Mortise chisel question
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Mortise chisel question
I have started to use the mortising chisels on a project. They are new, but it seems to take a lot of pressure to get them to cut. I have been "nibbling" at the mortise and I am getting nice clean cuts. I am using red oak. Is there a trick I need to know? How far below the chisel should the bit extend? I am useing 3/8 amd 1/4 in chisels.
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chiroindixon
- Gold Member
- Posts: 243
- Joined: Thu Jul 20, 2006 1:42 pm
- Location: QCA Iowa
Learn to sharpen...
If your chisel set did not come with the sharpening stone(s) and instructions....get them. You are now learning that all new (most.....Forrest excepted) tools need to be sharpened by the owner/professional for optimium results.
Keep your SS mortise chisels especially sharp. Your gear set in a SS is not a heavy duty like a dedicated mortise machine is. It's very easy to wear your quill, etc. out bearing down hard. Light cuts....sharpen often...
Keep your SS mortise chisels especially sharp. Your gear set in a SS is not a heavy duty like a dedicated mortise machine is. It's very easy to wear your quill, etc. out bearing down hard. Light cuts....sharpen often...
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Greenvilleguy
- Gold Member
- Posts: 240
- Joined: Thu Jul 20, 2006 12:55 pm
- Location: Greenville, SC
Depth of bit
DLBRISTOL,
I had the same question you do about how far the bit should extend below the chisel. Through some trial and error I discovered that if you "line up" the bit and the bottom of chisel; the cut is more difficult. If the bit extends slightly below the chisel; the cut is much easier but the bottom of the mortise is not flat.
Since there is little to no holding power in the bottom anyway -- who cares if the bottom isn't flat.
That said, a 3/8 mortise in red oak is going to be difficult. The SS manual suggest stair steps, i.e. make the mortise cuts progressively deeper in 1/16" increments. I confess I wasn't patient enough for 1/16", but stair stepping did help.
I also sharpened the new chisels before I used them. I was using walnut and had no problem, but red oak is harder.
I had the same question you do about how far the bit should extend below the chisel. Through some trial and error I discovered that if you "line up" the bit and the bottom of chisel; the cut is more difficult. If the bit extends slightly below the chisel; the cut is much easier but the bottom of the mortise is not flat.
Since there is little to no holding power in the bottom anyway -- who cares if the bottom isn't flat.
That said, a 3/8 mortise in red oak is going to be difficult. The SS manual suggest stair steps, i.e. make the mortise cuts progressively deeper in 1/16" increments. I confess I wasn't patient enough for 1/16", but stair stepping did help.
I also sharpened the new chisels before I used them. I was using walnut and had no problem, but red oak is harder.
Hi,
I have an older set maybe from 1978 or so and the instruction sheet calls for the 1/16" as was mentioned. It is also importain to run at the "saw or router/shaper" settings as the higher speed helps clear chip load. Make sure you use the hold down to keep the workpiece on the table.
As was mentioned the drill is cutting a hole and the chisel is cutting out the 4 corners. It should be sharp. Having said that the old set I have required 2 different stones as the angles were not the same on the set of chisels so you might need to check on that.
When you cut a series of over lapping cuts make sure that the overlap is about 3/4 of the width of the chisel. The first hole takes more effort then the rest due to having to chisel the 4 corners where the others will be chisel only 2 corners...
What I found was an issure for me was the pressure required was tipping the table a very small amount but enough to make the whole process harder then it needed to be. I used a 2x4 against the floor with a notch that the table would rest on, this provided a solid platform to work on. When I went to the 520 design I just used the provided telescopic legs... I personal found this to be a very importain step in the process.
It is also easy to overheat the bits by either not having enough space or pushing to hard... if they lose the temper then they will need to be replaced... having blue bits is not a good thing.
Ed
I have an older set maybe from 1978 or so and the instruction sheet calls for the 1/16" as was mentioned. It is also importain to run at the "saw or router/shaper" settings as the higher speed helps clear chip load. Make sure you use the hold down to keep the workpiece on the table.
As was mentioned the drill is cutting a hole and the chisel is cutting out the 4 corners. It should be sharp. Having said that the old set I have required 2 different stones as the angles were not the same on the set of chisels so you might need to check on that.
When you cut a series of over lapping cuts make sure that the overlap is about 3/4 of the width of the chisel. The first hole takes more effort then the rest due to having to chisel the 4 corners where the others will be chisel only 2 corners...
What I found was an issure for me was the pressure required was tipping the table a very small amount but enough to make the whole process harder then it needed to be. I used a 2x4 against the floor with a notch that the table would rest on, this provided a solid platform to work on. When I went to the 520 design I just used the provided telescopic legs... I personal found this to be a very importain step in the process.
It is also easy to overheat the bits by either not having enough space or pushing to hard... if they lose the temper then they will need to be replaced... having blue bits is not a good thing.
Ed
Chisel Issues / Thanks
Thanks Guys! I Haven't Yet Found The Sharpening Instructions, But I Was Able To Finish My Project Chiseling. All Of Your Info Was Helpful. Thanks Again