Filter or not to filter?

[Rob_Bish]

Surface High Speed Scallop. Was wondering what most people do in the way of filter ratio in general.

[mcpgmr]

I don't do allot of scallop but 2:1 seems to be the way to go when I do. Not going to sqeeze to much more out of it at 3:1 if any at all. JMHO.

[Guest CNC Apps Guy 1]

If I'm running HPCC mode off a Dataserver, no filter when finishing.

[Justin Beebe at Folsom Tool]

I've only ran scallop not high speed scallop, but I do as Paul does 2:1 with my total tolerance set to .001 or less for finishing. If I don't have a lot of memory and I am roughing I set my total tolerance to a higher number. It creates less code and most of the time I can get away with a less accurate toolpath on my rough opeation.

 

Justin

[DavidB]

James,

Does a non filtered finishing toolpath give a better surface finish than a filtered toolpath when using HPCC from a dada server?

 

If so why is this?

 

I would have thought any arc in the gcode would be a smother motion on the machine than small point to point moves even under HPCC.

 

Thanks

[Müřlıń®]

Point to point will always be more accurate.

There are always slight deiviations on circular interpolation depending on your tolerances set.

 

On the new HPCC controls, they filter the point to point for you that is why you do not need to use a filter in MC.

 

That is why you get the better finish on a Robodrill because of the "nano interpolation"..

 

These controls look as much as 500 blocks ahead blend the point to point paths into a smooth spline just like Mastercam's filter.

 

[ 05-02-2007, 09:26 AM: Message edited by: Murlin ]

[Rick46]

I use HPCC on the machine I run but use filtering of a 3 to 1 ratio.. makes for much less toolpath size ... dont notice any real difference in finish part...

[DavidB]

Take a simple surface finsh contour of a internal cone shape for example.

If I use filter I get arcs in the XY plane, if I don't the gcode is all point to point moves.

 

The filtered toolpath is much shorter and it verifies in Vericut and MC's verify much much quicker.

 

If the control is going to take the point to point moves and create arcs anyway why not do it in MC?

 

Interesting topic this one.

[Justin Beebe at Folsom Tool]

Dave,

 

Dave you make an excellent point about using the filter and the speed of verify. It is much faster.

 

Justin

[daryl_y]

Depends on your machine, we have some OKK's 2 VM5's and a VM900 with the Neomatic control. I got a bad finish once filting out surfacing op and I have not used it since. When running from the machines hard drive memory is nearly limitless anyway. I might turn the filter on to make the path verify or regen faster but I always turn it off before I post.

[Guest CNC Apps Guy 1]

In MY experience the non filtered path ran smoother in the machine. I didn't test for surface finish though.

[DavidB]

Thanks James smoother usually means better surface finish and quicker cut time.

I've always used filter 2:1 I'll do some non filtered toolpaths and see what happens.

 

[Guest CNC Apps Guy 1]

Be prepared for lots of code.

 

Here's some results for the various Look Ahead Styles ...

 

To say the difference in Performance of G8P1 and G5.1Q1 is stark is being FAR too kind. I'll let the numbers speak for themselves...

 

Fanuc Robodrill MATE

Fanuc Oi-MC Control

Programmed Feedrate of 250 IPM

 

1. NC Program - G5_1Q1ABS.NC

o Cycle Time – 1:27

o File Size - 52 KB

o HSM Algorithm - G5.1Q1

o Absolute Programming (G90)

o Arc Filtering

 

2. NC Program - G5_1Q1INC.NC

o Cycle Time – 1:27

o File Size – 50 KB

o HSM Algorithm - G5.1Q1

o Incremental Programming (G91)

o Arc Filtering

 

3. NC Program – G8P1ABS.NC

o Cycle Time – 3:07

o File Size – 52 KB

o HSM Algorithm - G8P1

o Absolute Programming (G90)

o Arc Filtering

 

4. NC Program – G8P1INC.NC

o Cycle Time – 3:07

o File Size – 50 KB

o HSM Algorithm - G8P1

o Incremental Programming (G91)

o Arc Filtering

 

5. NC Program - G5_1Q1ABS-NF.NC

o Cycle Time – 1:47

o File Size – 126 KB

o HSM Algorithm – G5.1Q1

o Absolute Programming (G90)

o No Arc Filtering

 

6. NC Program - G5_1Q1INC-NF.NC

o Cycle Time – 1:47

o File Size – 119 KB

o HSM Algorithm – G5.1Q1

o Incremental Programming (G91)

o No Arc Filtering

 

 

7. NC Program – G8P1ABS-NF.NC

o Cycle Time – 11:34

o File Size – 126 KB

o HSM Algorithm – G8P1

o Absolute Programming (G90)

o No Arc Filtering

 

8. NC Program – G8P1INC-NF.NC

o Cycle Time – 11:34

o File Size – 119 KB

o HSM Algorithm – G8PQ1

o Incremental Programming (G91)

o No Arc Filtering

 

9. NC Program – G8P1G5_1Q1ABS-NF.NC

o Cycle Time – 1:47

o File Size – 126 KB

o HSM Algorithm – G5.1Q1 & G8P1 Simultaneously

o Absolute Programming (G90)

o No Arc Filtering

 

10. NC Program – G8P1G5_1Q1INC-NF.NC

o Cycle Time – 1:47

o File Size – 119 KB

o HSM Algorithm – G5.1Q1 & G8P1 Simultaneously

o Incremental Programming (G91)

o No Arc Filtering