3D chamfer edge of hole in bar

[WildBill9000]

I am trying to chamfer the edge of a hole that is in the center of a bar. The bar is 3.5" and the hole is 2.36". 3D chamfer works as it should but the chamfer is only correct at the centerline of the bar. I played with the diameter of the bar and got it to work but was wondering if there is a way to make it perfect without trial and error, perhaps a formula or something. I think making the hole an ellipse will work also but again its still trial and error. I have attached a screenshot of the job.

 

[Mr. Wizzard]

unless you have more than 3-axis capabilities, it will only be "correct" at centerline. That is the only point at which you are putting a true 45 degree chamfer on two 90 degree perpendicular walls. You can make it look pretty, but it won't be "right"

[CJep]

^right on

 

The only way to create a uniform chamfer on the hole would be to run the toolpath as an axis substitution.

[within a thou]

You could also run a 3D parallel path to make it the missing areas consistant as long as your geometry is correct.

[mchin-pilot]

Model it up and surface ball nose it.

[WildBill9000]

I couldn't get mastercam or autocad to chamfer the hole. The job doesn't have the time to surface it (our equipment is big and slow) but I would love to know how to model that. We do get the occasional weld prep job so a heavy step over would be fine.

[crazy^millman]

The best way to get a chamfer on something like this is to turn this into surfaces and then make a chamfer between the 2 surfaces. That will give you the best edge. Now you could turn that into a solid from there. A different thing you could do is make a spline from the edge and use that to drive a object that could be then taken away from the solid. Making surfaces gives a lot more flexibility, but sometimes you can cheat like using a variable fillet for radii. If you had the same ability with chamfer then you might could cheat since in all reality it will never be the same size all the way through that type of part.

 

HTH

[MotorCityMinion]

"If you had the same ability with chamfer then you might could cheat since in all reality it will never be the same size all the way through that type of part." Truer words were never spoken.

 

At first I thought "How simple, only 3 objects, I'll whip this up in seconds. MC slaps me around some so I open up SW. It takes 5 objects and a boolean remove. 45.deg. no problem, but the width becomes variable all around and looks awkward. Scrap that idea. I then create a constant width rad around the edge and use those sections as drive curves to create a surface fill, extend those edges, thicken, then boolean remove. Edge is completely uniform in thickness but only checks 45. deg. at the top, something totally different around the bottom though. If I had to, I guess I could make multiple cross sections and do some fancy lofting to get it to look real good, but like Crazy said, it will never be the same all the way through so why bother.

[RandleXX]

Use a ballmill rather than a chamfer tool. It will be slightly concave, but just use a large enough ball mill to keep it within the required tolerances.

[WildBill9000]

I was pondering trying to convert a 4th axis toolpath to geometry and using autocad to extrude a chamfer along the toolpath.

[mchin-pilot]

Randle got the point in right diretion without ballnosing it.

It will need trick and playing around to get optimum center line toolpath for a ball nose cutter.

Once you got the center line close to correct, you can drive your cutter with 3d contour.

[WildBill9000]

Yea but I can't draw it yet...