Not clear why is it that way.

Messages
5,676
Location
Catalunya
At the risk of this post being a rant I can't but complain about the "Step over" setting in the tool database. Not being english my mother tongue, and despite having a good command of it, I had problems understanding the step over setting.
To me, as a foreigner who speaks english step over and overlap are almost synonyms in this case. But It has taken me a while to really understand that the step over setting, controls the displacement of the milling bit to the side, not the resulting overlap.

I believe that it would be more intuitive if the user would decide how much overlap wants on each pass rather than having to calculate the difference between the bit diameter and the step over setting. Moreover, when just next to it Vcarve calculates the % of that value vs the bit diameter which again is not the resulting overlap unless I have misunderstood the whole thing. So, the lower the step over value is the bigger the overlap is.
I include a schema and I would appreciate any of the more experienced members in CNC what they think o correct me if I am wrong.
Re-reading this I realise it is a rant, or I am getting old for certain things probably both...

STEPOVER.jpg
 
Tony, I never even think overlap at all.

When I decide on the stepover amount I just think stepover - exactly as you have it drawn. BUT - my mind is thinking the other side of the cutter. You dimensioned stepover on the left side. To me that makes me think of what is left behind. I prefer it to be on the right side of the cutter. My mind thinks, how much is being cut away. So, if I get my percent to 7% which is where I like to set my 3D ball cutter on a 3D finish cut.

If I am roughing and just want to remove a lot of material I want my cutter to be engaged to almost the full diameter of the cut so my percent of tool engagement is going to be 75 to 90 % of the cutter

It's all about "how much material the cutter is cutting.

I have never thought about "overlap" in my home shop or in industry.

Another thought is
When using a ball nose cutter - a large stepover will neave a scalloped bottom surface, but a small stepover will nearly eliminate the scalloped surface, hence my 7% setting
 
Toni,
Using your drawing, let me simplify what Leo is saying. (Old shop teacher here. :) )
Step over value = The amount of material you want to remove on the next pass (IMPORTANT)
Overlap = Area where material has already been removed (Not important)
Stepover percentage = Stepover/bit diameter Example .125 stepover/.5 dia. = .25 or 25%
 
Last edited:
Thanks to both of you. For some strange reason I always approached it from the overlap thinking, the more overlap you have one pass on top of the other the less material will the bit remove, (no matter wether is from right to left or viceversa), and that led me to struggle with the stepover setting thinking that it wasn't self explanatory; I also guess that the language barrier helped on that.

Wayne, thanks for your comment, "step over value = The amount of material you want to remove on the next pass"! it made it cristal clear, I bet that your shop students students miss you a lot.

To be honest I am glad I dared to ask. Thanks to both of you again.
 
Top