Here is the concept drawing and description of operation from the book 507 Mechanical Movements:
131. On rotating the disk carrying the crank-pin working in the
slotted arm, reciprocating rectilinear motion is imparted to the
rack at the bottom by the vibration of the toothed sector.
When I first designed my model in Google Sketchup, I wanted it to be relatively big in size. When I went to print the paper patterns, it way too big. Fortunately, Google Sketchup lets you scale your drawing, so I scaled it to 1/2
scale. Here is the Sketchup design:
I also created an animation of the design to make sure everything worked ok
before I built it:
Here are photos of the model as I built it:
The black plastic square I bought from Rockler sure is handy making the bases of these models! Before I bought it, I would have to adjust the clamps by trial and error, using a metal square to check the 90 degree angle.
The vertical dimension from the yellow rack to the quarter gear is critical to smooth operation of the model. I checked the fit as I glued up the 2 bearing assemblies. I tried to use the 2 tapered block support method for the bearings to position them, like on the steam engine model, but there is not a big enough gap below the bearings to use them. Patience is a virtue building these models
And here is the finished model:
Here is a video of the model in action:
This was a fun model to design and build. The rack and quarter gear run smoothly on the finished model. The yellow dyed straight rack adds color, plus the red padauk quarter gear.