Software posting accuracy?

[Mike Kohlmann]

Hello forum members,

I have a simple rectangle top that I am cutting out. I am using the "Profile" command tool option to cut the part out. When I measure the part on the screen (using the measuring tool, the measurements all are correct(11-5/16" & 16-1/8"), however when I ran on my CNC, the X axis cut the part bigger by about 3/16". The Y direction was dead on. I know this sounds more of a machine problem than software, however I have done several tests on the machine with a lazer light the machine move exactly 1" in both directions and found not issues there. The actual cut is nice and smooth. I have a call into the CNC company as well (Techno CNC Inc.).

Does anyone now of any posting issues, ran into this situation oneself, or is the Profile router not accurate for this type of work. Is there an easy way to check GCode for descepancies? Might this software have limitations to accuracy. I just want to cover all bases, both machine and software.

Any comments or help would be appreciated. THANKS IN ADVANCE! I have attached the file I am referring to.

[dldecker]

in your crv file the top is Y - 26.2104, X - 16.147

material size is y - 27.0, X - 16.375

check your machine for any play??

[Greolt]

I checked out your crv file. It produces gcode of the correct dimensions.

So that leaves your machine.

Greolt

EDIT

, the measurements all are correct(11-5/16" & 16-1/8"),

Your job total size is 16 1/8" by 26 1/8" in the crv file. This matches the gcode produced.

[moto633]

Check farther than an inch. Check the longest distance you can for each axis.

Nic

[zeeway]

Don't know what kind of machine software you have...but in Mach3 there is a special screen to calibrate axis movement...you can program your machine to move a set distance - say 36 inches. Then very accurately measure the actual distance moved, and input that actual distance, and the software will adjust its turns per inch to make the actual distance moved equal the programmed distance.

Even so, this actual dimension cut can be affected by dull tools, too-fast feed rates, tough material, loose collets...all the usual gremlins.

Angie

[MarkJohnston]

Mike,

Your measurements are right on 11.3125 (1/8) across the X axis at the very end of the notch but if you check the deepest part of the notch using a 1/4 inch end mill they are about 3/16 wider on the finished cut. This is because the 1/4 inch end mill is unable to cut a square inside corner in the notch. Below your toolpath list there are 2 boxes, put a check mark in the Solid box and you can see the toolpath in the 2D view.

I'm not sure if this is what you're talking about but you can see the difference in the measurements.

Mark

[Mike Kohlmann]

Thank you all for your tips, evaluation / confirmation of my problem. I will be using your suggestions along with the machine manufacture check to determine my problem. As of right now, the thought is that since the CAM software is correct, the scaling factor on the machine has to be off.

I will let all of you now what I find once I have done the required tests.

Once again, thanks for all your advise.