Do the thread spread for even glue distribution
Flooring installers know the importance of putting down a consistent layer of adhesive or thin-set mortar, and achieve that by using notched trowels. Similarly, you can get consistent glue layers on wood surfaces by using a coarse-threaded bolt. Here’s how to make a spreader like the one in the photo. First, use a hacksaw to cut off the head of a coarse-threaded ⅜" bolt. Then, saw or rout a half-round or v-shaped groove about 3/16" deep on one end of a piece of ¾"-thick wood as large as any scraper or putty-knife handle in your tool box. Trace the outline of that handle onto the wood (with the groove at its wide end) and cut the wood to shape. For a comfortable grip, rout ¼" round-overs on the handle’s edges. Apply three coats of polyurethane to the handle. Next, epoxy the threaded portion of the bolt into the groove. That’s it.
Now, use your new tool to evenly spread glue. Afterwards, wash off the glue using water – the poly finish will protect the wood.