Manual Tool Change Question for desktop CNC

[tomzoP4RXT]

Greetings

I am new to CNC, though I own a manual mill and lathe.   I am trying to figure out how to effectively do a manual tool change on a desktop CNC (Genmitsu 3020 Pro Max) which is collet based and can't really accurately have preset tool heights in the library.   I am milling (rather slowly) aluminum and will mainly be using a single fluted end mill but want to chamfer some edges with a 90 degree v bit.

While I am not quite sure how to do it, here is what I am thinking:

-  Set my XYZ zero points at some predetermined distance on the stock away from my part

-  Run the toolpath for the end mill

-  Have the end of the code tell the machine to return to the XY zero point but keep the spindle up at the retraction distance (or whatever is needed to effectively change the bit) and stop

-  swap the bits and then re-zero the Z which should be at the same reference point in XY as original program

-  Run a separate GRBL file with the V bit from there.  This file would be made from the same setup in CAM in F360.

In my mind I think this should work, but I am not sure how to command the machine to return to the zero at the end of the first setup.

As usual, my inexperience has probably led me down the wrong path here, so any thoughts from those who have already broken the bits would be appreciated!

Thanks

Tom

[hyperbolicindustries]

The end of the code for the first operation should have G53 or G28 which is a call to go back to machine home. Some of the hobby machines without limit switches require that you use [Clearance plane] which would just be a G0 Z value but in the same place.

[tomzoP4RXT]

My machine does have limit switches for home, but my parts are not placed in a defined location from that spot.   Were I to set the zero before beginning and told it to go to the home position at the end of an operation would it remember where my zero was when I initiate the next operation?   If that is the case my problem may be solved.   Perhaps I will need to do some testing on that when I get home...

Thanks

[tomzoP4RXT]

I tried this without success, but in doing so had another idea.   Since my main concern about the tool change is tool height I could turn a little tool on my lathe that has a fixed depth hole in it and use it to set the stickout for the first tool, and then use it again to set the next tool.   This way both would be at the same Z height.   In between operations I could use an Manual NC stop - or something equivalent - to make the tool change.  In my mind, this would retain the X,Y, and Z of the end of the tool.

Is this something that might work?   I still need to figure out the whole Manual NC stop thing, but that does not seem that difficult (of course I have not tried it yet).

Thanks

Tom

[hyperbolicindustries]

When your changing tools you are only concerned with setting a new Z value for it. And you got what is the regular workflow. Machine the first operation>tool change>Bring tool down on to where you set the first tool height, or use a custom spot/part like you are suggesting> set Z=0 for that new tool or Z=0.40 if you are setting on top of rough stock (depending on how much stock you have in your setup).> home Z and load/run next operation.

[jscott6SWZG · Accepted solution]

i have a 4030 and do tool changes  and bottom cuts (new setup) alot

I normally use a stock box point for the origin but you can certainly use a fixture point as you describe

i use candle and had a problem with the gcode from fusion loosing the work coordinates

https://forums.autodesk.com/t5/fusion-360-manufacture/lose-work-coordinate-zero-at-the-end-of-nc-pro...

this was a solution

[tomzoP4RXT]

Thanks - this is super helpful.  I will give this a shot.

[tomzoP4RXT]

I tested out this little tweak to the GCode and it worked!   Thanks!