For computers, yes a magnent can wipe them out. For our sewing/emb machines, no. The computer parts are to protected. I use the magnent seam guide on my emb machine and if you've ever seen how strong those magnents are on the metal hoops, you'd know a pin holder won't hurt them. I have one cheaper computerized machine and its had the magnetic seam guide being used on it for around 5 yrs and for the past 3 yrs I've had two of the top of the line Vikings and with the guide or the magnetic hoop (made by Viking) there hasn't been any damage or slowness on my machines.