I am just getting back to woodturning after many years. I have been working a metal lathe making brass parts for casting masters for ship model kits. I do ship model design as a retired profession. My problem is with the parting tool in wood. For metal, I use parting tools that are flat on top, just like a scraper and you cut directly on centerline or just a little below. Not the diamond parting tool for wood has me confused and I think I may not be using it correctly. It keeps getting grabed, pulling the tool down. I notice in a video I have of Bonnie Kline that she starts the tool high and then cuts down toward the center. When she starts high the angle with the wood is just like a scraper. Help please, on procedure and why is a diamond shape used in the first place? Thanks.
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Parting tool
- Thread starter LANKFORD
- Start date
parting tool technique
Hello there,
first the diamond shape...
the idea behind the diamond shape is that it relieves the cut. As the wider section to the rear of the front cutting cutting edge enters the wood it creates a wider access for the cutting point and following metal. This stops the tool binding in the cut. Personally I prefer a flat-sided parting tools...but that's just me!
As for cutting with any parting tool. The technique generally is to do as you have seen in the DVD. Start the cut with the tip of the parting tool at a high, and shear, angle, and cut in an arc that dips down and ends at centre hight. If your tool is sharp this will give you a very clean cut which should not bind or snag at all. You must keep in mind that the deeper the parting cut the more likely you are to have problems. If it's a deep cut then try and make some room for the tool first, to the left of the parting cut, with your spindle gouge, parting tool, or whatever other tool you are comfortable with clearing waste wood out of the way. Of course, if you have little wood left at the headstock end of the workpiece this will be difficult and a fine-bladed saw, such as a Japanese pull saw may be used to complete the operation.
Good luck, and welcome back to turning
Andy
Hello there,
first the diamond shape...
the idea behind the diamond shape is that it relieves the cut. As the wider section to the rear of the front cutting cutting edge enters the wood it creates a wider access for the cutting point and following metal. This stops the tool binding in the cut. Personally I prefer a flat-sided parting tools...but that's just me!
As for cutting with any parting tool. The technique generally is to do as you have seen in the DVD. Start the cut with the tip of the parting tool at a high, and shear, angle, and cut in an arc that dips down and ends at centre hight. If your tool is sharp this will give you a very clean cut which should not bind or snag at all. You must keep in mind that the deeper the parting cut the more likely you are to have problems. If it's a deep cut then try and make some room for the tool first, to the left of the parting cut, with your spindle gouge, parting tool, or whatever other tool you are comfortable with clearing waste wood out of the way. Of course, if you have little wood left at the headstock end of the workpiece this will be difficult and a fine-bladed saw, such as a Japanese pull saw may be used to complete the operation.
Good luck, and welcome back to turning
Andy
- Joined
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Andy described the proper use of the parting tool quite well. it is sort of a peeling cut.
One thing I would add is to make a clearance cut. in deep parting the tool tends to bind in the cut. The actual binding depth will vary with the tool and the wood. When the tool begins to grab I make a second cut 1/2 the width of the tool to one side of the first cut. This cut I coninue untilm the tool gets grabby. I keep switching bewteen the two cuts until the depth is reached.
I tell my students to cut as deep the point section then do the relief cut.
happy turning,
Al
One thing I would add is to make a clearance cut. in deep parting the tool tends to bind in the cut. The actual binding depth will vary with the tool and the wood. When the tool begins to grab I make a second cut 1/2 the width of the tool to one side of the first cut. This cut I coninue untilm the tool gets grabby. I keep switching bewteen the two cuts until the depth is reached.
I tell my students to cut as deep the point section then do the relief cut.
happy turning,
Al
Rethink What You Are Doing...
The approach is dependant on the type of parting tool you are using. This information is somewhat contrary to what the two previous postings recommend. I use a straight parting tool for a lot of applications and my method is what Stuart Batty taught me. Start tip low, enter the wood by maybe 1/32â€Â, then bring the tip up to the peeling cut. This method prevents ragging the surface fibers on each side of the cut. Mount a spindle and do the cut both ways and compare the results. You’ll see what I mean. Be sure your tool is sharp first. You should never do a finish part without first taking the tool to the grinder.
If you have a fluted parting tool, you need to just enter from a high angle as the previous posts mention. The fluted tool cuts completely differently. The points of the flute cut the fibers on either side of the blade.
I find no advantage to the diamond tool. In my mind the design theory doesn’t hold because the sides of the diamond continue to rub through the entire cut. There is no bur to help ease the friction. A straight tool, when sharpened properly, doesn’t do this. The straight tool has a bur on ALL edges. This bur clears wood by fractions of an inch on either side of the cut and this lessens the friction.
- Scott
The approach is dependant on the type of parting tool you are using. This information is somewhat contrary to what the two previous postings recommend. I use a straight parting tool for a lot of applications and my method is what Stuart Batty taught me. Start tip low, enter the wood by maybe 1/32â€Â, then bring the tip up to the peeling cut. This method prevents ragging the surface fibers on each side of the cut. Mount a spindle and do the cut both ways and compare the results. You’ll see what I mean. Be sure your tool is sharp first. You should never do a finish part without first taking the tool to the grinder.
If you have a fluted parting tool, you need to just enter from a high angle as the previous posts mention. The fluted tool cuts completely differently. The points of the flute cut the fibers on either side of the blade.
I find no advantage to the diamond tool. In my mind the design theory doesn’t hold because the sides of the diamond continue to rub through the entire cut. There is no bur to help ease the friction. A straight tool, when sharpened properly, doesn’t do this. The straight tool has a bur on ALL edges. This bur clears wood by fractions of an inch on either side of the cut and this lessens the friction.
- Scott
The best parting tools I have were made by welding a metal lathe part off blade onto a piece of round stock. They are tapered from top to bottom and very thin so I get a good cut with no grab and get better grain match when parting off box tops, etc. than with the wide diamond tool.
Wilford
Wilford
Great info. Thanks to all. In reply to Clark's reply, I assume that when I sharpen the parting tool, I should not hone the sides so as not to remove the burs along the edge.