RonC Posted January 28 Posted January 28 (edited) Hi All, For my current build i would like to use magnets for the cavity cover. I would like to use 4 magnets. Does anyone know what would be a good size and strenght of the magnets to hold the cover but also not too hard to get is off? Any experiences with this? Thanks! Ron Edited January 28 by RonC Quote
itu Posted January 28 Posted January 28 (edited) Nd. They are small and powerful. My fretless has 4+4 neodymiums that are Ø 4 mm. You want to open the cavity, use a plectrum: Edited January 28 by itu 2 Quote
velvetkevorkian Posted January 29 Posted January 29 Something like this I would think https://magman.co.uk/product/n52-4mm-x-1mm-disc-magnet-291g-pull-force/ 1 Quote
Matt P Posted January 29 Posted January 29 paging @Andyjr1515 the control cover on my swift is held on with magnets, I'm guessing he could point you to where they were bought from (it works very well on my bass) Matt 1 Quote
Rich Posted January 29 Posted January 29 13 hours ago, itu said: Nd. They are small and powerful. My fretless has 4+4 neodymiums that are Ø 4 mm. You want to open the cavity, use a plectrum: Security! He used the P-word! 2 Quote
SpondonBassed Posted January 29 Posted January 29 7 hours ago, Rich said: Security! He used the P-word! Stand still sir while I open your cavity with a plectrum. 2 Quote
Andyjr1515 Posted January 30 Posted January 30 I can't remember offhand but I'll have a look in the morning 1 Quote
RonC Posted January 30 Author Posted January 30 On 28/01/2026 at 20:21, itu said: Nd. They are small and powerful. My fretless has 4+4 neodymiums that are Ø 4 mm. You want to open the cavity, use a plectrum: Thanks! great idea, thats the best way to use a pick! Quote
RonC Posted January 30 Author Posted January 30 23 hours ago, Matt P said: paging @Andyjr1515 the control cover on my swift is held on with magnets, I'm guessing he could point you to where they were bought from (it works very well on my bass) Matt I've found several websites were to buy them and they're cheap! Most importance is to find the right strenght, so 4 magnets hold the cover steady and it must be easy to open aswell. 1 Quote
Richard R Posted January 30 Posted January 30 On 29/01/2026 at 07:00, velvetkevorkian said: Something like this I would think https://magman.co.uk/product/n52-4mm-x-1mm-disc-magnet-291g-pull-force/ 291g pull force per magnet. That seems like quite a lot to lever open with a pl3ctrum as you would presumably need to lift two completely off the back and then use your finger? 1 Quote
SpondonBassed Posted January 30 Posted January 30 7 hours ago, Richard R said: 291g pull force per magnet. That seems like quite a lot to lever open with a pl3ctrum as you would presumably need to lift two completely off the back and then use your finger? With four magnets that's more than a kilo. 1 Quote
Andyjr1515 Posted January 30 Posted January 30 (edited) I used 3mm dia x 1mm thick magnets with a 0.19kg pull from First4Magnets on my last build. I've used 5mmx1mm at 0.3kg in the past but that is a bit overkill for a standard size/weight hatch. Edited January 30 by Andyjr1515 2 Quote
Andyjr1515 Posted January 30 Posted January 30 1 hour ago, SpondonBassed said: With four magnets that's more than a kilo. Hmmm...not really. You tend to pull the cover from one side - at the most breaking the pull of two magnets as one half of the hatch lifts up with the other two acting like a hinge. But, even with that said, they are surprisingly powerful for such teeny things. 👍 1 1 Quote
Frank Blank Posted January 30 Posted January 30 My fretless bass has a magnetic cavity cover, it was built by @Jabba_the_gut, he might be able to give you some info. Quote
Frank Blank Posted January 30 Posted January 30 (edited) I was concerned that using fingernails (or indeed a pick) would, over time, possibly damage the cavity cover or body of the bass. @Jabba_the_gut came up with a solution... Edited January 30 by Frank Blank 4 Quote
Richard R Posted January 30 Posted January 30 Is that a metal insert? Blimey! Hats off to @Jabba_the_gut 1 Quote
Geek99 Posted January 30 Posted January 30 12 hours ago, RonC said: Thanks! great idea, thats the only way to use a pick! FTFY 2 Quote
Geek99 Posted January 30 Posted January 30 (edited) On 28/01/2026 at 19:21, itu said: Nd. They are small and powerful. My fretless has 4+4 neodymiums that are Ø 4 mm. You want to open the cavity, use a plectrum: I’m going to be charitable and assume that you’re not some weirdo deviant pick player and would have borrowed the filthy item from a guitard? And used gloves …. Edited January 31 by Geek99 2 Quote
Frank Blank Posted January 30 Posted January 30 1 hour ago, Richard R said: Is that a metal insert? Yessir. 1 hour ago, Richard R said: Blimey! Hats off to @Jabba_the_gut 2 Quote
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