Scientific Glassblowing

Scientific glassblowing is considerably different from what one thinks of as "glassblowing"; visions of Venetian masters working with long blowpipes, dipping into glowing furnaces of molten glass... not. We produce glass tools working from preformed tubing and other shapes made of borosilicate "Pyrex" glass, which we buy from larger manufacturers such as Corning, Kimble, and Schott.

Lawrence Berkeley glassblowing shop 1963 - Photo courtesy Tom Orr

scientific glassblowing in 1963 at LBL

We use glassblowing lathes to hold, heat, and work the glass tubing; to make seals, form shapes, construct glass apparartus, and tool fittings and flanges. Click the link to see a 3+ minute video of a flange being tooled in a glassblowing lathe. 

The glassblowing lathe is different from a machine or wood lathe in that both the headstock and tailstock are driven synchronously. And the basic process is fundamentally different as well. Whereas traditional machining is subtractive (ie material is cut away and removed), scientific glassblowing requires that the hot glass be redistributed. This presents challenges for numerically controlled, automated equipment, as the feedback loop necessary for this redistribution has proven difficult to perform quickly. Any complexity in the glass compounds this scenario significantly. This means that unless you need to make 10,000 parts or more, a skilled glassblower is still better than a machine. 

Old School glassblowing
Print by Charles F Ulric

old school glassblowing

Our processes are best thought of as a combination of thermal forming and welding: we can heat larger amounts of glass to make changes in the general shape of the glass, and heat smaller areas to fuse tubes and components together. We use welding torches and other larger torch configurations, with oxygen and gas or hydrogen for fuel. "Blowing" is certainly one of the techniques, as is sucking, spinning, slumping, etc.

Elaborated glassware, such as, condensers, cells,  jacketed vessels, etc, are constructed from the inside out.

Large diameter glass tubing requires Larger lathes and burners

scientific glassblowing at large glassblowing lathe

Winding small diameter tubing using a "ribbon"burner

scientific glassblowing at ribbon burner

In addition, glass can be cut, drilled, and milled in the manner of traditional machining using diamond tooling....

...as well as CNC waterjet cutting. A high-pressure abrasive slurry cuts thru glass no problem. 


The image on the right shows 1/2" borofloat plate glass and the part that has been cut from it using this method, including the hole pattern. The finished part will be fire polished in an oven.

 

waterjet cutting of glass

Laser cutting and drilling is possible in quartz, but problematic for borosilicate glass; borosilicate cannot withstand the thermal stresses produced by the process. We know that it is possible to "etch" the surface of borosilicate, but think it unwise from a strength standpoint.
Pictured to the right is a 3"x4" quartz plate that has a series of wells ablated into the surface. The geometry of the wells is dictated by the configuration and power of the laser beam.

There is a history of science and glass presented here as a PDF from the online magazine Science. 

Machines make testtubes.......

 

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