problems with motise holes
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Hello everyone. I’ve been having troubles with my mortise holes. I’ve added some pictures that hopefully help. I’ve cut around a dozen or some mortise holes now, not many I know, but I keep having the same problem which is having ridges on each side of the hole. Hopefully the pictures can help explain that a little better. Every hole I’ve chopped is the exact same. I’m not sure what I’m doing wrong. I’ve made sure to reference off the same face, I’ve measured numerous times to make sure things are lining up. I’m doing something that I’m not supposed to be doing but I don’t what it is!! Please ask if there’s any more details needed.
Thank you all in advance for the help. I’m new that this so I can’t offer much back but hopefully day I will.
Bob
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You must be logged in to view attached files.26 March 2015 at 1:34 am #125917Are you saying that the mortises aren’t meeting in the middle? If so, have you tried using the training jig that Paul demonstrated? When you first start chopping mortises and are standing to the side, like Paul does when chopping in the vise, there is a natural tendency to lean the chisel to one side. When chopping a mortise from both sides this error is magnified by two due to the flipping of the work piece. Build yourself the training jig and use it for a while. You will soon be able to feel when you are square and plum and won’t need the jig anymore.
When you use the jig, make sure that it is square to your workpiece, especially if you have a cheap vice like me. When you tighten the vice it could tighten the bottom of the vice more than the top, leaving you with a jig thats leaning slightly back, so just check that with a known square edge before you actually chop.
It appears as though you might be leaning the chisel and that is what is chewing uo the sides. You may get everything lined up, but when you swing the mallet/ hammer your body shifts and you need to control the both arms for two different tasks. Take small bites, and sharpen up for clean cuts. Make the jig as above,(i didnt but I’m stubborn… Lol)
26 March 2015 at 8:56 pm #125947Bob, I used the jig mentioned above on my most recent project and they came out very nice. But I want to make sure you’re doing one other thing properly. After chopping the mortise on one side of the board roughly half way through the board, are you referencing on the same side when cutting the other side? I’m not sure if I’m being clear. If not, let me know and I’ll expound.
On another matter, I notice that the ends of your mortise are not perfect. When making your first chisel chop on or near your knife line, go VERY, VERY gently. You can chop a little harder as you move away from the knife line. After you’ve removed a little material, it will be safer to chop a little harder at the knife line. With soft wood, it is tough not to damage the end of the mortise.
26 March 2015 at 11:26 pm #125952Hi bobcoz,
I would guess the chisel is twisting a bit to either side, causing roughness at the mortise sides. Regular bevel edge chisels are somewhat thin at the sides and require that you keep them perpendicular to the mortise length by hand. Don’t let it do the twisting by restraining with your hand, keeping it in position.
Also, if the chisel is not kept exactly in the same position (perpendicular to the sides and parallel to the ends of the mortise) the mortise hole will not have a uniform width.
Mortise chisels have a larger flat side and tend to do that less.
Got an update…..made the mortise jig and things really improved!! As was said by many I wasn’t holding the chisel perpendicular. The jig really helped. Still have a LOT of practice to do to get them perfect but I think I can finish my workbench now!!
Thanks again for the help, I’m glad there’s a site with people willing to help out.
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