Tapping in Mach3 with Fusion360

Hi All,

I have an AC Servo (step/dir) for a spindle on my DIY mill and am a total beginner (disclaimer). After reading Hoss' use of a stepper as an auxiliary spindle for tapping, I tried to get tapping working using the swap axis command in Mach3. This sets up your spindle as an A axis (in my case as a rotary axis in contrast to Hoss' approach). This has certainly been done before, but I think i may have added a new twist (apologies if this has been done before).

I read that one can pass 3 parameters in a macro call in Mach3. Therefore I wrote a single macro (M951) that gets a P, Q, and R parameter passed during the call. P = depth, Q = retract height, and R = pitch. Thus with one macro, you can tap any size thread. This macro has worked very well, but still required hand editing G-code produced by Fusion 360 (my preferred CAD/CAM).

So, I edited the post to intercept the G84 (specifically the "right hand tapping") call. Instead of producing a G84 output, it produces an M951 Px, Qx, Rx output for every hole in the list. Surprising to me, it really seems to work, and requires no hand editing. It is important to remember, this post will only intercept the right-hand tapping (not the "tapping" or "left-hand tapping" cycles in Fusion360). Also note- you must have the thread pitch entered in your tool library for the tap, or no information about the pitch is available to send to the macro.

Below, I attach the macro and the post in case anyone would like to try. Tomorrow, I will try to upload a video of it tapping. I will also try to upload a sample fusion360 file with its resultant G-code.

Note- as an added benefit, my macro homes the A axis prior to starting the tapping move- it should be possible to re-enter a tapped hole (if cleaning it up is necessary), at least on my machine which uses an HSK40C spindle (thus has a fixed angular position for the tool holders). I have not tried this yet (fear)...

hope this helps someone.
jake

Hi All-

Here are the Fusion 360 CAD/CAM file, as well as the G code output using the standard Mach3 post, as well as my modified post. I include the pair of G-code files for a simple M4, M5, M6 hole as well as a series of M4 holes. In the series of M4 holes, you can see that the M951 macro has to be called at every X/Y co-ordinate (unlike the traditional G84 approach). This took some time to get the modified Post to produce this correctly.

Also, here is a video of it tapping an M4, M5 and M6 thread. In the second video, I spin up the spindle and am able to re-enter the thread without galling it up- seems the spindle orient is sufficiently accurate.

Note- in the M951 macro I attached in first post- the feed rate is set to 36000 which is 100 rpm. In the videos below, I increased this to 72000 = 200 RPM. Because the A and Z axis are yoked, the feed rates entered in the Fusion 360 tool table for the tap is not used- if you want to change the tapping speed, you have to modify the M951 macro.

Wanted to thank Joel from JHChopper who sent me his Spindle Orienting Macro that got me started....

hope this helps someone.

best
jake

https://youtu.be/Qn6z8Gnm8q4

https://youtu.be/UVOg5347KXs

I know this is reviving an old post but are you able to shed any more light on how you were able to get this to work. I have a tap spining way to fast for the amount of z feed that is happening. Not sure where to start to diagnose.

Regards Daniel