The next toy I built from David Wakefield's book, was the Cross Crocodile.  The basic design is almost identical to the Hungry Hippo.

Wood

I had some more of the Brazilian Cherry to use up, so I used this wood for this model also.

Google Sketchup

I entered the patterns into Sketchup.

This Sketchup view shows how this toy works, with the 3/8" diameter dowel in each of the front wheels to raise the mouth.

Compound Scroll Sawing the Main Crocodile Body

This design borrows a standard technique used in the scroll sawing world, called compound scroll sawing.

You put a pattern on 2 sides of the wood block, then saw out side #1 and then side #2. You may have to tape the waste pieces from side #1 back in place to provide support for the 2nd cut.

I usually make 2 paper patterns and glue them onto the wood block.  Since I may make more of these someday, I made plywood patterns and penciled the pattern on the 2 sides.

I used the band saw with 1/8" wide blade to cut out the crocodile body.








Rotating Mouth Assembly

I used a fixture, as recommended by David Wakefield, to locate the pieces that make up the rotating mouth assembly.

I sanded off all the wood burn marks from band sawing. I had to use the Dremel drum sander and hand file to get at some places.

Error in the Book Pattern

I have been doing woodworking on and off again for almost 40 years. By now, I should assume any pattern will have some errors.

After I completed the rotating mouth assembly, I assembled up the whole crocodile before final glue-up.  One big problem arose, the mouth of the crocodile would not close!!!

I finally went back to my Google Sketchup model and tried rotating the mouth assembly, and I found it would not close either!!   An my Sketchup model matches the book pattern exactly.


The little piece that connects the two sides of the mouth, has the wrong geometry on the left hand side shown above.  It is too big, and won't allow the mouth to close.  Since I already had the 3 piece mouth assembly glued up, I used the Dremel 1/2" diameter drum sander and hand file to remove material from the little cross piece.  Once I reduced the size of the cross-piece so the mouth would close, then it would open and close properly using the 3/8" diameter short dowel in the wheel.

I am a little disappointed in Wakefield's design, in that the mouth doesn't open further.  It would take me a while to figure out how to change the original design, so I did not pursue it further at this time.  The higher the mouth  opens, the bigger the sound affect when it closes.

If you are going to build this model, send me an email, and I will send you the correct design for the little piece.  Or you could not glue up the 3 pieces that make up the rotating mouth, hold them with a clamp, and assemble it to the body. Using your eyeball, you can keep removing material until the mouth fully closes. After you have the correct geometry on the little piece, then glue up the 3 piece assembly.

Finished Cross Crocodile

I applied mineral oil to the finished crocodile.

You really have to see the model in action, to see how much fun it is to play with......so I made a Youtube video.

Closing Thoughts

I guess I re-learned the lesson that one should assume any pattern has some errors in it.  It is tough to get every drawing detail right, and then get it printed correctly on a pattern.  My Sketchup model did  not initially find the error, because I did not check rotation of the mouth assembly (this is a manual operation and takes a little work to do).

This should make a fun toy for the grand-children

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