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G2/G3 Arcs on Non-Orthogonal Planes

JBNimble

Plastic
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Mar 17, 2019
I have a HAAS ST lathe with Y axis. I'm setting up some radial holes milled through hollow bar. I'm using a bull nose end mill which will let me do some edge deburring if I'm really dialed in with my movements to run the mill radius along the profile of the edge formed by the intersection of the milled hole and bar stock o.d. I can achieve this with a bunch of short XZY lines, but it would be a bit nicer with arcs. So, two options may exist or not: 1. I might be able to define a G2/G3 arc in a non orthogonal plane, if such a g code exists. 2. I might be able to just use3 dimensional line segments but with radius transitions to blend it out a bit. Does anybody know how to do this? NO, I do not have CAM and have no plan to acquire. I'm looking for basic approaches with G codes to mitigate hand deburring. Thx.
 
Fusion 360 is free I can’t imagine owning a y axis lathe without a cam package. Don


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If you must hand code it, it'll be easier to use X,Z and C, than it will be to use X,Y,Z. I don't know the easy answer, Ox may know a quick way to get it close enough.

But I agree, you're in CAM territory.

R
 
I figured it out. It's just a series of helical cuts. The helix radius is the port radius minus the end mill radius plus half the end mill nose radius value. Each quadrant is identical, and I actually only need to program 4 segments per quadrant to reasonably chase the non-linear profile by treating it as 4 smaller moves that individually can be approximated as linear.
 
I figured it out. It's just a series of helical cuts. The helix radius is the port radius minus the end mill radius plus half the end mill nose radius value. Each quadrant is identical, and I actually only need to program 4 segments per quadrant to reasonably chase the non-linear profile by treating it as 4 smaller moves that individually can be approximated as linear.

Well, without seeing a pic of the problem, I don't think that I'm going to read that 5 times to try to wrap my head around the actual issue - see'ins how you've already solved the problem, but good for you!

Also - I'm pretty sure that Ortho is a pesticide company.
What doo they have to doo with trig and rads?
(never heard (or at least don't recall ever hearing) that term before.)


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Think Snow Eh!
Ox
 
I figured it out. It's just a series of helical cuts. The helix radius is the port radius minus the end mill radius plus half the end mill nose radius value. Each quadrant is identical, and I actually only need to program 4 segments per quadrant to reasonably chase the non-linear profile by treating it as 4 smaller moves that individually can be approximated as linear.

The circle would be too approximate, to the extent of being unacceptable. But, as long as it serves the purpose, it is fine.
 
I figured it out. It's just a series of helical cuts. The helix radius is the port radius minus the end mill radius plus half the end mill nose radius value. Each quadrant is identical, and I actually only need to program 4 segments per quadrant to reasonably chase the non-linear profile by treating it as 4 smaller moves that individually can be approximated as linear.

Please doo post the code, when you can.
 
The circle would be too approximate, to the extent of being unacceptable. But, as long as it serves the purpose, it is fine.
This is the question. For deburring, it'll be fine in any case, but I am curious how nice it will look. I'll post the results in April.
 
I have deburred like this in the past as well. I just did quadrant acrs in Z/Y plane, and added X values to compensate for the thru hole radius. I understand this not to be perfect, but for deburring purposes, it has worked out pretty well.
 
Pretty sure that's a no. I thought of helical interpolation for this but helical is a circle in one plane with linear in another. That's not what his geometry is. Not even close ...

I crunched some numbers today and it's actually incredibly close (for deburring). With just a few segments per quadrant, it's within a few thousandths along the whole path. Since it's mimicking a sin wave path, the key is to be tangent at the quadrants and max x rate at the inflection points.
 
Question, one which I think may work on a mill, not entirely sure if it would work the same on a Y-lathe

But if I needed to take a ball endmill and do an arc in y/z but at an angle, say 45 degrees from X, could we just use G68 in the G17 plane, then program the yz arc movement using G19? It seems like that should work?
 
Question, one which I think may work on a mill, not entirely sure if it would work the same on a Y-lathe

But if I needed to take a ball endmill and do an arc in y/z but at an angle, say 45 degrees from X, could we just use G68 in the G17 plane, then program the yz arc movement using G19? It seems like that should work?


45* from X?


Are you saying that in stead of going from 9 to 12 to 3, that you need to start at 7:30, up to 12, and then to 1:30?


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Think Snow Eh!
Ox
 








 
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