V-Bit Stepover and Stepdown Recommendations

[jdervin]

New computer and having to rebuild my tool database in Part Wizard...

I know that the basic rule-of-thumb for end mills is 40% of the diameter for stepover and up to 1.5 x diameter for stepdown, but I can't remember the similar numbers for use with V-bits; particularly the Onsrud 37-82 (1", 60°) that comes in the SB starter kit.

I've also come to the realization that I don't really know how stepdown relates to V-bits when they're doing 2.5D cutting or how stepover is applied since they come to a theoretical point.

Any help most appreciated!

[steve_g]

John

Part Wizard? please tell me that was a typo!

SG

[mtylerfl]

New computer and having to rebuild my tool database in Part Wizard...

I know that the basic rule-of-thumb for end mills is 40% of the diameter for stepover and up to 1.5 x diameter for stepdown, but I can't remember the similar numbers for use with V-bits; particularly the Onsrud 37-82 (1", 60°) that comes in the SB starter kit.

I've also come to the realization that I don't really know how stepdown relates to V-bits when they're doing 2.5D cutting or how stepover is applied since they come to a theoretical point.

Any help most appreciated!

I'll take a stab at it...

Stepdown (I assume you mean max. depth per pass while machining?) on a V-bit helps it not hog out too much material all at once...like any other bit, you don't want to stress your bit, machine, or cause material tear-out.

Stepover settings for a V-bit matters mostly when you specify a "flat" so the bit doesn't go deeper than desired. The smaller the stepover percentage, the cleaner the surface of the flat...again, like any other bit.

I hope that helps.

[jdervin]

Steve--

No, that's not a typo. While I use ArtCAM Pro for my own work and with my advanced students, I prefer the simplicity of Part Wizard for my introductory students. I also can't justify the upgrade price to Partworks when we're so invested into ArtCAM.

[jdervin]

Michael--

In regards to stepover, are you saying that it doesn't matter if no flat area is specified?

The thing that confuses me about stepdown is that I'm not sure if it works the same as any 2D cut or if it is ignored like it is with finishing passes in a 3D carving file.

[steve_g]

"No, that's not a typo"
Ahhh John I understand. With no ArtCam investment and an AutoCAD background... PartWorks was a breath of fresh air for me, especially with versions 3+.

SG

[mtylerfl]

Michael--

In regards to stepover, are you saying that it doesn't matter if no flat area is specified?

The thing that confuses me about stepdown is that I'm not sure if it works the same as any 2D cut or if it is ignored like it is with finishing passes in a 3D carving file.

Hi,

The stepover can affect the "cleanness" of a v-carve in general, but it's the "clearance" stepover setting (when specifying a "flat" area for a v-carve) that the stepover percentage can have a very noticable effect in quality (i.e., the flat area will have more noticable toolmarks at higher stepover percentages).

I don't if that helps or not - perhaps others will have opinions/knowledge/experience they can offer that may better explain this.

The stepdown (max pass) settings are not ignored in this case. Imagine cutting with a hand router...if you try to hog out too much material, you may have tear-out, burning, etc. The stepdown allows you to incrimentally (sp?) remove material with each pass, just like the way you would do when hand routing. As far as I know, all software for toolpathing for v-bits, obey this line of thinking.