Slumped glass platen is it possible?

[Fred Rowe]

I want to try slumping 2" wide by 1/4 thick glass to make a radiused platen. [48 inch radius] I've read a bit on temperatures to slump the glass, they can easily be handled by the elec. kiln.

The form could be made using castable clay with the resulting glass platen being epoxied to a mild steel base. I think the glass would run cooler and would not gouge as easily as steel.

The temps I believe are around 1200 to 1500fh to slump followed by tempering of the glass. If you have any insight I would appreciate it.

Fred

 

[BossDog]

I don't have anything to offer other than I sure would like to see pictures of how it goes for you..

 

[Fred Rowe]

I don't have anything to offer other than I sure would like to see pictures of how it goes for you..

This is definitely a worthwhile project. If the glass could be slumped correctly the options underneath, the steel part that attaches to the grinder proper, could be set up to cool the curved glass platen.

I'll be posting my progress.

 

[Knifemaker.ca]

I can't offer any experience, but will share a concern. A flat glass platen epoxied on to a less than flat steel platen will often fail. Epoxy may not be a good choice to support your project. When you say 'slump', I presume you are just arcing the glass plate. If you could cast it with one side curved and one side flat???

Watching with interest.

 

[Fred Rowe]

I can't offer any experience, but will share a concern. A flat glass platen epoxied on to a less than flat steel platen will often fail. Epoxy may not be a good choice to support your project. When you say 'slump', I presume you are just arcing the glass plate. If you could cast it with one side curved and one side flat???

Watching with interest.

I'm hoping to give the curved glass as much ventilation as possible. If the heat build up under the glass can be kept down, the temperature of the belt should stay much cooler. I'll build a mild steel base with three upright, 1/4 inch radius cut mild steel plates mig welded to an appropriate sized base; this can mounted to the grinder. :what!: When I first started considering this, I thought water cooled but I'll go with convective cooling for now.
The glass only has to slump 3/16 inch for a 36 inch radius and 1/4 inch for a 48 inch radius over 8 inches, the length of the platen.



Fred

 

[zbq]

Let me see if I'm understanding you correctly Fred.

You are wanting to make the glass concave on the back side so there is a space between the glass and the metal that it is mounted to for air flow to keep the glass and belt cooler, correct?

Do you want the face of the glass that rides against the belt to be flat, or curved?

You have me thinking on this now.
I have a good friend who owns a glass shop.
That is where I got my pyrex glass for my platen.
I had him put a 3/16" radius on the top edge where the belt makes the initial contact as it travels.
He did this by using a belt grinder that appeared to be a 1x42 two wheel vertical grinder.
The belt and bottom wheel ran in a fluid filled reservoir. I am assuming it was water. Not sure what kind of belt he was using.
Could you grind the concave section on the back using this type of grinding set up?

 

[Fred Rowe]

The purpose of this curved glass platen is hollow grinding. The slumped glass will be bow shaped, the mild steel base that it attaches to will have the same radius as the glass but instead of being a solid piece of metal it will be made up of three up rights welded to a flat base. My thinking is this will allow air to move along the bottom of the radius-ed glass keeping both the glass and the belt cooler. I don't know how much the heat affects belt life but I am assuming it is considerable.

I'll post pics when I get a little farther along.

Fred