Mortising Machines.pdf

Mortising Machines  There are 5 mortising machines o Common ones are  Hollow chisel mortiser  Chain mortiser  Slot mortise (oscillating bit) o Rarer ones are  Maka mortiser  Alternax mortiser o See power point for different mortise patterns  Hollow Chisel Mortiser o Old technology o Benchtop...

Mortising Machines  There are 5 mortising machines o Common ones are  Hollow chisel mortiser  Chain mortiser  Slot mortise (oscillating bit) o Rarer ones are  Maka mortiser  Alternax mortiser o See power point for different mortise patterns  Hollow Chisel Mortiser o Old technology o Benchtop top and floor models are available  Benchtop models need to be clamped/bolted down as they can easily tip  Benchtop models also require support for longer pieces o Uses a single flute auger bit spinning inside a hollow chisel  The auger wastes away most of the material and brings it out of the hole  The square chisel severs the wood fibers in the corners and pushes the wood waste into the auger bit for removal o Similar to a dress press but  Is direct drive  Single speed  Press arm is longer for leverage o Uses a keyed Jacob’s chuck to hold the auger bit o Does not leave a clean bottomed hole o Material should be held down firmly as the chisels often gets a little stuck o When setting up make to:  Insert chisel and auger into machine  Tighten chisel into collar first establishing a gap between the collar and the shoulder of the chisel  Bring the auger up into the chuck and tight to the bottom of the chisel  Tighten the auger into the chuck using all 3 holes  Loosen the chisel and bring it’s shoulder up tight to the collar  The gap between chisel and auger has now been established  Square the chisel to the work-piece  An unsquared chisel will leave a stepped cut  Exhaust port should be facing forwards or backwards  Set the depth of the cut required  Start with a shallow cut at one end of the mortise and then the other  Do not make the full depth cut yet  o o o Once the extremities of the mortise have been established, begin wasting away material in a pattern that always leaves an equal amount of pressure on the chisel sides (either all 4 sides or on 2 sides; pressure on 3 sides should be avoided)  Proceed to full depth cuts following the same pattern  Make sure that the center spur of the auger is fully retracted before moving to the next cut location  If not, the auger can be bent and the chisel may even get damaged The gap between the chisel and auger is important  Allows for the corner waste to be moved up  Prevents friction between the auger an chisel, which can cause overheating and loss of temper Hollow chisels are sharpened with conical diamond stones  Having sharp chisels is important, especially with hardwoods Bent augers and chisels should be discarded  Chain Mortiser o Uses a chain, like a chain saw, to create mortises o Very fast way to cut mortises o Different widths and thicknesses of chains are used to create different mortise sizes o High possibility of tear-out on the chain exit side of the mortise  A wood chip breaker is used to help prevent this  Can also use a knife ahead of time to sever the wood fibers on the exit shoulder o Single speed machines o Manually controlled with lever o Portable and floor models available  Portable models often used in timber framing  Slot Mortiser o Same machine we used to drill the holes for the commode door o Makes a series of cuts to get the desired depth o Most often used in chair industry o Usually used in conjunction with a slot tenoner  Tenon shape is difficult to achieve otherwise  Rounded ends with a flat bottom