Drill hole for G41/G42 path & feed control

BigJohnT wrote:

grandixximo wrote:

@BigJohnT

If you play it on EMC you can see where the machine will plunge in, and understand what i mean for it's random, i could say it's unpredictable....

I'm following almost to the letter the example that is show on the linked page above, the problem is that as you say the lead in when progressing into a cutter comp profile will depend on your start point and the side of the line you start your lead in move, as you see in the g-code i have to plunge at the beginning of the lead in, so it's difficult to predict this position unless you know exactly how EMC calculate the lead in move, and still it will get some thinking.

I apologize for the use of the word random, it maybe exaggerated, but i think i can freely say that it's hard to predict where the side miller is gonna go down.

One thing missing from your g-code is a pre-positioning move. Your starting your compensation lead in from an unknown position which will give you random lead in moves. You always move to a known start point before the G41/42. And I see that I left that off in my example g-code on that page... I have the exit moves but forgot the entry pre-positioning move, sorry.

I can't see from the g code why you have to plunge during the lead in move...

John

I don't start from a position, i start from the tool change position, T2 M6 goes to take the tool 2 in the tool change position, from there i activate Tool comp.
resulting in this

You see that small arc that the machine does before going on the G42 offset path, that small arc is unpredictable.

Ok i got you, i should first move to 0,0 then start, in that manner i think the position would be more predictable, i'll give it a try...

Still if there was an option to disable that small arc, it would be better in my point of view, from whatever position i come from i would start from the offset of my original path, and i can calculate that...

Also what do you think about the feed rate to match the programmed feed at the cut surface??

I would have to do that for each line and arc of my path?
Then what's the advantage of using G93 Inverse time mode?
Wouldn't it be easier to just calculate a feed for the arcs, and set that feed only on arcs, and then reset default feed for lines?

Once you know the ratio between radius of path and radius of tool, you just need to multiply feed by that ratio and set it on arcs only.

any plans to implement constant feed on programmed path?