Vbit issue I can't figure out

[Sawnsand]

I have a pocket cut that uses a 30 deg V and a 1/4" end mill. Pocket is set between the letters and the border ... The end mill does it's work, the 30 deg Vbit does it's cut around the letters and then goes after the corners and small pockets. When this starts, it appears the bit drops down to another level. I have gone over the tool settings and cut depths and I can't find anything to attribute this to, any thoughts or ideas would be welcome...

[martin54]

Are you sure you are setting your z zero correctly after your tool change?
If you could post a crv file (copyright permitting) one of the experts on the forum will be able to tell you if there is a problem with your file.

[Sawnsand]

Probotix Meteor machine ... It has an auto tool sensor that checks tool after each change, I zero all axis' at the start of the file. It cuts at the proper "Z" level while doing the first part of the tool cut, it when it cleans out the corners that the "Z" level appears to change...

...crv file is too large to upload... zipped it and that seemed to work

[JoeM]

The issue shows up in the preview pane. My guess is the problem is your bit selection.

The v-bit you're trying to use for your final pass is a 30 degree, 1/4" wide bit. The spaces that are giving the problems look about 1/4" wide or less. Maybe the computer can't figure out if you want it to just cut the parts that the point can fit to, without hitting the sides, or if it should drop down deep enough in the middle so that the sides of the bit can cut the pocket you're telling it to clear?

I tried a .125 V30 and it still didn't like it. Then I tried switching out the v-bit with a 1/32nd endmill, leaving the 1/4" endmill for the roughing, and it looks like it comes out a lot cleaner.

[Adrian]

It's not showing on the preview when I run it. If you hover the mouse over the cut areas the z stays consistent (allowing for the natural grooves left) all the way over.

There is something not right about the corners where the v bit has been in the photo. They are far too rounded. I wonder if the wrong size v-bit has been used compared to what has been programmed. Perhaps the included angle hasn't been set correctly so the program is expecting a 30 degree bit but a 60 degree one is being used instead.

[Sawnsand]

"There is something not right about the corners where the v bit has been in the photo. They are far too rounded."

I went over a couple spots with a dremel tool to see if I could improve on the situation, I think that is what you are seeing....

The more I look at this it seems that my issue has more to do with the table level and workpiece thickness. Examining closer I find that the depth of the cut increases as you go down the Y axis on this job. I acquired a set of inside calipers and am going to do a bit of research on the table level and the spindle, see what I can find there

[Sawnsand]

The issue shows up in the preview pane. My guess is the problem is your bit selection.

The v-bit you're trying to use for your final pass is a 30 degree, 1/4" wide bit. The spaces that are giving the problems look about 1/4" wide or less. Maybe the computer can't figure out if you want it to just cut the parts that the point can fit to, without hitting the sides, or if it should drop down deep enough in the middle so that the sides of the bit can cut the pocket you're telling it to clear?

I tried a .125 V30 and it still didn't like it. Then I tried switching out the v-bit with a 1/32nd endmill, leaving the 1/4" endmill for the roughing, and it looks like it comes out a lot cleaner.

I broke the original 30 deg Vbit I had, which was pointed, ... when I replaced it I got 30 deg bits with a .05 flat bottom so as to clean out the corners a bit better. I will be going over the tool setting for these to see if I have them correct

[Adrian]

Are you sure the settings for the v-bit are correct? You've got the diameter down as 0.25" which is something I would expect to see on an engraving bit and the stepover very low. It should be between 8% and 40% usually.