Summary

Fully extended, this actuator is almost 3x longer than retracted. It prints in place as a single finished piece and internal mechanisms are not visible. Operate with 12mm allen wrench.

Print Settings

Printer Brand:

Creality

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p>Ender 3</p></div></p>                                                                                <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>Yes</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>I printed it with PLA using default cura settings except a raft and some abutment supports around the outside (using the "custom supports reborn" cura plugin).  You might want to tune your settings to reduce stringing.</p><p>Note which end is which -- the extension is on the raft/printer bed, which looks like multiple concentric hexagons and circles.  You operate the other end, on the top when printed.  This end exposes only one hexagonal hole (where you turn with an allen wrench) and one ring that separates the inner turning part from the outer body.</p><p>To break any stringing and get it to extend the first time, insert a 12mm allen wrench <em>deeply</em> to distribute the twist across more of the plastic.  I use the longer handle end, insert it all the way, then hit the other end of the allen wrench with a hammer.  One solid hit should do it.  Note: turn it CLOCKWISE to extend.  Yeah, sorry, its the opposite from what you expect.  If it bothers you too much, mirror the STL.  I'll get around to reversing it.</p><p>Once you have it extending and retracting, crank it all the way in and out a bunch to help wear off the rough edges.  Then lubricate while fully extended (I used vaseline).  Get the outside of the two extensions and try to get some deep into the screw mechanisms.  I used a long stick to get a gob deep into the works.</p></div>

How I Designed This

The basic mechanism is not my idea. There is a good explanation on youtube called "Mechanical Principles - Screw 2-Stage Telescopic Actuator". (This is my first posting on thingiverse and I haven't figured out how to add the link without it being the first thing shown on this "thing" page. I want you to see my thing first, not some other guy's cutaway model and explanation!)

I started with FreeCAD it was sooo impossibly slow. Eventually I gave up on FreeCAD and generated the STL directly in python. It needs more work before I share the code, but I figured I could at least share the actuator! I want to mount a motor to one end next. Stay tuned...

Telescoping actuator 9in to 24in, print-in-place