Inventor HSM Flow Strategy linear moves

[soldanr]

I would like to find out why the Flow strategy is giving me a gazilion linear moves.

I tried all different settings in tolerance and smoothing and I never seen it be this horrible.

Usually the Tolerance is always 0.0002 and smoothing is always 0.002 on my computer and it works very well.

Flow can be a strange toolpath... Possibly the best one to use on fillets but it lacks quite a bit on functionality. 😞

[andriy.badin]

Hi @soldanr

Can you share the model? Without inspecting geometry it is hard to say anything definite, but if that curve is represented as NURBS as opposed to arc, than it will be linearized.

Andriy.

[soldanr]

Sure can!

The flow toolpath is the last one. Inventor 2019

No NURBS surface used. It is an Inventor IPT file with a radius fillet. All native.

https://a360.co/2NFsvjv

[ArjanDijk]

This can never be smoothed unfortunatly. There is a lot of really small Z movement. I would use Contour in this case.

[andriy.badin · Accepted solution]

@soldanr unfortunately there is (almost) no way to accomplish smooth toolpath at the end. All ISO cuvres for Flow are linearized before passing to Kernel. Once toolpath is generated, and if you have Smoothing option toggled on, we attempt to fit generated toolpath to arcs. That's where "almost" part comes in play. Depending on combination of geometry/number of passes/tolerances you may be able to achieve smooth result. Unfortunately this is matter of guess and luck.

Unfortunately, for now there is no solution to your problem. I will talk to Kernel team to see if we can change that.

Best regards,

Andriy.

[soldanr]

Thanks for the clarification. I was wondering if I had done something wrong. I could deal with the toolpath being linearized on the XY plane. But the small Z axis movements would leave lots of tool marks. I don't get why it would do those super small Z movements on a perfect 2D curve. I would think that the smooth option would take care of it. Even a 2 or 4 thousands of a inch smooth doesn't fix it. 😞

I will stick to the contour toolpath.

Thanks for checking!

[ArjanDijk]

Smoothing is for fitting lines in arcs, not for simplifying lines

[soldanr]

I use it for a best fit of arcs in lines.

Probably the most important aspect of knowing HSM. Tolerance Vs. Smoothing 

Secret to a good Gcode is to make it very small. If it is more than 300Kb you are trying to hard.

People nowadays just go crazy on it, otherwise how would they make parts in CNCs in the 80s? 

[ArjanDijk]

You need to make it small if your machine can not keep up. Many modern machines have little to no problems with a lot of lines of code because they smooth internally.

Simple smoothing should be enough, but if you have an old machine or and slow control you need more radical solutions.

[soldanr]

Agreed... but...

If you let the modern machine solve all the shortcomings of your CAM software the elegance is gone.

Sure, My little HAAS can do 80 lines per second but a G02 or G03 makes a better arc than a G01 by far. Not to mention faster too.

Plus I don't think any modern machine could smooth the 8th line from the top very well.

[ArjanDijk]

And that is just how you see it. If the machine control is not fast "CAM has to solve the shortcomings". The problem is appearantly HSM does not see a curve. Smoothing does take a curve from your model, it assumes that when it "looks like a curve, it is a curve", so it makes up information.

I agree that Flow should be able to create cleaner toolpath then this. I hope that this is a "in progress" toolpath.