Rest machining/tapered ball nose end mill

[Chuck Keysor]

Hello Shopbot Friends:

I am making a match pair of carved wooden decorations for the outside of a house, the Aspire model is the first attachment. I simulated roughing and first finish passes with no problem. Then I used "Rest" machining to go and clean up all the detailed areas. I first simulated the "Rest" machining with a generic 1/16" ball nose end mill. The simulation turned out as I expected, OK.....

BUT, I said wait, I do NOT have a 1/16" ball nose end mill. I have a 1/16" TAPERED ball nose end mill (Amana 46282). I had better update my tool library. The closest thing I could find in the Aspire tool library was an engraving bit, so I used that, entering the included angle of 5.4 degrees, tip diameter of 1/16", and main shaft diameter 1/4". The only thing wrong was the real bit has a radiused end, but the model shows a flat. I said, gee, what difference will that make?

I edited my existing "Rest" machining tool path to switch in the new model for my Amana tapered ball nose end mill, and created a total disaster. The hoped for little bit of surface clean up instead ripped deep grooves into my part in the tool path simulation. :( See the second attachment.

I am supposed to cut a demo version of the attached applique by Saturday. I thought I was all set. Can I model my Amana tapered ball nose end mill in some way to avoid this problem? What do I do???? Or has something else gone wrong?

Thanks in advance, Chuck

[adrianm]

Aspire supports tapered ball noses. Click New in the Tool Database and select Tapered Ball Nose from the Tool Type dropdown.

[Joe Porter]

Chuck, if you go to the tool list and down at the bottom you can select "New" and then a drop down list will come up with a "Tapered Ball Nose" option and you can go from there...joe

[ssflyer]

Hi Chuck,

Adrian and Joe have it right - unfortunately, you probably wouldn't have seen much difference, if you simply used your tapered ball nose, with the existing ball nose settings.

[Brady Watson]

Just 3D Rough that puppy out & keep the boundary vector constrained so that the 1/16" ball doesn't 'fall off the edge' of the top. Successive TP simulations will tell you where to adjust the boundary vector via node editing - then re-toolpath. Then just toolpath it with a 1/16" ball (raster) and do a 2D cutout.

I would be willing to bet that it would not take much longer to rough out & finish with the 1/16" ball than it would to get involved with rest machining, since it has a tendency to hop around a lot & eat up a lot of time. It is very rare I rest machine anymore...it's not that efficient in the real world & that part is pretty straightforward.

-B

[Chuck Keysor]

Thank you Adrian, Joe, Ron and Brady.

a) Thanks for the guidance to the tapered ball nose end mill template! But Ron, you were right, I didn't see any difference.

b) I must have messed up something else when I switched from the standard ball nose end mill to using the engraving bit, because the both bits simulate as cutting through my work piece. I went back and tried using the standard ball nose end mill, which did work, and this time it didn't.

c) I decided to simply jump to Brady's elegant solution of eliminating the rest milling, and did all of my finishing with the 1/16th tapered ball nose end mill. That simulated without problem. I would NEVER have EVER guessed to use a 1/16th in bit for doing all of that finishing, but it fulfills the old saying that the best solutions are the simplest solutions. (Is that Achem's Razor?)

Thanks again! Chuck

[Joe Porter]

I think this may apply to this situation..While at the last Aspire Camp at McGrew's, Tim Merrill showed an example of doing a finish cut with the regular .125" ball nose and chose a toolpath color to show up on the finished piece. Then, to see of Rest Machining would be of any advantage, he figured another toolpath with a 1/16" ball nose a chose a contrasting toolpath color to show up on top of the original. This would show if the Rest Machining would be worthwhile. I think he concluded that this would show him which size ball nose bit to use in the original cut, instead of using the Rest Machine strategy at all...joe