Quite excited about this stem I made recently. Hoping to have on of @shovelresearch 's pretty adjusters on this one 
Made from 4130 with 1.5-1.6mm wall thickness
1 1/8th steerer
26mm bars
73º to match head angle 
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What are the little nubbins coming out the top and bottom?.is that for the cable to pass through?
These are some I’ve made - more work than just buying one, but they are a nice custom detail for a custom frame.
The King stem will be on one of the bikes I’ll bring to Made 2024
Thank you for using our logo front stem plate! Can wait to see it in two weeks!
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Yeah! Could probably have made fine without it, but I thought it was cool to guide the cable through the stem 
It looks really nice!
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This is a stem I did as an early CNC project. It is two halves that bolt together solid on one side of the steerer and with a gap on the other. I’m very tall, so even with custom geo and full length steerer tubes, I still need a high rise bar to get a comfortable position. I made this stem to give me lots of rise so I would be less limited in handlebar selection.
Yes, the handlebars are wood…and yes, they did break.
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to design and manufacture a custom hi rise stem in order to have a less limited handlebar selection, and then choose to ride a custom wooden bar AND then to snap it feels like one of those especially THOROUGH learning experiences.
I commend you on your (familiar feeling) pedantic want for extremely specific things, and I really hope you’re ok.
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Love the weirdness and chaos. That is how we come up with new ideas! That stem is really cool. it bumps up the rise without looking goofy. Great job!
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Some of my Sinep stems and the inspiration. The top one has a stainless cap held in place with an o-ring.
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That’s hilarious. In Australia sinep is penis backwards, used in pig latin, and not a mustard. Were they taking the piss when they branded that poduct? (pun intended)
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Where this is made sinep means mustard 
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Whenever we visit Finland, we bring home a few tubes!
Yesterday’s work. Custom stem for a local guy’s winter bike.
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I’ve got a request on a custom stem.
The current fork has 55mm steerer tube over the headset and they want a 75-80mm stack stem matching the 5º top tube.
Didn’t do excact calculations, but lets say this leaves 20-25mm stem unsupported in the top.
Would you consider this a problem strenght-wise?
I can of course make the angle of the extension tube, but for aesthetics I would like to keep it in line with the top tube.
Quick sketch:
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Below is how I would approach this but it’s mainly based on superstition. I would be very interested if any of the CAD gurus here can come up with a model to test a couple variations (slot in front, slot in back, etc).
You probably have your own process but in the interest of the forum and getting feedback from others:
-I would start with .065" walled tubing for the steerer clamp.
-Drill vent hole for the extension
-Braze on the extension - 30mm from the top or so?,
-silver braze 2 binders to the front of the steerer clamp
-solder a 5 or 6mm stainless washer around the relief hole location at the top of the slot (up 50-60mm from the bottom); Make sure the hole remains below the top of the steerer.
-If you have a lathe, stick the stem on an arbor, chuck it up and face the bottom of the steerer so it sits square against the headset with even pressure - you can do this as the last step as well. I like to do it before the slot is cut. see picture below.
-Turn a steel top cap with relief for the cinch bolt head.
-Silver Braze steel cap into the top
-Ream the steerer clamp and bar clamp to size.
-Center punch and drill out the slot relief hole in the washer
-Cut the slot up to the hole. (50-60mm long).
The brazed cap will provide some structure to the top and stop it from flexing under pressure.
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Assuming the stem is built with sufficient wall thickness and a good clamp it shouldn’t be a problem at all. Below is a link to Taiwanese made stem with a similar design. It’s made in a factory so you’d think the design has been properly tested (read: it’s probably overbuilt). The minimum insertion required with a stack height of 75mm is 50mm. So roughly the same 20-25mm you’re considering.
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Cool, if the factories approve of 25mm it’s probably gonna be alright!
I’ve got 1.5mm thick 4130 tubing that I normally use for stems. The Crust ones looks like about that thickness to me, but they might be thicker?
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I haven’t built a stem so will let others comment on the wall thickness. I did find this Sklar stem which says min 65mm insertion for 75mm stack. I know Adam @adamsklar is occasionally active here so maybe he can chime in with some info on the limits of the design and maybe the wall thickness used.
No problem at all, scroll up in this thread to Aug 2023 and see my weird tall stem. Mine is 5-1/4" tall and works great!
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