Rare-earth magnet fragility

Richo B

Richo
Senior User
I bought some several years ago and have used them on several projects. They came from a place that included paperwork with severe instructions about not letting them get near each other and cautions for using them in general. I didn't expect that. It was like I was buying them from a scientific supply company. Mine are a little over an inch in diameter and very thin. People on-line complained that they had problems with the magnetics breaking or shattering though I've never had that experience. I bought them around 2016. Though I've got a few left, most have been used in the construction of my Dutch Chest, Specialty plane suitcase and Work caddy.
 

Gotcha6

Dennis
Corporate Member
I have some I use for holding the chuck on the drill press when not in use and other things. They are the size of a nickel and are so powerful I can put on on each side of the palm of my hand and they will stay there in any position - and I've got big hands. And yes, I've had them shatter on me. I also have some bar types that were shipped with spacers so they could be pulled apart.
 

Keye

Keye
Corporate Member
I was about to post a question about magnets when I found this thread. I do not know anything about magnets. I am pretty sure I just proved it. I bought some rare earth magnets off Amazon. My only requirement was size. I thought all magnets were created equal. They are 1" in diameter and thin. I thought 2 would work but I had room for 6 so I mounted 6 held in place with double sided tape. I am making a template using 1/4" plywood 8" x 14". I thought I would have trouble removing the piece but it was barely held in place.

What do I need to know to find stronger magnets.
 

Jeff

Jeff
Corporate Member
What do I need to know to find stronger magnets.
What happens if you take 2 of your magnets and put them together face to face without double sided tape on them? I don't understand how you're trying to use them for your template.
 

Richo B

Richo
Senior User
I was about to post a question about magnets when I found this thread. I do not know anything about magnets. I am pretty sure I just proved it. I bought some rare earth magnets off Amazon. My only requirement was size. I thought all magnets were created equal. They are 1" in diameter and thin. I thought 2 would work but I had room for 6 so I mounted 6 held in place with double sided tape. I am making a template using 1/4" plywood 8" x 14". I thought I would have trouble removing the piece but it was barely held in place.

What do I need to know to find stronger magnets.
I also don't understand what your "piece" is that you are trying to secure to the magnets and how the 8x14" plywood fits I to this. I have very similar magnets to what you described and they are strong enough to hold small tools to the sides of tool boxes that are carried including things like a small router plane and a 12" L Square. One alone can hold a cabinet scraper very tightly.
 

tvrgeek

tvrgeek
User
What are you trying to attach to? Does it get in full contact? If so, one small button size holds a lot.
 

Keye

Keye
Corporate Member
I obviously did a poor job on my first try at this. Let me see if I can do a little better.

Jeff, not sure what word to use other than template. I have looked at a lot of ways to make a better dust collector for a BS. I am trying to come up with one which will work for me and the way I use the BS. I have a Delta 14" with enclosed base. I really want a quick and easy on/off. I sometimes change the blade several times a day.

I recessed the magnets so they are flush with the surface of the plywood. I held them in place with double sided tape. The tape is just temporary. I am using the magnets and the BS table pin to hold the plywood in place, on the side of the BS table, so I can take measurements and mark where holes need to be cut. I had hoped the magnets and pin would hold everything in place. Do not think this is going to work as the plywood slides down the side of the table with almost no additional force other than the weight of the plywood. As it slides it rotates around the pin.
 

BWhitney

Bruce
Corporate Member
I obviously did a poor job on my first try at this. Let me see if I can do a little better.

Jeff, not sure what word to use other than template. I have looked at a lot of ways to make a better dust collector for a BS. I am trying to come up with one which will work for me and the way I use the BS. I have a Delta 14" with enclosed base. I really want a quick and easy on/off. I sometimes change the blade several times a day.

I recessed the magnets so they are flush with the surface of the plywood. I held them in place with double sided tape. The tape is just temporary. I am using the magnets and the BS table pin to hold the plywood in place, on the side of the BS table, so I can take measurements and mark where holes need to be cut. I had hoped the magnets and pin would hold everything in place. Do not think this is going to work as the plywood slides down the side of the table with almost no additional force other than the weight of the plywood. As it slides it rotates around the pin.
Keye,
Sorry, but I'm still confused. Can you post a picture of your setup?
And the magnets I have that are 1" should hold a piece of plywood to metal with NO problems, much less using 6 of them. Even if you have a 4" hose going through it.
 

Bill J

New User
Bill
I've had good luck with K&J Magnetics. They have mountable rare earth magnets that will hold over 200 pounds each.
You might have trouble getting the jig off if you use one that is too large. They are probably not the cheapest place to get magnets but I usually buy small ones in bulk and pay more for shipping than the products.
There is also a good related thread in this forum (see below).
Rare-earth magnet fragility
 

Keye

Keye
Corporate Member
The 3 pictures above are what Bruce wanted. Posting pictures is wearing me out.
These are inexpensive magnets from Amazon. Like I said before the only thing I know about magnets is they have polarity.
 

Jeff

Jeff
Corporate Member
The 3 pictures above are what Bruce wanted. Posting pictures is wearing me out.
These are inexpensive magnets from Amazon. Like I said before the only thing I know about magnets is they have polarity.
Maybe your bandsaw table is aluminum instead of steel. Magnets won't stick to aluminum, Put a few magnets flat on the table surface and see if they stick to it.
 

dwminnich

Dave
Senior User
If I’m understanding your pictures correctly, you’ve got those magnets inset into a piece of quarter inch thick plywood, right? The strength of a magnetic field drops off quickly with distance, so you really want the magnets to be in direct contact with the metal rather than having the wood between them and the metal. If you flip your piece of wood around, how strongly do those magnets hold?


Sent from my iPhone using Tapatalk
 

BWhitney

Bruce
Corporate Member
I used a piece of scrap 1/4" ply and attached four 1" magnets using double sided tape in 1" holes. Pic 1
I used a fishing scale (not the most accurate way to do this but all I've got) to measure the attractive power with the plywood between the magnet and the saw table. I measured around four pounds of pull before it released. Pic 2
These type of magnets do better when the magnetic field is focused so I put washers on the magnets and measured around 7-8 lbs of pull before release. Pic 3
I took off the washers and turned the plywood so the magnets were touching the saw table. I measured around 8-9 lbs. of pull before release. However this time the release was the magnets pulling away from the double sided tape. Pic 4
20200910_183823.jpg 20200910_184057.jpg 20200910_184220.jpg 20200910_184406.jpg
 

Keye

Keye
Corporate Member
Maybe your bandsaw table is aluminum instead of steel. Magnets won't stick to aluminum, Put a few magnets flat on the table surface and see if they stick to it.
The table is definitely not aluminum.
 

Keye

Keye
Corporate Member
If I’m understanding your pictures correctly, you’ve got those magnets inset into a piece of quarter inch thick plywood, right? The strength of a magnetic field drops off quickly with distance, so you really want the magnets to be in direct contact with the metal rather than having the wood between them and the metal. If you flip your piece of wood around, how strongly do those magnets hold?


Sent from my iPhone using Tapatalk
The magnets are flush or slightly proud of the plywood. If I flip the plywood it falls off.
 

Keye

Keye
Corporate Member
Well, what is it?

Bruce's experiment might give you some answers.
iron
I used a piece of scrap 1/4" ply and attached four 1" magnets using double sided tape in 1" holes. Pic 1
I used a fishing scale (not the most accurate way to do this but all I've got) to measure the attractive power with the plywood between the magnet and the saw table. I measured around four pounds of pull before it released. Pic 2
These type of magnets do better when the magnetic field is focused so I put washers on the magnets and measured around 7-8 lbs of pull before release. Pic 3
I took off the washers and turned the plywood so the magnets were touching the saw table. I measured around 8-9 lbs. of pull before release. However this time the release was the magnets pulling away from the double sided tape. Pic 4
View attachment 196487 View attachment 196488 View attachment 196489 View attachment 196490
The first thing I noticed is the side of your table is smooth and not coated with anything. Mine is rough and coated all the way around.
Trying to compare apples to apples I used the top of my table. With the plywood between the magnets and table top I measured no difference picking up the plywood. I used my digital fish scales to measure with. With the magnets touching the table top four of six magnets pulled free and the force was about 1.5 pounds. If one of the magnets is on the table top I can not lift it without first using my knife to lift one edge.

Please send me a note on how to post thumbnail pics.
 

Gotcha6

Dennis
Corporate Member
I think you're on to something here with the smooth statement. These rare earth magnets are very slick, and usually have to be slid apart laterally. Friction would help to hold them in place better, I believe. Try putting a piece of masking or friction tape on the contact face of the magnet and see if it slides. You may end up covering the side of your bandsaw with it, too.
 

Our Sponsors

LATEST FOR SALE LISTINGS

Top