How close to the element ?

[Carl]

Hi all

Bought myself a drop ring the other day and today made a 4 inch stand for it. When I put it in the kiln I noticed that I was getting quite close to the top of the kiln, as the element is in the top it is going to be very close to the glass. Does anybody know it I should be worried?

Carl

[Glyn Burton]

How close is it? normally if you slow down your ramp rate it should be ok. I fire within 50mm on my big kiln with a very slow initial rate soaking at 200C and again at 400C to enable things to even out, there is a danger that the upper surface is hotter than the core otherwise. Something else to consider is the initial thickness of the glass, if you are planning a 4inch drop I guess you will be using 6mm plus so the soaking periods are even more critical. Best of luck with it.

[Carl]

I know it as been a while but I did get around to trying out my drop ring, the results where not good.

drop vase by carl.grigg, on Flickr
looked lovely but the clear glass was much to thin to coldwork the top.
I think my main faults where I had not pre fused the glass together and did not get everything level also used Tekta not Bulseye clear glass. No matter it was good enough to encourage me to try again.

[Zeldazog]

Look forward to seeing what you try next...    I've never tried a drop out...


Curious though, why you say one of the faults was using tekta and not bullseye...?

[Stephen Richard]

Several things can lead to thinning at the shoulder of the drop:
Too hot a top temperature
There is possibly not enough glass for the length of the drop. For a 100 mm drop I would expect a 4 layer or 12 mm blank.
Glass being caught on the ring.  This can be alleviated by having the ring sloped toward the hole, allowing the glass rim to slide toward the hole as the drop occurs.

There are probably other reasons too.

The Glass Tips blog has a series on aperture drops:
http://glasstips.blogspot.com/2011/07/aperture-drops-introduction.html

Stephen

[Stephen Richard]

.........
I think my main faults where I had not pre fused the glass together and did not get everything level also used Tekta not Bulseye clear glass. No matter it was good enough to encourage me to try again.

I don't think the problem was with the Tekta.  You have combined clear, blue and white.  These have different viscosities.  The white is the slowest to flow, and the blue (depending on its colour density) may be the quickest.  All the opalescents are slower to move than their transparent equivalents.

So I think your result is a combination of glass characteristics, rather than Tekta vs the other clear Bullseye machine rolled glass.

Stephen

[Warm Glass UK]

Totally agree with you Stephen - we have done lots of experiments here at Warm Glass since Amanda Simmons course a fortnight ago and it is amazing to see how different colours flow faster or slower than others - especially with opals versus transparents. We made pre-fused 12mm blanks to avoid the thin glass you got at the top Carl.

Pippa

[Carl]

Thanks to all for the hints and encouragement. When describing my first attempt I may have misled slightly, to clarify the clear glass was thin all the way down not just at the top. As Stephen and Pipa said this is probably due to the different glasses acting so differently.
I have had another go but this time pre fused a 3mm sheet coloured bulls eye with 3mm Tekta.
 
Try 2 by carl.grigg, on Flickr
The glass thickness is allot more even this time and I hope will survive the next stage. Will hopefully get another drop going and have a go at cutting this one later.

It's later already The mark 2 stood up to cutting and polishing and the mark 3 is annealing as I type hopefully i will be more brave and try a more interesting shape for the top of that one. Thanks again for the advice.

cut by carl.grigg, on Flickr

[Sandera]

I'm like a cat on a hot tin roof. Got my first ever drop vase in the kiln anealing away. I won't know it it's been a success until tomorrow morning.  I'm working on the basis that it will have worked (happy optimist or deluded fool!?) and I'm already trying to work out how to get rid of the rim bearing in mind that I have a tile saw and a normal grinder and nothing else. Did you use any fancy equipment to achieve the look you got (which I really liked btw)?

[Sandera]

Hurrah - it worked!

I think you'll be able to see the photos if you click on this link http://www.flickr.com/photos/redhotglassuk/

Erm I think so anyway!

[Glyn Burton]

Nice one Sandera, You could try letting it drop a little further on to a flat base so that it stands up on its own. Did you make the slumping ring? I have been using ceramic fibre board with my students to good effect cutting a variety of shaped holes. We use a flat lap grinder to finish the edges  if need be.

[Sandera]

Thanks Carl.
T
o be honest I prefer the bowl shape and a simple ring underneath keeps it very stable. I'll continue to experiment! Wish I could afford a flat lap grinder though

[Stephen Richard]

If you have a flat bed grinder or access to one, you can grind a flat spot on the bottom to enable it to stand on its own.

[Sandera]

I'd love a lap grinder but it's way out of my reach I'm afraid. I'll continue to experiment although I like the fact that the piece can be displayed both conventionality with the ring and without it. When it's tilted it looks planetary 

[Carl]

sorry or not getting back sooner been busy with other projects. I have not got a lap grinder so cut the rim off with my trusty dremmel and a diamond disk, then polished with micro-mesh. Loved your peacock feathers bowl on flickr.