Optirough, steps on top edge

[JB7280]

Any time I use an optirough/rest toolpath, it wants to make this little step at the top of the part.  It's almost never necessary for the sake of roughing, in my experience, and wasted cutting time.  How can I avoid this?   I can't share this file, but on this particular tool path, I have stepdown/stepup set the same, to pay attention to just the flats.  

 

[Jobnt]

I got no solution but I feel your pain. Daily. I don't remember if it was MC back in the day or Gibbs, but there was a Detect Flats feature that would try to ID all the flats in your part and set depth cuts to those. You could also type in your own step depths. 

Since most of my parts are not prismatic Opti rough really is tough to get good paths with. I'd love for some insight on how to do this. Now I just create wire geometry and use that. 

[JB7280]

3 minutes ago, Jobnt said:

I got no solution but I feel your pain. Daily. I don't remember if it was MC back in the day or Gibbs, but there was a Detect Flats feature that would try to ID all the flats in your part and set depth cuts to those. You could also type in your own step depths. 

Since most of my parts are not prismatic Opti rough really is tough to get good paths with. I'd love for some insight on how to do this. Now I just create wire geometry and use that. 

I learned from a post here, and I also noticed it says the same in the help file, that setting stepup/stepdown the same is supposed to detect flats.  But it doesn't seem to work like it should very often.  

[Jake L]

I also feel your pain. If there is a way to get rid of this step around the edges I'm all ears. As far as I'm concerned these cuts around the edges of the part just waste time and wear out the tool.

My understanding is this happens when you tell MC to leave stock on the floor and the walls. I'm having trouble figuring out how to explain it, but the way I think about it is MC doesn't realize it should also be leaving stock on the edge of the part. It sees the surfaces and as long as it is leaving the correct amount of stock relative to each surface, if there's still stock left, it will try to chase it. Though I could be way off in my thought process.

Here's another thread that may help: EMC Post

[TFarrell9]

1 hour ago, JB7280 said:

I learned from a post here, and I also noticed it says the same in the help file, that setting stepup/stepdown the same is supposed to detect flats.  But it doesn't seem to work like it should very often.  

Indeed, if your stepup and stepdown are equal, all flats will be cut to the correct stock amounts.

Can you share a sample of this file in question? There are usually at least a couple of solutions for the "weird" things optirough/rest will do by default.

[JB7280]

18 minutes ago, TFarrell9 said:

Indeed, if your stepup and stepdown are equal, all flats will be cut to the correct stock amounts.

Can you share a sample of this file in question? There are usually at least a couple of solutions for the "weird" things optirough/rest will do by default.

Tomorrow I'll try to recreate it on a different model that I can share.  

 

As far as detecting flats, I have another part, where I used same stepup/down and it didn't seem to pay any attention to the flats rule.  There was a large radius on the part that is still wanted to treat as though there were .050" stepups.    Parameters set to .300" stepdown, .300" stepup.

 

[TFarrell9]

26 minutes ago, JB7280 said:

Tomorrow I'll try to recreate it on a different model that I can share.  

 

As far as detecting flats, I have another part, where I used same stepup/down and it didn't seem to pay any attention to the flats rule.  There was a large radius on the part that is still wanted to treat as though there were .050" stepups.    Parameters set to .300" stepdown, .300" stepup.

 

That's interesting. I can't say I've ran into that from memory, so an immediate solution doesn't come to mind. I'd be curious to see a sample of that file as well if possible of course.

[Leon82]

That's because to leave the stock correct amount there should be a radius there. If it's square there is more stock at a 45 degree angle.

 

You could dynamic face it, then set the optirough below the top of the part. Or make a dummy rough solid and use no stick to leave.

[Aaron Eberhard]

There's a few situations where this can happen.

As Jake L says, if you tell it to leave .05" or whatever on your rough surface the model it will machine against is "puffed up,".  If you have something like a 1" deep part, and you're telling it to take a 1" DOC, it will recognize that the part is now 1.05, so it has to do an extra step to not engage that additional material.  

Especially if you're using stock models to drive it, It could also be that the depth of the stock compared to my stepdown means that there's a smidge of material left at the top, and the math means there's a few thou of material at the top so it does an additional pass to clean it up.

In either case the easiest solution is to use the "Steep/Shallow > Minimum Depth" set below the top of the part.  For example, if your Z0 is the top of the part, maybe set the Minimum Depth to -.1":