Making a baseball bat is fun. It's a relatively straightforward woodturning project. As little leaguers graduate from aluminum and composite bats, it's good for them to hone their skills with a classic wood bat.
Step 1: Tools and supplies
The tools and supplies needed are
36" wood bat blank
fine Japanese saw
Step 2: Choosing the wood
The first thing to do is to find a good blank of either hard maple or northern ash. The rough size should be approximately 3" round and 36" long. The straighter and tighter the grain, the less chance it will break when you use it. Material that's been graded for making bats is much better than what you find at the local hardwood store. You can find a number of good sources online.
If you can't find a round blank, you can start with a blank that's square in cross section. Then chamfer the long edges in order to make it octagonal in cross-section
The blank should be about 3" longer than the final length to allow for waste at both ends
Step 3: Marking the center
The next step is to mark the center of the cylinder on both sides. You can use a center finder, if you have one. If not, a good trick is to use a square to inscribe a right angle inside the circle. Draw a line where the legs of the square intersect the circumference. That line goes through the center. Do the same thing again after rotating the square 90 degrees and the intersection of those two lines is the center.
At the center, use an awl to make a hole that the centers will fit into.
Step 4: Roughing out the blank
Mount the blank on the lathe. I use a live center at the tailstock and a steb center at the headstock. I mount the bat so the barrel will be closest to the headstock. I find it easier to turn this way and it seems to vibrate less but if you mount it with the barrel at the tailstock, most of th cuts are "downhill".
Turn the blank into a cylinder making sure it's at least 2.75" along it's length. I use a roughing gouge to do this as I'm more interested in balancing the piece than the surface finish. If you have a lathe that can adjust speed, 800 rpm is a good speed.
Step 5: Marking out the bat
I now mark out the bat by laying pencil lines every 3" on the blank, including the end of the handle and the barrel. Just hold a pencil up to the spinning blank and it will leave a clear line.
Step 6: Gauging the depth
Starting at the end of the barrel, I use a parting tool to make a small channel. I leave the diameter within this cut about 1/8" larger than the finished dimension. I usually cut to depth the first 3 or 4 of these marks starting from the barrel down.
If you're copying an existing bat, use the calipers to transfer the measurements. Set the calipers by measuring the existing bat. Add about 1/16" to the measurement to allow for cutting and sanding. Using a parting chisel, cut the blank until the caliper just barely slips through.
If you're working from a drawing, you can set and measure the calipers or use a dial caliper directly.
Step 7: Shaping the barrel
I use the roughing gouge again to remove most of the waste between the depth cuts. At this point, I usually turn the lathe up to 1200-1600 rpm. I try to keep a fair curve between the cuts by focusing on the back of the silhouette of the barrel. I then use a skew gouge to smooth the surface. While I'm mentioning the tools I like to use, other turning tools can work just as well.
I usually sand the barrel with 100 grit sandpaper (or whatever the surface finish calls for) before I move on to cutting the rest of the bat. This allows me to get a good surface before the bat gets too whippy on the lathe.
Step 8: Shaping the handle and knob
Continue using the parting tool to mark the appropriate depth of the cuts. Use the spindle gouge or the skew chisel to fair the curve between the channels cut with the parting gouge.
The shapes and sizes of knobs vary greatly and are a matter of personal preference --- they don't affect the performance.
Step 9: Supporting the center
The trickiest part of turning a bat is that down near the handle, a bat is relatively thin compared to its length. As you start cuttingtowards the handle, the bat will vibrate and cause the tool to bounce and make spiral chatter marks. The first thing to do is to make sure your tools are as sharp as possible. The second thing to do is to find a way to support the stock in the middle. The best and most convenient way for the experienced turner is to put your hand right behind the cut and support it. This may be a little daunting for the novice and you can use a store bought or shop built steady but I find support from behind to be the most versatile and effective way to prevent chatter marks.
Step 10: Sanding the bat
Depending on the surface quality and fairness of the curve, you'll need different amounts of sanding. If the surface is rough and the profile not perfectly smooth, you should start with 80 grit sandpaper. To help smooth out the shape and not make the imperfections worse, it's helpful to back up the sandpaper with a small piece of wood so you're not merely polishing the peaks and valleys.
If the surface is better, you can start sanding with 100 or 120 grit sandpaper. I usually sand in several steps up to 220 but have been cured of trying to sand it smoother by watching my kids throw the bats around and cover them with pine tar.
Step 11: Applying finish
I've found a mixture of oil and varnish to be the best finish. You can buy these types of finishes in the hardware store or make your own mixture. I usually put a few coats of finish on while the bat is still mounted on the lathe. I load a rag up with the mixture and hold it up to the spinning bat.
Step 12: Trimming the ends
I use the skew chisel held vertically to make super clean cuts on the end grain. I hone my skew just before making these cuts. If you're using a gouge or a scarping tool, be careful here because cleaning up the marks left in the end grain is almost impossible. Then I clear some room with a parting chisel and leave a shoulder for the saw to ride on.
I cut the protrusion at the top of the barrel to about an inch across (I'm going to make a hollow at that end of the bat) and cut the end at the handle to about 1/4" (to leave as little as possible that I have to sand).
Then I remove the bat from the lathe and use a small Japanese saw to trim off the little nubs and sand the ends
Step 13: Hollowing the end
Most bats these days have a small hollow in the end but it's definitely optional. You can just leave the end slightly convex and sand it when you take it off the lathe.
Because I've made enough of these I've built a jig to hold the bats upright while I rout a hollow at the end. I use a 1/2 spiral upcut bit and guide the router with a template bushing. And then follow that cut with a 1.25 inch round nose bit following a circle template set atop the end of the bat.
Some of the commercial bats I've looked at seem to do this step with a drill
Step 14: Engraving the bat
If you have access to a laser cutter, you can really make the bat look special. I mount it on a rotary device on the laser cutter and cut whatever the player wants on it. Before engaving, I cover the area to be cut with blue masking tape as it makes for a cleaner cut.
If you don't have access to a laser cutter, you can use a wood burner or you can paint logos and names on the bat.
Labels are traditionally applied to the face grain of the bat and the player knows not to hit it on the label (or 180 degrees opposite). This would be a good one for Mythbusters to see if it goes further or breaks more often in one direction than the other.
Step 15: Finishing the bat
The last step is to apply more finish. I generally wet sand the finish at this point with 400 grit sandpaper and do as many coats as my patience or kids allow before one of them wants to take it out and hit with it.