I'm a student at community college, enjoying working with metal. I've become stuck on a fairly simple thing, cutting a chamfer with the lathe. My fellow students and teachers have different ways of doing it; I realize there are often several ways to perform a particular operation, but beginners like me can sometimes mix and match parts of different approaches and end up being either unsafe, confused, or just inefficient. I've used hss tool (simple shape, just a 45deg point) and a carbide insert, both fairly successfully, but mostly I get mixed up with the set-up, the angle of the compound and tool post, when to cut from left to right and when to go right to left. Am hoping to become confident cutting chamfers on the outside edges of pieces, in the middle (in a thread relief section for instance), and on the inside of a bored hole. Thanks in advance.
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How to cut chamfer on lathe?
- Thread starter Darla
- Start date
- Joined
- Jan 22, 2011
- Messages
- 8,032
Two basic approaches:
Slab it on there with the cutting edge at the desired angle. Works fine for small edge breaks, particularly on the OD, typically the end of the part. With proper grinding, a thread relief can be cut in a single operation if the left edge is square to the axis of the work, and the right side at the desired angle (typ 45° for UN threads). Often, if the relief is wide enough, straight groove tool can cut the relief and a tool similar to a threading too, except 90° included, can be used to slab the leading and trailing edges. Thread reliefs aren't always that wide in practice though.
Profile, or compound it on: Here you have more flexibility. You can catch an OD edge with a boring bar by simply reversing the spindle and using the compound to move the tool. I do this quite often. I'll finish an OD, and proceed with the bore, and when I compound the chamfer on the ID, I'll just reverse the spindle and to the OD. The only slightly tricky part of this is determining exactly when you have removed all of any burr that may be raised up, so that you can start making measured moves to hit a specific size. If you have good eyes and a soft touch, it's not hard to get used to. Also, you can easily swivel the compound to whatever angle you need and not have to grind a special tool. Another advantage to this method as opposed to slabbing is that you can compound a larger bevel or chamfer without chatter.
Sometimes, if it's my own work, I'll cheat on the back side of a thread. I will use a 35° diamond inserted tool to finish turn, but have the compound set at 45°. When I get to the shoulder I am threading too, I simply plunge the turning tool in, and pull it away from the shoulder until I get the width of relief I want. The holders are not neutral, so they don't really like cutting wrong-handed, but they will well enough to do a thread relief. That angle is NOT 45°, but after it is threaded, so little of that surface remains, it is not a problem.
There's more to tell, but I'll let others chime in too.
Slab it on there with the cutting edge at the desired angle. Works fine for small edge breaks, particularly on the OD, typically the end of the part. With proper grinding, a thread relief can be cut in a single operation if the left edge is square to the axis of the work, and the right side at the desired angle (typ 45° for UN threads). Often, if the relief is wide enough, straight groove tool can cut the relief and a tool similar to a threading too, except 90° included, can be used to slab the leading and trailing edges. Thread reliefs aren't always that wide in practice though.
Profile, or compound it on: Here you have more flexibility. You can catch an OD edge with a boring bar by simply reversing the spindle and using the compound to move the tool. I do this quite often. I'll finish an OD, and proceed with the bore, and when I compound the chamfer on the ID, I'll just reverse the spindle and to the OD. The only slightly tricky part of this is determining exactly when you have removed all of any burr that may be raised up, so that you can start making measured moves to hit a specific size. If you have good eyes and a soft touch, it's not hard to get used to. Also, you can easily swivel the compound to whatever angle you need and not have to grind a special tool. Another advantage to this method as opposed to slabbing is that you can compound a larger bevel or chamfer without chatter.
Sometimes, if it's my own work, I'll cheat on the back side of a thread. I will use a 35° diamond inserted tool to finish turn, but have the compound set at 45°. When I get to the shoulder I am threading too, I simply plunge the turning tool in, and pull it away from the shoulder until I get the width of relief I want. The holders are not neutral, so they don't really like cutting wrong-handed, but they will well enough to do a thread relief. That angle is NOT 45°, but after it is threaded, so little of that surface remains, it is not a problem.
There's more to tell, but I'll let others chime in too.
- Joined
- Aug 20, 2011
- Messages
- 527
Hello Darla , and welcome, I am by no means an expert on the lathe and I always try to err on the side of SAFETY when I use my lathe or any machine for that matter. There are many safe ways to do what you seek I would be more concerned with my toolpost than my crossfeed or compound if I was going to put a 45degree chamfer (on a pipe lets say) I would use the 45 degree tool you mentioned and go straight in with the apron and lightly touch it off on the outside same thing on the inside both would be on the closest side of the pipe to you with the lathe in forward. That is one way Always make sure everything will clear the chuck before start-up
as far as relief for threads I usually will use a cut-off type tool...I have tools I've shaped just for that...I suggest you watch as many videos as you can on the use of the lathe and always ask your Teacher and then look at his hands to make sure he has all his fingers.....machines have no compassion and can't think .....
as far as relief for threads I usually will use a cut-off type tool...I have tools I've shaped just for that...I suggest you watch as many videos as you can on the use of the lathe and always ask your Teacher and then look at his hands to make sure he has all his fingers.....machines have no compassion and can't think .....
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