The linear projectThere are a number of "fucking machine" DIY plans out there, with varying degrees of thoughtfulness. There are several consumer products that achieve this, with varying degrees of quality. I think there is space for a RepRap-style distributed engineering project to tackle the design problems as they exist, with a goal of being affordable while offering more functionality than current designs. For example, the typical cam design does not replicate biology that well; very slow movement is (usually) not possible, and stroke length is mechanically fixed. This could be fixed with a slip disk and a linear actuator on the cam- but I don't think the answer is in adding complexity. My hunch is that the answer will be in lead or ballscrews- first finding a working design before tackling the possibly-bigger problem of making it quiet.
I hope to clean this page up, and update it with more and more sources for each section.
The project can be broken down as:
- Linear motion
- Variable stroke length- during use- as a requirement, at least between 1/2" and 4" stroke
- True positional design, where the device can constantly go to arbitrary displacements
- Speed must be able to be arbitrarily slow without stalling; fast enough to please everybody
- The quieter, the better
- Human-usable, stable, safe housing
- "The datum problem." If one part is moving, it has to be relative to the housing, which is not moving. Many cheap designs throw some crap suction cups on the bottom & call it a day; many expensive designs use heavy scaffolding and rely on a giant frame. Neither of these are good.
- The scaffolding, at least, generally allows the device to be placed at various angles; even if it is an Ikea project to remove from the closet each time.
- I've never seen a device that attaches to thighs; but this may be something to explore.
- It needs to be safe, with no user-accessable pinch points. Hismith "solving" this problem by putting a "YOUR FINGERS MAY BE CRUSHED HERE" sticker is hilarious and should be considered unacceptable in product design.
- I am second guessing my decision to use a bulleted list here, but we're in too deep now.
- Sensing and feedback
- The device should always know its current displacement
- A load cell or strain gauge axially in the stroke, to know how much force it's applying, would enable both safety features & some interesting software to be written
- Universal toy mounting
- The linear device needs to be able to accomodate a large as possible range of toys mounted to it- XLR connections? A proprietary vac-u-lock? Ugh. It needs a fabric interface to accomodate anything with a flared base, with the same performance as a vac-u-lock.
- It should be able to accommodate designs that need power for vibrating, heating and sensing; and other auxillary functionality like "cum tubes."
- User interface
- Since we connect everything to the internet now, I assume much of the UI design will be done within an app. Regardless of whether it's done in software or hardware, thought will need to be given to what variables the user controls, and how these are communicated.
- Sexual Alpha maintains a market review list of fucking machines
- The SafeworD/s Club article
- Machine Yourself has resoures on cam designs
- Qdot has a video teardown of a Fleshlight Launch, showing a leadscrew design.