Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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- Aug 20, 2004
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Flatgrinder requested some info on mortising.I wrote this up and thought I would post it as well for others.
To mortise any handle material (Micarta is one of the easiest), this is how I do it.
I take the scales and the finished blade and decide what shape I want the handle to be.I draw that on the top and lay the blade on it to see if everything looks about right.If it is OK I tape the scales together and drill them for the Corby rivets.Do one hole first,put in the rivet,then the second,put in the rivet,then any other rivet holes you want.Now the scales are bolted together with a profile drawn on one side.I again check to see if I like the profile ,and if it is OK I saw it out on the band saw (the scales assembly stays bolted together).I do a bit of rough shaping on the profile, and shape, finish, and polish the front where the blade will be (you can't sand and polish this area after assembly!).All this time the sides are still flat.Take the scales apart and stick the female bolts in one side.Put the blade on them and draw around the tang (you should have already drilled the bolt holes before HT). Do the same for the other scale (using the female bolts again).Now you can take a dremel tool with a router bit or a flat wheel bit,and lower the mortise 1/2 the tang thickness.At the end where the blade enters the handle,don't take it down all the way,leave a little to remove for fitting .The main inletted area can be a little over 1/2 tang thickness,to make sure there is no binding .The other way to mortise is to use the milling machine or a drill press.Chuck in a straight router bit or cylinder burr and set the height to remove slightly less than 1/2 tang thickness. Freehand cut the mortise.Then while in the center of the mortise slightly lower the bit to take a little more out of everywhere but the edge where the blade enters the handle.Once mortised by either method, put them together on the tang,They should not quite come together at the ricasso.Take a small file and slowly lower the lip until it exactly fits the blade and the scales just touch together.Give it one stroke more with the file to make its not too tight a fit.Now you can bolt the handle on and check again.If it is OK, disassemble, glue it up with a good grade resin or epoxy,let it dry well,and sand the handle to finish. Remember to wipe off the squeeze out resin at the blade and polished end when the handle is drying (check it several times,as the resin will continue to squeeze out as it cures). It is a lot easier to do then ,then when hard! Use a little acetone to clean every bit off this area before it is cured.
You don't have to mortise both scales if you don't want to.You can take it all out of one scale if the blade is completely flat at the ricasso.Remember to grind the extra thickness off the unmortised scale when sanding to the finished shape,and it will look fine.The joint line will be at the side of the blade,not down the center,but that is not an issue on most user knives.Properly done,the joint is nearly invisible,anyway.
I'll attach some pictures of a batch of Japanese chef's knives I have working ( the top two are a set for an ambedexterous Japanese Chef,one cuts left and the other right),and a pic of a western chef's knife that has the handle ready to go on as soon as the HT is done.You can see that I have done the handle scales for this full tang knife the same way I told you about doing a mortised tang.It makes the problems at fit-up much less.I know the scales fit,the rivets line up,the blade looks right on the handle, - in short,everything but the glue joint and final shaping is ready to go!
A note about Corby rivets (actually,Corby bolts). - There is not a stronger way to join two pieces of wood.Buying them in dozens (or by the gross) makes them quite reasonable. You will never have a scale lift up off the tang if done with Corby rivets.You can add a mosaic rivet between the Corbys , for a fancy embellishment ,if you like.They come in brass,nickle, and stainless.Available in several sizes,too.
Hope this helps.
Stacy
To mortise any handle material (Micarta is one of the easiest), this is how I do it.
I take the scales and the finished blade and decide what shape I want the handle to be.I draw that on the top and lay the blade on it to see if everything looks about right.If it is OK I tape the scales together and drill them for the Corby rivets.Do one hole first,put in the rivet,then the second,put in the rivet,then any other rivet holes you want.Now the scales are bolted together with a profile drawn on one side.I again check to see if I like the profile ,and if it is OK I saw it out on the band saw (the scales assembly stays bolted together).I do a bit of rough shaping on the profile, and shape, finish, and polish the front where the blade will be (you can't sand and polish this area after assembly!).All this time the sides are still flat.Take the scales apart and stick the female bolts in one side.Put the blade on them and draw around the tang (you should have already drilled the bolt holes before HT). Do the same for the other scale (using the female bolts again).Now you can take a dremel tool with a router bit or a flat wheel bit,and lower the mortise 1/2 the tang thickness.At the end where the blade enters the handle,don't take it down all the way,leave a little to remove for fitting .The main inletted area can be a little over 1/2 tang thickness,to make sure there is no binding .The other way to mortise is to use the milling machine or a drill press.Chuck in a straight router bit or cylinder burr and set the height to remove slightly less than 1/2 tang thickness. Freehand cut the mortise.Then while in the center of the mortise slightly lower the bit to take a little more out of everywhere but the edge where the blade enters the handle.Once mortised by either method, put them together on the tang,They should not quite come together at the ricasso.Take a small file and slowly lower the lip until it exactly fits the blade and the scales just touch together.Give it one stroke more with the file to make its not too tight a fit.Now you can bolt the handle on and check again.If it is OK, disassemble, glue it up with a good grade resin or epoxy,let it dry well,and sand the handle to finish. Remember to wipe off the squeeze out resin at the blade and polished end when the handle is drying (check it several times,as the resin will continue to squeeze out as it cures). It is a lot easier to do then ,then when hard! Use a little acetone to clean every bit off this area before it is cured.
You don't have to mortise both scales if you don't want to.You can take it all out of one scale if the blade is completely flat at the ricasso.Remember to grind the extra thickness off the unmortised scale when sanding to the finished shape,and it will look fine.The joint line will be at the side of the blade,not down the center,but that is not an issue on most user knives.Properly done,the joint is nearly invisible,anyway.
I'll attach some pictures of a batch of Japanese chef's knives I have working ( the top two are a set for an ambedexterous Japanese Chef,one cuts left and the other right),and a pic of a western chef's knife that has the handle ready to go on as soon as the HT is done.You can see that I have done the handle scales for this full tang knife the same way I told you about doing a mortised tang.It makes the problems at fit-up much less.I know the scales fit,the rivets line up,the blade looks right on the handle, - in short,everything but the glue joint and final shaping is ready to go!
A note about Corby rivets (actually,Corby bolts). - There is not a stronger way to join two pieces of wood.Buying them in dozens (or by the gross) makes them quite reasonable. You will never have a scale lift up off the tang if done with Corby rivets.You can add a mosaic rivet between the Corbys , for a fancy embellishment ,if you like.They come in brass,nickle, and stainless.Available in several sizes,too.
Hope this helps.
Stacy