[killersoundz]

Hi guys I have a bunch of orders to fulfill and I thought I had this issue ironed out by telling mach3 to switch to exact stop mode on angles above 89 degrees but on random corners it still seems to try to run them in constant velocity mode.

It seemed fine the last program I ran but since then I did reduce my acceleration on my x axis but I also don't feel like that's relevant, otherwise feeds and speeds are the same.

It's not a gcode issue, i'm using vectric aspire and the rounded corners aren't consistent from vector start points or anything it really just seems random.

I can't afford to make anymore scraps, if anyone can tell me some settings to look for or change it would be highly appreciated.

Since these programs are just squares and rectangles you think I should just switch to exact stop mode for these? My only concern then is when I do run a program with other shapes or engraving and I know that stuff runs terrible in exact stop mode so I'd like to figure it out while leaving it in constant velocity if possible.

random rounded corner


good corner

[ger21]

Reducing the acceleration is likely the culprit. In CV mode, the lower the acceleration, the more rounding you'll get. If acceleration low, Mach3 needs to start turning the corner sooner in order to try and maintain constant velocity.

If you look at the toolpaths in Aspire, you'll see that the toolpath "rolls around" the corner, which is common practice.
The problem is that there is no 90° corner in the toolpath, so setting Mach3 to Exact Stop at 89° has no effect.
The "corner" is a 90° arc tangent to the sides, so there is no corner.

You'll need to increase acceleration, or cut slower.

I don't think it's possible to get toolpaths from Aspire that don't "roll around" the corner, but I'm not positive.

[killersoundz]

Reducing the acceleration is likely the culprit. In CV mode, the lower the acceleration, the more rounding you'll get. If acceleration low, Mach3 needs to start turning the corner sooner in order to try and maintain constant velocity.

If you look at the toolpaths in Aspire, you'll see that the toolpath "rolls around" the corner, which is common practice.
The problem is that there is no 90° corner in the toolpath, so setting Mach3 to Exact Stop at 89° has no effect.
The "corner" is a 90° arc tangent to the sides, so there is no corner.

You'll need to increase acceleration, or cut slower.

I don't think it's possible to get toolpaths from Aspire that don't "roll around" the corner, but I'm not positive.

Now that's the kind of response I'm looking for. Thanks man that all makes sense. One question what would you say is a minimum acceleration number to get away without much issues with constant velocity. My x axis really needs as low acceleration I can get away with

[ger21]

It's directly related to how fast you are cutting. You can get away with an accel of 10-15 in some cases, if you aren't going too fast.

[killersoundz]

It's directly related to how fast you are cutting. You can get away with an accel of 10-15 in some cases, if you aren't going too fast.

Ok cool. My x axis will do 20 but it's much happier at 10, and 15 hits a resonance for some reason. I had lowered it to 5 that's when I encountered these problems lol thinking it would be real happy there. It is mechanically but obviously not running the program. I'm back at 10 and it's actually doing fine now. 126ipm. I'll need to build a better machine to go much faster I guess

[Bashidap]

This was Usefull Gerry! What happens if you increase the acceleration too much? I dubbled it and till now it looks good.

[ger21]

The only negative to high acceleration is that it can cause your machine to shake if it's not rigid enough.
Generally, the higher the acceleration, the better.

[davy182]

If you have a newer version of the program there is a round or sharp corner feature in the toolpath area that drove me nuts until I found it

[davy182]

it is in the corners feature.

Ramps Leads Order Start At Corners