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I have made over 20 wood hand-cranked models for kids to play with. Before the virus, I would take them to several different community events, set them up on a 4×8 piece of plywood on sawhorses, and the kids would have a ball playing with them [often the adults had as much fun as the kids!].

I have about run out of ideas for new models to build, but some of my old engineering friends are always on the look-out for new ideas to send me. One of my friends ran across a computer simulation on Youtube and sent that to me to convert into a wood model.

Someone patented the basic crankshaft in the 1800s, so several guys came up with alternative designs to convert the reciprocating motion of a piston into rotary motion…....versus paying royalties to the crankshaft patent holder. The compute simulation was for one of these alternative concepts.

Most of these alternative crankshaft designs relied on a huge amount of inertia on the driven rotary output. Therefore it is not possible to build a wood model where you hand crank the reciprocating piston. However, you can drive the mechanism backwards and it should work.

I also had to change the bearing design for the reciprocating motion, so it would package into a reasonable size for a wood model. It took some trial & error, but I got a design figured out that worked.

Most of the model is red oak, including all but one of the gears. The spur gear that mates with the rack gear is yellowheart. The rack gear is red padauk. The main horizontal slide is maple. I added some red padauk and light maple inlays for decoration.

I made a YouTube video of the model in action…....


You can read about my trials & tribulations of building this model, and there were many, on my woodworking web site.


Thanks!

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· Premium Member
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Really Great! Love these kind of things and yours is: "Really Great!"
 

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Very well done! Nice write up on your webpage.

- Redoak49
Thanks. I try to document my process on my web pages. Once I while, I come back and build the item again,
so the web page is really helpful.
 

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Love it…

I try "similar engineering concepts" driven through SketchUp as well, but I have the luxury of a laser cutter for precision. Putting the great design aside, I admire hand cut efforts.
 

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Love it…

I try "similar engineering concepts" driven through SketchUp as well, but I have the luxury of a laser cutter for precision. Putting the great design aside, I admire hand cut efforts.

- LittleBlackDuck
It is time consuming, but I can cut pretty accurate wood gears using my scroll saw. I print out the pattern from Sketchup, drill the axle hole, then carefully cut out the gear. When I am done, I use a wet rag to remove the Elmer's glued on paper pattern excess….....and if in a hurry…I dry the wet gear a 120F in the oven for 15 minutes.

I use GearDXF program to generate the gear profile, then import into sketchup. For my gears, I use 20 degree pressure angle and a 7 diametral pitch. Most of my gears are made from red oak.

 

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FAIW, I use Matthias Wendel's Gear Generator... well worth the $26 if you make a lot of gears with various configurations… has a SketchUp dedicated load.
Sorry for the spruik… You are probably aware of it, however, others may not be.
 

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Very interesting and creative project.
 

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Impressive and cool. Nice work DaleMaley
 
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