Stepover in a 2D Profile Toolpath

[BJRphbow]

I use a combination of VCarve Pro and RhinoCAM at work. When I cut a profile toolpath in "thick" material (3/4 MDF), I prefer to do a stepover so that the slot that is machined in the material is a bit wider than the bit ... this helps to clear out chips (especially useful when using a straight cut bit). In RhinoCAM, this is pretty straight forward as there is a stepover setting in the profile toolpath, however I can't find a setting for a stepover in VCarve Pro's profile toolpath. Is there a setting or strategy I'm missing?

Thanks in advance,
Jeff

[Adrian]

In VCarve you would use the Do Separate Last pass setting. Make sure you have Show advanced toolpath options checked in the toolpath to see it.

[BJRphbow]

"Do Separate Last pass setting"

I'm familiar with this setting but that only helps clear chips with the "last pass". All previous passes will be a single slot cut until it gets down to the last pass. I'm looking to do a stepover for each pass from top to bottom.

My last job was 1-1/2" thick letters made from MDF. I used the "Separate Last Pass" for the clean edges, but until I got down to the last pass, the chips were not clearing out of the narrow slot. Ideally, I would like to be able to do a stepover starting form the top. I'm guessing this isn't an option ...

Thanks.

[Adrian]

How many passes are you doing? I cut MDF in two passes with a down cut bit (first pass offset 1mm and 3/4 of the cut depth, last one the rest and no offset) and if I'm using an up cut bit I do it one pass right up to 32mm thick.

I can't think of any easy way of doing it with more than two passes if you want each pass to step sideways. The only thing that springs to mind is multiple toolpaths with different start depths and allowance offsets then use the merge toolpaths with the by part feature so each set of toolpaths completes before moving onto the next one.

[BJRphbow]

I'm using a 1/4" diameter straight cut bit ... the straight cut gives me the cleanest/crispest top edge in mdf. In the 1-1/2" material, I did four passes which means I wasn't getting good chip clearance for the first three passes. I tend not to go deeper than the diameter of the tool but with MDF I'm comfortable pushing it a little, but wouldn't be comfortable with just two passes at 3/4" deep each. I could always invest in a deeper cutting 1/2 diameter bit and go for just two passes with the offset.

Sounds like there's not an easy software solution, which is not a big deal. If stepover wasn't available as a setting in RhinoCAM's profile toolpath, I wouldn't have considered it for VcP. It comes in handy for expelling chips in deeper material and when cutting aluminum to minimize chips "smearing" the side walls of the machined slot.

Thanks for the suggestions.

[Adrian]

Try a 1/4" spiral down cut bit or upcut if you've got hold down facilities. I've been cutting 30-40 sheets of 8x4 mdf a week for well over ten years now and that's pretty much the only bit I use in my ShopBot. The edges are cleaner than the factory cuts.