Is this a good way to grind beans for espresso?
If you're trying to actually make espresso in an espresso machine, a blade grinder won't do it, regardless of your method. It's simply too inconsistent. You'll get some small bits, some big bits and some dust. 

Espresso needs to be ground fine - more fine than drip or French press or cold brew. You need a purpose-built grinder for this. You might get away with a high-quality burr grinder but for really great quality espresso, you need a specialty grinder. 

Now, if you're just using espresso beans in your normal coffee maker, that's not espresso but your grind doesn't need to be as fine. 

Info about grind taken from here and there's a lot more in-depth there, too.