3D toolpath trouble for simple groove

[Blackhawk]

I know that I have to be missing something simple, but I cannot get this to work right. I just want to use a 1/2" ball endmill to create (2) 1.0" wide grooves and (2) 1.125" grooves at a 30° angle. I want the depth to be half of the width. I created the 3D components using a 2 rail sweep. My rails are exactly 1.0 and 1.125 apart and the half circles are exactly 1.0" and 1.125" diameter, respectively. I did my 3D roughing and finish toolpaths based on the "model boundary". It works for the most part but I get all these squiggly lines at the top of the groove where it meets the top surface for the finish toolpath. You can see this in my picture in the both the preview screenshot and 3D view. I have the finish toolpath set to raster at 30° to match the groove orientation, so all the lines should be straight. They are straight at the bottom of the groove, but not at the top. I cannot figure out why.

The 3D roughing toolpath has a similar problem at the top as you can see in the pic. It is worse on one side of the groove than the other.

The other strange thing is that when I go to my material setup tab from the toolpath screen. It always has my "gap above model" set to .015". If I change it to 0", it updates and sets it to .005". Then I can just hit OK, and when I go back to the material setup, it has changed the "gap above model" back to .015"???

Please help, thanks

[mtylerfl]

Did you add a Zero Plane? (standard procedure for negative Raster carve items like this)

Can you post your file so we can help you figure out why the gap is changing?

[Blackhawk]

Here is my file. I had to just leave in one groove to get the file size down. I thought the zero plane was automatic? If I added one, I didn't know that I did.

[Adrian]

The zero plane is not automatic as it's not always needed. You can add it from the Modelling tab. It's the last icon on the top row.

[Blackhawk]

Michael and Adrian,

The zero plane helped to smooth up the edges for the 3D roughing toolpath, thanks. But, Aspire now wants to machine the entire flat surface between the grooves since the zero plane is a component now. I added vectors around the grooves that extend .25" past the material block, since I am using a .50" ball nose, see first pic. I then edited my toolpath to use these vectors as the machining boundary. But, even though the vectors extend only .25" past the material the preview shows the endmill dipping down below the bottom of the grooves at each end. The toolpath would have to be violating the vector boundary for this to happen, so I am a little puzzled on that??? I attached a 2nd pic showing the 3D roughing toolpath where you can see this.

For the finish toolpath, I still have the squiggly lines at the tops of the grooves. I still do not understand why? Pic attached.

Thanks,
Brad

[mtylerfl]

You have your models falling off the “edge of the world”. That’s why you see the tool plunging at the end.

Make your material size larger so that it encompasses the complete area of your models and vector boundaries.

Then use a Profile to cut out the piece to desired size. Or, if your actual material is a fixed size, you can still use the above procedure to make the Toolpaths behave (without a Profile cut out), but you’ll need to pay close attention to how you set your XY zero location in relation to how you place your material on your machine bed! Could potentially be a bit of a brain-teaser.

[Blackhawk]

Michael - I just tried making the boundary vectors line up with my material. In other words, I go rid of the .25" offset on either side of the material. This fixed the tool drop off, see pic attached. I guess the vector boundaries must contain the center of the tool instead of the OD of the tool.

I still can't get rid of the squiggly lines for the finish toolpath though, any ideas?

[mtylerfl]

Hi,

As mentioned previously, you make the material larger so that your models and boundaries don’t fall off (or meet or line up with) the edge. Making your boundaries line up with the edge doesn’t solve the squiggle problem, as you have seen.

Yes, make sure the end boundaries extend beyond the ends by at least the largest bit radius or, as I usually prefer, the Bit diameter. Also make sure the boundaries are contained within the virtual material setup (not even with with the edge).

[rscrawford]

You will never get a good result using a finish tool path on these grooves. This is where you should be using the moulding tool path. The moulding tool path uses vectors to create the tool paths, rather than 'pixels'. Much more accurate. As well, you can vary the stepover so it cuts more smoothly on the vertical walls of your 'groove'.

[Blackhawk]

Michael - The squiggly lines are within the boundary of the model. The grooves are running at a 30 deg angle and I have the finish toolpath set to raster at the same 30 deg angle. In this way the tool will travel in a straightline. As you can see in the zoomed in picture, the 3D finish toolpath lines are straight in the bottom of the groove, which is what they should be. As the finish toolpath gets about 1/2 way up on the sides, the Z coordinates start going up and down which is why you see the squiggly lines. Why would the toolpath lines be straight in the bottom and then changeover to squiggly?

[rscrawford]

That has to do with the resolution of the model (made up of square pixels rather than smooth curves).

Use the moulding tool path instead and you will get perfectly smooth cuts because it uses vectors rather than pixels.

[rscrawford]

Here is what your cut file would look like with the moulding tool path.

[Blackhawk]

Russell - That worked, thank you! I had never used the moulding toolpath. I just recently upgraded from 4.5, so that is a new feature for me.

The only minor thing that I noticed is that on the one top edge, the tool cuts into the top face about .011" deep for just a short distance. This area is shown on the right side of my attached pic, where the red arrow is. Did you see this in the file that you created?

Thanks,
Brad

[jimwill2]

You may have done this but when you set up the moulding toolpath and select the tool, if you check the "vary stepover" as you come up the sides it will put the cuts closer together for an even smoother cut.

[Blackhawk]

If I add any boundary offset at all, the small area that was cut at the top goes away. From the pic attached, you can see that I only have a .001" offset and that step is gone. Must be a glitch.