Glass cylinder for light fixtures?

[Doug Chaussee]

A Two Part Question.....

Does anyone know of a place to buy glass cylinders in various colors for light fixtures? I have had a few customers ask about replacement shades measuring 5" in diameter and length ranging from 11" to 17.5". My searches have found a few in the 4" diameter but nothing in 5" at all.
While I have made some smaller cylinders offhand in the past, the logistics of making them this size, in my mind, would necessitate using a cylinder mold of some sort to assure exact dimensions.
Has anyone found something to use to accomplish this? Is anyone currently making such replacement shades? I made a 3" "mold" out of stainless steel pipe for drinking glasses but found that the piece will stick inside of the pipe if it is blown out all the way. Would a blow mold long enough to create the 17' piece have to have a slight taper to allow for removal of the piece once blown out?
As always, your help is greatly appreciated!

[Steve Stadelman]

Look in the archives for information on corking molds, you can make a mold out of pipe and split and hinge it to open up once the form is done and with corking the inside it will be really neat and nonstick. I wish you could come out and watch the guys here at Elements Glass shoot lamps into molds, 24" amd 30" parts all day long.

[Scott Dunahee]

Doug, We just did some of these. We needed 20" cylinders 4" in diameter. We inherited the job from another glassblower here in town who couldn't break 18". Anyway.

We ordered a 24" split cherry mold from Gary Guydosh and it works GREAT!

Pasted molds work GREAT for tumbler molds. I welded a flange to the bottom to keep it form coming along with the glass when I pull out. It helps. Next time I have to re cork it, I'm gonna weld on a loop handle for putting it back in the water when it's hot.

BSD

[Tom Marma]

Scott,
Are you getting any seams with the cherry wood molds? Anyone know any good tricks to avoid chill marks and seam edges?

[Scott Dunahee]

One of my tumbler molds is a piece of 3" pipe 8" high with a heavy flange welded on. That is then pasted with linseed oil (actually, Bob's magic mold paste, but I'm pretty sure it's just linseed) and cork in 2 layers. I spin in the mold while blowing. slick and easy.

The wooden cylinder mold is also a spin mold and the surface is pretty darn clean. You have to to into the mold HOT. And it's some trick to get a very moving 18" long 3" diameter parison outta the glory hole, about as hot as you possibly can and cleanly hit the mold after climbing up on the step. It's quite a bit of steam pressure to hold closed, but it also chills the glass and sets it up pretty fast so it's maybe a 15 second blow in the mold then out to flash.

So no, I'm not having any line problems because everything we do in molds is in spin molds, except for the square mold and we don't really use that very much at all. To avoid chill marks, go in hot, blow to shape and get out.

BSD

[Scott Novota]

Scott on those long fixtures are you punting up and opening or just sawing them off?





#2 Scott.
.

[Scott Dunahee]

sawing both ends off. We're cracking off the pipe into the oven.

BSD

[Steve Stadelman]

The guys at Elements (Ian and Aaron) don't spin the pipe when blowing into the mold, they just work it back and forth a bit to eliminate the breakline.

I have never done it but it is really neat to watch them.

[Scott Dunahee]

I've never claimed to be an expert on mold blowing by any stretch. I do do a fair amount of it, however and I get pretty good results at what I do. I've never tried a back and forth wiggle and truth be told, I don't even remember where I learned to spin in the mold as blowing.

At work, we're still making vases with a PVC mold lined with sheet cork. We've re-lined that thing maybe 8 times now and I'd guess we have at least 400 reps in the mold(?). If you let the sheet cork dry out, it's done, but keep it wet and as far as I can tell, ya gotta burn through the cork to hurt it. It is STARTING to warp a little out of round so next time we recork it, we'll probably replace the PVC sleeve too. I love it when stuff shouldn't work and clearly does.


I would love to see Ian and Aaron work those big molds they have. I'm really looking forward to GAS. They are some of the most skilled glassworkers I have ever had the pleasure of watching work. I went to school with them in Wisconsin and they taught me more about glassblowing than anyone in school. Period. They're good guys and really DO know what they're talking about.

BSD

[Barb Sanderson]

PVC - as in that white plastic stuff in the plumbing aisle of the hardware store???? Really?

On a related note....where are you buying sheet cork that you use in the molds please? Thanks.

Barb

[Michael Stoddard]

CorkStore.com has sheet cork a plenty

[Steve Stadelman]

Corkstore, it sounds like B.S. until you hear about places like fuses unlimited.

[Scott Dunahee]

I just get it at the local hardware store. They sell it as automotive gasket in a roll 12" by whatever the roll length is. Get the 1/8" stuff for longevity. Glue it into the pipe with a waterproof glue. This last time we used Gorilla glue. It worked fine.

You want a snug fit, so get out your Pi calipers and be ready to trim to fit before glueing.

BSD

[Doug Chaussee]

Thanks to all for the good suggestions! PVC? Who would have thunk!
A trick I learned when doing veneer replacement is to overlap the edges and then cut through both layers at one time, that way you get a perfect fit with no measuring needed.
One question Scott, is the PVC tube cut in half and hinged or just used whole?

Thanks again!

[Jeff Wright]

Corkstore, it sounds like B.S. until you hear about places like fuses unlimited.

Actually those guys do a great job. In the archives you should find some more info I posted a couple of years ago about these guys and creating cork paddles from 2 inch thick cork.

[Scott Dunahee]

our PVC mold is a straight piece of pipe. I've never considered making a split mold outta PVC.

It works pretty good for anything up to about 12" in our 4" pipe mold.

For bigger, I'd buy a split wood mold from Gary. They aren't that much money and are good for MANY reps. You can pass the savings along to your first commission on a new mold. :)

BSD