My simulation is not cutting properly. Help.

[alexccmeister]

Hi all,

I am playing around with Mastercam trying to mill a part with Delrin. So I simulated the milling process. But I am having problem with the cutter cutting into the side wall as can be seen in the picture below.

As you can see in the pictures, the circled area showing where the wall of the part was over cut at the sloping face. The wall thickness should be 3mm. But the cutter toolpath was right at the wall edge. How do I adjust so the toolpath is half the diameter away from the wall? I tried many ways but I just haven't got a clue how to fix this. Anyone can help? Thanks.

[ImanCarrot]

Have you got tool radius compensation set to on? and if so, have you got it the right way (Left or Right compensation)?

Apologies if you have.

[alexccmeister]

Hi,

Thanks for your reply. No need for apology. I am so new here I should be the one apologizing for not understanding the milling process. But anyway, I have attached the parameter for the roughing process. Where do I go to check the tool radius? I can only see Tool Containment and Tip Compensation settings. I tried adjusting these but no difference.

[SORCHEROR]

alex, i think the problem is your surface boundries,after you cut your 2d pocket programs you cut with the surface parallel tool and than it gouged the wall,a ball cutter will run off the edge of a surface,you need to either create trim boundries to contain or create some check surfaces

[SORCHEROR]

create a trim boundary by offsetting your 3mm wall edges by half your cutter diameter and rewrite the program and chain the trim boundary to contain hte cutter inside what you want

[SORCHEROR]

if the walls are surfaced out too just use them as check surfaces in your program so not to cut into them

[SORCHEROR]

easy way to create a trim boundary is to use,create curves on one,or all edges of a selected surface,than you can trim the curves to where you need to and so on not easy as it sounds,but once you learn how it easy

[alexccmeister]

Hi Sorcherer,

Thanks for your reply. I am sure its not difficult once I get a hang of it. But you explanation is bit off my head at the moment. I am learning the real basic of Mastercam and at the same time trying to do 3d milling without understanding the basic of 3d milling.

My problem with the above exercise is this. I have a part I want to mill out and it is say 36mm in width. My stock is say 40mm. So I need to contour off 2mm on either side if the stock is centred on the milling table. If I use a 5mm diameter flat endmill, will the program automatically draw out the toolpath that is 2.5mm away from the final surface? My concern is that if I cut the stock, I may end up with a 34mm width part instead of a 36mm width. With all the settings available to my disposal, I am sure I may miss out soem setting. That is exactly what I am seeing is being done on the above example.

I just thought the program will automatically set the toolpath so I can cut 36mm width exactly or am I wrong and I need to do some setting? Thanks.

[DJPLAST]

I am just learning MC also. I may not have the terminology correct. When you selected the "sloped area" to cut, did you let the tool path "know" that the surface that was gouged was in existance? It needs to be a "check surface". after it is selcted as a "check surface" the tool path will look for it and not touch it with the cutter. Anyone with more experince with MC, let me know if this is correct, I have deduced this the hard way, just like alexcc.

[DJPLAST]

I just checked in MC and learned something. When you are cutting a surface parallel, on the next screen where it says rough or finish, down at the bottom of the list is "drve" "cad file" "check" "contain" , when you click on check you get a "U" "N" or "S". This is "U" all unchecked surfaces are check surfaces. "S" is for manualy selecting surfaces and "N" is off.
Hope this helps.

[alexccmeister]

HI DJ,

Thanks for the info. Will try that and report back.

In the mean time, if anyone is interested to take a look at the part I am trying to machine. Please download the files below. Thanks for your help in advance.

P.S. When you look at the mcx file, please remember I am a newbie in this.

Alex

[SORCHEROR]

yes that is correct DJPLAST,as i mentioned in above post about check surfaces
alex,i will look at your file later tonite and draw some trim lines to show you one way to do it and send it back to you so you can get an idea,you could use check surfs,but i prefer to draw trim boundries,guess im old fashioned