Protohaven Member Forum

Door knobs

I have some pretty old door knobs at my house that I can’t find modern replacements for and the only ones that I am finding on ebay are currently at $75 a piece! I’ve only seen about six or eight of them show up in the past two years. At that price I figure that I might as well make my own. It will probably end up costing me more in the end but at least I’ll have fun doing it.
The knobs themselves are glass with a brass part near the door. The only problem is that I don’t have the right equipment for working with glass. Does anyone here work with cast glass?

Hi, Jack. Have you checked with construction Junction? They have quite a broad selection of old door knobs, reasonable prices.

Yes, every time I go. It’s a pretty unusual one. Here’s a picture:

I’ve only seen a handful of them pop up on ebay and the seller wanted a lot more than I was willing to pay.

The Pittsburgh Glass Center on Penn Ave would definitely be able to help. (I do a lot of glass work there, but I’m not really a caster.) I can’t tell from your picture; is this a a solid, smooth clear piece, or is there some kind of inclusion? There doesn’t appear to be any faceting. Casting them would be a slow (and expensive) process, and they’d probably have to be polished (tedious) but that would probably be the best option for faceted knobs.

If it is the flattened ball it looks like in the photo, it might be possible to make them out of hot worked glass, which would much faster and eliminate a lot of the cold working. There’d probably be a bit of trial and error to figure out the connection to the brass base, but I’d be willing to take a look and do some asking around. Sounds like an interesting problem, and I’d love to make some glass doorknobs for my house!

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As best as I can tell, it looks like it is cast and has had just a little touch up to eliminate the seam lines. The door side of the knob has a ‘rosette’ pattern. I think that it may be there to help engage the brass piece better but I’m not sure. I’m also guessing that it is attached to the brass part with a brass sleeve that was formed over the part that attaches to the door mechanism and the glass part. I think that method is more likely than the glass being in a molten state and pressed into the cavity of the brass piece.

As far as casting goes, I had a roommate who used to work with glass and she said that slumping forms were made out of graphite. I have a CNC router that could cut a mold out of graphite if that is how molds are made as well. I guess that it would have to be a three part mold but I could make that fairly easily (Once I have time)

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Hi, Jack!

As best as I can tell, it looks like it is cast and has had just a little
touch up to eliminate the seam lines. The door side of the knob has a
‘rosette’ pattern. I think that it may be there to help engage the brass
piece better but I’m not sure.

OK, thanks. I couldn’t make out any of that from the picture!

I’m also guessing that it is attached to
the brass part with a brass sleeve that was formed over the part that
attaches to the door mechanism and the glass part. I think that method is
more likely than the glass being in a molten state and pressed into the
cavity of the brass piece.

Yeah, I’d agree on that.

As far as casting goes, I had a roommate who used to work with glass and
she said that slumping forms were made out of graphite. I have a CNC
router that could cut a mold out of graphite if that is how molds are made
as well. I guess that it would have to be a three part mold but I could
make that fairly easily (Once I have time)

That sounds plausible. I was thinking of plaster or sand casting, which all
leave rough surfaces. Even slumping on a metal form requires some kind of
“release”, which leaves a less-then-lovely surface. I’ve never done any
slumping on graphite, but it’s certainly used in a lot of glass-working
tools,
so that doesn’t sound implausible to me. I’d be happy to talk to the
warm-shop
folks (where we do casting, fusing, and slumping) and see what they think,
or put you in touch with someone. The mold is definitely the trickiest part,
but if you can CNC that, the rest is essentially just heat and time.

– Mary

That would be great but let’s hold off for a bit. I don’t have the time at the moment to really jump into what would probably be a fairly big project. I’ll probably be ready in a couple of months though.

No worries.(I’m not drowining in free time either!)

But I may do some preliminary poking at PGC, because I’m definitely
intrigued!

– Mary

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I have a bag of old brass doorknobs from our house. The previous owner replaced them with newer ones. So if you wanted all brass, I am happy to bring these in…

Thanks but I like these glass ones quite a lot so I’ll either end up making some myself or I’ll buy them if any ever show up on ebay again.