Weird cracking on points

[eegee]

I noticed something weird today that I can't explain. I had a few points laying on a bench in my workshop. 2 25mil and 2 31 mil points about 3" long (plus handles) all laying side by side. They've been pulled in the last few days and have been sitting around. They might have been lightly bumped against each other if somebody bumped the bench, but they havent been knocked around or anything. This morning 2 of the points had a crack across them AT EXACTLY THE SAME SPOT. This evening - the other two also had cracks AT EXACTLY THE SAME SPOT. There's only handles on one side and they are closed on the other - so if you lined them up by the closed end, the crack is straight across all 4 points.

Whassup with this? Coincidence or some weird glass thing I just never seen before?

[CosmicGlassInc]

Wierd, maybe its crappy glass? What kind of boro are you useing? They could have cooled enough to stress your point and crack when you set the points on your point holders. Sounds sketchy though hmmmm.....

Throck

[Mr. Whale dick]

thats why we anneal glass......

[eegee]

Its Simax. And yeah - I guess the crack could be right were I set them on the point holders - but they didnt crack until long after - they were just flat on the table.

hasslenuts - do you anneal your points before you use them?

[somberbear]

its just stress build up is my guess.... where you placed them on the rod rest gave it a short drain of heat compared to the rest of the point... the stress was slight but over time it cracked....

just my guess...

[Mr. Whale dick]

naw i don't anneal them...but they will crack weeks l8r sometimes....

[Orrza]

Hi Eegee.
Creacknig doesn't always appear in the first few minutes, It sometimes happens days or years later - try to flame cool your points a little.
I didn't really understand what's that point holder you had, but I got a thick plate (about 50 mil) with drilled holes in it, I always put the point standing so the hot area will cool unifrmly in the air.
I know some just lay them on the bench... I am trying to avoid it.

Peace,
Orr.

[eegee]

Ya - I just lean them against a bent piece of steel with notches cut in it to cool - then lay them on my other bench to store after cooled. I just thought it was whacked that they all cracked in exactly the same place - maybe I'm obsessive about where I position them to cool and positioned them all exactly the same - but I've never noticed that I do that :rollin

[duh]

i suggest you don't lay your points down on/touching anything ESPECIALLY while cooling. it just causes the glass to cool down at different rates and makes stresss..

[Mike_Aurelius]

I don't use points, I fuse on a 12 mm blow pipe, but had similar things happen very near the fuse point. I still use my rod holder to prop the glass, but I now hold it until it no longer moves, then lay the far end of the tube on the rod holder and the tip of the blow pipe on the table top. Plenty of air movement and no more breakage.

[NUBBLET]

heating the glass creates a great deal of stress , even just fire polishing the end of a blowtube . Try heating a little more even and as mentioned make sure no hot glass touches a cool rest , I like th "pin cushion" style gig mentioned above , I typically set the hot point over the edge of the table with a rod stuck in the handle (or more weight if needed ) to keep it from falling , I am anal enuf to balance the points or pieces to be used on the kiln wall using the method to balance . My door is in the middle with an element below and above , I just lay them across the "door jam" bottom .

[eegee]

Well, I might have over-engineered things - but I took a 2" thick piece of graphite today and drilled holes in it so I can stick my points or rods in handle first standing up. I even drilled a 1.5" hole for when I'm flame cutting big rod. Then just to be super anal - I plugged a few of the holes with graphite rods that stick up about 6" so I can throw my flame cut tubes over them to cool. Now anything hot will air cool and touch nothing :rollin

The only thing I dont know is if I can safely eat graphite - as I'm sure when I stick my blowtubes or points in the holes in the graphite I'll get some graphite dust/residue on them.

[jusbag]

I just drilled a bunch of holes into a chunk of 2x6. works great.