[proto_lambda]

The first sentence of your comment was structured like this: [reason to use lead], but [reason to use tungsten]. At least I expected the second sentence to expand on the pros of tungsten, when in fact it was about the pros of lead; interpreting it as the former would mean lead is a hard material.

[theelous3]

The article explains the beneficial properties of tungsten with rad shielding. Tungsten sheilds better than lead. Lead is easier to form to simple shapes (flats, straight forward wraps). It is essentially impossible to form it in to complex shapes. Tungsten has a high temperature resistance, and low deformation under load. Broadly speaking it can be relied upon to stay in the shape it's machined to. But getting in to that shape is very expensive and difficult - an understatement.

I can't explain everything in every comment. You can research the materials if you want to understand the discussion in more context.

Tbh I have no idea how you came away thinking I said lead is hard. "also difficult". "this" is the material that is the center point of the discussion. Context, yo.

[proto_lambda]

> Tbh I have no idea how you came away thinking I said lead is hard.

I did not, in fact, come away thinking lead is hard. I did, however, explain and spell out for you how @kragen probably did so; I'm not sure how I can make it any more clear.

[kragen]

i appreciate you being willing to clarify the things that were hard to understand or that we were wrong about

(i actually had the impression that working lead on a lathe was very easy indeed due to its softness, but i've never tried doing it myself, and my bachelor's degree from youtube is worth what i paid for it)

i think you may have misunderstood something in the comment you were replying to yourself

[theelous3]

Lead is a nightmare to machine. It's gummy. You'd think aluminum was easy because it's softer than steels, but that comes with it's own challenges. Lead is worse so. You're right that this isn't so bad on a lathe as opposed to a mill or (lol) a grinder, but you're not going to see a need for a lot of solid round shielding.

A little bit of lead in steel will increase machinability, but only a teeny amount. Similar to adding a small bit of phosphorus.

It's also hard to hit dimensions in lead, and if you do hit them, the second the temperature changes you'll lose them. Additionally, whatever you make can't see any stress, or the part is donezo.

Idk if you've ever handled lead - but considering you can bend thick sheets of it by hand and melt it on your stove, I'm sure you can imagine the kind of issues you might have integrating expensively machined chunks of it in to hot high pressure environments with moving parts.

Even though lead is cheap and this filament is expensive, actually getting the lead to shape by machining or working it is also a costly process. 3d printing has a sort of cost ceiling. Once a part is designed, all of the real work is done. For fabrication and machining - once the part is designed the work has only begun.

What might look like a small and simple combination of geometric shapes can cost thousands to machine.

I'd rather spend 500 on filament and a day's engineering labor on a part than the same day's engineering, 100$ of lead, and 1k or more on manufacturing. Not to mention the lead times on machined parts can be wild.

[kragen]

i think all the post-manufacturing problems you describe with lead — dimensional instability, thermal creep, plastic deformation, incompatibility with hot high pressure environments, vulnerability to wear — are even worse with this filament

maybe an exception is that petg's maximum elastic strain is larger than lead's

[theelous3]

Considering lead's modulus of elasticity is essentially zero, yes :) You can drill, tap, and generally rely on this material to stay in the shape it was printed at in maaaaaany more situations than lead.

Of course the petg in there is a limiting factor, but even plain petg is an order of magnitude better than lead at retaining its shape under a wide range of loads. You can print gears for lathes in petg! And they last years! (If you're wondering why you might do this - it's a good idea to have a cheap point of failure on devices that have enough power to rip themselves to shreads.)

Not to mention this is only v1 of the material. We could see exotic plastics that are far more heat resistant like PEEK get a secondary filler for niche radioactive usecases.

[kragen]

https://www.matweb.com/search/DataSheet.aspx?MatGUID=ebd6d2c... says lead's modulus of elasticity is 14 gigapascals and https://www.matweb.com/search/datasheet.aspx?MatGUID=cb9580a... lists one variety of petg as having a modulus of elasticity of 2.2 gigapascals; i think you are confusing your material properties with one another

(at such low filler loadings the tungsten will change the modulus of elasticity very little)

petg does have higher yield stress than pure lead (53 megapascals vs. what https://nickelinstitute.org/media/1771/propertiesofsomemetal... says is 17 megapascals) but there are lead alloys that are in the same range of yield stress, including regular lead-tin solder. but they won't last if you try to make change gears out of them precisely because they're harder than petg

by the same token, though, i think you're going to get a lot of springback and long-term distortion out of petg you aren't going to get with lead