# Probe magnets and rotary motor **URL:** \ **Category:** šŸ’„ Amazing fail\ **Created:** [November 18, 2025, 12:26pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985 "2025-11-18T12:26:13Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![ma.dubois](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/aca169/32.png) [@ma.dubois](https://forum.sienci.com/u/ma.dubois)\ **Post date:** [November 18, 2025, 12:26pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/1 "2025-11-18T12:26:13Z")
I am not sure if I post this in the right section. I recently learned the hard way the sensitivity of closes loop motor to magnets. By inadvertance, the probe magnet stuck to the housing of the vortex closes loop motor, resulting in the motor heating and destroying itself. To whomever Read this post, be careful! ---
**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\ **Post date:** [November 18, 2025, 3:05pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/2 "2025-11-18T15:05:35Z")
Wow, who would have thunk. Thanks for posting! ---
**Author:** ![Chucky\_ott](https://forum.sienci.com/user_avatar/forum.sienci.com/chucky_ott/32/8692_2.png) [@Chucky\_ott](https://forum.sienci.com/u/Chucky_ott)\ **Post date:** [November 19, 2025, 10:08am UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/3 "2025-11-19T10:08:41Z")
Hmmm. Interesting, as I keep a magnet on one of my table legs to pick up metal screws that get in my t-track slots. Will be to be careful. I was curious to know more so used Google. Found this: [Closed loop stepper motors and magnetic fields. | MASSO Community Forums](https://forums.masso.com.au/threads/closed-loop-stepper-motors-and-magnetic-fields.4571/) At 2:30, the stepper starts behaving erratically when an external magnetic field is applied ---
**Author:** ![ma.dubois](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/aca169/32.png) [@ma.dubois](https://forum.sienci.com/u/ma.dubois)\ **Post date:** [November 19, 2025, 5:53pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/4 "2025-11-19T17:53:31Z")
Thanks for the video. I should receive another motor soon. I will put pictures of the problematic unit here as soon as I change it! ---
**Author:** ![Dnick](https://forum.sienci.com/user_avatar/forum.sienci.com/dnick/32/9326_2.png) [@Dnick](https://forum.sienci.com/u/Dnick)\ **Post date:** [November 20, 2025, 2:52pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/5 "2025-11-20T14:52:01Z")
There is a magnet in the back cover of the Vortex Headstock Rear Cover to hold the Chuck Key. It is several inches away from Motor, but maybe that is not a ā€œgoodā€ place for a magnetā€¦ ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [November 20, 2025, 4:16pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/6 "2025-11-20T16:16:57Z")
@Dnick Iā€™ve had my vortex since day one. In my experience, the magnet is too weak for its intended purpose. I am quite sure that it is far enough away from the motor and weak enough that it is not causing any issues. YMMV of course. ---
**Author:** ![ma.dubois](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/aca169/32.png) [@ma.dubois](https://forum.sienci.com/u/ma.dubois)\ **Post date:** [November 20, 2025, 11:29pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/7 "2025-11-20T23:29:43Z")
As promised, here is a picture of the carnage. ![image](https://forum.sienci.com/uploads/default/original/2X/b/b513e6a0c6112977828acbbe99bb3ad0ec3ee410.jpeg) ---
**Author:** ![Jens](https://forum.sienci.com/letter_avatar_proxy/v4/letter/j/d2c977/32.png) [@Jens](https://forum.sienci.com/u/Jens)\ **Post date:** [November 20, 2025, 11:43pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/8 "2025-11-20T23:43:19Z")
Ouch !!! That magic smoke left in a big hurry ā˜¹ ---
**Author:** ![ma.dubois](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/aca169/32.png) [@ma.dubois](https://forum.sienci.com/u/ma.dubois)\ **Post date:** [January 26, 2026, 7:05pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/9 "2026-01-26T19:05:38Z")
Update on this situationā€¦ Couple of weeks ago, after the incident, I orderd a new motor from Sienci and changed the broken one. Everything worked fine since recently when I fried the new motor. This time, I was simply doing a basic MDF preparation using only the X,Y,Z axis. For no apparent reason, the A axis motor just fried again, so I doubt my previous explanation regarding the magnet was the real reason for the first fail, maybe it was just pure coincidence. I opened a case with Sienci, but I am really hesitant to just change the motor againā€¦ Anyone had similar experience? Thanks ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [January 26, 2026, 7:26pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/10 "2026-01-26T19:26:44Z")
@ma.dubois If I understood you correctly, the project is not a rotary project. You have the rotary connected by are not using it for this project?? What machine do you have and what controller? ---
**Author:** ![ma.dubois](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/aca169/32.png) [@ma.dubois](https://forum.sienci.com/u/ma.dubois)\ **Post date:** [January 26, 2026, 8:14pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/11 "2026-01-26T20:14:35Z")
@gwilki You understood correctly, This specific job was not a rotary one, I was just using the X,Y,Z axis. My machine is a Longmill MK2 30x30 with a Vortex Rotary Axis with the upgraded close loop so I can work with 4 axes. I usually machine relatively complex shapes in Acetal homopolymer (Delrin). From time to time, I however need to mill surfaces like MDF. ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [January 26, 2026, 8:21pm UTC](https://forum.sienci.com/t/probe-magnets-and-rotary-motor/24985/12 "2026-01-26T20:21:19Z")
@ma.dubois Tks. Iā€™ve lost track of all the model specs and didnā€™t know that the Mk2 came with the SLB. I hope that you will post back when you get this resolved. It sure seems like too much juice is getting to that motor.