stress risers
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Yep, I’ve printed a few seat tube clusters like this and need to ream all of them. I print it only ever-so-slightly undersized (0.2mm) in the diameter and ream to fit once I get them. I 3D print a jig that’s designed to clamp around the outside of the part so I can do the rougher reaming in my mill before welding on, then do a final ream to fit once joined to the actual tube after welding.
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gschwell great looking parts.
One option you might consider is replacing the two threaded portions of the seat cluster with hexagonal recesses sized to hold captive nuts.
Such an approach may lower the print weight/cost by a small margin, sidestep any issues or difficulty in printing or tapping the heat treated and printed material, as well as make the threads a sacrificial and rather easily replaceable part should they ever get buggered over the frame’s life.
Just a thought.
Please keep us posted on the progress as well as the costs of the prints if you’re willing; I’d love to see more data points on the timeline/price/shipping/tariffs costs parts like this end up with.
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About heat treatment and hardness. Here’s a quick rundown of some common alloys folks are using on bike stuff:
- 316L: More heat generally means softer material, so generally speaking, ‘heat treatment’ of 316L will make it more ductile, and easier to cut in most circumstances.
- Ti64: Properly stress relieved or annealed, it will make it EASIER to cut/tap than ‘as-printed’. However, if it’s heat treated improperly (too hot, or in an oxygen or nitrogen environment) the results may be unpredictable and undesirable in all sorts of ways. Titanium is complicated. I advise this stuff MUST be heat treated, but it MUST be done properly. If not… it may crack, warp, or just cause you trouble.
- 17-4: Annealed or ‘stress relieved’ (condition A) will be easier to cut than as-printed or hardened, but has the least desirable performance mechanically. 17-4 should be used either as-printed or solution annealed+age hardened. I don’t recommend this alloy for bikes, though lots of nice bikes have been make with it successfully.
- AlSi10Mg: This is the most common 3D printed aluminum. If you are getting printed aluminum- it’s almost certainly this stuff. It is ‘safe’ in any heat treatment condition, but properties can change significantly depending on what is done. Here is a summary:
- As-printed: highest strength it’ll ever be, but often brittle. Properties dependent on specific printer settings used to make it with. Highest anisotropy. Unpredictable.
- Low temp stress relief (~170-220C): keeps most strength but becomes slightly less brittle. Gains some fatigue life. ~40ksi yield.
- Moderate temp stress relief (~250-350C): Gains some usable ductility (maybe 10% elongation) but loses significant yield strength). ~30ksi yield
- T6: just don’t do this. Its expensive and makes parts distort. Does give probably the best overall balance of properties, but at a cost.
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