Lead time

[ewmayer]

Paul, I'm just curious - In catching up on your counterweight exploits, I'm looking at a little steel dumbbell sitting on my exercise bench. It's one of those common home-style adjustable ones, the ends of the handle are screw-threaded and one slides various-weight cast-iron plates onto those and then locks down by way of scewing on metal collars. I would think repurposing something like that would work well as a counterweight, and avoid the hazards of home lead smeltage. After all, Pb is dense but not *that* dense, only ~50% more than Fe. Did the repurposed barbell idea occur to you, and if so, curious why you ended up going with lead.

[xilman]

Originally Posted by ewmayer

Paul, I'm just curious - In catching up on your counterweight exploits, I'm looking at a little steel dumbbell sitting on my exercise bench. It's one of those common home-style adjustable ones, the ends of the handle are screw-threaded and one slides various-weight cast-iron plates onto those and then locks down by way of scewing on metal collars. I would think repurposing something like that would work well as a counterweight, and avoid the hazards of home lead smeltage. After all, Pb is dense but not *that* dense, only ~50% more than Fe. Did the repurposed barbell idea occur to you, and if so, curious why you ended up going with lead.

I never even thought of it!

Thanks. I'll bear it in mind in case I ever need to repeat the exercise.

[ewmayer]

Originally Posted by xilman

I never even thought of it!

Thanks. I'll bear it in mind in case I ever need to repeat the exercise.

You can thank me (and the York Barbell Co. of Pennsylvania) when you get round to your "bucket list" build of a 1m scope. (I've actually seen mirror blanks of that size for sale on e.g. Cloudy Nights.) You'll obviously need an array of heavy-duty glass-installer-style suction cups to be able to maneuver the top tool-blank in your hand-grinding of that monster, but just think how buff your upper body will be at the end of it. A kind of ATM version of the bull-carrying myth around legendary ancient Greek wrestler Milo of Croton.

[kriesel]

Originally Posted by xilman

The Unhappy Me portion is that some molten lead splashed onto my right hand and, despite immediately plunging it into the cold water in which the wood had been soaked, I now have two mildly painful blisters each about 5x10mm in size. No permanent damage done but I am going to have to be careful for the next few days.

I suggest you be glad it was only your hand. Some good leather gloves might have prevented that, such as welders wear. As a college student employee I was tasked with recasting dozens of old beat up lead hammers, used in a university's machine tool array for seating workpieces in chucks. The large shop area had over a dozen lathes, and various quantities of mills, shapers, drill presses, etc. It was used to give engineering students hands-on experience with manufacturing tools and processes, and similarly occupational therapists so they would understand the nature of the work of injured machinists that they would treat during their careers. So on a Friday afternoon in the basement casting room, I set about making the hammers like new. After a couple hours I thought I was done, and started cleaning up, including quenching the ladle in water. By then it had accumulated some slag. Then I noticed one last unfinished metal bare hammer handle. So back into the pot of molten lead went the ladle, and half a second later there was a steam explosion under the surface of the melt. Some water had stayed hidden in the slag on the ladle until it went into the pot. The lead spray pretty well coated the underside of the ventilation hood with lead foil spatter; created the smell of burned hair and flannel shirt, and some of the spatter melted into my safety glasses or reached my face. One blob bridged my lips and froze there after melting some skin. I don't recall there being much if any safety instruction beforehand, or safety equipment beyond gloves and glasses. A full face shield would have helped. I finished the last hammer and cleaned up the area a bit. Spent a couple hours that weekend picking lead bits out of my shirt and hair, and part of Monday cleaning up the casting area.

[Uncwilly]

Originally Posted by ewmayer

You can thank me (and the York Barbell Co. of Pennsylvania) when you get round to your "bucket list" build of a 1m scope. (I've actually seen mirror blanks of that size for sale on e.g. Cloudy Nights.)

I have seen a 1m dob in person. It was a one-off by the company that produced it. They needed a truck with a liftgate to transport it. My understanding it was a hit at star parties.