by

In:In the Shop

Comments Off on Dovetail Joinery: Part 4- Chisel Work

Part 3 of this series wrapped up the saw work for the tail board.  Now there’s just a little chisel work to take care of before moving onto the pin board.  For smaller work, I like to lay the parts on my shooting board.  This gives me something to back the work against and also provides a sacrificial surface that can be gouged with a chisel on occasion.  Make sure the board is clear of debris before you start working or you may press something into the face of your board, denting it.  This is quite aggravating if you’re working on a drawer face or the outside of a box.  I can say “quite aggravating” now because I’m typing, but if this happens in the shop and potentially ruins an otherwise flawless piece of work… well, my grammar may be quite different.  The real issue here is at first the work surface may be clean, but as you start chiseling out the waste those bits of wood fall on the bench or shooting board.  Then without thinking, you flip the board over and start chiseling from the other side and one of those stray wood fragments gets embedded in your board.  So every time you move or flip the board, make a habit of clearing the debris.

A simple chisel set up

A simple chisel set up

When chiseling to the baseline, there’s a few things to keep in mind.  First of all, unless you’re really good with your fret or coping saw, you probably have a decent amount of waste to clear… maybe 1/16″ – 1/8″ of material for most people.  Typical advice is to remove half the waste at a time until there is such a small amount left that you can’t split it, then drop the chisel in the baseline and finish it off.  That’s actually a good method to use.  Chopping through too much waste at once drives this chisel back into the board, crushing wood fibers behind the chisel in the process.  If you drop right into the baseline and the chisel is driven back, you’ve just crushed good wood and you’ll be looking at an unsightly gap when the joint is assembled.  So don’t get greedy, take the 2-4 chops you may need to take and work your way back to the baseline.  Another important tip if you’ve never considered this is which way to pry the chisel.  If the chisel gets stuck in the board you need to pry it loose.  Not a big deal, but you need to push it away from the baseline.  Prying back against the baseline will again crush the wood fibers and carry the chisel across the baseline.

The chisel on the left is prying itself loose by pulling against the baseline... this is bad.  The middle picture is pushing away from the baseline... this is good.  You can see on the right now the chisel crossed the baseline.

The chisel on the left is prying itself loose by pulling against the baseline… this is bad. The chisel in the middle picture is pushing away from the baseline… this is good. You can see on the right how the chisel crossed the baseline.

As to the chopping process itself, I stand on the side of the board hold the chisel vertically (basically what is pictured above).  If you’re positioned in front of the board you can’t tell if the chisel is vertical or not.  If you have to, undercutting the joint is perfectly acceptable 90% of the time or better, at least in my opinion.  Chop about half way through the board, then flip it over and chop the remainder in from the other side.  This avoids blowing out fibers which is almost a given if you chop entirely through the joint.

The last bit of chopping, dropping the chisel right into the baseline.

The last bit of chopping, dropping the chisel right into the baseline.

Once the waste is chiseled out between the tails, clamp the board back in the vise and clean up the outside shoulders, then check everything for squareness.

Clean up the shoulder

Clean up the shoulder

When checking for square, the smaller the tool the better.  My square is a vintage Millers Falls model, but Starrett and Vesper Tools also offer nice squares similar to what’s shown.  Check your shoulders, baseline, and the cheeks of the tails.  Any humps in the baseline should be removed, with an undercut if need be.  The tails should never need squaring if you’re sawing correctly… but if they are out of square you have to fix it now or you’ll never have a tight joint.  If you can’t get a chisel between the tails to fix a skewed cheek you may be out of luck and need to start again.  The joint can still go together obviously, but you’ll be filling gaps for sure.  Again, with a little practice at sawing you should never need to adjust the tail cheeks, just the baseline.

Square Shoulder...

A square shoulder is your friend.

If the square can't touch the baseline at both sides there's a hump.  Go back and remove some more material.

If the square can’t touch the baseline at both sides there’s a hump.  Remove some more material.

Check the cheeks.  With a little practice these should always be square, right off the saw.

Check the cheeks. With a little practice these should always be square, right off the saw.

Next up we’ll be tackling the pin board.

-WMT

Tags: , , , , ,