120 degree V bit with sharp point tip....
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120 degree V bit with sharp point tip....
So far my search for a pointed tip 120 degree V bit has not been successful.
Sellers claim their bits have a sharp point, but when they arrive it turns out they are not sharp pointed. They have a small flat at the tip like a conventional drill bit.
I have two 120 degree bits with the small flats that the local grinding shop says they can modify to a shape point. I'd prefer to find one that comes from the factory sharp pointed though.
Actually, I did find one that is sharp pointed, but it has replaceable carbide cutting edges with a quoted price of around $175. Something closer to 50 bucks is my price range.
Sellers claim their bits have a sharp point, but when they arrive it turns out they are not sharp pointed. They have a small flat at the tip like a conventional drill bit.
I have two 120 degree bits with the small flats that the local grinding shop says they can modify to a shape point. I'd prefer to find one that comes from the factory sharp pointed though.
Actually, I did find one that is sharp pointed, but it has replaceable carbide cutting edges with a quoted price of around $175. Something closer to 50 bucks is my price range.
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- Vectric Apprentice
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Re: 120 degree V bit with sharp point tip....
Why do you need the point? I use many 120 v-bits with the small flat at the tip and have never had an issue, ramp your entrances .
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- Vectric Wizard
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Re: 120 degree V bit with sharp point tip....
The problem with any sharp point bit (besides the difficulty of grinding it precisely and not ripping the delicate tip off while using) is that there is no cutting edge left to speak of at the very tip and the surface speed that close to the rotation axis is very small, even at high rpm. As a result the is no good cutting action and the tip mostly drags through the material leaving some fuzz at the very bottom of the groove defeating the intent to get it really sharp and clean. When the chip load is almost as much as the local bit diameter this is just not going to work. I guess that is the reason most v-bits have that small tip flat or radius. Obviously, the tip should not be just dull.
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Re: 120 degree V bit with sharp point tip....
potz'
I plan on using the 120 degree bit to do V carving of shallow star shapes. With the small flat at the point of my existing 120 degree bits I can't get sharp points in the workpiece.
I can get the visual appearance I want when viewed straight down using the star shape supplied with the Desktop software using my 90 degree sharp point bits. The problem is the star is too deep at the center and doesn't give the shallow appearance I'm looking for when viewed from the side angles. The stars will be on the outside of a round, straight sided box in very dark wood (think dark like ebony) with the stars being a very subtle, hardly noticed feature. The deep center stars are not subtle at all.
BTW: the program to cut the stars is hand coded to give a more chip carved effect. Desktop generated code does not give the chip carved effect and is too deep anyway.
I plan on using the 120 degree bit to do V carving of shallow star shapes. With the small flat at the point of my existing 120 degree bits I can't get sharp points in the workpiece.
I can get the visual appearance I want when viewed straight down using the star shape supplied with the Desktop software using my 90 degree sharp point bits. The problem is the star is too deep at the center and doesn't give the shallow appearance I'm looking for when viewed from the side angles. The stars will be on the outside of a round, straight sided box in very dark wood (think dark like ebony) with the stars being a very subtle, hardly noticed feature. The deep center stars are not subtle at all.
BTW: the program to cut the stars is hand coded to give a more chip carved effect. Desktop generated code does not give the chip carved effect and is too deep anyway.
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Re: 120 degree V bit with sharp point tip....
Tall'
I'm aware of the fragility and the effective low to zero cutting speed at the center of sharp pointed bits. In spite of those issues bit makers have no hesitation in offering 45, 60 and 90 degree sharp point bits that give acceptable results. So I'm looking for the same in 120 degree. As I said. an insert type bit is available for close 200 bucks after tax and delivery costs, I don't want to spend that kind of money though.
I'm aware of the fragility and the effective low to zero cutting speed at the center of sharp pointed bits. In spite of those issues bit makers have no hesitation in offering 45, 60 and 90 degree sharp point bits that give acceptable results. So I'm looking for the same in 120 degree. As I said. an insert type bit is available for close 200 bucks after tax and delivery costs, I don't want to spend that kind of money though.
Last edited by Doug98105 on Tue Sep 11, 2018 4:04 pm, edited 1 time in total.
- Rcnewcomb
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Re: 120 degree V bit with sharp point tip....
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop
10 fingers in, 10 fingers out, another good day in the shop
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Re: 120 degree V bit with sharp point tip....
Thanks, I'll give them a call. From the picture that bit doesn't appear to be 120 degrees, but the picture may not be representative of the actual product. Also it's a negative rake cutting geometry.
- Rcnewcomb
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Re: 120 degree V bit with sharp point tip....
From my understanding a negative rake angle should increase the strength of the cutting edge and help with a smoother finishnegative rake cutting geometry
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop
10 fingers in, 10 fingers out, another good day in the shop
- Jim_in_PA
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Re: 120 degree V bit with sharp point tip....
The Amana insert V-bit has a sharp point...at least when new.
- adze_cnc
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Re: 120 degree V bit with sharp point tip....
Unless that sharp point is perfectly in the centre of the bit you'll still get a mushy cut.
If there are not too many stars how about cutting them with any old v-bit via CNC then manually creating a sharp V by using a wood-cut tint tool or some small v-gouge?
Many times I get students saying they want to use the CNC because they want the result to look exactly like their model. I like to remind them that their model is perfect because it doesn't really exist and the tools use to cut it on the preview are equally perfect and non-existent.
If there are not too many stars how about cutting them with any old v-bit via CNC then manually creating a sharp V by using a wood-cut tint tool or some small v-gouge?
Many times I get students saying they want to use the CNC because they want the result to look exactly like their model. I like to remind them that their model is perfect because it doesn't really exist and the tools use to cut it on the preview are equally perfect and non-existent.
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Re: 120 degree V bit with sharp point tip....
I may have a solution for the bit. The Centurion bit Rcnewcomb linked to may be the best choice. Thanks for the link.
I talked with Centurion, the man confirmed their bit is a negative rake type cutter. As he said, it isn't the best situation, but it does have a not so fragile, sharp point. He's aware of what V carving is all about and has customers using these bits for that purpose.
He mentioned because of the negative rake cutting action depending on the wood sometimes you have to take a second pass to clean up any fuzz. A second pass is kind of a given anyway so no problem with that.
When you cut a groove with a typical bit one side may be cutting with the grain, the other side may be cutting against the grain. The groove side cut against the grain will be where there could be fuzz or not so clean a cut. Because of the cutter geometry this bit can run in forward or reverse rotation, perfect for me since I'm using a CNC machine with a reversible spindle. I'll run the first pass in forward rotation and the second in reverse to clean any flaws in the cut.
I talked with Centurion, the man confirmed their bit is a negative rake type cutter. As he said, it isn't the best situation, but it does have a not so fragile, sharp point. He's aware of what V carving is all about and has customers using these bits for that purpose.
He mentioned because of the negative rake cutting action depending on the wood sometimes you have to take a second pass to clean up any fuzz. A second pass is kind of a given anyway so no problem with that.
When you cut a groove with a typical bit one side may be cutting with the grain, the other side may be cutting against the grain. The groove side cut against the grain will be where there could be fuzz or not so clean a cut. Because of the cutter geometry this bit can run in forward or reverse rotation, perfect for me since I'm using a CNC machine with a reversible spindle. I'll run the first pass in forward rotation and the second in reverse to clean any flaws in the cut.