Problems with tool diameter

Hi all,

Trying to sort out some accuracy issues. My current setup and work flow is Autocad - Cambam - LinuxCNC -3040 Router.

I fixed the first accuracy issue I originally had by changing the accuracy in Autocad from 0 to 0.000. This fixed the issue i was having with dimensions being different from Cad to Cambam.

My next issue was figuring out what tool bit diameter I have. Im using a 3.175 endmill, the supplier lists the diameter as being as 3.175, but i found i was getting the best results at 3.08.

The other day while playing around I managed to get it to be within .01 mm accurate while cutting some plastic, which I was happy with. But then I went to make the exact same cut and it was .35mm~ out. I cut two squares right next to each other in the same run, so I know its definitely something to do with my settings.

Linux CNC has the tool table setup with the same dimensions as Cambam, so I wonder if both are making a compensation for tool bit diameter, but then it would be another 3.08mm out, right??

So annoyed that it worked for one go around and then not again.

Does anyone have any ideas or experiences ?

Do you have any cutter compensation programmed in your Gcode? Maybe G41, 42, etc? I program a G40 at the beginning of all my Gcode which removes any programmed compensation from prior settings. The next thing I would wonder is machine/spindle flex. I would run those squares at noticebly different speeds to see if the error differs. Mabe something small came loose after the first run....

Only throwing out ideas. Hope you get it taken care of...

Paul

Hi mate, my gcode has a g40 in the header , so I then looked at the rest and it looks as though it is compensated for in the coordinates , I pulled apart the spindle and it has a busted bearing, so that will get replaced along with the y axis linear bearings as they seem to have play as well. My first thoughts were that the programs wee causing this as I achieved a high accuracy on one pass, I may have just gotten lucky. I'll replace those parts and with any luck I should be back on track. Cheers

Sent from my GT-I9505 using Tapatalk

Attachment 243858 This is how i decided to fix some issues. New makita Router and some new mounts. Bought some more bearings to replace the shoddy Y axis ones on the machine. Should be a good upgrade for my little 3040..

If you are cutting with that bit, you'll see some deflection for sure.
I'd use the shortest bit you can for the cutting depth you will use.

Oh for sure, I haven't managed to mount this to the machine yet, but before that, these chinese bits will be getting cut down. I've got some proper stub bits on order