Using a 4 inch mini circular saw blade, enlarge the Arbor hole to work with a grinder. That's it. Put the mini saw blade on a scrap block of wood and drill the arbor hole to whatever size your grinder takes. Mine is 7/8 inch.
Some are 5/8 inch.
Here's a link to where you can buy a mini saw blade:
Step 1: Safety Concerns
The RPM of a grinder is way faster than the RPM of a circular saw. Which means faster cutting than a typical mini-saw, but also, you've got to hang on tight because the thing because the kickback is going to be strong.
If you're worried about the RPM being too high, you can reduce the rpm using a router speed control.
Here's a link to a router speed controller that would work to slow the rpm of this grinder:
I'm gonna say though, my grinder is around 7-8 thousand RPM and the the wood cutting blade works fine without reducing the RPM.
This is NOT meant to replace a circular saw, but can be used in a pinch to cut easily through plywood or even 2X4's if you make a cut from the front and the back. Like any tool, there are things that it's good for and things that it's not so good for.