perimeter issues

[alk-3]

Hey Everyone. I've just downloaded the MadCAM trial, and am thinking about buying it. I've been playing with my new cnc machine, and trying to get the g-code sorted out before I actually cut some parts. I have a question regarding the stock size in MadCAM. When I select the part to be milled I get the green box defining the theoretical stock size for the part to be machined. the problem I have is that it's milling away all the waste rather than just cutting out the outline of the part. For instance, I'm trying to mill a carved top guitar body. madCAM sets the tool path to mill away all the waste so it takes forever to actually finish the part. is there some way to set it up to just carve the top, then just cut around the perimeter, leaving the waste as a big solid piece I can discard, rather than reducing the whole waste piece to sawdust on the mill itself?

[warrguitars]

I would either make an "offset curve" about .5 of an inch than your profile and then use it as your "Select Region Curves" in MadCAM or make an "offset curve" about .5 of an inch, extrude it as a solid and them select it as a "Select Model Stock" in MadCAM.

[warrguitars]

I find that if I make the profile curve 1/2 the width of my tool (larger than the original profile curve) that it works best for my purposes. In my previous post I stated .5 larger... Sorry for being too vague.

[alk-3]

okay, I did as you suggest.. sort of. I have no idea what I'm doing with rhino or madcam, so I am totally stumbling along and trying to figure things out as I go. I have no background in this stuff, so I'm totally lost.. having said that, I have managed to create an offset curve, and then I selected it, extruded it to be 10mm high, then when I clicked on "select model stock" in madcam, I get a message saying that the function is not supported in the entry level version of madam.. there must be some way to do this.. if I select the part, get the green box, them make a tool path but check the little box that says exclude all flat surfaces, I get almost what I want, but not quite..

[warrguitars]

Did you click all three aspects of the trial version when madcam firsts starts up?

Make sure pro is selected for evaluation.

Make sure your stock box is at least as big as your part. One trick I have found is if you start the process of madcam by clicking the "select surfaces", the working bounding box appears. I then use this "working box" as my way of "snapping" the extrusion of the offset curve you made from your profile. This way your guitar body "model stock box" object is the exact same height of the working bounding box that was created when you did the "select surfaces" of madcam. Then after tool selection, you click the "select model stock" button in madcam.

Hope this helps. I am very much a newbie with madcam - 22 days left of trial

So far I like it. I have been using rhinocam for several years now and have been happy with it. I downloaded madcam for the heck of it and now I am finding myself really liking it. If your very new to cad/cam then I think that madcam is great for guitars due to the ease of madcam.

[alk-3]

yes, by default all three boxes are checked when madcam starts up. I tried it again, and unchecked the entry level box.
I have made the extruded curve the same height as the bounding box, so that doesn't seem to be the issue. the box is the same size as the piece to be carved so no issue there.
I'm getting frustrated that such a simple task is eating up hours of tinkering with this stuff. I just want it to cut out the outline, it seems like it should default to this option to begin with, rather than place a huge box around the piece.

[warrguitars]

It seems like most cam programs create a bounding box as its part stock. In Rhinocam you need to have the pro version to make a custom stock; just like madcam does. Sorry you are having trouble with it at this time. Maybe try to uninstall and re-install madcam again.

For the time being, make the entry level bounding box and use your offset profile curve as a region in the madcam box area. That should do the trick until Joakim can help you (write him an email). In the simulation mode you will still see a big block but the cutter will do what you want; cut just the profile.

[Rodent]

Curious ... You note you're hacking your way thru. Have you considered completing the basic training exercises that are downloadable for Rhino and others online at the MadCAM site? You really should have a reasonable understanding of the Rhino basics prior to diving into any CAM package - bad geometry modeling workflows equal poor quality gcode no matter what CAM package you use.

Also, to cut the body perimeter/outline, why manually create an offset curve in Rhino when you can simply specify leaving x amount of material when you cut the curve? I only create a parallel offset curve on something like a neck pocket where I want to rough the pocket but cut the depth correct, and then follow up with a clean up cut to detail the pocket walls


You could also outline your workflow so that it can be checked, and then dive further into niche details. No sense digging on a misplaced process step when OT would be irrelevant if everything was done in the right order. Make sense?

All the best,

R

[svenakela]

Yes, as Rodent says you can use the edge curves of your guitar body as a 2D curve and then specify in the cutting dialog if material should be left. It actually works in both directions, either you keep material or you can cut off more than the curve. I do that almost every time I cut a laminate core to compensate the thickness of the laminate.

What you should use for your profiling is't a 3D toolpath, you should use a 2D contouring.
Here's an old but still valid example of 2D pocketing and contouring.
MADCAMCNC: Making an extender with 2D contouring

[svenakela]

Yes, as Rodent says you can use the edge curves of your guitar body as a 2D curve and then specify in the cutting dialog if material should be left. It actually works in both directions, either you keep material or you can cut off more than the curve. I do that almost every time I cut a laminate core to compensate the thickness of the laminate.

What you should use for your profiling is't a 3D toolpath, you should use a 2D contouring.
Here's an old but still valid example of 2D pocketing and contouring.
MADCAMCNC: Making an extender with 2D contouring

[alk-3]

Originally Posted by Rodent Curious ... You note you're hacking your way thru. Have you considered completing the basic training exercises that are downloadable for Rhino and others online at the MadCAM site? You really should have a reasonable understanding of the Rhino basics prior to diving into any CAM package - bad geometry modeling workflows equal poor quality gcode no matter what CAM package you use. Also, to cut the body perimeter/outline, why manually create an offset curve in Rhino when you can simply specify leaving x amount of material when you cut the curve? I only create a parallel offset curve on something like a neck pocket where I want to rough the pocket but cut the depth correct, and then follow up with a clean up cut to detail the pocket walls You could also outline your workflow so that it can be checked, and then dive further into niche details. No sense digging on a misplaced process step when OT would be irrelevant if everything was done in the right order. Make sense? All the best, R

Yes, I am doing the tutorials, but there doesn't seem to be anything relating to this problem in them, both for rhino and for madcam.

"Also, to cut the body perimeter/outline, why manually create an offset curve in Rhino when you can simply specify leaving x amount of material when you cut the curve?"

mainly because I don't know how to do this. if you, or anyone else could tell me specifically how to do this, I would be grateful.

[alk-3]

I think I'm starting to get some understanding of this, but I'm having a problem selecting curves. When I try to create a region so that I can isolate the cutting area to just the part itself and not the waste, I click on select region curve,but when I try to select the region curves, I cannot select any lines at all. nothing will highlight.