FRV - Feed Rate Variation New Function <FRV and SSV are now standard features of CNC12 v5.2+ >

[suntravel]

Since Pecking is not available in all Intercon cycles, I made a quick PLC mod to oscillate the feed rate....



Uwe

[suntravel]

3-6-25 ********* cnckeith writes "both SSV and FRV are now standard features built into CNC12 with easy Setup in the Centroid CNC Wizard!

so no need to roll your own anymore.

thread below is left for archival only. no need to edit the PLC program. just open the Wizard and set it up and start using it!"


*********** Below is for Archive **************

Here ist the PLC, search FRV to find what I have done for this function if you want to implement it in your PLC.

Feedrate Override will not work with FRV on.

It is just a stupid simple mod done before breakfast

It would be cool if this became a canned version with sine curve time adjustable and adjustable zero feed time...

Uwe

[friolator]

Interesting. Thanks for doing this. I may have to dig into PLC stuff finally to try to implement this. I'd love to see something like this integrated into the base software though. I mean some materials just don't chip well unless you do something like this.

[suntravel]

The function on Fanuc CNC is an expensive option and it will only work with fast servos, since the oscillation is done on every spindle rotation (with I0).

Description is here:

https://newtech.cz/files/produkty/CMZ/A ... utting.pdf

But IMHO my stupid simple version (PLC is not fast enough to do this every rotation) is also a significant improvement in chip breaking with better surface quality compared to pecking.

Uwe

[suntravel]

Maybe I can make a function in g-code for a sin modulated feed attached to the spindle rotation.

I have done a math test in excel already, the orange line is feed with 0,18mm/rev, the blue line the modulated feed.

Uwe

[friolator]

But IMHO my stupid simple version (PLC is not fast enough to do this every rotation) is also a significant improvement in chip breaking with better surface quality compared to pecking.

I'm not convinced it has to be done on every rotation. I mean, at least with something like Delrin, the biggest issue is keeping the work area clear. I cut the Pawn file from a 25mm delrin rod. The first deep cut was about 1mm deep and what I had was a massive hairball at the end of the cut. Working manually, I'd have pulled the tool back and just brushed the swarf off the piece before resuming. But I decided to let it go and see what happened. So much swarf built up that it was unable to reach the end of the cut after a couple more passes.

Honestly anything that can keep the work area relatively clear of cutoff material is welcome!

[suntravel]

My PLC version is not oscillating every revolution and working ok, but the faster the oscillation the shorter the chips, with 2 times/rev there is no way a chip can wrap around the part.

But what you can try also is cutting in +Z direction, this will avoid birds nests near the chuck. Common trick for turning plastic.

Uwe

[friolator]

But what you can try also is cutting in +Z direction, this will avoid birds nests near the chuck. Common trick for turning plastic.

Unfortunately, the vast majority of what I will be making on this machine looks something like this:

...only with a deeper groove in the middle. So really it's the same problem no matter which direction you're moving the tool.

[suntravel]

For this part I would use Groove in Intercon, it is with pecking.

Uwe

[friolator]

Cool. I'll give that a try. Haven't tested that yet.