Tree Gecko

Projects in process.

Posts Tagged Glass Grinding

More bottle cutting

Mar 28

Posted by admintg in Glass Work | Comments off

I practiced cutting a few more bottles yesterday.  Trying to refine my technique.

Prepared for cutting

Prepared for cutting

I decided that rather than risk thermal shock to the entire bottle I would pre-warm the bottle by filling it with hot water.  I filled it up and let it sit for a few minutes to come to temperature.

Heating bottle

Heating bottle

I then scored it and ran the score line under the cool water from the faucet.  I then watched as the score line became thicker as it fractured through the bottle.  I did need to reheat the score line with more hot water, and repeat by running under the cool water.

Success

Success

I was able to get a fairly clean cut of the bottle.  I ended up with only one irregularity in the cut.

One jag in the cut

One jag in the cut

To smooth this out I used emery cloth to reduce the size of the jag, and to dull the edge of the bottle.

Removing the jag

Removing the jag

Once the rim of the bottle was relatively flat, I moved on to the grinding phase.  I used silicon carbide powder on a piece of glass.  I dropped some on the glass and used a water bottle to wet it.

Wetting the glass for grinding

Wetting the glass for grinding

Then I ground the glass for about 15 minutes, re-wetting and adding additional silicon carbide as necessary.

Grinding the Bottle

Grinding the Bottle

I verified lightly with the emery cloth that the edges were not sharp, and then carefully checked on bare skin.

Finished

Finished

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Bottle Cutting Experiments

Mar 14

Posted by admintg in General Activities | Comments off

I have been wanting to cut down some of my Port bottles for some time.  But never got around to it.

I did some investigation last weekend on the web as to the best methodology for cutting bottles.  I ordered a bottle cutting jig from Delphi Glass. It arrived on Friday, and this weekend it was time to finally attempt to cut some bottles.  I had low expectations from other web blogs which advise that a failure rate of 50+ percent is normal.  Part of the problem is the glass which is used to make bottles is not to the same quality as plate glass.

I scored the glass using the jig, and then it was time to convince the glass to nicely fracture.  There are many different methodologies for getting the glass to fracture at the score line.  I chose to use a methodology that uses boiling water slowly dripped over the score line, then shocked by slowly dripping under a cold water faucet.  The first attempt was a complete failure.  My score was not consistent and that caused the fracture to spider in a variety of directions.

The second attempt got a clean cut at the score line, but a weakness in the glass caused a large fracture to go down the glass.  So I ended up with a pencil holder rather than a glass.

Port Bottle Pencil Holder

Port Bottle Pencil Holder

Once the cut is made the top of the glass is smoothed out with emery cloth, then ground flat.

Here is the fracture.  It occurred where the glass was thinnest.  I may have used too much hot water and caused more heating than expected, or it could have been unavoidable.

Glass Fracture

Glass Fracture

I will take more pictures net bottle so that the process is easier to follow.

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Glass Grinding

Jan 4

Posted by admintg in Videography | Comments off

When I started planning for grinding glass for my own Depth of Field adapter, I found the following link on Dokas Photos very useful.  They are grinding the glass for a focus plane for a large format camera, but the information saved me much time.

I purchased my grinding abrasives from Willmann-Bell.  I purchased eight ounces of 500 grit Aluminum Oxide and eight ounces of 5 micron Aluminum Oxide Lapping Powder.  I didn’t even use an 1/8th of what I purchased, so starting with the 4 ounce size of each will allow you to grind a few blanks if required.

Abrasives

Abrasives

My glass blank was a 10″ x 12″ piece of glass that I picked up at home depot.  I decided to use a glass tile as my grinding tool.  I wanted a thicker piece of glass to allow me to easily hold onto the glass.   My post on my glass grinding tool shows where I ended up.

I collected everything so I could begin.  I used eye and a dust mask to minimize the amount of Aluminum Oxide I breathed in (though the 5 micron dust probably passes through the mask anyway).

Starting with 500 Grit

Starting with 500 Grit

I ground with the 500 grit Aluminum Oxide for about 45 minutes.  I added water and more abrasive as it seemed necessary.

I then washed off the abrasive from the glass and inspected my work.  One thing I realized was how much different the wet glass looked from the dry glass, as can be seen below.

Wet and Dry Glass

Wet and Dry Glass

Below is an image with the glass completely dry with a glove underneath but not touching the glass.

Example of scattering of light

Example of scattering of light

I then started grinding with the 5 Micron Aluminum Oxide Lapping Powder using my improved grinding tool.  As you can tell from this image, I was a little too generous with the powder and ended up wasting much of it as it immediately was pushed off of the grinding blank.

5 Micron Lapping Powder

5 Micron Lapping Powder

Use caution at the edges, it is very easy to allow the grinding tool to go too far off the edge and rock down on the table.  This can cause the glass blank to easily chip at the edges.

Careful at the Edges

Careful at the Edges

The glass tile worked pretty well as a tool, though it was not entirely flat at the edges.  The following image shows how the edges did not end up ground.  The good news was that the remainder of the piece of glass was consistently ground.

Grinding Tool Edge

Grinding Tool Edge

We will have to wait and see if the final product was worth the effort.  Hopefully with-in a couple of weeks I will have the new version of the depth of field adapter functional.

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