Is a roughing pass always needed?

[Davo]

I use the recessed bowl version of the models and the finishing pass always starts on the high side working deeper, to me it seems like I could just run the finishing as it would gradually go deeper instead of starting deep

Would same me a lot of time, does anyone ever skip roughing?

[Kyle Stapleton]

The default final pass for 3d is set for .040" so if you need to cut deeper you should do a roughing pass. Of course it depends on what you are cutting. Ex: hard maple final .040" foam could be deeper.

[Davo]

In aspire my final finishing pass goes full depth right off the bat, I do not see the option for depth control in it

[Ger21]

Lot's of people skip the roughing.
It works best with a tapered ballnose, as they are much stronger than straight shanked ballnose bits, especially small ones.

[dmidkiff]

When ever I use the dished version of the 3D model, I very rarely used a roughing pass. I used raster with the grain and only very little material is cut. The most that is cut is the very first line and unless you make a mistake and start too deep in the wood you only cut small amount of material. If you make a mistake and start too deep, the first line is the only line that will cut a lot of material. You should be using 8-10% step over so all cuts after first one is removing small amount of material. Hope that made some sense.

[Davo]

I should have mentioned it's a tapered 1/8 ballnose

[dmidkiff]

The Onsrud tapered bits from Gary Beckwith are really good ans strong.

[scottp55]

Near bottom of this thread, Dale did some experimenting with no roughing pass.
http://forum.vectric.com/viewtopic.php?f=2&t=22051

[cowboy1296]

I typically have a lot of z in my 3-d. So i dont do it and always do a roughing. But that said i am not convinced that i couldn't get away without the roughing.

[Brady Watson]

There's a relationship between how deep the relief is and the diameter of the bit. If you are cutting out clipart - then the chances are pretty good you don't need a roughing toolpath, unless the part is large enough to warrant it.

For most things, I run a roughing pass. Sometimes it seems like a waste of time, but you can run the finishing pass faster and cleaner than without one. The tapered bits let you cheat this a bit - but it is extremely rare I run a tapered tool because many of the things I cut require straight sides. A tapered bit erodes away the top of walls.

Wood, foam and soft plastics are very forgiving. You wouldn't dream of not running a roughing pass (or 2 or 3) in any kind of metal.

-B

[Davo]

What types of speeds to yall run for finishing?

I've been doing 13k at 2ips

[cowboy1296]

just a little faster, but remember i do roughing tools paths first. but 2.6 inch per second feed and 2.4 plunge. i generally cut black walnut or cherry.