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alk-3
12-25-2011, 06:58 PM
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
12-25-2011, 07:21 PM
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
12-25-2011, 07:43 PM
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
12-25-2011, 08:09 PM
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
12-25-2011, 09:56 PM
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
12-25-2011, 11:05 PM
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
12-25-2011, 11:16 PM
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
12-26-2011, 01:22 AM
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
12-26-2011, 04:06 AM
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 (http://madcamcnc.blogspot.com/2011/01/making-extender-with-2d-contouring.html)

svenakela
12-26-2011, 04:06 AM
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 (http://madcamcnc.blogspot.com/2011/01/making-extender-with-2d-contouring.html)

alk-3
12-26-2011, 09:11 AM
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
12-26-2011, 11:35 AM
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.

svenakela
12-26-2011, 03:27 PM
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.

A region must be a closed curve.
And guess what - I have an example for that too. :)
MADCAMCNC: Making regions (http://madcamcnc.blogspot.com/2011/11/making-regions.html)

turmite
12-26-2011, 04:26 PM
alk if you don't mind making a ph call to the US, go to madcammike@gmail.com and I will talk you though this. BTW, I use Rhino/madCam for guitars as well.

Mike

warrguitars
12-27-2011, 12:19 PM
Sorry all-3 about the advice regarding the stock box. I was focusing on my project at the time which required 3d tool paths along with your concerns about a big block showing up on your project; I over looked that you were wanting to just do a profile cut.

It's great to see that there is great advice and help on this forum!

alk-3
12-27-2011, 12:39 PM
Thanks everyone for the help. I got it sorted out. Turned out the curve I was trying to select as a region was not a Closed curve. I joined all the piece together, and it worked perfectly.
Now I have a new problem. When I output the gcode and open it which mach3 the part is shown as a huge piece. It appears after a quick inspection that mach3 is maxing each mm of the model into inches. So instead of the part being 200mm wide it is 200 inches wide.
The person who initially set up and built the machine configured it for inches rather than mm. I understand this is a mach3 concern, not a madcam cencern, but does anyone have advice regarding how to change the mach3 setup to use mm? Just setting the units to mm in the drop down window doesn't actually appear to do anything.
Thanks again for everyone's help. This forum is making the learning curve very manageable!

alk-3
12-27-2011, 06:55 PM
alk if you don't mind making a ph call to the US, go to madcammike@gmail.com and I will talk you though this. BTW, I use Rhino/madCam for guitars as well.

Mike

Hey Mike. Thank you very much for the offer! I may take you up on that if I run into a particularly difficult problem.

So I've managed to get pretty much everything figured out. I calibrated the table properly, and got everything working in mm. Everything seems dialed in just right. I've become pretty familiar with the mach3 program in general, and it all seems to make sense for the most part.
I do have one new problem that I have not been able to figure out. I have the top carve set up and zeroed where I want it, and I did a few tests without the cutter, and it seems to be working really well. The only problem I'm having it the feed rate seems very slow. It's taking me quite a while to cut the part. I have set the feed rate in madCAM on the tool selection section to all sorts of different values with no change to the machines actual feed rate. I not sure if this is something I need to work on in MadCAM or in Mach3. I'm going to try googling it some more.

alk-3
12-27-2011, 06:57 PM
Sorry all-3 about the advice regarding the stock box. I was focusing on my project at the time which required 3d tool paths along with your concerns about a big block showing up on your project; I over looked that you were wanting to just do a profile cut.

It's great to see that there is great advice and help on this forum!

No need to appologize! You're advice was very helpful, as was everyone's. :)

turmite
12-27-2011, 07:19 PM
alk can you look at your output gcode and see what feedrate is set to? Just to make sure your tool bit feedrates are included in the post? What feed are you trying to cut at?

Mike

alk-3
12-27-2011, 07:37 PM
alk can you look at your output gcode and see what feedrate is set to? Just to make sure your tool bit feedrates are included in the post? What feed are you trying to cut at?

Mike

Hey Mike. The feed rate in the Gcode says F350. The default feedrate in madcam is set to 350 for this particular tool, but I have changed this value and it still outputs the Gcode with a feedrate of 350.
I don't really know what feedrate I would like it to be, but from experience, this value is much too low. My friend cuts one of these parts on his machine in 30 minutes with a 0.030” sidestep. I have my sidestep set for 3mm and the run time is 2 hours for the part.
Btw, what does this value mean? I presume it is 350mm per minute?

turmite
12-27-2011, 07:43 PM
alk 350 is only around 13+ inches per minute. Try 3500 feedrate and see if your machine runs faster. If not you will need to take a look at your post processor to see if something is wrong. Have you tried to edit your post processor by any chance?

Mike

alk-3
12-27-2011, 07:44 PM
I think in mach3 I can manually edit the Gcode to a greater value than 350, but this would be a workaround. I'd rather find and solve the root cause..

alk-3
12-27-2011, 07:47 PM
alk 350 is only around 13+ inches per minute. Try 3500 feedrate and see if your machine runs faster. If not you will need to take a look at your post processor to see if something is wrong. Have you tried to edit your post processor by any chance?

Mike

Hey mike, I'm not sure I understand how to do what you're suggesting. I've adjusted the feedrate on the tool selection pane in madcam to 3500 and the Gcode still gets output from madcam as 350. I've tried it several times with different values, and it still always outputs the Gcode as 350.

turmite
12-27-2011, 08:21 PM
alk send me the gcode file and tell me which post processor you are using. Is it custom or a std madCam Mach post?

Send it to the madcammike address. If you have a gmail account we can chat instantly as well.....makes for pretty good support

Mike

turmite
12-27-2011, 08:23 PM
alk I just thought of something. When you changed the feedrate in the tool selection pane, did you save the tool? If not, it will post at it's previous feedrate.

Mike

alk-3
12-27-2011, 08:41 PM
got it! awesome! okay, so i wasn't saving the tool, and that was the problem after all. now it's cutting the part in 11 minutes! :)
so basically now i have the part being cut on the machine at a decent feedrate, and it is no longer milling away all the waste in multiple passes, but i still have not figured out how to get a toolpath that just cuts out the perimeter after its done milling the top carve. I will work on this, and see what i can figure out.
i have to say, this is all making a lot more sense now that ive gotten into it a bit. seems fairly intuitive. Mike, thanks for all your help! very much appreciated!

alk-3
12-27-2011, 09:25 PM
okay, got the perimeter cut figured out as well. so I've output a gcode that appears to be just right. I have the machine cutting the carved top, then it pauses while I switch out the tool, then it continues on to cut out the perimeter leaving a bit extra material around the perimeter. The only minor concern is it seems to slow down a great deal when cutting the perimeter around the corners. is that normal? seems like is should cut at a constant feed rate around corners as well as the straight sections.
I have not actually tried this newest gcode on the machine, I'm just running it in the simulator.

turmite
12-28-2011, 11:45 AM
alk what do you have the for feedrate on the bit you are cutting the perimeter with. Each tool bit has to have it's own feed rate, and that might be your problem, but if it is a drastic difference, it might be the setting in Mach that deals with constant velocity or exact cut, I think. It has been so long since I have had to change anything in mine. In fact, I still use Mach2. Other than beta testing all of madCam's versions, I am one of those fix it, leave it alone till it breaks kind of guy.

Mike

alk-3
12-28-2011, 11:49 AM
alk what do you have the for feedrate on the bit you are cutting the perimeter with. Each tool bit has to have it's own feed rate, and that might be your problem, but if it is a drastic difference, it might be the setting in Mach that deals with constant velocity or exact cut, I think. It has been so long since I have had to change anything in mine. In fact, I still use Mach2. Other than beta testing all of madCam's versions, I am one of those fix it, leave it alone till it breaks kind of guy.

Mike

Hey Mike. I have the feedrate set for 3000, which is pretty fast. it goes along very fast at the straight areas, but around tight radiuses, it slows down quite a lot. I don't think this is a mach3 setting, because it even shows it slowing down in the madCAM cutting simulator.

turmite
12-28-2011, 12:33 PM
Well if it is tight radii that is slowing it down, this sounds normal. A cnc machine has to ramp up and down along the tool path as it encounter fairly rapid direction changes, and those small radii are in fact much smaller line segments and the machine is going to have to make chances and the angle of each line changes to make up the curve.

I would have to see it to know for sure but why don't you check your Mach settings and see if it is set to exact stop.

Mike

alk-3
12-28-2011, 12:39 PM
Well if it is tight radii that is slowing it down, this sounds normal. A cnc machine has to ramp up and down along the tool path as it encounter fairly rapid direction changes, and those small radii are in fact much smaller line segments and the machine is going to have to make chances and the angle of each line changes to make up the curve.

I would have to see it to know for sure but why don't you check your Mach settings and see if it is set to exact stop.

Mike

I will check the Mach settings. This does actually seem normal though, based on what one seen with this perimeter before, on other machines.