DIY Magnetic Folding Shelf Brackets

Page 4: Read More, FAQ, SN List

Page 1:  Overview & Step 1 
Page 2:  Step 2:  Prepare & Glue Magnets
Page 3:  Step 3:  Magnet Coating
Page 4:  Read More, FAQ, SN List

under construction
read more further details added here as to not bog down instructional steps
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Understanding Magnetic Field Strength Relative to Distance 

Inverse Square Law (and Magnetic Field Strength)
Magnetic Field strength follows the Inverse Square Law (same as gravity, light, sound, etc.) which states that intensity equals the inverse of the square of the distance from the source.  As you move farther away from the source of the field, the field lines spread out over a larger area, causing the field strength to decrease but magnet field strength doesn’t drop off in a linear manner as distance increases.  If you double the distance from the magnet, the strength doesn’t half, it reduces to 25%.  This makes intuitive sense if you have basic understandings of circle area to diameter ratios as engineers, electricians and plumbers do.  If you double the diameter of a pipe how much more water can it carry, double or quadruple?  How much more volume or area do you have by doubling the diameter of the pipe?  Don’t do math, just think it through.  Look at circle diagrams below if needed to intuitively understand.
 

How this pertains to my Magnetic Brackets.
To reduce the chance of magnets detaching from bracket, we want the magnets glued to the bracket to have a stronger magnetic attraction to the bracket than to the mounting surface (elevator controller, panel door, etc.).   Taking advantage of the Inverse Square Law, we can accomplish this by making certain that the paint and clear coat layers are thicker than the layer of glue between the magnets and the bracket.  If desired we can weaken the mounting force by adding layers of clear coat to fine tune to our preference.  

Concentrated Near Fields vs Broad Far Fields.
We can manipulate magnetic fields by configuring the poles of an array of magnets. For our purposes we want a strong magnetic attraction close to the bracket to hold it to a surface.  We don’t need or want those magnetic fields to travel far from the bracket where they could cause damage, interfere or just be a nuisance by attracting other objects.  Alternating the poles of the magnets keeps the magnetic flux lines closer and more dense at the surface of the magnetic vs poles facing the same direction.  This increases the strength of the magnetic Near Field and reduces the strength of the magnetic Far Field. 

We can further increase the strength of the Near Field while reducing the Far Field by increasing the pole count by using more, smaller magnets.  The same area of magnetic surface is significantly stronger up close by using smaller magnets but the magnetic fields don’t extend as far away.

See scale magnet diagram of three magnetic configurations (1/2” x 1/2” x 1/16”), ( 1/4” x 1/4” x 1/32”) & (1/8” x 1/8” x 1/32”).  Fields are approximated for illustrative purposes.

Cool video distorting the near and far fields for “seemingly” impossible results:  https://youtu.be/h69bbH1PwU4

Pull Force of magnets:
1/2”x1/16″ N52 4.45lbs (1,625 Gauss Surface Field)
1/4”x1/32″ N52  0.79lbs (1,625 Gauss Surface Field) (0.79 x 4 = 3.16lbs)
1/8”x1/32″ N52 0.3lbs (3,030 Gauss Surface Field) (0.3 x 4 = 1.2lbs) 

Total Pull Force: 
1/2”x1/16″ (8 magnets x 4.45 = 35.6lbs per bracket)
1/4”x1/32″ (60 magnets x 0.79 = 47.4lbs per bracket)
1/8”x1/32″ (280 magnets x 0.3 = 84lbs per bracket)
*note the 1/2″ is 1/16″ vs 1/32″ when evalutation pull force and strength.

(Qty 4) 1/8” magnets have the same surface area of (1) 1/4” magnet but are 51% stronger.
(1) 1/4” = 0.79lbs;   (4) 1/8” = 0.3lbs x 4 = 1.2lbs.  (51.9% more)

Note that these pull forces are not complete indicators of shelf load capacity when comparing the 1/2” x 1/16” magnets that have 6 of the 8 total magnets mounted at the top (where most of the pull force is needed due to leverage).  It’s a better indicator of the strength of 1/4” vs 1/8” because both have magnets all the way down but it still can be a little misleading.  Though 1/8” config has 77% more total pull force than the 1/4” config (for reasons already explained), that doesn’t mean it will hold 77% more weight on the shelf due to leverage and other factors.

Ferrous metals have a higher permeability than air which means magnetic field lines will concentrate more densely in ferrous metal.

Magnetic Sheilding
Magnetic Field lines don’t like to travel through air.  They much prefer to concentrate in a ferrous material than spread out in air which is one way magnetic shielding is accomplished.  If magnets are stuck to metal, the magnetic fields from that side of the magnet concentrates in the metal will very little extending past.  We use this to our benefit as the metal bracket acts as a magnetic shield for that side of the magnets.  Which means you can store your portable magnetic laptop shelf in a bag next to a laptop or tablet, just face the board side toward the electronic device and magnets other direction.  This is really only a minor concern if using the 1/2” magnets, using the smaller magnets with better near field characteristics is really no practical concern of issues with magnetic fields interfering with electronic devices.  I don’t recommend it but I have put the 1/4” and 1/8” magnet brackets directly on computers without any issues (video and pics soon).  Once the magnetic bracket is mounted on a surface practically all the magnetism is shielded by the metal of the bracket and by the metal of the mounting surface.  If still concerned about magnetic fields while storing or transporting magnet brackets you can use magnetic shielding bars.

(Pic laptop bag with board, maybe diptic or gallery old pic with new pic in back pack)

Magnetic Shielding Bars
Though I don’t use magnetic shielding bars on my Portable Magnetic Folding Shelves, I do use them when transporting my heavy duty magnetic brackets.  Also on my diy magnet mounts for sensitive electronic equipment or cables as seen in my Work Station Build post:  https://www.kevingittemeier.com/editing-workstation/ .  A strip of metal sealed in Mounting Tape folded over works well for magnetic bracket shielding bars and the Mounting Tape acts as a cushion and spacer for easy removal.

(Pic diy shielding bars, one mounted one laying to side)

Plastic Poker Chips with metal inlays make great Magnetic Shields and I use on many super powerful magnets as seen here.  For 1/2” magnet models with magnets only at the top and bottom, poker chips may be the better option.

(Pic old 1/2” models with poker chip)

FAQ

Q–Do you build these to sell them?
A-No, I don’t built “to” sell. See below
Like most of my builds, I designed and built these out of personal need because no such product existed at the time.  I got in the Elevator Industry (IUEC) in 1999 and after watching frustrated mechanics hold laptops with no place to put them, I designed my first portable laptop shelf in the year 2000.

Q-Do you sell Brackets or Laptop Shelves, can I buy one from you?
A-Sometimes & Maybe. I don’t build items with the intent to sell them. Sometimes as I am fine tuning a build I will sell off variations to mitigate my monetary losses. Notice I said “mitigate losses” not maximize profits. In some builds a lot of material is purchased in R&D to see which works best. Those are loses I will not recoup, I have never broke even selling off variations of any build. Most purchases have been from co-workers & local members who want them really bad and either swipe their company credit card or expense it as a “specialty work tool” and I have swapped for tools and material (Milwaukee, Dewalt or Rigid Bins see here).
*See availability list below

Q-Can these magnets damage my computer or other equipment?
A-It’s possible but practically speaking, it’s unlikely with reasonable common sense precautions.  Don’t directly place the magnets on sensitive equipment.  If storing in a laptop bag, just store the laptop shelf with magnets facing away from the computer, towards outside of bag.  This is really only a minor concern if using the 1/2” magnets, using the smaller 1/4” & 1/8” magnets with better near field characteristics is really no practical concern of issues with magnetic fields interfering with electronic devices.  I don’t recommend it but I have put the 1/4” and 1/8” magnet brackets directly on computers without any issues (video and pics soon).  Once the magnetic bracket is mounted on a surface practically all the magnetism is shielded by the metal of the bracket and by the metal of the mounting surface.  If still concerned about magnetic fields while storing or transporting magnet brackets you can use magnetic shielding bars (see Magnetic Shielding above). 

Q – Can I use different magnets? Can I use cup magnets?
A – Don’t! I highly recommend using the magnets I link in the exact configuration shown. It’s more work to mount cup magnets, it’s not as low profile and the magnet is more dangerous.  See above about magnet fields.

Q – Can I use a different folding bracket?
A – Don’t! This is the lowest profile quality folding bracket I could find and I bought over $100 worth searching. Others had sharp edges, poor or no coating or they just weren’t low profile. These brackets are ferrous so the magnets stick to them, some aren’t which means only the glue holds the magnets to the bracket. The Folding Brackets and Magnet Configuration is what makes this shelf uniquely compact and light. If not for that just buy the Magbench, Utilishelf or Omnishelf.

Q – How much weight can each magnetic configuration hold?
A – More than a laptop! I may do a giveaway with the winner being the one who can guest the closest for all magnetic configurations. If interested in this giveaway idea comment below!

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The current list of magnetic configurations is as follows:
1/2 x 1/2 x 1/16 Magnets 6 total per bracket.
1/2 x 1/2 x 1/16 Magnets 8 total per bracket.
1/4 x 1/4 x 1/32 Magnets 60 total per bracket.
1/8 x 1/8 x 1/32 Magnets 280 total per bracket.

Bracket Serial Numbers & Details

Bracket SN and data to track durability of magnet configurations, glue, prep and coatings over time. Not started until after model _024 Magnetic Shelf

Bracket SN	Bracket Magnets	Coats & Total	Coatings	Bracket Base Filler	Magnet Glue	Sanded Bracket Mag F/B
001_1/4/32NPC7	1/4×1/32 (Wht)	2 Wht 7 Clear (9)	Nail Polish / Clear	Clear GG 1.75	Clear GG 1.75	Y/Y/Y
002_1/4/32P2A2C4	1/4×1/32 (Wht)	2Pr 2Wht 4Clr (8)	Primer/Auto/Clear	Clear GG 1.75	Clear GG 1.75	Y/Y/Y
003_1/4/32C7	1/4×1/32 (CLR)	7 Clear Coats	Rustoleum Acrylic Enamel Paint+ Primer Gloss Clear	Clear GG 1.75	Clear GG 1.75	Y/Y/Y
004_1/8/32C7	1/8×1/32 (CLR)	7 Clear Coats	Rustoleum Acrylic Enamel Paint+ Primer Gloss Clear	Clear GG 1.75	Clear GG 1.75	Y/Y/Y
005_1/4/32B3C3 (A&B)	1/4×1/32 (WHT)	3 Wht 3 Clr (6)	Behr Gloss White 52 Paint + Primer / Rust Clr	Clear GG 1.75	Clear GG 1.75	Y/Y/Y

P = Primer (Etching Auto Primer)
A = for auto paint Duplicolor perfect match
B = Behr
R = Rustoleum
C = Clear Coat Gloss (I don’t use Matt bc too much friction)

Sanded Bracket and Front and Back of Magnets (Most Yes to all but may leave some unpainted unsanded magnets just to see).

Results immediately and over time

Bracket SN	Results Immediately	Results over time
001_1/4/32NPC7	Thick and uneven, must be sanded but very strong finish
002_1/4/32P2A2C4	Primer or accelerant ate into glue
003_1/4/32C7	Good
004_1/8/32C7	Good
005_1/4/32B3C3	Behr “Lifted” between coats and had to be sanded

General Coating Result Notes

Coating	Results Immediately	Results over time
Electric Tape	Good and easiest to apply	Wrinkles & must be replaced periodically
Nail Polish	Thick and uneven, must be sanded but very strong finish	TBD
Nail Polish & Clear Coat	Good	TBD
Auto Paint	Good	Chips at edges with hard use
Auto Paint & Clear Coat	Good	TBD
Behr P&P Gloss Wt 52 & Clr Coat	Behr Bad, lifted	TBD
Krylon Fusion	Good	Didn’t hold up well

Glue Poperties & Results

Glue	Properties	Results immediately & over time
Gorilla Glue Clear Silicone	Flexible/Pliable
Clear GG 1.75
Super Glue	Hard/Brittle

Clear GG 1.75 = Clear Gorilla Glue 1.75 oz

Magnetic Shelf SN & Recipients List

Shelf Build Post: www.kevingittemeier.com/magnetic-shelf-v2/

Serial No.	Board	Model	Etchings	Magnet Configuration	Magnet Coating	Recipient
KTFG_P1	MS	Red Recessed		Bar Cub Magnets – 4	Electric Tape	Kevin Gittemeier
KTFG_P2	MS	Red Flat	SN WS2 IUEC.60	1/2×3/4×1/16 – 14 Full	Electric Tape	Kevin Gittemeier
KTFG_001	MS	Gray w/b Recessed	SN Initials	???	Electric Tape	David Luther
KTFG_002	MS	Red Flat	SN	1/2×1/2 – ? 1/2×3/4 – ?	Electric Tape	Kevin Gittemeier
KTFG_003	MS	Aqua Recessed	SN Initials	1/2×1/2×1/16 – 8	Electric Tape	Eric King
KTFG_004	MS	Gray w/b Flat 1/2	SN Initials	???	Electric Tape	Fabian Bravo
KTFG_005W	MS	Gray Flat 2/2	SN Initials	???	Electric Tape	Fabian Bravo
KTFG_006	MS	Gray Recessed	SN Initials	???	???	Andrew Sauer
KTFG_007	FBR	White Flat/Flat	SN WS2	1/2×1/2 -6 1/2×3/4 -2	Rustoleum Flat	For Sale $185
KTFG_008	FBR	White Flat/Flat	SN WS2	1/2×1/2×1/16 – 8	Rustoleum Flat	Cole Bonno
KTFG_009	MS	Gray w/b Flat 1/2	SN	???	???	Kevin Gittemeier
KTFG_010W	MS	Gray Flat 2/2	SN	???	???	Kevin Gittemeier
KTFG_011	MS	Blue Flat 1/2	SN Initials IUEC.100 IUEC.50	1/2×1/2 -4 1/2×3/4 -4	Auto Paint	Travis Hutcherson
KTFG_012W	MS	Blue Flat 2/2	SN Initials IUEC.100 IUEC.100	1/2×1/2 -4 1/2×3/4 -2	Auto Paint	Travis Hutcherson
KTFG_013	MS	White w/b Flat	SN WS2	1/2×1/2 -6 1/2×3/4 -2	Rustoleum Flat	Jake Waddell
KTFG_014	MS	Red Recessed	SN	1/2×1/2×1/16 – 8	Electric Tape	Raul Ramos
KTFG_015	MS	White Flat	SN WS3	Board Only		Not Built
KTFG_016	MS	Gray Recessed	SN	1/2×1/2×1/16 – 8 ???	Electric Tape	Bud Oneal
KTFG_017	MS	Red Recessed	SN Name	1/2×1/2×1/16 – 8	Electric Tape	Jimmy Jones
KTFG_018	MS	Blue Recessed	SN	1/4×1/4×1/32 – 80	Rustoleum Flat	Kevin Gittemeier
KTFG_019	MS	Blue Recessed	SN2 WS3 IUEC.62 IUEC.100	Board Only		Not Built
KTFG_020	???	???	???	???	???	Missing
KTFG_021	Dex	Yellow Recessed	SN2 WS3 Name IUEC.50	1/2×1/2×1/16 – 10*	Nail Polish	Tony Carter
KTFG_022	Dex	Green Recessed	SN2 WS2 Initials	1/2×1/2×1/16 – 8	Auto Paint	Frank Mellor III
KTFG_023	Dex	Blue Recessed	SN2 WS4 IUEC.100.2	1/4×1/4×1/32 – 60	Auto Paint & Clear	Frank Mellor Jr
KTFG_024	Dex	Yellow Recessed	SN2 WS3	1/8×1/8×1/32 – 280	Nail Polish	For Sale $205
KTFG_025	Dex	Red Recessed	SN2 WS3 IUEC.62 IUEC.100	Board Only		Not Built
KTFG_026	Dex	Blue Recessed	SN2 WS2 IUEC.62	Board Only		Not Built
KTFG_027	Dex	Gray Recessed	SN2 WS2	Board Only		Not Built
KTFG_028	Dex	Gray Recessed	SN2 WS2	Board Only		Not Built

Shelf Build Post: www.kevingittemeier.com/magnetic-shelf-v2/

MS = Mainstays Recessed Board 11 x 14.5
Dex = Dexas Recessed Borad 11 x 14.5
MS/Dex = Either or. Dexas makes Mainstays for Walmart.
FBR = Faberware Basics Flat 11 x 14.

Recessed = Recessed Top
Flat = Flat Top
w/b = With Velcro Cable Bag

H = Hand Engraved
LE = Laser Engraved

W = Wide Brackets to stack in pairs
1/2 = 1 of 2 of Stackable Pair
2/2 = 2 of 2 of Stackable Pair

Flat/Flat = Both sides of board are flat (Faberware Basics)
NH = No handle (None built yet bc I like the handle)

SN# = Serial Number by number of times etched
WS# = My website Kevin Gittemeier .com by number of times etched
(etchings are on front and back)
Name = Recipients Name
Initials = Recipients Intials
IUEC.100 = IUEC Logo 100mm .2= 2 times (.50.2 = 50mm twice etc.)

1/2 x 1/2 and 1/2 x 3/4 magnets are 1/16 thick.
1/4 x 1/4 and 1/8 x 1/8 magnets are 1/32 think

Page 1:  Overview & Step 1 
Page 2:  Step 2:  Prepare & Glue Magnets
Page 3:  Step 3:  Magnet Coating
Page 4:  Read More, FAQ, SN List

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If any questions regarding a project or tutorial, ask in the Comment Section of the web post or YouTube video, not by email. That way the answer can help many people with the same question.

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