Been machining some plastics lately, and the pile behind the lathe is growing, and growing, and growing-
Anyway that's not exactly what I'm posting about. Yesterday I glued some pvc discs into some abs pipe sections. Today I needed to cut most of the pvc out, leaving basically just a ring behind. Because that would represent most of the material being wasted, and too much time to bore it all away, I decided to hole saw it. Mounted the hole saw in the tailstock and made a press-fit fixture to mount in the chuck to hold the pieces I'm working on.
As I bring the hole saw into the workpiece the swarf fills the gullets in the teeth very quickly. This means I have to withdraw the hole saw, clean the swarf out of the teeth, and go again- and again, again, etc. Too time consuming. Then I went for a different hole saw, one that I had sharpened and deepened the gullets somewhat. That was faster and I got the job done- still needing 3 cycles of withdrawing the tool and cleaning the gullets out. All is well.
As I'm working on this I'm reaffirming what I already know- swarf needs a place to escape to. Most of us here know this, but for the sake of the newbies I thought I'd bring it up. There are several reasons to pay attention to this. One is that the swarf can remain in the cut, filling the gap and preventing the cutting tool from continuing to take a proper cut. Another is that it can be dragged along the cut, possibly scratching up the nice finish. Another is that it can wedge between the tool and the cut, again scratching up the surfaces and possibly damaging the cutter, not to mention overheating things. And it can cause tool wander and unexpected over-cutting. If you don't already have a good strategy for dealing with swarf, it's definitely something to think about.
Anyway that's not exactly what I'm posting about. Yesterday I glued some pvc discs into some abs pipe sections. Today I needed to cut most of the pvc out, leaving basically just a ring behind. Because that would represent most of the material being wasted, and too much time to bore it all away, I decided to hole saw it. Mounted the hole saw in the tailstock and made a press-fit fixture to mount in the chuck to hold the pieces I'm working on.
As I bring the hole saw into the workpiece the swarf fills the gullets in the teeth very quickly. This means I have to withdraw the hole saw, clean the swarf out of the teeth, and go again- and again, again, etc. Too time consuming. Then I went for a different hole saw, one that I had sharpened and deepened the gullets somewhat. That was faster and I got the job done- still needing 3 cycles of withdrawing the tool and cleaning the gullets out. All is well.
As I'm working on this I'm reaffirming what I already know- swarf needs a place to escape to. Most of us here know this, but for the sake of the newbies I thought I'd bring it up. There are several reasons to pay attention to this. One is that the swarf can remain in the cut, filling the gap and preventing the cutting tool from continuing to take a proper cut. Another is that it can be dragged along the cut, possibly scratching up the nice finish. Another is that it can wedge between the tool and the cut, again scratching up the surfaces and possibly damaging the cutter, not to mention overheating things. And it can cause tool wander and unexpected over-cutting. If you don't already have a good strategy for dealing with swarf, it's definitely something to think about.
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