Holes cutting larger than designed

[tjandt (Tim Jandt)]

Recently purchased an XXL to augment my woodworking/engraving business.

Trying to make an MDF waste board with 0.26" holes spaced about 2 3/8" apart.

I laid out the board in CAD, exported DXF, imported to carbide create, and everything looked good. Radius of holes shows as 0.13" in carbide create.

For the toolpath, I chose standard 1/8" endmill, set the depth per pass of tool to 0.1", set offset direction to pocket with a max depth of 0.1".

My expectation was that the 1/8" end mill would move to location, plunge 0.1", pocket 0.01" and retract.

Instead I am getting holes that are right on the 2 3/8" center, but are .375" in diameter, not 0.25" The holes are round, evenly spaced, but too big.

Any idea what I’m doing wrong? Pretty dejected that I can’t even make a waste board to actually start trying to do more accurate stuff at this point!

[Andy_MM (Andy)]

Can you upload your file? or screen shot of the simulation?

[gdon_2003 (Guy Donham)]

Folks will look at your file but in the mean time have you checked your calibration. There is something on the wiki about calibration but here it is in a nutshell:

Make a Square 6x6 inches (or about similar in MM). Create a tool path that is “tool 102” (because it is default but any tool you want) “Contour” “Inside Left” “Depth .125”

I used a 12x12 material that was .75 inch thick but any size bigger than the 6 inch square works and any thickness thicker than the cut.

Zero your machine and make the cut. After the cut is finished get out your calipers and measure X and Y distances and if they are exactly 6 inches (outside edge to outside edge) your calibration is good. If the measurements are not 6x6 then flip your work piece over, and make it again and if consistently wrong then you can go through calibration. But before going through calibration and if your measurements are not consistent between the two squares then check your pulley set screws and/or other mechanical issues, do not calibrate until you can cut a consistent square even if not exactly 6x6. A loose or slipping stepper motor screw will cause inconsistent results on the same job or binding of mechanical movement.

If necessary to calibrate your stepper motor steps the answer is on the wiki

[Andy_MM (Andy)]

My thought is that it seems to perfect to be calibration. Most likely one of these:

(but calibrating is always a good idea)

[tjandt (Tim Jandt)]

Sorry, really new here . How do I upload the file?

[Andy_MM (Andy)]

save as .c2d file like this:

Then:

[gdon_2003 (Guy Donham)]

Just “Reply” and you have to have at least 20 characters then just drag the files you want into the window and they will upload, then hit Reply.

[tjandt (Tim Jandt)]

Thank you all for the help. The winner winner chicken dinner of the night is Andy. As it turns out, I’m really a much bigger n00b than even I realized!

It was, in fact, me telling CarbideMotion that I had a .125" end mill in the machine, while the router was happily cutting away with a 0.25" end mill installed! Sorry for the fire alarm. Seems like in addition to a big learning curve, I’ll need to also work on my observation skills!

Thanks so much for the help. Waste board complete! Now on to more trouble!

[gdon_2003 (Guy Donham)]

Most success comes from failure. Everyone that is successful has had failure. Just keep moving forward.

I keep a log book and I document my projects with what works and more importantly what does not work. Keep a journal and review it and stay current. Works for me. Good luck.