Lee Valley & Veritas Woodworking
Lee Valley 35 Years  
  Volume 7, Issue 5 - May 2013    
A Quick and Easy Board Jack
This board jack works with a tail vise or clamped to one leg of your bench. It uses an upright pipe with a moving jaw from a pipe-clamp set to allow for fine adjustment. Two blocks of wood hold the pipe in place.

What You Need
  • A 3/4" wrought-iron pipe with a length slightly less than the height of your bench
  • The sliding jaw of a 3/4" pipe clamp
  • A bench fitted with a tail vise, or a clamp with a capacity slightly greater than the width of your bench leg plus 4-1/2"
  • Two blocks of 2x6 structural lumber, each 4-1/2" long
  • A power drill with a 1-1/8" spade bit
  • An adjustable square and a pencil
  • Masking tape
Mark the base block   The Base Block
The base block requires a hole bored partway through to make a cup that supports the pipe. The cup should be positioned near the middle of one edge. To start, mark a corner-to-corner cross on one of the pieces of wood to find its center. Use your square and pencil to draw a line through the center of the cross in the direction of the grain.
Use a square to further mark the base block   Adjust your square to 7/16". Use the end to draw a line at right angles to the center line, 7/16" in from one long edge.
Use your bit to make a mark through the center line   Place one side of the widest part of your spade bit against this edge line. On the other side of the bit, make a mark that crosses through the center line.
Use the point of the bit as an awl to mark the top for drilling   With your spade bit still positioned between the edge line and the newly made mark, pull the bit back until its point touches the center line. Raise the shank end of the bit 90° and use the point as an awl to mark the top for drilling.
Make a depth gauge on the bit   To ensure that you don't drill through completely, make a depth gauge on the bit. Hold it against the edge of the block as though the point were just poking through and mark it with masking tape.
Drill through   Chuck the bit into your drill and clamp the block to a piece of scrap wood. Drill through until the masking tape meets the top of the wood. Unclamp and check to see that you have a point hole on the far side.
Mark the top block   Top Block
The top block has a through-hole in the same position as the base cup. Clamp the base block, cup upwards, on top of the top block with the edges squared. Remove the drill bit from the chuck and use it as an awl through the point-hole to transfer the position of the center hole.
Clamp the top block onto a piece of scrap wood   Unclamp the two blocks. Now clamp the top block onto a piece of scrap wood and drill through until your masking tape depth gauge shows the point is just through the wood.
Drill through to complete the hole   Turn over the top block and re-clamp it to your scrap wood. Drill through from the other side to complete the hole.

If you are making the clamp version, the top is done. If you are making the tail-vise version, you may need to adjust the top block to fit the vise. Grip the top block in the tail vise, flush to the top of the bench with the hole running through it vertically and in from the side of the bench. Any part of the block that protrudes from the side of the bench is waste that you'll need to saw off.
Mark the waste and saw off marked side   Use the edge of your bench to mark the waste and use your adjustable square to mark the line all around the block. Saw off the marked side.
Placing the bench slave with a clamp   Placing the Board Jack With a Clamp
Before starting, have a rough idea of how low the supporting pipe-clamp jaw should be to hold your work. It can be adjusted more accurately later. Place the base block on the floor at the other end of the bench from the front vise. Put it right against the leg with the offset cup hole nearest the front of the bench. Ensure your clamp is within easy reach. Seat one end of the pipe into the cup in the base block. Slide the top block onto the pipe with the hole towards the front as on the base block. Slide the moving pipe-clamp jaw onto the pipe above the top block, placing it roughly where it needs to go. Clamp the top block to the leg.
Placing the bench slave with a tail vise   Placing the Board Jack With a Tail Vise
Place the base block on the floor under the tail vise with the offset-hole side toward the front. Seat one end of the pipe into the cup in the base block. Slide the moving pipe-clamp jaw onto the pipe and slide the top block onto the pipe. Clamp the top block in the tail-vise jaws.
Using the Board Jack
With one end of your work held firmly, but not too tightly, in your front vise, the other end can be supported and adjusted for level by moving the sliding jaw of your board jack up or down before you tighten the front vise.
Completed board jack in use
Text and photos by David Randall

A native of Colchester, England, David Randall was a member of the non-profit organization Remap, designing custom equipment for people with disabilities. In 2010, he moved to his wife Christine's hometown of Seattle, Washington. David brought his hand tools, but gave away most of his power tools before moving because of the differences in voltage and frequency. Other than a very useful drill/driver, he hasn't replaced them. He is, of course, always buying more hand tools.
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