That is exactly what I tried to say. Newly exposed metal surfaces oxidize quickly. Normally, the reaction of that surface oxidation generates some heat and that heat is dissipated by the bulk of the metal and the thickness of that oxidation is a few hundred nano-meters thick in the the first seconds after the cut.
The smaller a metal particle gets, the higher it's surface area to volume ratio is.
At some point, the surface area to volume gets so high that the heat that dissipates into the particle when the surface oxidizes can turn the particle red hot.

When the micron-scale particle is red hot (molten), the cast iron rusts (oxidizes) all the way through the particle.
since iron oxide is much less dense and has a higher melting point than iron, the particle grows in size like popcorn popping. And that popped piece of metal quickly blows apart into nano particles that are so small they can hang in air like smoke for a long time. Smoke is just a bunch of particles that are so small that air currents can keep them suspended in a way that seems to defy gravity.

I also wanted to assure you that, even though the color of the dust is not the traditional red rust of iron oxide that you'd see on an old car, it is still oxidized iron.
In the end, I was trying to say, your dust doesn't seen like any cast iron turnings because they are so fine and oxidizing as they leave the saw wire

I have a friend who owns a company that manufactures pigment additives for concrete. Some of the colors that he makes, like black, gray, red and yellow are all made from the same thing: iron oxide. So yeah, what you say makes complete sense to me. It's all about particle size.

I hadn't thought about the "popcorn effect" that you've described, though. Very interesting stuff.

 

I have a friend who owns a company that manufacturers pigment additives for concrete. Some of the colors that he makes, like black, gray, red and yellow are all made from the same thing: iron oxide. So yeah, what you say makes complete sense to me. It's all about particle size.

I hadn't thought about the "popcorn effect" that you've described, though. Very interesting stuff.

The pressure that can be generated as iron rusts (oxidized) can be huge as the oxygen from air or water adds to the volume of the iron. The best example is rebar oxidizing in concrete - just pulverizing the concrete to create potholes in roads or split concrete off of bridges or buildings.

 

Having also machined a bit of cast iron in the past, I can say this is different than what I've seen. The cast iron "dust" im used to is like, I don't know, sand?

Your not taking the cut right if that is your experience. Probably a result of too small a feed or cutter not ground right.

Why use cast iron to make your lathe? Aluminum is as strong or a little stronger, and less expensive than the cast iron that is available in the same shapes.

 

Your not taking the cut right if that is your experience. Probably a result of too small a feed or cutter not ground right.

Probably so.

Why use cast iron to make your lathe? Aluminum is as strong or a little stronger, and less expensive than the cast iron that is available in the same shapes.

rigidity, mass, vibration dampening. And because it would mean I made this saw for no reason.

 

 

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How long did it take to get that far? Is the tablet showing the work time? 1:47:17?

 

How long did it take to get that far? Is the tablet showing the work time? 1:47:17?

Not sure when each pic was taken but that last one was toward the end and I cut for 2.5 hrs so 2:00-2:15 I would say. It is a very slow process.

 

I cut/pasted this quote from the "Picture this" thread

You should slide some surprisingly uncompressible news paper in your kerf to minimize binding on the wire and keeping your stock flat(ter).

I have been going on my old diamond wire experience which suggests this is not needed. This is one of the selling points of diamond wire; no blade to pinch in the cut. We would often cut very (very) heavy objects off at the base with nothing supporting the weight overhead. In fact we built a test jig to simulate the effect of cutting under immense weight:



It may be hard to perceive the scale; that pipe is 14ft diameter with wall thickness of about 5". The enerpac pumps you see at the bottom are applying 300 tons of compression force to the pipe. You can see the kerf gap is closed up at the back of the cut.

This was never a problem. It didn't matter if the kerf gap closed. The place which has just been eaten away by the wire, will always be the same dimension of the wire, so there is no issue.

Until the very end of the cut. At the very end, when there is a point where the wire essentially sweeps the feet out from under whatever it's cutting, and the tiny sliver that's left of it buckles and pinches the wire. At this point though, it can be lifted by crane and that "tag" will snap as if it weren't there.



I started this post with "I have been going on my old diamond wire experience" because I have experienced today the most frustrating series of unexpected failures I think I've ever managed to accumulate in a single day, and I think I should stop assuming that this wire is playing by the same rules. I will try anything. You suggest newspaper, you got it. Thank you for the suggestion, I'll try it.

 

I remembered about this from your thread. I had run across it by chance, the price is eye-watering.

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I remembered about this from your thread. I had run across it by chance, the price is eye-watering.

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Yeah the technology is not cheap. That seems inflated but still...

we paid less than that for a similar (but hydraulic) diamond wire system that included a trailer-mounted HPU




One of the things that attracted me the most about this project is that it's something almost exclusively NOT a DIY-friendly endeavor, and I like making things hard on myself.

 

Well, Hilti is Hilti. It's like buying Fluke, you might not be getting better specs for your money but you are getting Hilti and if you are big enough to pay for it, you will have the assurance that Hilti is behind the tool.

 

Well, Hilti is Hilti. It's like buying Fluke, you might not be getting better specs for your money but you are getting Hilti and if you are big enough to pay for it, you will have the assurance that Hilti is behind the tool.

If you expect one of these little red trucks to show up as soon as you have a problem, a few extra bucks are expected...
I don't think Harbor Freight offers mobile service trucks.

 

rigidity, mass, vibration dampening.

I'm sorry I'm late to responding to this statement. But I know what you said is true when it comes to something made of a casting, a single piece. But when things get bolted together from many parts, like a gear box made from slabs of cast iron, like I assume your going to do, I don't think the iron will make a real big difference. Each individual part will vibrate independently.

 

I'm sorry I'm late to responding to this statement. But I know what you said is true when it comes to something made of a casting, a single piece. But when things get bolted together from many parts, like a gear box made from slabs of cast iron, like I assume your going to do, I don't think the iron will make a real big difference. Each individual part will vibrate independently.

Well, Everything I think I know about this stuff suggests that it will make a big difference. But "everything I think I know" gets torn apart and remade into a different cartoonish picture more often than my unistrut contraptions, so who knows? Probably you, but we'll see. Actually maybe we won't; I'd have to build the same machine twice, once of aluminum and once of cast iron.

 

First video in which I invested an identifiable amount of effort in editing.

 

Don't know what is happening with me seeing this tread, it wasn't here this morning when I was on the forum.

But @strantor, you may get faster cutting if there was a way to make your arms so they could be closer to the object being cut. With them so far apart on what your cutting you get quite a bit of an angle between the arm end pulleys and the item being cut. So when that happens it cuts more on each edge of the part than in the middle of the part. You don't want the arms/pulleys too close, but like around a couple of inches from the part on each side.

 

Don't know what is happening with me seeing this tread, it wasn't here this morning when I was on the forum.

But @strantor, you may get faster cutting if there was a way to make your arms so they could be closer to the object being cut. With them so far apart on what your cutting you get quite a bit of an angle between the arm end pulleys and the item being cut. So when that happens it cuts more on each edge of the part than in the middle of the part. You don't want the arms/pulleys too close, but like around a couple of inches from the part on each side.

agreed. The permanent (welded, not out of unistrut) version of the saw should have hinged or otherwise adjustable arms in order to suit whatever is being cut. This one though is made per the dimensions of the forklift which it was born to cut. I have been thinking how I would like this configured if I decide to make a permanent version, and I think the best form factor is that of a familiar bandsaw, in which case the sliding arm takes on this duty.