Knurling, what’s that? A slang word from the 80’s? Knurling, dude! …..not quite.
Knurling is a criss-cross pattern commonly added to handles. But how do you do that? Well there’s a special tool and method…but you don’t need all that. Here’s how to add knurling to the handle of your own props using EVA foam!
First of you’ll need the following:
- EVA foam flooring
- 2-3mm EVA craft foam
- Barge Cement
- X-acto blade
- Ruler (it helps to have an square ruler too)
- Wooden Dowel
- Heat Gun
First step, you’ll need a foam cylinder with internal support. To make that, jump on over to my previous tutorial on adding internal support to foam props.
Once you’ve got the base to your handle, it’s time to grab that thinner 3mm craft foam. Any color works, but I like white as it’s much easier to see your lines. Also you’ll need a long ruler, for this 10″ handle demo piece a 24″ ruler was plenty long. You’ll need to first figure out the circumference of your handle. To find that, take a small straight piece of the 3mm foam and wrap it around the handle, use a pen to mark it. Unwrap the strip and cut on the line you marked. Now you have the circumference. Now divide that by 4, or however many diamond shapes you want going around your handle, here I need 4 as I am dividing by 4.
The number that you just got is going to be the with of your diamond, and by diamond I mean a sideways square. The next step is a little easier to show in a picture rather than explain. You’ll need to find the dimension of the diamond/square, and then create a grid that’s 4 squares high and X squares wide, (around 20″ long for this demo). For the piece shown here, I made a grid of squares that measure 7/8″ by 7/8″, I used a long metal ruler and 90 degree ruler to line them up and draw out the grid.
Once this was done I carefully cut it out using the metal ruler as a straight edge when cutting. Then I trimmed the end at a 45 degree angle like shown in the image. Before I glued anything I test fit it, wrapping it around like shown at the 45 degree angle. What’s important is that there is no excess or puckering where the edges meet. When lining it up make sure the corners/tips of the diamond are lined up, like in the picture shown with a red mark. It may also help to draw a guide line along the foam shaft to help when wrapping and gluing. It may be a good idea to wrap it with out glue a couple of times so that you get a feel for lining it up.
Apply your barge to both sides and let set till tacky. Taking your wrap and slowly lining up the corner and edge of the wrap, slowly twist it around. making sure not to pull or stretch the foam as it will warp it and no longer line up properly. Once it’s all gently wrapped around, then go back and press firmly making sure that there is good adhesion.
Now you’ll need your X-acto knife, make sure it’s sharp, you may need to sharpen it a couple times during this next step. Starting at one side, slowly cut along the line around the handle, twisting as you’re going, then repeat for the next line, and so on. Don’t go too deep, just through the 3mm layer of foam. You don’t need to do this for the seam, it’s all ready cut. After all the lines are cut get your heat gun and on the low setting go over the handle. Don’t stay in one area for too long or it will burn the 3mm craft foam. I like to start at one side and slowely spin the handle, working my way down. The lines you just cut will pop open and create the knurling effect. You can always go over with the heat gun again if you want them to pop open a little more. A word of caution though, if you stay too long in an area, the tips will curl up, you can fix this by removing the heat gun and quickly rolling the handle on a flat surface to press them back down. If you use your hand, then you will get finger prints and an uneven look.
Congratulations, you’ve created a knurled foam handle! Don’t fret if you took you a couple of tries, even I screw up the first time I tried it.
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