awesome shop magnets

[keithh999]

Everyone needs a few superstrong magnets lying around the shop to pick up all the lathe shavings or milling dust or even to silence the anvils ring....and if you have or dumpster dive for old burnt out microwaves you have a source for 2 very strong magnets. Remove the cover and remove the magnetron (that fancy aluminum spaceship looking thing with cooling fins on it) usually its held in with 2 or 3 phillips head screws. A pair of hefty pliers and a vice will help you open the edges up and you can see the magnets inside the cooling fins..cut the two copper wires (more stuff to toss in the recycle bin) and remove the other magnet. Be careful not to get your fingers between these magnets as they are designed to channel microwave energy so they are VERY strong. Just a note of safety....DO NOT dissasemble the microwave whilst it is plugged in lest you want to become a flaming redhead. and as an added precaution you might want to short circuit the capacitor to release any stored electricity (use a pair of needlenose pliers for this....just touch the two contacts and then you are good to go).. any questions on this just holler...

[RainsFire]

it'll turn me into a flaming redhead?
lol..
good idea, some speakers have fairly strong magnets in them also.. good find.

[Ice Czar]

while your at it poking around that Microwave save out the transformer,
get enough of em and you can wire them in series to build yourself an arc welder (also have to rewire the secondaries)

Homebuilt arc welder

Ive bought the plans he offers (above and beyond the basic tutorial linked) which seem very complete, will post progress

I will reveal the following, microwave transformers can vary from 700 to 1500 watt units and you can build 70 amp120volt unit with between 2 to 4 transformers the sky is the limit for how many transformers you want to wire up in series but for a 250amp240 volt arc welder it would be between 8 to 16 transformers

most of the rest is likely laying around your shop (wire, cordplug ect) maybe even the cables and electrode stinger, however you will probably need to buy a Silicon-controlled rectifier (solid state rectifier to control current flow) about $25

for extra brownie points you can try a DIY Plasma Cutter

also the magnets in a Hard Drive are rare earth magnets
Rare earth magnets for fun and profit

[blubrick]

Another source of powerful magnets is computer disk drives. They are a really odd shape, kind of like a squashed crescent, and quite small (about 2" long).

Again, do not let your fingers get caught between these puppies, they are very strong! If you do get your hand or fingers between them, don't just slide them off your open hand, they will probably just pinch the webbing between your thumb and forefinger (or so I've heard )

[Ted T]

Magnets and Blacksmithing
I have a lot of uses for MAGNETS inside and outside of my shop.
Here are just some of my favorite tricks that I do with a magnet:
#1. Cleaning up the drill press table that is covered with oil and steel shavings.
I simply cover a strong magnet with a plastic covering such as baggy (sandwich bag).
This allows me to use a magnet in such a way that it will not be covered with oil or steel shavings when I am through cleaning.
The oil residue and small steel shavings stays on the outside of the baggy. Then all you have to do is just pull the baggy off from around the magnet and you still have a clean magnet.
Here are some other uses I have found for magnets;
#2. I use magnets to position steel that I am welding.
#3. I also drag a magnet over the gravel area out side of my shop where I weld sometime. I cannot afford to have flat tires due to leaving a welding rod end, or a piece of the steel hidden in the gravel that I have cut off while welding.
#4. I use a magnet to quickly stick up a drawing or blueprint onto a piece of steel in the area that I am working in.
#5. I also have magnets that have clips glued onto them. I use them sometime to hold instructions and or photos of things I am building.
#6. Pick up tool. I can hardly bend over any longer due to arthritis. I have had a stick with a magnet glued on one end. It works out great for picking up things I drop. It has saved me from a lot of pain. In fact, I just bought me a magnet with an extension handle at HF. It is like gold to me.
#7. At one time, I have placed a magnet on my anvil to reduce the ring.
#8. And last but not least, I use a magnet to make sure steel has reached critical heat when I am forging.
How did I ever live before magnets were available? I just don't know
Be safe!
Old Rusty Ted

[evfreek]

while your at it poking around that Microwave save out the transformer,
get enough of em and you can wire them in series to build yourself an arc welder (also have to rewire the secondaries)

Homebuilt arc welder

Ive bought the plans he offers (above and beyond the basic tutorial linked) which seem very complete, will post progress

I will reveal the following, microwave transformers can vary from 700 to 1500 watt units and you can build 70 amp120volt unit with between 2 to 4 transformers the sky is the limit for how many transformers you want to wire up in series but for a 250amp240 volt arc welder it would be between 8 to 16 transformers

most of the rest is likely laying around your shop (wire, cordplug ect) maybe even the cables and electrode stinger, however you will probably need to buy a Silicon-controlled rectifier (solid state rectifier to control current flow) about $25

Hi Ice Czar. I built a welder out of a microwave oven. It is not easy. I also saw the plans, but decided on a simpler approach. The painful part is rewinding the transformer. It sounds easy, but it is reall painful . First you need to remove the high voltage secondary. This is absolutely no use for a welder. Fortunately, the secondary is wound on a different section of the transformer. I am not quite sure how I did it, since it was so long ago, but I believe that it involved a hacksaw and a drift. You have to be very careful to make an angled cut so that you don't nick the primary. If you do, the transformer is junk. It is really unpleasant knocking the fine wire out of the core. Once you can get 10-20 percent of it out, the rest will fall out naturally.

Then, you have to rewind with thick magnet wire. dansworkshop recommends THHN, but this is really cheesy. THHN is only good to 105 degrees, but even worse, when used in transformer service, it must be derated because the wire is overlapped and under pressure. Use good magnet wire and kapton tape. Magnet wire is expensive. in the thicker sizes. If you use surplus, it will have little holes in it, and you must enamel the transformer with red enamel dope. This enamel should really be vacuum dried, but a vacuum drying chamber is usually not present in a blacksmithing shop. If you don't vacuum it, the transformer will eventually vibrate itself apart from humming and may explode .

The core must be disassembled (angle grinder with zip wheel ). Do not attempt to rewind the core without disassembling it and making a decent bobbin. You will nick the insulation and the transformer will be dangerous.

Do not knock out the magnetic shunts. These play the same role as the screw in core on a buzzbox. They limit the current to the arc. The reason is that the magnetron in a microwave oven has similar characteristics to an electrical arc: negative resistance. There has to be a means for current limiting. Remember, with the shunts in, the transformer will be "inefficient" in terms of line current. Not all the flux will be available to excite the secondary. Some will leak around the shunt. So, you will need slightly more than one turn per volt on the secondary. Really, you will have to make a test winding to see what the real ratio is. I shot for 30 OCV. This is pretty low, but any higher, and you will have weak current. At 30 OCV, the maximum theoretical current is about 120/30 X 10 or 40A. This is weak.

Since it is so weak, it needs to be a DC welder. I bought 4 Schottky diodes surplus at a flea market, and heat sinked them hot into some cutoffs from a salvaged rackmount unit (aluminum plate). At the low OCV and current, this will not even hold an arc with 3/32 6013. It makes a weak carbon arc wihch will barely melt brass. It needs a smoothing choke. This can be made out of a heavy high current transformer. Carefully remove all the wire, and quadruple it up, and rewind it. This is painful, since it does not behave well. Since it will not go in smoothly, you will eat a lot of the core window with air gaps. Again, these air gaps will spell death by vibration from the humming, so it must be heavily varnished with coil dope.

Even then, it makes a poor, cold arc, even with 3/32 6013. Probably no better than a Harbor Freight 120V cheap welder. Almost useless for stick welding.

But, I held on to this little welder for the time that it would be useful. Remember, there is really no lower limit with TIG. Use the microwave oven capacitor, along with two power resistors for a HV bypass, and bypass all the diodes with film capacitors. Connect it to a HF box for TIG welding. Negative to the torch for DCEN. Turn on 10 cfh of argon. Fire up the HF. It works, and it works well! Just the ticket for fixing boo-boo's and tiny welds. Very smooth and nice arc. Use 1/16 copper coated filler rod.

Good luck with the plans.

[Ice Czar]

thank you for all the extra advice (lots of good search terms)

luckily I do have an old autoclave and Welch vacuum pump
I also have an old 380 transformer, though Ive yet to determine how I might be able to employ it in this venture (not even sure if its coaxial, split bob, functional or blown) need to dig it out from under a pile in the garage :p

[ThomasPowers]

I keep a disk drive magnet in the medicine chest, in a sealed pill bottle so it doesn't pick up magnetic dust.

I use it for pulling steel splinters out of my hands and once picking out a steel piece that was riding along the surface of my eye---got it before it managed to get stuck into it requiring a Dr visit.