Changed my mind about using a 2x4 as a straightedge for cutting plywood

I was building a workbench in my garage last week and grabbed a spare 2x4 to guide my circular saw, thinking it was 'good enough'. The cut ended up being off by almost 3/16 of an inch because the board had a slight bow I didn't see. What's a cheap but actually reliable method for getting a perfectly straight cut on a 4x8 sheet?

3 comments

3 Comments

avery3892mo ago

Honestly, just screw a factory plywood edge to your sheet.

avery3892mo ago

My old boss used a chalk line and a level clamped down for years on job sites. I mean, 3/16 of an inch is what, the thickness of a couple pennies? For a workbench leg, that's probably fine. I get wanting it perfect, but sometimes I feel like we overthink this stuff. A factory edge is smart, but even that can get beat up if you're not careful.

janaw119d ago

@avery389 I feel you on this one, seriously. I've definitely had those moments where I'm staring at a 1/8 inch gap on a workbench leg and just think "who the hell is gonna notice this besides me?" lol. My old shop teacher used to say "if you can't see it from a galloping horse, it's fine" and honestly that stuck with me. For a workbench especially, it's going to get knocked around and marked up anyway. I get wanting it to be perfect but sometimes we gotta pick our battles, you know? A little wobble can always be shimmed later and nobody's gonna die from a 3/16 difference.