Fully Mechanical (No‑Motor) Rotating Sleeve for Handy 2 Pro — Need Help Modeling in CAD

[Ta_7890]

Hi everyone,

I’m looking for someone who can help me model a small mechanical idea I’ve been working on for the past several months. I’m teaching myself Fusion 360 just for this project, but I’m still too early in the learning curve to build it properly on my own.

The concept:

A fully mechanical, non‑motorized rotating sleeve attachment for the Handy 2.

The idea is to convert the Handy’s up‑and‑down stroke into rotational motion using a very simple gear train:

• The Handy’s moving carriage would have a vertical rack gear on its side.

• A pinion gear meshes with that rack, so when the carriage moves, the rack forces the pinion to rotate.

• That pinion sits on a shaft, and on that same shaft is a bevel gear.

• The bevel gear is angled so it physically meshes with the input gear of a small planetary gear system mounted off to the side.

• As the bevel gear turns, it drives the planetary sun gear, and the planetary output rotates the sleeve.

The motion chain is: rack → pinion → bevel → planetary → rotating sleeve.
It’s intentionally simple — just a few gears converting linear stroke into rotation. I have some pictures below the design apology it looks more confusing it needs to be I had to use AI to at least create a picture that I could share with everyone

I have a 3D printer and can produce high‑quality test parts. If someone helps me model this, I’d be happy to print a finished version for you using strong materials and send it your way.

Thanks in advance, and feel free to ask any questions!

[g90ak]

Can’t offer up any help, but that is a damn ingenious analog idea. Props to you. Hope you get it working!

[Ta_7890]

Thanks friend! I honestly tried for the past 8 or 9 months to learn how to design it myself using CAD software like fusion 360, I must have spent hours watching tutorials and was planning on releasing it for free to the community but it’s just too difficult for someone as an inexperienced as I am.

I really hope a hero steps forward and can help out.

[g90ak]

I hate to say it out loud, but have you tried Claude or anything? Seems like you have the specs down, and you got a printer, it may just be a case of telling it to design you stls for each part and then testing and adjusting gear ratios.

I personally don’t even like Twist, but I do really think you have a cool idea. Simple, elegant, doesn’t require modifications to the actual operation of the Handy (other than increased load, but that’s where the gear ratios will come in). Really cool.

[Ta_7890]

Lol no worries truth be told, I’ve already tried Claude, but I don’t have the paid version so I run out of usage fast, and even if I did, I wouldn’t really know how to use it for 3D modeling. I could barely describe the project well enough to get a few rough images out of Claude/Copilot. I’m sure someone out there with more experience using LLMs/Claude could get far better results than I can.

I’ve never generated a 3D model through any AI tool before, so I honestly wouldn’t know where to start. Even websites that are intended for AI 3D modeling can’t really nail down the complexity in the gears for those projects That’s why I figured I’d come here first, I’ve seen people in this forum create some really impressive designs, so I thought it was worth asking for help.

As for the load‑bearing concern, I always imagined using something lightweight, similar to the Quickshot from Fleshlight (link below). It’s extremely light and wouldn’t add much stress to the mechanism. With 3D printing, using low infill and smart geometry, the whole attachment could easily stay under 100 grams.

[SoulesMoon]

neat idea but its not finished yet it needs something to properly attach to the handy firm enough to account for the weight and motion/momentum, additionally the turn amount is decided by the amount of gear teeth more means faster and more rotation less means less.

it needs a couple more comb overs before it gets into functional territory.

[NeoScripter]

@Ta_7890

I tried building something similar.

Just sharing my experience.

It can be done, but the click-in style sleeve attachment really makes mating a bit tricky on the H2. A rack and pinion setup works (on the H2 side of things) with a worm gear driving the spur gear on the Twist assembly.

However, when the action really gets going, you realize you need stabilization on both sides of your twisting assembly which requires a very secure connection to the H2. Any amount of wobble and the system breaks free, or breaks altogether. That’s where I’m stuck.

Another issue is finding the correct bushings for your design (especially the twisting housing) since plastic creates a lot of friction, binds, and breaks down pretty quickly with any real speed unless you grease the hell out of it.

I started looking at designing a “cup” (for lack of a better description) like a bicycle-mounted water bottle holder that you place the H2 down into. The only thing that would be plastic would be this main “cup” structure. It would allow for a click-in location for the twisting component to attach to the H2 and provide a very needed sliding rail on both sides to help with stability.

The gears, slide rails (which get inserted into the cup), and the entire sleeve holder assy should be metal imo to reduce as much noise, vibration, and friction as possible.

That all said, it’s a lot of work for a mechanical-driven twist action, which will likely only provide a quarter to 1 full turn up and down, even if you do everything right. That’s why I stepped away and I’m looking at using an electric motor. If I find the right motor and attach a sensor that reads a striped bar sticker slapped to the side of the H2 housing, it would make everything a lot easier and far better. You would no longer need anything attached to the handy except a sticker, no cup, no side rails, just internal gears on the sleeve holder. Then you could use a speed control to bump up just how much it spins on its trek up and down the H2.

If I figure it out, I’ll provide a parts list and any models for free.

If you stick to it and figure out a full mechanical system, you’ve got a lot more patience than me.

[Ta_7890]

I appreciate the response. I do have some ideas about that. One thought I had was creating an external case for the Handy that the gears attach to. Then, the planetary gear assembly could be added onto that. It seems like it would be much easier to model all of this out if I had the CAD skills to work through these problems one at a time.

Right now, though, so much of it is still conceptual that it’s difficult to think about factors like weight, momentum, or overall mechanical performance.

[Ta_7890]

Appreciate the response, man. That’s some really good insight.

I feel like with 3D printing, I could design it in a way that makes everything as secure as possible. For example, I could create the sleeve attachment so that when it clicks into place, it stays locked in even while rotating.

I’ve already printed a few planetary gears and tested the friction. I think there are a couple of ways around that issue. The first is using a better material than something like PLA. I prefer ASA, ABS, or even carbon fiber reinforced filaments since they’re much more durable and better suited for a project like this.

Honestly, I expected to run into a lot of problems along the way, but my plan has always been to tackle them one at a time as I prototype, model, print, test, and repeat until I eventually have a finished unit. The trickiest part for me right now is designing the gears. It’s hard to orient everything correctly unless you really know what you’re doing in CAD software.

As far as the twist action goes, it honestly doesn’t need to be extreme for me to be satisfied. Even a quarter inch or half an inch of movement would be enough. I think all those little details add up and contribute to the overall experience.

If you have any ideas for an electric motor that could work, I’d love to hear them. I could always design and 3D print a housing for it. My modeling skills are good enough for something like that. What I’m less certain about is how the motor would be controlled, since otherwise it would just spin continuously.

I really want to stick with this project, even though it’s pretty difficult from where I’m currently at. My next step is to use Claude to help create a baseline prototype in a CAD program so I can start visualizing everything. I’ll definitely let you know if I make any progress, and I’d love to keep bouncing ideas back and forth.

I’ve always felt that projects like this are difficult for one person to tackle alone, but if you had four or five people with different skill sets working together, it would actually be pretty straightforward to bring it to life.

So much of it is still conceptual at this stage that it’s hard to fully explain through text alone. Hopefully one day I’ll have something tangible to share with everyone. I just need a little help along the way.

Thanks again for your response. I really appreciate it!

[Kumon]

possibly with some further design, you could make it rotate in one direction only

[Kumon]

I have some experience with connecting AI to CAD and make a 3d model. if you want we can have a live chat this weekend on Discord where we can try to build the CAD model ready for printing, i got some time

[Ta_7890]

That would be awesome, just sent you a DM with my Discord account