CORE OP­TIONS AND OPIN­IONS

The Family Handyman - - DIY ESSENTIALS -

The ma­te­ri­als used to make plywood’s in­ner core af­fect sev­eral im­por­tant char­ac­ter­is­tics: weight, strength, rigid­ity, sta­bil­ity, flatness, screw-hold­ing ca­pa­bil­ity, con­sis­tency of thick­ness, and even­ness of the ve­neer.

VE­NEER CORE is made up of many lay­ers of hard­wood bonded to­gether. The lay­ers are as­sem­bled with al­ter­nat­ing grain di­rec­tion, called cross­band­ing. This makes a strong, rigid, light­weight sheet with ex­cel­lent screwhold­ing ca­pa­bil­ity. Be­cause of these qual­i­ties, ve­neer core is my first choice in most cases.

PARTICLEBOARD CORE is the least ex­pen­sive op­tion. Like MDF core, it’s flat and sta­ble with con­sis­tent thick­ness. But particleboard core is a bit worse in the screwhold­ing cat­e­gory. Also, it’s a spe­cial-or­der prod­uct, at least from my lum­ber­yard, whereas MDF core is read­ily avail­able.

LUM­BER CORE con­sists of edge-glued strips of wood, usu­ally bass­wood. On both sides of the core, there’s a cross­banded ve­neer, then the face ve­neer. Like ve­neer core, it has ex­cel­lent screwhold­ing ca­pa­bil­ity, strength and rigid­ity. But it’s con­sid­er­ably more ex­pen­sive and harder to find than ve­neer core, so I al­most never use it. How­ever, it’s a good choice for long shelves.

MDF CORE has a few ad­van­tages over ve­neer core. The thick­ness is more con­sis­tent, and MDF gives a smooth, even sur­face for the face ve­neer. It’s also more sta­ble and it’s typ­i­cally flat­ter. How­ever, MDF core isn’t as strong as ve­neer core, it doesn’t hold fas­ten­ers as well and it’s heavy. But if I’m mak­ing one-piece doors, I’ll choose MDF core ev­ery time be­cause of its flatness and sta­bil­ity.

COM­BI­NA­TION CORE weds the best at­tributes of MDF core and ve­neer core. The cen­ter cores are cross­banded hard­wood, pro­vid­ing strength, light weight and screw-hold­ing ca­pa­bil­ity. The outer cores are MDF, giv­ing a flat, uni­form sur­face for the face ve­neers. How­ever, com­bi­na­tion core is a com­pro­mise: It doesn’t have the screw-hold­ing ca­pa­bil­ity and rigid­ity of ve­neer core, or the flatness and sta­bil­ity of MDF core.

BALTIC BIRCH AND APPLEPLY are top-notch ve­neer core ply­woods, which you’ll only find at a lum­ber­yard. Their 1/16-in.-thick core ve­neers of­fer bet­ter sta­bil­ity than typ­i­cal plywood with 1/8-in.-thick core ve­neers. The raw edge is at­trac­tive when fin­ished and of­ten used as a de­sign el­e­ment. Baltic birch or ApplePly is my first choice for draw­ers and shop jigs. ApplePly is avail­able in thick­nesses from 1/4 in. to 1-1/2 in., and in many face ve­neer species.

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