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neodymium magnets

miziomix

miziomix

Über on my mind
Commercial User
Sep 28, 2009
1,675
368
Kuala Lumpur.
www.mubcustom.com
Disclosures
Bass builder @ MüB.
#1
Has anyone tried fitting Neodymium magnets to truss rod and elect. cavity covers?

Would a 1/8" x 1/16" piece with .8 pounds pull force be enough to hold the t-rod cover in place?

How about cavity covers - would the magnetic field interfere with electronics?

thanks :bassist:
 
#2
Not sure about the truss rod, but considering how damn powerful neo magnets are, I wouldn't trust them so close to the electronic components in the control cavity. I've killed a pot with a magnet already, so I try to keep them separated as much as possible.
 
#4
No clue. I just know that, after coming into contact with a strong magnet (one of those telescoping pickup stick things) the pot didn't work anymore. That's something I've been meaning to research, actually.
 
#5
I'm no physicist, but I doubt that the magnetic field had anything to do with the pot's demise.

There are several builders that use the Nd for covers. Yes, the smallest one that you can find will be strong enough for direct exposure. If you are insetting them from behind you will want to consider larger magnets based on the depth of inlay and distance between poles when in use.

You will also want to use more than one to prevent rotation; i.e. at least two for a TR cover.
 
#6
Yup, they work well. No interference that I can detect.

IMG_1637.jpg

IMG_1638.jpg
 
#7
miziomix said:
Has anyone tried fitting Neodymium magnets to truss rod and elect. cavity covers?

Would a 1/8" x 1/16" piece with .8 pounds pull force be enough to hold the t-rod cover in place?

How about cavity covers - would the magnetic field interfere with electronics?

thanks :bassist:
Click to expand...

Yes, I did it with a guitar that I'm currently working on and no, I have not run into a interference. The past 3 instruments I've built have a had neo cavity covers. I use 4mm dia. 1/16" thick neo magnets.

27746_120981307934876_100000690223859_146459_2047125_n.jpg

27746_120981311268209_100000690223859_146460_7877383_n.jpg

27746_120981321268208_100000690223859_146462_5760214_n.jpg

27746_120981327934874_100000690223859_146463_6265529_n.jpg

27746_120981337934873_100000690223859_146464_4131699_n.jpg

30296_119038341462506_100000690223859_138918_4417225_n.jpg

27746_120981341268206_100000690223859_146465_4713749_n.jpg
 
#8
Hi.

While it's doubtful that a neodymium magnet of the size (3-4pcs of 3mm) that's required to hold a recessed TR- or a control cover will be able to bend the wiper of a pot, 10mm (?) ones like in BassShifter21's pic will. After that the potentiometer is pretty much toast.

Obviously there's plenty of grades of neodymium magnets, few near to a regular ceramic.
The strong ones will only cause trouble in applications like this, stick with the weaker ones.

IIRC, there was a TB luthier who had the recess at an angle on one end, so the control cavity cover was removable without prying.


Regards
Sam
 
#10
Thank you all for your replies! It's great that some of you could upload pictures as well - extremely helpful. By the look of them I gather that tiny 1/8" x 1/16" should do the job.

I noticed that BassShifter21's bass mounts magnets on both cover and cavity edges.

On the other end, Jason has opted for magnets on the cover and screws on the cavity edges.

is it safe to assume that two sets of magnets of the same size will provide a stronger bond. Or is it irrelevant and the two solutions offer pretty much the same result?
 
#12
miziomix said:
is it safe to assume that two sets of magnets of the same size will provide a stronger bond. Or is it irrelevant and the two solutions offer pretty much the same result?
Click to expand...

It will offer a stronger hold.....however, I'd rather enjoy the capability of being able to adjust the height with set screws, rather than no adjustment (thin wood moves around occasionally and could therefore cause one of more of the magnets to not properly "seat" and cause the cover to rock. A magnet to screw bond is strong enough to hold a cover on, but you can also set the screws on a way, that would offer the ability to press down on one side of the cover, to lift, with no need for an additional access.
 
#16
miziomix said:
Will keep that in mind, thanks ;)

BTW, did you use super glue to hold the magnets in place?
Click to expand...

Yessir. i use a "gel" viscosity, not the thin. Also be sure that it adheres to wood and not the copper foil, as one of my pics shows, it does not bond too well with it.
 
#17
T-Bird said:
Hi.

"While it's doubtful that a neodymium magnet of the size (3-4pcs of 3mm) that's required to hold a recessed TR- or a control cover will be able to bend the wiper of a pot, 10mm (?) ones like in BassShifter21's pic will. After that the potentiometer is pretty much toast."

Well, actually, no they haven't. Been in there a year and no problems whatsoever. :) However, I am going to go with a little bit smaller magnets on the next one, simply for ease of fabrication.
Click to expand...
 

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