precision keeper cutting....

[StarryNight]

When you deform iron (or any metal), you add dislocations in the crystal lattice. This increases the hardness of the metal because the higher dislocation density blocks the movement of free dislocations. The internal strain also blocks the easy movement of magnetic domains. This raises the coreloss and decreases the permeability. Magnetically soft iron (that allows easy movement of magnetic domains) is also physically soft. Soft iron for magnetic circuits is typically used in the unstrained (or annealed-last) condition.

man, i love this forum I can imagine an analogy of a stack of drinking straws being cut. The staws become bent or pinched along the cut line which would impede anything flowing through them. Metal does have a kind of cellular structure doesn't it? or is it more fiberous?

[David Schwab]

When you deform iron (or any metal), you add dislocations in the crystal lattice. This increases the hardness of the metal because the higher dislocation density blocks the movement of free dislocations. The internal strain also blocks the easy movement of magnetic domains. This raises the coreloss and decreases the permeability. Magnetically soft iron (that allows easy movement of magnetic domains) is also physically soft. Soft iron for magnetic circuits is typically used in the unstrained (or annealed-last) condition.

Now of course we don't use soft iron, but this is easily testable. I'd wager the change would be nil for a spacer. You are talking about a very small gap between the magnet and pole screws. Also, you can use hardened steel set screws as poles and they work just fine.

[David King]

A cold saw is the common tool for this. Keep an eye on craigslist for one. The Barker mill that Bruce has is a lot more versatile but will require more tooling to get going.

[Diablo]

Now of course we don't use soft iron, but this is easily testable. I'd wager the change would be nil for a spacer. You are talking about a very small gap between the magnet and pole screws. Also, you can use hardened steel set screws as poles and they work just fine.

Didn't the original patents for the humbucker pickup call out "soft iron" in the specifications?

[David Schwab]

Didn't the original patents for the humbucker pickup call out "soft iron" in the specifications?

They use steel. No one uses "soft iron", and we've had this discussion here before and no one can even figure out what soft iron would be in the context of something you can buy.

Low carbon steel, and some of the leaded varieties is what's commonly used.

I'm sure someone here knows what the alloy of keepers are... probably 1018 or something similar.

[Possum]

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Soft iron is an old term not used anymore. And yes stamping cold works the alloy. Look at any TTop keeper, they were stamp punched and look like pretzels, surely its adding brightness.....

[Diablo]

They use steel. No one uses "soft iron", and we've had this discussion here before and no one can even figure out what soft iron would be in the context of something you can buy.

Low carbon steel, and some of the leaded varieties is what's commonly used.

I'm sure someone here knows what the alloy of keepers are... probably 1018 or something similar.

Possum has it right. Soft iron is old terminology. It means without cold work, or in the annealed last or soft condition as measured by a hardness test. There is also "full hard", "half hard" etc. This means with various amounts of cold work or after giving the material a partial anneal. In the context of a magnetic circuit, soft iron means "magnetically soft" - with low coercive force.

[Possum]

......

Take your keeper out and beat it with a hammer and see if it changes tones .....

[Bill M]

Possum, I tried the abrasive cut off wheels. It worked fine, but it made the keepers very red hot at the ends. Not very good. So, now I use my $85.00 wet tile saw with a good diamond blade and it works like a charm. The saw has an adjustable stop and I make fast work out of a 12ft piece of soft bar stock with little to no sanding afterwards.

[David Schwab]

Take your keeper out and beat it with a hammer and see if it changes tones .....

If you align it north-south and give it a good whack it will become slightly magnetized.

[David Schwab]

Possum, I tried the abrasive cut off wheels. It worked fine, but it made the keepers very red hot at the ends. Not very good. So, now I use my $85.00 wet tile saw with a good diamond blade and it works like a charm. The saw has an adjustable stop and I make fast work out of a 12ft piece of soft bar stock with little to no sanding afterwards.

You must have been going too slow. I use a big chop saw type of abrasive wheel cutter to cut 1/8" X 3/4" steel bars. They get hot, but not red hot. I can handle them a few seconds later. Takes me about two seconds to cut through the bar.

But yeah, that's a good way to work with the adjustable stop and all.

[Bill M]

You must have been going too slow. I use a big chop saw type of abrasive wheel cutter to cut 1/8" X 3/4" steel bars. They get hot, but not red hot. I can handle them a few seconds later. Takes me about two seconds to cut through the bar.

But yeah, that's a good way to work with the adjustable stop and all.

I don't know the rpm's, but it is one of the harbor freight cut off tools that uses the 6" cut off discs. The tile saw does work great, no heat at all. I cut my keepers to length and my machinest friend mills and drills them for me.

[David Schwab]

I don't know the rpm's, but it is one of the harbor freight cut off tools that uses the 6" cut off discs. The tile saw does work great, no heat at all. I cut my keepers to length and my machinest friend mills and drills them for me.

Oh that's the same cutoff saw I have. I do keep some water handy to cool them off, but the tile saw is a good idea.

[Bill M]

Oh that's the same cutoff saw I have. I do keep some water handy to cool them off, but the tile saw is a good idea.

Its a decent cut off saw. Soft steel does heat up very quickly so thats why I decided on the tile saw. Plus it cuts a lot cleaner.

[David King]

Keep in mind that the diamond abrasive will actually get dissolved into the iron if you use diamond to cut steel and you let the temp get too high. The water is a must. Meanwhile the iron can still gum up the blade and render it useless. Diamond is intended to deal with ceramic materials only. That said you got to break the rules to get anywhere but sometimes it's useful to know what the rules are so you don't throw your money away.