Summary

This is a demonstrator of a rack-and-pinion gear mechanism. The 20 pinion gear teeth have an involute profile, while the 15 rack teeth have a flat trapezoidal profile. Both have a module of 2mm.

This builds on an earlier gear demonstrator of mine which investigated the involute tooth profile.

The holes in the base a meant to accomodate a #8 screw for mounting.

Print Settings

Printer:

Wanhao Duplicator i3

                                            <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.2mm</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>%20</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>Print with a low bed heat (or none) to avoid any <a rel="nofollow" href="http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#elephant">elephant's foot</a>, which will cause mechanical interference between the gear teeth and make additional post processing necessary.</p></div>

Post-Printing

This model is designed to be assembled using three M3x5mm Threaded Inserts, inserted into the slightly undersized holes using a soldering iron. (Matterhackers has a good guide to this method). The pinion is held by a small (~8mm x m3) machine screw. The rack is guided by two screws of the same type.

How I Designed This

The Involute profile was hand-modelled in Fusion 360 using an approximation method. The rack dimensions were calculated using the equations in Part 3 of This Page. and verified with the Rack and Pinion Calculator from Otvinta.

Rack And Pinion