Introduction: Forearm Curl Bar

About: Hobbyists woodworker.

I created this forearm curl bar for a friend and workout fanatic. This device is a hand-shaped bar made from hard maple wood with a length of 550 cord to attach to a desired weight of your choice (dumbbells, plates, etc). Convenient and portable for a go anywhere workout.

Most users attempt to use the bar with their arms straight out, but it is more comfortable and effective when used with your arms to your sides and bent at the elbow. (details at the end)


- Notebook

- Straight edge or ruler

- Pencil

- Wood of choice

- Hand planes (#4, #5, #102, and rabbet block plane)

- 6" double square

- 24" ruler

- Tape measure

- Marking gauge

- Marking knife

- 6" center finder

- Auto awl

- Bracebit with 7/32 bit

- Panel saw, dovetail saw

- Lathe chisels (gauge, skew, and pairing)

- Lathe caliper

- Digital caliper

- Sanding block (medium and fine)

- Mineral spirits

- Lint-free rag

- 550 cord

- Polyurethane spray

- Eye protection

---Not Pictured---

- Lathe

- Table saw

- Chisel

- Lighter

Step 1: Draw Plans

For my design, I first thought about previous experiences with similar workout equipment. If the diameter of the bar is too small, you focus more on gripping the bar without actually exercising your forearm muscles. The same is true with a too large diameter handle.

I have found a good happy medium at 1.5" diameter for the bar.

I chose a length of 15" long to give the user some wiggle room with hand placement. Keep in mind that the hands should remain close to the center for maximum effectiveness.

The octagonal shape of the handles serves to provide extra grip during the workout.

The recessed area in the center of the bar was created to contain the rope so it does not interfere with grip on the handles.

Step 2: Choose Wood and Cut to Length

Select a piece of wood that you like. I chose hard maple for its strength and the fact that it will be used with heavy weights. Due to the decreased diameter of the center area of the bar, and the addition of a hole for the 550 cord, I needed a strong piece of wood.

I obtained my desired board, measured out a 15" piece and cut it down using a panel saw. I then took this piece over to the table saw.

Step 3: Dimension Wood

I ripped the maple to 1 5/8" on the table saw, then took it to the bench to plane two adjacent sides square.

Returned to table saw to rip the last side to 1 5/8".

I ripped it over 1.5" because I do not trust my table saw to be square. So I returned to the bench and used the marking gauge to mark 1.5" from each of the sides I squared up first and planed down to the lines, one at a time.

Checked to make sure all sides were square with each other with the double square.

Step 4: Marking

I took my small center finder and marked two adjacent corners on both ends to find the center of the piece in preparation for the lathe. Use the auto awl to make a center indentation.

I then marked the center of the length of wood to mark off 1.5" off either end to give me a 3" section to recess during turning.

Next I measured .5" from each side to split the width of each face in 3rds. To do this I just marked the tops and used a pencil and my fingers as a fence to carry the line through the length of the piece. The last picture shows all the markings I am trying to achieve.

Step 5: Octogonalizing and Lathe Prep

I mounted the wood on my tail vise and took my rabbet block plane to each corner. Plane down to the lines you just marked in the previous step, rotate 90 degrees and do it again. When you knock down all 4 corners reconnect the lines you made in the center of the piece that mark the 3" recess we will be making on the lathe next.

I also took the center finder again and marked with pencil one of the ends to kerf it with my crosscut saw. I used the crosscut because it leaves a bigger kerf than the rip saw. I also used a 7/32" bit and drilled in the center about 1/8" below the kerf lines. This is for mounting on the 4 prong drive center. (picture on the next step)

Step 6: Turning

This step, on the lathe, is not absolutely necessary but if you want to keep it under an hour it sure does help. The first forearm curl bar I made of walnut was hand carved with a few chisels.

The first picture shows what the kerfs I made before are used for. They give the lathe a place to bite the wood without trying to hammer the piece in on the lathe. (good way to ruin your bearings)

Eye protection is a must on this step!

Start by gouging out the bar between the lines you made in the center. Gouge just deep enough to round out that 3" section. A simple way to tell if you are round or not is to take the back of your chisel and feel for bumps, if you have any flat spots the chisel will bounce. Take your pairing chisel and pair right on the inside of the lines you made to go in deeper and gouge the bulk of the wood in the middle. This helps your gouge not go outside of your lines. When you get close to your final diameter take your dial calipers and set them to 1.15" and set your turning calipers to this width. Holding the calipers in one hand and the pairing chisel in the other (be very careful doing this, ask for help if you need it) drive your pairing chisel in at the shoulder line with the calipers on the cut line until they fall through. When the calipers slip through you know you have a 1.15" diameter. Repeat on the other shoulder line and then gouge out the remaining bulk of the wood. I used a skew chisel next to just slightly round over the shoulders to give it a softer feel on the hands. In the pictures you can see where I didn't go quite to the right shoulder line. I just used the pairing chisel again to take it down to 1.15" and rounded the shoulder edge again.

Step 7: Boring and Final Shaping

Take your ruler and find the center of the 3" recessed section. Use your auto awl and mark a spot for your drill bit. I always start with a few turns in the opposite direction just so my bit does not wander when I start to drill. Take your brace bit and drill a hole 7/32" down the center. I don't get too carried away with it so I just eyeballed it.

Next I took my dovetail saw and took the ends down by about 1/4 of an inch from each end. this is to get rid of the marks left by the lathe mounting process. Once this is complete I took my 102 block plane and knocked the corners down about a half inch from the end of each of the 8 sides on both ends. Now take a sharp chisel and start to carve away at the ends working towards the center to round out both end caps. (sharp chisel on hard maple is a must here, you are making a series of end grain cuts and do not want any tear out or crushed fibers)

Finally, sand the piece with your medium sanding block working on softening up all edges. I like to knock down those hard octagonal angles on the grips, the shoulders of the recessed area, and the ends of the piece. (not too much if, like me, you like the hand chiseled look) Take a fine sanding block and repeat the process.

Step 8: String It

I next took a line of 550 cord and stretched it out about a full arms-spread-out length. Cut it down and make a stopper knot on one end. (google it) String it through the hole you bored down the center. Getting a bit in the hole first then twisting the cord as you push it through will help you string it. Pull it all the way through and make a simple knot on the other side of the hole. At the opposite end of the line make a non-slip loop knot. (google it) Make sure you make the non-slip loop big enough for the forearm curl bar to slip through. (more to this on last step)

Finally, use a lighter to cauterize the ends for a no-fray workout experience.

Step 9: Finish

Now that you've sanded the piece down to your liking, wipe it down with a lint free cloth. I follow this step with just a tad bit of mineral spirits on the same rag (fresh side) and give it another quick wipe. Let the mineral spirits evaporate off before the next step.

Take your spray on polyurethane in one hand and your forearm curl bar by the string in the other and spray away. make sure to follow the instructions on the can for best results. I used 3 coats. Hang to dry and you are pretty much done. I used the handle of my grill to allow it to spin freely in the wind with no obstructions.

Step 10: Use

Most people who use these bars choose to do so with arms straight out. I just wanted to note on this last step why this may not be the best choice for beginners. Your delts (front part of your shoulders) are not as strong as your forearms and will tire sooner than your forearms while you are doing this exercise, causing you to sway about and break form before you get the weight all the way up. Alternately, use the bar at about hip height and do the exercise twice. Also, make sure to control the weight on the way down.

To use the non-slip loop to attach weights you just pull the string itself through that hole and put it over anything you can 'noose' in place. For plates or as my example here shows, water jugs. just put the loop through the hole and then thread the whole piece of wood through the non-slip knot.

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