Help getting a good finish on a circular boss

[maxine]

I am just learning 3D surfacing with MC X and have been trying to use a flowline finish pass on a circular boss after using rough pocketing to get the shape roughed out. It is a 1" diameter by 1" tall boss and I am cutting it with a 1/2" carbide insert end mill on my little Haas TM1. I bought the surfacing video from Tipsformanufacturing.com and I am following the lessons there. When I finish cut the rough pocket I get a nice smooth and even finish but then when I then apply the flowline finish pass I get a series of short linear segments that leave a very noticeable prismatic sort of surface. It's not chatter, it is a nice regular pattern of little short line segments. Can anyone point me to what setting I need to mess with to refine the finish? A bearing will press onto the boss so I need a better surface. This is the first time I have tried to use flowline surfacing so I know I must just be missing something simple but I can't seem to find it. I would appreciate some advice.

Thanks, Maxi

[ObrienDave]

By default, all 3D surfacing cuts in Mcam, except for contour, break surfaces into linear moves.
Otherwise known as point-to-point.
Every cadcam system I have ever used behaves basically the same.
The way around it is to over tolerance the toolpath, then filter the linear moves into arcs.
I normally set toolpath tolerance 10x finer than the control resolution.
For a .0001 control I set tolerance to .00001
It seems to help once you filter into arcs.
Attached are my settings for V9

[maxine]

OK thank you. I checked and found that the tolerance was set at 0.001 and filtering was set to "off". I will try setting the tolerance down to 0.0001 or even 0.00001 and give it a try. I don't understand what filtering does for me though. Like I said when I checked it was set to off. Options are 1:1, 2:1, 3:1 and custom. I watched the "finish flowline" section of the training CD again and I see now that it says to set filtering to 2:1 but it doesn't say why or what that does for me. Can someone help explain briefly what filtering does?

Thanks again for offering help, Maxi

[weirdharold]

http://www.haascnc.com/solutions_3D.asp#3D Hope This helps. Harold

[maxine]

Originally Posted by weirdharold http://www.haascnc.com/solutions_3D.asp#3D Hope This helps. Harold

Thanks Harold, I was not aware of that reference material on the Haas site. It helps me a lot ! Maxi

[Mike Mattera]

Maxine: On your Tips For Mfg Training 3D Surfacing CD For X....

These 2 lessons explain the functions of the Filter and talk about the accuracy of the cut on the surface. They show how to use the Filter to convert Linear moves into Arcs, reduce the amount of code and smooth the toolpath.

Toolpath Info - Roughing - Lesson 7

Toolpath Info - Finishing - Lesson 1

Hope that helps.

Mike Mattera

[cadcam]

I think John Nelson wrote that about 4 or 5 years ago and did a great job but now changed out of Applications now.

[maxine]

Originally Posted by Mike Mattera Maxine: On your Tips For Mfg Training 3D Surfacing CD For X.... These 2 lessons explain the functions of the Filter and talk about the accuracy of the cut on the surface. They show how to use the Filter to convert Linear moves into Arcs, reduce the amount of code and smooth the toolpath. Toolpath Info - Roughing - Lesson 7 Toolpath Info - Finishing - Lesson 1 Hope that helps. Mike Mattera

Thanks Mike. I have been working through the lessons one at a time by first watching the lesson then going to the shop and cutting test parts based on what the lesson topic was. The question/problem hit me as I was working through roughing lesson 7 when I tried to do a test part in my machine. I thought I understood the lesson but could not get a good finish on the part. So after seeing your reply I jumped ahead to Finishing Lesson 1 last night and then rewatched Roughing 7 and that helped. I'll try another test part using flowline rough and finish this weekend. Also instead of working through the lessons one at a time I'll watch all the lessons through to the end, then go back to roughing 7 and pick up my step by step learning process where I am making test parts that practice learnings from each lesson. The CD's are really good but I also have to go to the shop and actually try it with my own hands to really feel like I have it down cold. Thanks again for the help, Maxi