strange pocket error

[knighttoolworks]

this is on aspire 3.504 and it is a simple pocket with a ball nose bit. when I cut it to a depth of 1.5" with one toolpath it was fine. but there were toolmarks on the bottom. so I copied the toolpath told it to cut 1.45" deep then the second tool path to start a 1.45 and cut .05 with a much smaller stepover. but the cut is way past the vectors for some reason. looks like it cuts in about 1/8" larger. it does not show in the toolpaths but if a preview it does.

[mezalick]

A curious problem.
Can it be possible that you have two tools in your data base, both named Ball Nose .75 ball,,but one is actually a 3/8” ,,,, not 3/4” ??
If so, maybe the program picked up the wrong bit info...

Just thinking..
Michael

PS,, but that would not account for the larger size pocket....still thinking....
~M

[BrianM]

Hi Steve,

For your 2nd toolpath you have a start depth set of 1.45 inches. This tells Aspire that there is nothing of interest above this height, it is as though the surface of the job was starting at this height. You then cut a pocket 0.05 inches deep with a large 0.75" diameter ball nose.

When you cut a pocket, the vector you have selected represents the TOP edge of the pocket. As the ball nose tool comes much higher than 0.05" depth you have requested, the toolpath is offset out so that the ball nose tool at a depth of 0.05" exactly cuts on the line you have told the software represents the edge of the pocket.

The Start Depth setting is usually used for machining features in the bottom of already machined pockets, if you were using an end mill you could get away with the approach you are using as it has parallel sides, with a ball nose you would need to set the cut depth to 1.5" for that toolpath if you wanted a single pass.

Brian

[knighttoolworks]

When I have done this I have only done it with a straight bit. but the customer likes the lip it causes so now I need to do it with a regular toolpath. post pics in a little bit.

[knighttoolworks]

so I could also just use a 3/4" straight bit and it would work. but the cleanup pass takes too long adds too much cost.

[knighttoolworks]

here is a pic. we liked the lip this is a salt holder and the lip keeps the salt in. but the ballnose bit rubs under and on the shaft adding the lip. so the error was good but even when I got it to work without the notch the cut was too rough.