I'm on the hunt for a reliable router sled to help me flatten my workpieces instead of shelling out cash for a planer. Also, quick question—does my workbench need to be perfectly level to achieve a flat board? Cheers!
3 Answers
You can build a router sled out of 3/4" plywood or melamine. I've wondered about the flatness issue too because I see folks using dimensional lumber as rails on their benches. Just keep in mind that the rails need to be flat and parallel, and the area your workpiece rests on should be well aligned too!
Your workbench doesn't have to be level, but it definitely needs to be flat! That's the key to getting a good result when flattening your boards.
There are two popular ways to make a router sled: one method uses straight MDF, while the other incorporates aluminum extrusions with linear bearings. It really depends on what you value most. Check out some build videos for both setups and do a quick cost analysis to see which will suit your needs better!

Thanks for clarifying! I figured flat was important, but good to know leveling isn’t as critical.