I know, if you had a workbench, you wouldn't be building a workbench. Even so, you'll need some sort of work surface, even if it isn't as stable or capable as a proper bench. The traditional solution is to throw a hollow-core door over a couple of saw horses. The advantage of hollow core doors is that they're flat, stiff, and cheap. I used a folding table and a hollow core door I had bought for a future project.
So drill the benchdog holes through the MDF layer. Begin by laying out their positions. You'll want these to be precise, so that the distances between the holes are consistent. The vises you are using will constrain your benchdog spacing. My front vise worked most naturally with two rows of holes four inches apart, my end vise with two pairs of rows, with four inches between the rows and eight inches between the pairs. Because of this, I decided on a 4" by 4" pattern.
If the holes of the first jaw are in the proper position, drill holes in the same locations on the other jaw. I lined the drilled jaw on top of the undrilled jaw, clamped things down, and then drilled about 1/4" into the undrilled jaw, to mark the location. Then I removed the drilled jaw and drilled out the marked locations the same way I did the first.
We are especially proud of Post Woodworking’s Brunswick style shed. It has all the rugged features and simple, beautiful mystique of a Maine coastline. Natural-wood siding options, in pine or cedar, offer a rustic aesthetic. Or, choose a vinyl color that complements our home. Once inside the Brunswick, its unique, two-sided sloped roof maximizes headroom, making space for you to better maneuver a rake. Black architectural hinges and hardware lend distinguished contrast and quality to this basic but appealing storage solution.