DIY wire saw designed to slice up a forklift

[rwm]

So assuming you can cut the cast iron into blocks or slabs, how will you create more complex geometry like you need to build a lathe? You could mill the blocks but that would require an awful lot of material removal. I am thinking that this is why most machine tools are cast. Not trying to sound critical just curious about the plan.

 

[jwmelvin]

You could mill the blocks but that would require an awful lot of material removal. I am thinking that this is why most machine tools are cast.

Should work okay to bolt together slabs, right? Brazing could reinforce.

 

[strantor]

So assuming you can cut the cast iron into blocks or slabs, how will you create more complex geometry like you need to build a lathe? You could mill the blocks but that would require an awful lot of material removal. I am thinking that this is why most machine tools are cast. Not trying to sound critical just curious about the plan.

I agree that's why most machine tools are cast; That, and for mass production. Making patterns/molds is a big up-front expense that only pays for itself after X amount of units have been produced. I'm only making one.

If I have to remove a lot of material I'm ok with that (easy to say right now). I think maybe we have different mental images though; maybe you're picturing a full size machine? What I want to build is like... take a Taig/Sherline CNC lathe, scale it up by a factor of 1.5 or 2, delete every aesthetic feature, fill every void that doesn't serve a purpose, and replace every bit of aluminum with cast iron. It will be made of the simplest geometries possible. Where Taig/Sherline uses a hollow aluminum extrusion elevated on cute little feet, I'll use a solid rectangle of cast iron. I will cut the parts out of the cast iron chunks using the wire saw or any other suitable saw as close to final dimension as I dare cut, so not as much needs to be removed. This will be a very heavy machine for its size. It's to be a production machine, just on a smaller than usual scale.

When I'm done it will probably be something that wouldn't make much sense to cast copies of. Too much "wasted" material.

 

[Joe in Oz]

Actually, you could make very intricate parts - like you can with wire EDM. Nothing stopping you from moving the 'workpiece' in two directions.

 

[strantor]

Actually, you could make very intricate parts - like you can with wire EDM. Nothing stopping you from moving the 'workpiece' in two directions.

In sheet material, yes, as long as the distance between the cutting edge rollers is well controlled and you're doing it free-hand. If you're talking about CNC then some software corrections will need to be made to account for the wire bending and the resultant cut path lagging a bit behind actual position.

In the case of cutting thick materials, I think there will be problems. The wire deflection within the material (it follows an organic spline or maybe catenary curve, not sure what the right word is) is something that I think would be very hard to compensate for. You can see what I mean in this screen grab below from the video I'm editing right now. I shot this clip to illustrate this very caveat.



If you imagine this for example trying to cut a round slug out of a 6" thick plate, what you would get is an hourglass shape that is unable to be removed from the parent material. This wire curve effect could be minimized by:

• bringing the rollers as close as possible to the work
• slowing down the feed rate
• increasing tension
• doing a pause/dwell at the end of each movement before changing directions, giving the wire a chance to "catch up" to itself and be closer to perpendicular.

But...

• you can only get the rollers so close
• the process is already painfully slow
• you can only put so much tension on a 0.3mm wire
• the dwell is a thing of logarithmic return on investment of time. I think you would have to dwell to infinity to reach a perfectly vertical position before changing direction. We don't need perfectly vertical, just within a tolerance dictated by the diameter of the wire (more accurately, the width of the kerf), to ensure that the cut piece can be removed from the parent material. But even for that, my intuition indicates (ex: cutting a 6" square out of 6" plate) that the dwell time required would be several times longer than the time to cut each side. It would probably take days to cut.

IMO this wire cutting method is best suited to making planar cuts all the way through thick materials.

All that said, there's this guy:

He's got a few things working in his favor:

• he's using a much thicker wire, so the tolerance to be able to remove the cut piece is much more forgiving
• he's making a sculpture, so the dimensions are not critical and the hourglass effect is not much concern.
• he's using wire designed for stone, on stone. So his cut time is much more reasonable than for cutting steel/cast iron with wire designed for silicon.

 

[strantor]

Spoiler: Yeah, but will it cut a forklift?

 

[strantor]

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

 

[woodchucker]

First, you have a very cute daughter, and the fact that she gave up a Barbie for you is amazing.
Second, have you tried any coolant. It will speed up the cuts (lube) and cool the metal and cutting wire. I'll assume that you are creating hard spots with the heat. Especially if you are igniting the dust. That may help remove the swarf so you are not re-cutting it, and speed it up. It's worth a try. I realize that you may wind up with a mess on your spool, and am wondering how you clean that up.. maybe a high pressure sheet of water on the exitting wire to keep it clean, which means both sides need it, just have to turn on which ever side is in use (electronically)

 

[strantor]

First, you have a very cute daughter, and the fact that she gave up a Barbie for you is amazing.

Thank you! That's my middle child and she's a daddy's girl. Now that I think about it, she probably would have given me one even if she liked it. So I think I owe her a replacement of her choosing.

Second, have you tried any coolant. It will speed up the cuts (lube) and cool the metal and cutting wire. I'll assume that you are creating hard spots with the heat. Especially if you are igniting the dust. That may help remove the swarf so you are not re-cutting it, and speed it up. It's worth a try. I realize that you may wind up with a mess on your spool, and am wondering how you clean that up.. maybe a high pressure sheet of water on the exitting wire to keep it clean, which means both sides need it, just have to turn on which ever side is in use (electronically)

Thanks for the suggestion. No, I have not tried coolant; I did not want to deal with the mess in my shop. But I will be forced to if I'm to continue. Editing these videos takes so long that by the time you see it I'm already way further along. I've already started on the forklift and in something that thick it's as you predict: the kerf gets so packed with ultra-fine metal powder that going back through it (like you can see in the end of the transmission cutting clip) is like cutting virgin metal again. Long story but the forklift presents unforeseen challenges. I think there is no way around using coolant to keep that kerf flushed out. It's going to make a big rusty mess in my driveway but I'm too hard headed to give up on account of that.

 

[brino]

Great video!
Thanks for sharing it here.

I gotta wonder if an accidental thermite reaction is a risk.
Initially I was wondering about it in the shop (maybe on the cart), but even in the shop-vac.....

Play Safe!
Brian