Intro: Giant Baseball Bat
I always wanted a giant baseball bat similar to the one that was held by Babe Ruth in this photo.
I made it at Tech Shop!
I think that the one in the photo is about 6 feet long. Mine ended up being almost 8 feet long.
This is the Tech Shop Softball team warming up with the bat ;-)
Step 1: Vectric Cut-3D Software
The first thing that you need for this is a 3D model of a Bat. I could have drawn one, but I wanted to save some time -- I downloaded one from the free 3D models located at AutoDesk. After you have a 3D Model (or any shape), you need to pull the model into Cut-3D.
Use Cut-3D to slice the model into the size material that you have on hand.
I could have used ash, but the cost would have been about 4 times as much as the plywood -- this is for show -- it's not like someone is going to be able to swing the bat. It does make a great Halloween prop though...
These are some screen shots from Cut-3D.
Step 2: Use a ShopBot to Cut Out the Individual Pieces of the Bat
Start with two (2) 4x8 sheets of cabinet grade plywood. Rip them into 5 pieces that are 9.5" x 96 Inches.
Secure each piece to the ShopBot and run the rough-out pass CNC file, then run the finish pass CNC file. Depending on the size of the peice, each one of the 12 parts will take between 40 minutes and 2 hours to run.
Total CNC time is about 20 hours for all 12 parts. I ran them at 150 Inches Per Minute / 12000 RPM for both the rough and finish cuts.
The rough passes are cut with a 1/4" 2 flute end mill, and the finish passes are cut with a 1/4" 2 flute ball end mill. I didn't use an 1/8" ball end mill, because it would take way too much time, and I knew that it would be quicker to sand the bat once it was together.
I used Vectric's Cut 3-D software to make the layers for the bat. I used V-Carve Pro to cut the alignment pins.
Step 3: Some Close-ups / Video of the CNC Machining Process
Note that there are holes cut in the end of the bat. I used V-Carve Pro to make them. These will be used to align the parts with 3/8" dowel rods during the glue-up process.
Here's some video of the CNC cutting the finish pass for the bat:
If you look at the screenshot of Cut-3D, you'll see that this is the same part that has the three holes.
Step 4: Glue-Up Time
Dry-fit everything and cut the 3/8" dowels to the right length. Since the CNC router drilled the holes for the alignment pins, it makes it easy to put the bat together so that it fits perfectly.
Glue one half of the bat together using original Titebond glue.
Each time you glue a plywood layer, clamp it, then shoot about 15 - 1 3/8" brads into the layers.using an air powered brad nailer.
Let the glue in the 1st half of the bat dry over night.
After the glue bat is dry, the next day -- start assembling the upper half of the bat.
Note the glue bottle that is sold by Rockler Woodworking. It helps in applying the glue and spreading it quickly. The bat has about 24 oz of glue holding it together.
When you are done gluing up the layers, you'll need to clamp the ends of the layers where they taper. Let this dry over night.
Step 5: Unclamp and Sand the Tool Marks
Once the glue on the bat is dry, it's time to sand it smooth.
I used 60 grit sand paper on an orbital sander. It took about an hour.
After all of the tool marker are gone, you need to liberally use Elmer's wood filler to fill all of the imperfections between the plywood layers.
I put about 8 oz of wood filler on the bat and let it dry for an hour. I then sanded the bat smooth with 60 grit again.
Note the air shield that I am using. You don't want to breath the fine dust that the wood filler makes.
Since there are 12 layers of wood that make up the bat, you're looking at nearly 17 feet of seams per layer. That is nearly 140 feet of seams to fill. It is a lot of sanding -- approximately 2 hours worth.
Once all of the wood filler is sanded, check the bat for imperfections, and fill those found again.
Do a final sanding with a keen eye for inspection to make sure that all of the tool marks are gone and any "dings" have been filled.
At this point, all you need to do is to apply the finish to the bat. You have rounded the club house turn!
Step 6: Apply Two Coats of Polyurethane
Apply a coat of minwax pre-stain to the bat. This will help seal some of the pores in the wood and serves as a prep for the polyurethane. Let this dry for about an hour.
Apply a thin layer of polyurethane using a china bristle brush to the top half of the bat. Allow this to dry for 12 hours, then turn the bat over and do the bottom half. Let dry for another 12 hours.
Use 220 grit sand paper and hand sand the entire bat so that the second coat of polyurethane adheres well.
Take a lint free cloth and dip it in mineral spirits. Wipe off the dust that was created sanding with 220.
Apply the second coat of polyurethane in the same manner as above -- one half at a time.
Let dry over night.
Step 7: Admire!
Two coats of satin polyurethane looks great. I thought that I would need a 3rd, but this looked ok to me!
This project was fun to do.
I made it at tech shop.