# M6 tool change bit plunge **URL:** \ **Category:** Troubleshooting (X35/X50)\ **Created:** [June 30, 2021, 10:01pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476 "2021-06-30T22:01:04Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![jkanzaki](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jkanzaki](https://forum.onefinitycnc.com/u/jkanzaki)\ **Post date:** [June 30, 2021, 10:01pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476/1 "2021-06-30T22:01:04Z")
Hi Everyone, New to the forum here, Just got my onefinity recently I am very happy with it but I encounter a small problem, i am wondering if anyone can shed me some light. So I have am cutting some foam for a school project 2 inch thick, and I program two tool for this job both 1/4 shank one short 1 inch LOC and 1 long 2.25 LOC. Programmed in fusion 360 with m6 post processor enable. Upon M6 tool change, I am suppose to flip the back of the probe and measure the Z offset (which the system prompt me to do), after i swap out the shorter bit to the longer big bit and perform the z probe procedure the machine would plunge into the probe after the bit make contact with the probe. Luckly I am cutting foam so the long endmill press the probe into the foam which the foam absorb all the pressure so I didn’t ended with a broken endmill. Can someone tell me why this is happening? Is there something I missed? I notice I use imperial (inches) for my cam and in the M6 tool change command it uses g21 (mm), should I change it to G20, if so should I change G38.2 Z-10 to another number? ## Here is my original m6 tool change gcode ## (Runs on M6, tool change) M70 **G21** S0 M0 M6 (MSG, Change tool and attach probe) F100 (probe to minimum z soft limit, which is -10) G38.2 Z-10 G92 Z15.4 g0 Z30 M0 (MSG, Remove probe, start spindle) M72 Cheers ---
**Author:** ![cyberreefguru](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/cyberreefguru/32/27385_2.png) [@cyberreefguru](https://forum.onefinitycnc.com/u/cyberreefguru)\ **Post date:** [July 9, 2021, 5:46pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476/2 "2021-07-09T17:46:55Z")
> [@jkanzaki](#): > > So I have am cutting some foam for a school project 2 inch thick, and I program two tool for this job both Seems like a connection issue with the probe. Does it work without the M6? ---
**Author:** ![jkanzaki](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jkanzaki](https://forum.onefinitycnc.com/u/jkanzaki)\ **Post date:** [July 9, 2021, 6:04pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476/3 "2021-07-09T18:04:42Z")
Good Morning, The probe and machine perform normally if I execute “Probe XYZ”. This phenomenon of my Z axis pluging down with loose connection(possibly) only occur while during M6. It’s not a regular occurrence. The speed of the plunge is very fast it’s not the usual 35 or 75mm/s probe speed. I am trying to capture it on video and post it here if it happen again. That’s what I am thinking its a connection issue, but it baffle me that even if the probe has a loose connection the Z axis shouldn’t pick up speed and plunge down (In this case my bit will push the probe down). Luckly i am cutting foam but if iam cutting any other material I can say bye bye to my bit, but this doesn’t give me confident about using the probe or m6 toolchange sequence if iam cutting harder material because i don’t want to break my bit since they are not cheap per pop. ---
**Author:** ![WaywardWoodworker](https://avatars.discourse-cdn.com/v4/letter/w/e79b87/32.png) [@WaywardWoodworker](https://forum.onefinitycnc.com/u/WaywardWoodworker)\ **Post date:** [July 9, 2021, 6:14pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476/4 "2021-07-09T18:14:11Z")
The F100 in the above G-code sets the “feed rate” which in this case will control how fast the Z axis is lowered. You can reduce this value to something more to your liking. ---
**Author:** ![jkanzaki](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jkanzaki](https://forum.onefinitycnc.com/u/jkanzaki)\ **Post date:** [July 12, 2021, 4:22pm UTC](https://forum.onefinitycnc.com/t/m6-tool-change-bit-plunge/6476/5 "2021-07-12T16:22:56Z")
i tried that , but it is still happening. I made a new post with video to show how that happen. > [@Bit change my plunge update + video](https://forum.onefinitycnc.com/t/bit-change-my-plunge-update-video/6661): > > Hey Everyone, In my previous post I have pointed my onefinity would give me qurks like plunging into the probe during a m6 tool change. This happen to me at least 5-6 times, I would say its quite frequent so I have capture it in video to see if anyone or onefinity can give me some pointer. Note\* this only happen during M6 gcode tool change, if I use probe Z it doesn’t happen or at least I haven’t experience it happen [[onefinity tool m6 tool change bug ?] ](https://www.youtube.com/watch?v=IMNlCKmdDQo) Another quirk I notice …