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TB333 Rev2 – Tangential Knife Setup Tech Bulletin
What is a Tangential knife
Tangential Knife is a Rotary C Axis that orients a knife blade to always face in the direction of
the cut
Tangential Knife is commonly combined with oscillation to enable the ability to cut thicker and
harder materials
What would a Tangential Knife be used for?
Tangential Knives are commonly used for soft material such as vinyl foam poly carpets and
cardboard
CNC 12/ Wizard Set Up for a Tangential Knife C Axis
Axis Configuration
In this example Image you can see the Tangential Knife C axis is in Axis 4
The Axis Type has been set to Tangential Knife
Overall Turns Ratio
With a Tangential Knife axis the Overall Turns Ration is defined as Turns/Rev This is Turns of
the Motor per Axis Revolution
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TB333 Rev2 – Tangential Knife Setup Tech Bulletin
Hint If the Revolutions per degree is already known for the Tangential knife then multiplying
the rev/deg by 360 will equal the Turns per revolution
Jogging rates
Jogging rates includes max rates fast jog and slow jog rates
Tangential Jog rates are defined as Revolutions per minute rev/min
Rev/min is how many revolutions of the tangential knife will be completed in 1 Minute of time
Hint If the Degrees per Minute is already known for the Tangential knife axis then the
revolutions per minute can be found by Dividing the Deg/min by 360
Inputs
It is common for a Tangential Knife to have a Home Position indication This will be used when homing
the Tangential knife axis In this example build the Indicator will be wired to input 7 and
FourthAxisHomeOk will be assigned to IN7 in the wizards input menu
Outputs
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TB333 Rev2 – Tangential Knife Setup Tech Bulletin
Tangential Knives commonly Oscillate while cutting
The Oscillation has been wired to Output Seven on the 8 Output Relay Board and the
Oscillation On output has been assigned to Out7 on the Wizards Output Menu
Oscillation
Oscillation On can be called in the G code via M39 for Oscillation ON and M40 for Oscillation
off
Example Tangential Knife G Code
Note The M39 and M40 for turning Oscilation On and Off
G64 Turns smoothing on for better rotary transition moves
Additional resources
The following link is to a post on the Centroid forums by Joey His post outlines use of a
EcoCam Oscillating Tangential Knife He has provided a download for a Sheetcam Post as
well as a link to a Google photo album with videos showing using Sheetcam to generate G
code for the tangential knife
https //centroidcncforum com/viewtopic php?p=94456&hilit=Tangential+knife#p94456
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