wleingang Posted October 1, 2010 Report Share Posted October 1, 2010 Hi guys. I just picked up a JBM-5 Mortiser. It has a couple of burn marks near the end of the 1/2" chisel that's on there probably from getting really hot down in a mortise from the previous owner. I set it up and plunged into a pine 2x3 I had laying around. After plunging about an inch I noticed it would bind up and stall the machine. I'd have to turn it off, clean out the blazing hot chisel and then it would be fine again. Question, is this because I was mortising really soft wood? Or should I be concerned about the chisel? I haven't read anywhere that these things jam so easily. Just curious since I've never used one before. Thanks! Will Quote Link to comment Share on other sites More sharing options...
Lawrence Brown Posted October 1, 2010 Report Share Posted October 1, 2010 You probably need to throw away that chisel and get a new one. Looks like the temper is completely gone on that one, and I'll bet it's got hardly any edge left at all. You need really sharp edges on mortisers to work properly. You don't show the end of the bit, but I'm sure that's gone, too. You can try sharpening them, but I think you'd be better off by just getting a new one. We're there other sizes included that look to be in better condition that you could try Quote Link to comment Share on other sites More sharing options...
wleingang Posted October 1, 2010 Author Report Share Posted October 1, 2010 Yeah there are a couple of brand new ones (3/8" and 1/4"). The chisel pictured feels razor sharp but you're confirming my suspicions. I will try to install the others and try those. Quote Link to comment Share on other sites More sharing options...
mdbuilder Posted October 2, 2010 Report Share Posted October 2, 2010 You also need to make sure there is a little extra extension of the drill past the end of the chisel, about the thickness of a dime. Quote Link to comment Share on other sites More sharing options...
dryhter Posted October 3, 2010 Report Share Posted October 3, 2010 Hi guys. I just picked up a JBM-5 Mortiser. It has a couple of burn marks near the end of the 1/2" chisel that's on there probably from getting really hot down in a mortise from the previous owner. I set it up and plunged into a pine 2x3 I had laying around. After plunging about an inch I noticed it would bind up and stall the machine. I'd have to turn it off, clean out the blazing hot chisel and then it would be fine again. Question, is this because I was mortising really soft wood? Or should I be concerned about the chisel? I haven't read anywhere that these things jam so easily. Just curious since I've never used one Thanks! Will Bench top mortisers just aren't really up yo the task of cutting mortises, or at least a lot of mortises. These machines should probably be called mortise cleaner-outers and really that is the hard part about cutting mortises and they do this job pretty good. Drill out as much of the waste as you can, just don't get crazy about it you are just trying to get some room in the mortise so the machine does not have to work so hard. You are going to need a grinding bit like these BITS to sharpen the chisel, or THIS . Dave Quote Link to comment Share on other sites More sharing options...
wleingang Posted October 4, 2010 Author Report Share Posted October 4, 2010 I wish I lived on a street in which all of you were my neighbors. Quote Link to comment Share on other sites More sharing options...
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