I am making some simple spice racks to be mounted inside my cabinet doors. The parts have a lot of interlocking tabs and slots. To get my learn on, I designed it in Fusion 360 using parameters. I didn’t enter a single dimension onto the parts directly.
I thought I had dialed in the power/speed settings for the acrylic I am using, but some parts were not separating completely. Sometimes it would cut the acrylic but not the back protective sheet. So I slowed down the laser down. But that made the kerf a little bigger and the fit a little sloppier.
SIDETRACK #1 : Dialing in the settings
I have a couple test fit gauges for some materials to see how different kerfs work. Time to get serious! I took my setting spreadsheet and added a “code” column. I would give each material its own unique code to engrave onto the test fit gauge.
I am working with SA001. (S=Synthetic. A=Acrylic. ) which after some tests I found cuts best at 160/Full. I then made a Test Fit Octagon. Part one is a tab that is 10mm wide with power/speed settings printed on it . Part two is eight sided with slots cut into it, progressively smaller, .05 mm at a time. Each slot is printed with the kerf size; .025 mm bigger each slot. The code and thickness are also printed on it. They are connected together with a little chain.
That showed me that a good acrylic bond would be had with a .15 mm kerf. This rig also demonstrates how the cut isn’t perfectly 90 degrees. If you find a tight fit in one slot then flip the tab over it fits differently. For something super precise that might be important.
SIDETRACK #2: Will my parametric design work in a different material?
I made a second Test Fit Octagon™ out of Home Depot plywood. A tight fit kerf exceeded the original gauge so I made a second one.
A tight kerf here is .2 mm. So I entered the new thickness and kerf into my design and it worked!
BACK ON TRACK: Getting Back to Making Spice Racks
I am getting back to cutting some tight spice racks but I leave you with this tidbit. 100 ft of chain and a fist full of connectors can be found at www.ballchain.com for $25 (not a sponsor of this post)