roughing cut

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mrbill62
Posts: 14
Joined: Sat Oct 24, 2009 12:44 pm
Model of CNC Machine: cnc shark
Location: EauClaire Wi

roughing cut

Post by mrbill62 »

This is my first post so I hope im in the right area.I have a cnc shark and when using vector art 3d machinist doing dish carvings is ther a rule of thumb when to make a roughing cut? I am using ball nose 1/8 and 1/16 cutters for finishing tool path

GaryR6
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Re: roughing cut

Post by GaryR6 »

Welcome,
I use the rough cut, even if it only takes a few minutes. For me it is worth the time, although I have friends that go straight to the final cut. I suppose if its a shallow cut then it may not be worth the time and set up. The previews tell me if there will be any material removal on the rough cut. But you know, I do my best work when I go slow and follow the process. For me, speed mucks things up (and damages or breaks bits). I am not in the production world so I can take the time.
I have a shark pro and have been cutting for about a year. Hope it helps.

mrbill62
Posts: 14
Joined: Sat Oct 24, 2009 12:44 pm
Model of CNC Machine: cnc shark
Location: EauClaire Wi

Re: roughing cut

Post by mrbill62 »

Yes this helps, I was wondering if I was unnecessarly doing an extra step

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GripUs
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Re: roughing cut

Post by GripUs »

If I am doing the dished out version I never do a roughing pass. Most of mine are done with 1/8" ballnose bits,180-200 ipm and a 6-9% stepover.

Joe
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http://www.gripus.com/

jhop
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Re: roughing cut

Post by jhop »

I wonder if James B has an opinion on this.

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JamesB
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Re: roughing cut

Post by JamesB »

I generally think machining choices are often down to personal preference and have so many variables its hard to give someone specific advice. Certainly most people on this forum have way more experience of actually carving the parts than I do too!

Generally though I would say Joe's way of doing this is pretty typical for most customers on dished part. As long as the toolpath starts on the edge of the dish then you know the first cut is going to be very shallow and so not load up the tool at all. After that as long as you have set a typical small finish stepover <10% then each pass is going to just remove a very thin slice off the area its cutting and the shape of the dish creates a natural ramp in and out. So you can get away with a much deeper cut than you normally would without roughing it. I have seen people cutting into an un-roughed block using the 1/8" tip diameter tapered ball noses cutting up to 0.5 inch deep at normal finish speeds and getting good results. Which is essentially what Joe said but more succinctly :)

Cheers,
James

mrbill62
Posts: 14
Joined: Sat Oct 24, 2009 12:44 pm
Model of CNC Machine: cnc shark
Location: EauClaire Wi

Re: roughing cut

Post by mrbill62 »

I havent done many 3d carvings yet so im shure practice will help, but I like the idea of no roughing cut because when I change bits my z axis is sometimes hard to get exact

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Tony Mac
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Re: roughing cut

Post by Tony Mac »

Worth noting that a roughing toolpath could be calculated using the
same cutter being used for the finishing. This will quickly remove the
excess stock using a larger stepover and an allowance. The roughing
and finishing toolpaths can then be run without needing to change
the cutter.

Tony

mrbill62
Posts: 14
Joined: Sat Oct 24, 2009 12:44 pm
Model of CNC Machine: cnc shark
Location: EauClaire Wi

Re: roughing cut

Post by mrbill62 »

Good one Tony, Ive learned alot from my liitle post. Thanks

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