Spiral feathering in circ. pockets...

If yer pocketing a circle, it dawned on me that there is no easy way to
feather in/out, to avoid undue marks/divets.
afaict, The only real way would be entry/exit spirals. See wiki for
examples, proly the Archimedian spiral being the most practical AND
Does anyone have a macro to do this?
Do some machines have canned cycles to do this?
I would imagine cadcam allows this, eh? :(
I guess jb would know all about this....
In lieu of this, I guess I'll just do the regular g3, in rough and a second
very fine finish pass.
What do others do?
My application is really not that critical now, but at some point it would
be nice to do this--in production, this certainly would seem to be a time
saver, visavis a second pass.
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Proctologically Violated®©
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Mr. PV:
Arc in & arc out, with a small overlap is normal.
Or you could helix down into the hole.
Never heard of anyone using an Archimedian spiral for this purpose, but anything's possible I suppose.
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"Proctologically Violated®©" wrote in message news:487c191a$0$20929$ snipped-for-privacy@cv.net...
Iv'e spent a lot of time dealing with this issue on the wire edm long ago.
Here's some thing's I was doing... I tried to overlap...didnt work. It caused the area to cut twice and be oversized...leaving a mark. I tried a radius leading, suggested my mitsubishi, the cutter(or wire) diameter +.010. That left a mark because again it creates a cut twice condition as the two radius's meet. leaving a mark. I tried a giant lead iradius...bigger mark. I tried putting G40 and G41 in different places to get the comp to turn on and off in random places, never got rid of the mark. I tried tons of passes, that never worked either, just kept getting smaller and smaller but never disapeared. So here's how I fixed it, and it leaves no mark whatsoever...
In the cam system I drew my leadin and leadouts instead of filling in a leadin/out prompt. Then I pulled the leadin and leadout radii away from each other and trimmed them. With a .010 wire I found this number to be .002 each way. So now imagine a triangle of meat left between the leadin/out radiu's.
This can be done in cam systems sometimes easily by setting a negative value in the overlap sometimes.
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If you are planning on writing a macro this can help you define your variables.
I have circular pocketing macros CW and CCW for FANUC but they are not Archimedean.
I do have finish pass circular macros with arc lead in and out, similar to G12, G13. I posted them to this group some time ago for JB to use. The arc lead in and out should eliminate the "witness marks" you were talking about in your post. These could be easily added to the circular pocketing macros for a finish pass.
If you are interested I need to ask you a question or two, send me an Email with "Circular Macro" in the subject line and I will follow up with you snipped-for-privacy@aol.com.
If you are going to use my macros as a template for writing FADAL macros I will need to explain every variable & function to make the translation easier for you.
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I wonder how cutter diameter would effect this? Smaller or Largest possible diameter (radius) making contact in the circle. I know cutter diameter effects feedrate on internal circular moves. Without hurting the rigidity of the cut if going smaller though.
Would Helx Angle of the cutter help or hurt? Say 35 Degree compared to 50 Degree. It's all about how the cutter is making contact and then leaving the cutting zone.
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Gibbs has that function. I also often spiral in to the bottom leaving few thousands and finish walls with a " spring pass" ( additional 360 deg pass) and that takes care of any in and out marks. It is a part of Gibbs but not very well known. Jerry
"Proctologically Violated®©" wrote in message news:487c191a$0$20929$ snipped-for-privacy@cv.net...
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Try this programme,it has a section to generate G code for circular pockets
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