[kreed]

Hello everyone,
I've got a Fadal 4020 vmc with a cnc88 control. I am programming with Bobcad V24, and trying to cut 3 axis programs. The control does not follow the profile of the part very well. Instead of the machine creating the arcs in the program, it generates straight cuts over the part. I talked with others about this and they seem to think that the control needs to be upgraded. We are trying to decide if this is the way to go. Will this fix the problem or is it a waste of money? Anyone out there have any answers? P.S. I can attach a program that I've created if necessary

[jvangelder]

What post processer are you using

Is the post adding plane selections before the arc's? IIRC our fadal needed them.

[DareBee]

Lets see some code.
I bet you are outputting arcs as linear segments in BobCad and there is nothing wrong with your Fadal

[StephenD]

Try inserting a G8 in the program on same line as E1 offset.

[DareBee]

G8 is only read ahead, it won't add arcs.
You are not outputting arcs from your software.
Fadal usually uses output as I,J,K

[kreed]

Thanks all for responding, I've been trying to figure this out for quite some time. I've been using Fadal_CNC88_Format_1_Rev2 as my post to generate the code. This is the only one my machine likes. All the other post programs add a header and my machine doesn't like that. I've attached a copy of my posted code for viewing. Maybe this would help. Keep in mind that this control only transfers code at a maximum speed of 9600 baud rate. A little slow for 3d programs.

[DareBee]

Yup - your code is linear segments.
IDK anything about BC but I can fit arcs in my CAM which drastically reduces the amount of code. This will allow you to run smooth at low baudrate.

Your options are to optimize your programming to suit your control or put a new control on your machine.

[kreed]

Thanks DareBee,
I started looking at other machine posts, and used a Haas mill-post to create my G-Code. I had to alter the post, but got a code that output I & K as well as X,Y&Z. This is working for now until I get a Fadal post made.