This Instructable covers the steps involved to make your own Chladni plate resonance experiment at home or school. Many methods I've seen produce poor results and after trial and error we've found a reliable and simple set up that you'll enjoy making and testing out.
Step 1: How to Make a Chladni Plate at Home!
You'll need sturdy coned Mid Range speaker (We used a 10" Mid Range PA speaker that covered 45hz-4000hz)
5mm threaded bolt (enough to cut four 5-6" length rods out of and one longer rod that'll go from the cone to the chladni plate).
Approx 20 5mm nuts and washers
Either wood, metal or plexiglass for the chladni plate stabiliser. Cut a square that allows for rods to pass from speaker mounting holes through the corners of the square. (We cut a 10" x 10" square out of ply wood to match the size of the speaker"), you'll need to mark the centre point of this and drill a hole to allow you to fit a bush of some sort, it could be brass, plastic or metal or anything that'll allow for the rod to slide up and down smoothly whilst holding it stable. (we used a 5mm nut, drilled it through to about 6mm filed it smooth then tapped it into the centre of the plywood and held in place with some epoxy glue).
Sheet metal, We got some free off cuts from a local steel fabrication company, ours measured 10" x 10" and had a gauge of 0.9-1.0mm, (1.5mm is too thick ?..we used aluminium) .
Depending on the speaker you have you'll need something to be able to fix the main rod to and fix to the speaker cone, We used a strong plastic cap from a gallon of engine oil. Drill a 5mm hole and pass thread bolt through cap, fasten with nut and washer on either side of cap. (Make sure it's centered).
Now take the 4 lengths of rod, pass one through each of the mounting holes on the speaker at equal lengths so your stabiliser sits level once mounted, tighten rods in place using nut and washer on either side of the rod. Use thread lock on all nuts to prevent them coming loose with vibrations.
Once all 4 rods are in place run a nut and washer down each of the rods onto which the square stabiliser will rest.
Now before going further with the stabiliser, it's time to take your length of rod with the cap attached to it and bond it to the speaker cone, (we used aryldite rapid set epoxy). Make sure the cap is fully centered, mark it, check and double check its level and centered. Allow this to set until it's solid. (The centre of the cone on our speaker was a flat plastic which made it easier to centre and stabilise).
Back to stabiliser
Once you've drilled holes in the stabiliser that match the mounting holes and rods it's time to pass it over the center rod and rest it on the nuts and washers you've placed on the 4 smaller rods, LEVEL and fasten into place with nuts and washers from above. (Tighten both sides of stabiliser). You should now have a speaker, 4 rods in the mounting holes and the rod and cap connecting to the center of the cone that'll eventually have the chladni plate mounted to it passing through the center of the stabiliser.
Sheet Metal...take your square piece of sheet metal, mark the center and drill a 5mm hole. If your sheet is not smooth, sand it and paint it. Matt black is used a lot as it allows for good photos and distinguishes the sand/salt from the plate well. Run two 5mm nuts and a washer down the center rod (one will act as locking nut), keep enough thread on the top side of rod to allow for a nut and washer to fasten the plate in place from above. Position and tighten plate to rod.
You now have your own chladni plate experiment kit.
You'll need an amplifier that can cope with whatever speaker you're using.
You'll also require a tone generator (we just went to a tone generator website and used the laptop).
I'll add some pictures soon. Not taken many