Hi,
This is on 4130... dimensions are in the first pic... Maybe I'm overthinking this and yes I dont have the ideal tools but I'm trying to deal with a flat bottomed hole with a radius going to 40degrees then a straight taper then another radius to 90 degrees to make the walls. I only have small CCMT boring bars (up to 16mm) and a TNMG in 19mm... and yes it would be great to get another bar for this but I only need to make 6 of these.. so.. yeah.
Attached is a crappy mspaint version of what I'm trying to make... Plus my current concept of my 4 toolpaths to complete it. Basically, use an almost flat u-drill, then bore axially to the max flat bottom depth with a sharp reverse angled retract so the tool doesn't 'wedge' when retracting (i.e. go + in Z at the end of the bore diameter on each pass). Then run a finish pass axially on the finished bore and include the first curve since it would be at the better angle on my 85 deg CCMT, with an arc out. Then start at X0 and do a finish pass outwards taking up the last bit of the U-drill tip and the deeper curve, arcing out once past the previous machined depth. Both finish passes would arc out so in theory I would have a nice blending.
BUT.. this seems lame to me.. The last path the curve is "against" the intended cutter angle (as far as I can tell), and I cant envision the 2 finish passes not burring or having a step, i.e. a shitty blend line. What would you guys recommend for accomplishing this, or am I being a cheap stubborn bastard and I should just get or MAKE one of those V shaped bars that apparently can radius... or should I just giver in one path and hole i dont bust the tool ??
This is on 4130... dimensions are in the first pic... Maybe I'm overthinking this and yes I dont have the ideal tools but I'm trying to deal with a flat bottomed hole with a radius going to 40degrees then a straight taper then another radius to 90 degrees to make the walls. I only have small CCMT boring bars (up to 16mm) and a TNMG in 19mm... and yes it would be great to get another bar for this but I only need to make 6 of these.. so.. yeah.
Attached is a crappy mspaint version of what I'm trying to make... Plus my current concept of my 4 toolpaths to complete it. Basically, use an almost flat u-drill, then bore axially to the max flat bottom depth with a sharp reverse angled retract so the tool doesn't 'wedge' when retracting (i.e. go + in Z at the end of the bore diameter on each pass). Then run a finish pass axially on the finished bore and include the first curve since it would be at the better angle on my 85 deg CCMT, with an arc out. Then start at X0 and do a finish pass outwards taking up the last bit of the U-drill tip and the deeper curve, arcing out once past the previous machined depth. Both finish passes would arc out so in theory I would have a nice blending.
BUT.. this seems lame to me.. The last path the curve is "against" the intended cutter angle (as far as I can tell), and I cant envision the 2 finish passes not burring or having a step, i.e. a shitty blend line. What would you guys recommend for accomplishing this, or am I being a cheap stubborn bastard and I should just get or MAKE one of those V shaped bars that apparently can radius... or should I just giver in one path and hole i dont bust the tool ??
Attachments
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shitty drawing.jpg79.2 KB · Views: 95
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shitty drawing - op1.jpg80.3 KB · Views: 72
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shitty drawing - op2 - cnmg axial cuts.jpg79.9 KB · Views: 59
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shitty drawing - op3 - cnmg finish pass axial radius.jpg80.1 KB · Views: 66
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shitty drawing - op4 - cnmg finish pass bottom and radial radius.jpg84.6 KB · Views: 71