3d printed stem spacers???

[Queen of Skulls]

I'm going to design and print some custom spacers for my vb218 build. How much does matter if they are one or two piece? also I am going to make computer mount... and maybe a flashlight mount in the future.

mount similar to this. https://www.printables.com/model/38316-improved-wahoo-elemnt-steerer-tube-headset-mount/

stuff like this is eazy peasy for me. I just want to make sure I am doing it right. is there a point to them being 2 peice?

[Sakizashi]

Ive made some functional spacers. What do you mean one or two piece? Like split spacers vs. not? Or uses either a CF or metal insert for compressive strength?

Regarding the latter, if the spacers are under the stem they need to hold preload. It’s not a lot of force but its safety critical to prevent damage to the steerer. I am pretty conservative with this stuff but personally would only make spacers without an insert out of something like MJF Nylon12GB. It’s the 3d printed material closest in properties to the injection molded nylon 66 that OEM solutions seem to use.

Plenty of examples of 3d printed spacers from Extralite, etc failing.

[Wet Noodle]

More pieces means more adjustable, but structurally you'd want less (not that there was a meaningful difference).

However, typical plastics for consumer-grade machines may creep quite a bit under load (not sure if the ones filled with carbon dust fare better). You might have to retension the headset from time to time.

Is the frame one of those modern contraptions with headset parts and spacers being full of holes for cables and stuff? That might complicate things slightly. Other than that, it is doable. I've ridden a bike with a combined headset cone/collar* printed from pla for years.

*Not sure how those parts are called. I mean the conical ring that slips between upper bearing and fork shaft and then the usually more decorative part above that.

[Queen of Skulls]

More pieces means more adjustable, but structurally you'd want less (not that there was a meaningful difference).

However, typical plastics for consumer-grade machines may creep quite a bit under load (not sure if the ones filled with carbon dust fare better). You might have to retension the headset from time to time.

Is the frame one of those modern contraptions with headset parts and spacers being full of holes for cables and stuff? That might complicate things slightly. Other than that, it is doable. I've ridden a bike with a combined headset cone/collar* printed from pla for years.

*Not sure how those parts are called. I mean the conical ring that slips between upper bearing and fork shaft and then the usually more decorative part above that.

Like I said making them is easy and its the velobuild 218. its just sitting down and doing it.  I already got pics and measurements.  and yes cable routing.

[Queen of Skulls]

Ive made some functional spacers. What do you mean one or two piece? Like split spacers vs. not? Or uses either a CF or metal insert for compressive strength?

Regarding the latter, if the spacers are under the stem they need to hold preload. It’s not a lot of force but its safety critical to prevent damage to the steerer. I am pretty conservative with this stuff but personally would only make spacers without an insert out of something like MJF Nylon12GB. It’s the 3d printed material closest in properties to the injection molded nylon 66 that OEM solutions seem to use.

Plenty of examples of 3d printed spacers from Extralite, etc failing.

the spacers that come with the velobuild 218 are each are 2 peice that intertlock with the stem so they line up with the stem. so there is a right and a left.

[Queen of Skulls]

the spacer inter loch via the lil nubs. the riight and left and the one lower and higher. so it links together. heres a pic of them together

[Wet Noodle]

making them is easy

Nobody questions that, the geometry is easy (1 sketch, 2 features). The concerns voiced in this thread are all about the part holding up (or not).
And it wasn't really clear what you where on about with the 2 parts, thx for the picture Going one-piece would be the easiest, but then mounting/removing the thing would be an absolute pain(?) I mean, the split is there for a reason.

We're assuming fdm and no "super materials", right? In that case: The original parts looks a bit thinwalled, what's the measurement? I would look to beef it up somewhat. Also, judging from the picture, the split should be slightly altered for fdm. The transition from the frame structure to the hinge bit could be a breaking point. Then, you can't fdm tiny pins like that standing up (sure, your printer might be able to, but we don't that for structural parts); easy fix without processing cost: do through holes on both parts/sides and use filament pieces as pins.

[coffeebreak]

I'm thankful for the two piece design. Can't tell you how many times I missed weaving the cables through dust cap which is one piece and then had to pull all cables out and route them through the cap. If spacers were also one piece one would have to pass all the cables thru them during the routing and before tightening the headset/stem. I wish the dust cap was two piece too. You can just pass the cables in the frame and later assemble cap and spacers.

[Tijoe]

I am in the same camp as Sakizashi regarding the material used in spacers below the stem that have to maintain the headset bearing pre-load.

On my road bike, it doesn't appear to matter that much what material the spacers are, but on my gravel and mountain bikes, the front end of the bike takes a beating and I see wear/powder on my carbon spacers where they vibrate and absorb impacts passed through the fork to the stem.   I have to tighten up my headset about every 6 months.
(This never used to happen when I ran aluminum spacers.)

[Queen of Skulls]

I'm thankful for the two piece design. Can't tell you how many times I missed weaving the cables through dust cap which is one piece and then had to pull all cables out and route them through the cap. If spacers were also one piece one would have to pass all the cables thru them during the routing and before tightening the headset/stem. I wish the dust cap was two piece too. You can just pass the cables in the frame and later assemble cap and spacers.

What do you mean super materials? Because these spacers are just abs maybe nylon from what I can tell. I was thinking of using Asa or petg. As abs is a pain to print. I was thinking of using a roll pin to hold them together. At least on one side. Like a hinge.

[Sakizashi]

I dont know what the original Velobuild ones are made of, and it looks like the EXS handlebars are coming with MJF printed nylon spacers but not sure what they are made of.

FSA sells spacers made from polycarbonate, carbon fiber, and nylon. Deda uses aluminum or nylon. There are also a lot of carbon / glass reinforced nylon in use. Unfortunately, 3d printed stuff is weaker in compression than injection molded stuff with MJF the only process that comes close (with like materials). This is just a place where I think a few extra dollars is worth it for safety as when not in preload the bending moment increases exponentially. This is what causes steerer tubes to snap or more commonly develop those grooves (and eventually snap) as they bend and grind against the bearings.

Regarding the shape. Because you want to eventually add mounts to these spacers i think one piece makes sense, but they will be a pain in the ass to fit and test.

[Wet Noodle]

What do you mean super materials?

The really expensive stuff that is hard or impossible to print on consumer machines. Nylon, I'd consider borderline; if you can print it, good.

The original part may very well be ABS or nylon as you say, but I'd assume they use glass or cf filled material. This makes a significant difference in stiffness (and helps against creep as well, I think) - which you want. Additionally, keep in mind that home-made fdm parts are always weaker than anything the big boys do. So, if you can get and print with filled material, consider it; and where you have the choice, go rather thicker than thinner.

[gmh]

Before Velobuild started shipping the split spacers, I designed and printed spacers for my 177.  They were 1-piece but with a split and sort clipped around the cables and steerer.  A 2-piece design would have been better.  You will definitely need to use something like nylon at a minimum for this and print at 100% infill for as solid of a part as possible.  In the end I just got a set of their split spacers and used them. 

Why do you need custom spacers?

[Queen of Skulls]

Well I need a taller stem height. I am 6ft and all torso. I want to eventual want to go down. I am not that flexible yet. And my big ass boobs get in the way too.

[gmh]

I hear ya.  If you're set on using a consumer FDM printer, you can design in some holes for metal pins.  Then you'd have some more solid material to take up the preload vs the plastic.

Best of luck!