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Final Project


CNC Router Project

Task: Create something big.

First Project:

To become familiar with using the ShopBot router, I cutout a rocking horse from a 3/4" thick sheet of plywood.  The file was imported into Partworks as a 'dxf', toolpaths were applied, and the shapes were cutout using a 1/4" carbide cutter.  Once the drawing was nested in Partworks, circles were placed in the drawing to locate the placement of screws to hold down the sheet.  Two programs were created, a drill program for starting screw holes (1/4" diameter, .100" deep), and the program for to cut the profiles (1/4" diameter cutter, 4 passes)



The pieces were assembled without using any fasteners.  The shapes pressed into undersized holes or had cutouts for the pieces to fit together. 
 


The end result is a working model that only needs a pilot. 

Some issues encountered:
-A few holes were undersized too far, so a file was needed to enlarge them so the pieces would pass through.
-Cutting speed was too fast, chipping occurred on certain grain structures.
-The shape of the side pieces were copied in the drawing, when a mirror should have been used.  The plywood had a sanded side and un-sanded side, so the result was one side rougher than the other.





Second Project:

To setup for a composite project, I started designing a canoe.  Before jumping into cutting wood, models were created from paper and corrugated cardboard to test the design shape. 

The initial paper model fit together, but the true fitment wasn't derived from the model. 






Another design was created (added more facets to create a more sweeping curve), and a corrugated cardboard model was cut on the laser.  Assembling the pieces using scotch and duct tape didn't last very long, but did prove the shape better than regular paper.




The next step is to create sectioned pieces that will fit on a 4' x 8' sheet of plywood, and cut on the router.  Assembling the true scale pieces will utilize a butt joint, so the options to seal the joints/seams are being investigated.




UPDATE:

After making models, the full scale version was produced. Partworks was used to program the toolpaths, and the ShopBot was used to cut 3/8" thick plywood.  The side pieces of the canoe were cut down to lengths that fit on a 4x8' plywood sheet, and utilized a dovetail joint to aid in alignment when gluing them back together.  All the pieces fit on two full sheets of plywood.

  

Once the pieces were cutout, they were fit together using plastic cable ties.  To test the shapes, the short sections were tied together first.


The shape fit together nicely, and was taken apart so the side pieces could be joined together at the dovetail joints. 

The final shapes were assembled into a canoe shape. 


Next step is to create an epoxy fillet in the seams, and fiberglass it all together.  After the top rail is attached, the final test is to see if it floats (tough to test right now with 24" of ice).

Some hiccups in the road to produce this:
-The router lost position during the first cutout program.  The machine zero was not setup to the proximity sensors, so adjustments were needed.
-The first sheet was cut using 3 passes, the second sheet utilized 2 passes. Similar finish on both sets, the second took less time.
-Cutting out forms to fit inside the hull once cable tied together helped to hold the form. 
-Seat design is next on list.  Need to design comfortable seats that fit the space available.