Magnetic Chuck

[34by151]

I was grinding a toothbar the other day.

Pic of one installed on my Kubota BX23s Tractor


I grind the cutting edge with a 9in grinder first as a roughing cycle then finish off the edges in the mill.
Its a lot quicker than doing it all on the mill

The bar is 1240 long 350 grade steel 10mm thick

When grinding I hold it using one of the clamps on the bench
When milling I do the same one magnet unit on the mill but move the part.
Ive also done it with both magnets one on each end
Nothing moves

In saying that while grinding with the 9in when the grinder is clost to the maget, say 100mm away, the pull on the grinder is easily felt.
Does not seem to have any efect on the motor operation though

This is the main reason for collecting more microwaves to make more magnets. Id like 2-3 dedicated for the mill, one for the gearhead drill press and 1-2 for the bench.

Made the first ones to really find out how well they work. They work so well and make life so easy need to make more to stop having to shift them around. I did a test one one of them using a 12v car battery for power. Clamped it to a 2400x1200x12mm sheet of steel laying flat on the floor. Picked it up using the forks. No issue at all aprox weight 280kg. Second test moved the camp to the side and picked it up moving the sheet from horozontal to vertical, no issues or slip. That was with 12v, im using 48v on them now which is a massive increase in clamping power

In saying all that I still use my vices and indexer on the mill. Its just giving me more options but I must admit i use the vice a lot less

My drill press is a 1.5hp gear head unit. MT4 spindle 3 axis power feeds and coolant. Really a mini mill.
I rearly use the vice on it nowdays

On the bench the magnet is the goto for parts holding, rarly use calmps or a vice

Where it wint work is the welding bench. Not good to have the welding current pass though the magnet and they are too powerful anyway and would bend your welding arc

 

[Flyinfool]

Hmmmmmm.....
I wonder how the molten puddle of steel would react to the magnet. Or is it that the steel is no longer magnetic above some certain temp?

 

[34by151]

Havent tyied it

Dont wnat the current to go through the magent coils. Im often using 400A 3 phase welder worried it could burn out the coil or destry the psu.
As for the arc it will definatly bend the arc. It pulls my 9in grinder as i use it!!

If you try it would sugest turning up the shelding gas as the gas wont be affected by the bend in the arc and you may have weld exposed to perosity

 

[Shotgun]

I'm not seeing how the current would pass through the magnet coils. They should be insulated already.

Also, and electromagnet's strength is a function of current. . .not voltage. The 12V battery could have been pushing 200A, whereas I have a big 48V supply that is limited to 30A.

What happens to the chips as you're using one of those on the mill? I would think that it would make cleanup easy, but do the chips stick in the cutter?

 

[34by151]

When you cut the transformer and remove the coils you need to cut the terminals off.
When building the magnet I just trimmed the wires to length and stripped the insulation (scrape it off) then soldered my lead on

I doubt the battery I used could supply 200a. It's a dead one that wont hold a charge, wont start a car
I just use it as a capacitor on an old unregulated battery charger. This provided the power supply for my 12v diesel pump. This draws from a 44gal drum.

Re chips it really depends on what your doing and how tall/wide it is
If the chips fall on the magnet they will stick but dont pose an issue. If they buildup close to the job your toll will move them anyway.
I havenot seen any issue with the cutters operating any different to normal

PS I havent maeasured the current I do run the 2 coild in paralell on the psu when cutting. I rin them in series or paralell on the bench depending on what im doing.

I need to move some 12mm sheets next week these weigh about 500kg. They are stored in the old vertical rack. So I need to puck them up and move them hotozontal. I normally use my plate grab but I will it again with the magnet for you.
I try with a 12v, 24v and the 48v psu's

 

[Dabbler]

Or is it that the steel is no longer magnetic above some certain temp

Anything ferrous has a 'currie point' the temperature where it loses its magnetic properties. This differs a lot for each alloy, but usually molten steel does not respond (much) to magnetic forces.