In the spirit of the Community Challenge #21 I’m looking for a project I’m currently working on to include magnets. That said if I made something with neodymium magnets that would be used fairly close to the Shapeoko would the magnetism from these powerful magnets have any adverse effects on the machine itself such as the stepper motors or anything else.
I would suggest staying away from the stepper motors, the control board, the limit switches (proximity sensors) and the spindle / router with the magnets. High speed bearings in particular do not do well in strong magnetic fields. A few cm clearance is all that’s needed though, magnetic field drops off very quickly unless you have some suitable magnetic material to help it along.
It’s best not to have the magnets move quickly relative to any nearby (a few cm) wiring.
I will note that the Sweepy uses such magnets, as do the later BitSetters w/ the replaceable tops.
Agree w/ @LiamN 's specifics though.
The closest ones would be about 4" to 6" away from the controller and stepper motors on the Y axis at the extremes (gantry near the front and rear). During the operation of the machines these magnets would be stationary as well but will go with my original plan A if this could interfere with the reliability of the machine.
Edit: the Neodymium magnets I’d be using are much larger (ie. 1.5" diameter and 1/16" thick) and have 18lbs pulling force.
I’d be surprised if there was a problem, like Will says there are magnets in lots of the better dust boots. So long as you stay away from the limit switches and steppers by more than an inch or so I would not expect issues.
May I suggest sticking (or taping if there’s no steel there) some of the magnets on the machine and trying it out?
Edit: What Liam said
There is unlikely to be any issue at that distance with such a low pull force magnet. Have a vague recollection from physics class a long time ago that it drops off with inverse of distance.
Also I recall that “pull force” isn’t a particularly good way to characterize the field strength of a magnet as it is somewhat a function of the magnet shape/surface area. And some manufacturers “cheat” the number in that it is the force required to pull apart two identical magnets (opposing poles of course) rather than what might better be called a lifting force – a magnet vs. flat steel plate.
Actually, its inverse squared; even better!
Thanks for the responses, much appreciated. My magnets should be arriving today so I’ll just put them on the hybrid table as I cut my next parts but based on the feedback it sounds like it should be just fine.
Just don’t make yourself a mu-metal helmet with magnets in for trans-cranial stimulation, or if you do, don’t wear it when driving or shopping…
I think that is the flux density that is 1/r^2. Field strength is 1/r and I should have said flux density as field strength is more about the field formed by a current in a conductor.
Anywhoo, it drops off.
LOL, had to look up trans-cranial stimulation which seems the application is to help ease symptoms of depression and improve mood. Glad to report I will not need to make the magnetic helmet as working with the CNC already helps tremendously in this area.
I just turned 67 years old. I got my Shapeoko about two years ago. I am retired and in the summer months I have a lot to keep up. In the winter months outside work is little to none. Now my winter months is only about 3 months long in deep east Texas. The Shapeoko has really helped an old dog learn new tricks. I have been doing traditional woodwork for over 45 years but the Shapeoko has stretched my mind tremendously. Glad I got it to supplement my traditional woodworking.
This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.