G02 and G03 Radius Calculations
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    Default G02 and G03 Radius Calculations

    Ok so I was given a task to fix some of the programs at my job and reprogram some of the radii. I am have a bit of an issue with this as my print for this particular part only gives the size of the radius and the location of the middle of said radius, how do I calculate to find the beginning and end points of say a R.375 with the middle located at -4.502 off the face of the part using G02 and a R.750 located at -5.684 off the face using G0315731575053601605119177.jpg

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    We're going to need more info, a pic even.

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    Quote Originally Posted by AMCarson View Post
    with the middle located at -4.502 off the face of the part
    ... eh, the middle off to where?

    I'm not exactly a noob at these things but I have no idea what you mean

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    My print only gives me the middle of the radius, not the start and end points

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    Pic has been added, sorry I'm a noob in a small mom and pop shop left to learn on my own

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    Quote Originally Posted by Tichy View Post
    ... eh, the middle off to where?

    I'm not exactly a noob at these things but I have no idea what you mean
    The middle of the radius....I gave the location from the face of the part to the middle of the radius as my print doesn't give start and end point as shown in the pic in my first post

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    Quote Originally Posted by AMCarson View Post
    The middle of the radius....I gave the location from the face of the part to the middle of the radius as my print doesn't give start and end point as shown in the pic in my first post
    Oh we're talking lathes, yeah I don't even qualify as a noob at lathes

    But well sure:

    If you want the start and end points the easiest way is probably to load some simple sketching software (Cimco, TrigFix, practically any cad or whatever) and draw the straight lines and add the radii. Tho of course calculating that CAN be done.

    But why do you need them? Can't you just program G1 ,R on your lathe? If I'd treat this as a milling detail and I assume smaller piece radius is 10 and bigger is 20, just something like

    G1 X-10
    G1 Y-40,R.375
    G1 X-20 Y-30,R.750
    G1 Y0

    I'm sure you'll find people who are more helpful tho

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    how's your math? It's simple algebra.

    Define the radius as R^2=X^2 + Y^2 and the lines as Y=mX + b, then just solve for the intersections.

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    G1 won't take an R value as G1 is linear not circular. G2 and G3 are circular

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    Quote Originally Posted by AMCarson View Post
    G1 won't take an R value as G1 is linear not circular. G2 and G3 are circular
    You are wrong.

    G01 Linear Interpolation Motion (Group 01)

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    Quote Originally Posted by Larry Dickman View Post
    how's your math? It's simple algebra.

    Define the radius as R^2=X^2 + Y^2 and the lines as Y=mX + b, then just solve for the intersections.
    My algebra is quite rusty so I may need some help with that.

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    Quote Originally Posted by Tichy View Post
    You are right, I am definitely wrong, still doesn't really help me with figuring out the start and end points while at the machine. I don't have access to a computer to do it any other way than calculating it by hand.

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    To help you further in an easy way:

    Adding an R value to a G1 rounds the intersection between this straight line and the following straight line. G1,R must be followed by another G1. (Compare ,C for chamfering.) So calculating/drawing to solve start and end points is required when the rounding leads into a circular motion (G2,G3,) but on your drawing it does not.

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    Quote Originally Posted by AMCarson View Post
    You are right, I am definitely wrong, still doesn't really help me with figuring out the start and end points while at the machine. I don't have access to a computer to do it any other way than calculating it by hand.
    Ok I am SUPER rusty / nonexp at lathes but you don't NEED to calc it in this drawing. You are saying "-4.502 off the face of the part using G02 and a R.750 located at -5.684 off the face using G03"

    So minor radius is 4.502 and major is 5.684 right? And we deal with X and Z coordinates. You haven't given the Z's so I'll invent them.

    G1 X4.502 Z0.
    G1 Z-10.,R.375
    G1 X5.684 Z-11.1,R.750
    G1 Z-20.

    Unless I'm woefully mistaken about lathe syntax... Problem solved.

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    Quote Originally Posted by Tichy View Post
    Ok I am SUPER rusty / nonexp at lathes but you don't NEED to calc it in this drawing. You are saying "-4.502 off the face of the part using G02 and a R.750 located at -5.684 off the face using G03"

    So minor radius is 4.502 and major is 5.684 right? And we deal with X and Z coordinates. You haven't given the Z's so I'll invent them.

    G1 X4.502 Z0.
    G1 Z-10.,R.375
    G1 X5.684 Z-11.1,R.750
    G1 Z-20.

    Unless I'm woefully mistaken about lathe syntax... Problem solved.
    Those values are the Z values I listed. Z-4.502 and z-5.648. But those z values indicate the middle of the radius, not the start or finish position.

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    Quote Originally Posted by AMCarson View Post
    Those values are the Z values I listed. Z-4.502 and z-5.648. But those z values indicate the middle of the radius, not the start or finish position.
    You don't need them. The G1 ,R automatically rounds it off. What are the X values then (the small and big radius of the piece?) The "middle of the radius" is given because that's the most helpful measurement - that is where the straight lines (if they weren't rounded) would intersect!

    Post the X values and I'll give you a pic to explain.

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    Quote Originally Posted by Tichy View Post
    You don't need them. The G1 ,R automatically rounds it off. What are the X values then (the small and big radius of the piece?) The "middle of the radius" is given because that's the most helpful measurement - that is where the straight lines (if they weren't rounded) would intersect!

    Post the X values and I'll give you a pic to explain.
    15731627092281528877189.jpg I also want to clarify I'm not looking for a workaround, I want to know how to calculate for those values that aren't given on my print.

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    The easiest way to do it is to sketch the lines in CAD and pick off the points using dimensions. Otherwise, brush up on your trig skills.

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    Quote Originally Posted by AMCarson View Post
    15731627092281528877189.jpg I also want to clarify I'm not looking for a workaround, I want to know how to calculate for those values that aren't given on my print.
    Well no offense (no, really) but in this case saying you're not looking for a workaround is the same as saying you aren't looking for learning to code, and if you don't master basic G-code syntax that should probably rank higher than learning more trig at this point.

    This is your detail.

    detail.jpg

    The G1 "R" function adds the rounding you see in the picture. You program the G1 to the points marked.

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    Quote Originally Posted by rklopp View Post
    The easiest way to do it is to sketch the lines in CAD and pick off the points using dimensions. Otherwise, brush up on your trig skills.
    As stated before I don't have access to a computer or cad. Would love for someone to just explain it to me instead of giving me workarounds and being difficult...is it too much to ask?


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