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Post by jfoinmo on Jan 3, 2020 13:53:25 GMT -8
I have built the core for my 6" Batch rocket and am looking to add an economical glass "door" for it.
I have two approaches I'm considering:
1. Use a 9x13 glass cooking pan (of borosilicate glass) and a high temp epoxy to attach a handle to it, then use refractory mortar to shape the firebox opening to hold it. I got the idea from seeing a casserole dish cover used - not sure of the long term viability it had though - but they are too small for a 6" system opening.
2. Salvage the glass from a discarded stove/oven - either the viewing glass in the oven door, or if I can find a ceramic cook top, then the glass from the top. Not sure if they are the same glass type though. Then similarly affix a handle with high temp epoxy and make a mortar lip to hold it.
Can any tell me if these two approaches are viable? Thanks!
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Post by Vortex on Jan 3, 2020 15:15:03 GMT -8
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Post by jfoinmo on Jan 3, 2020 17:38:03 GMT -8
Thanks. The linked thread was very informative.
Sounds like the Pyroceram, Neoceram, or Robax are the safest bets for high temps and that a borosilicate glass may work for period of time, but would likely break at some point if it came into contact with something cooler. Sadly the Pyroceram runs about $100 per square foot where I am. I'll have to put that expense off for now....
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Post by josephcrawley on Jan 3, 2020 20:01:18 GMT -8
If you can find an electric cook stove with the glass top it is the high temp stuff but a little difficult to remove.
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Post by wisc0james on Jan 4, 2020 5:39:09 GMT -8
Any concensus on what kind of heat stress these can take? I'm planning on calling a modified dsr with one. I was thinking of placing it about 15 inches above the internal exhaust. Thoughts?
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Post by peterberg on Jan 4, 2020 8:47:21 GMT -8
Any concensus on what kind of heat stress these can take? I'm planning on calling a modified dsr with one. I was thinking of placing it about 15 inches above the internal exhaust. Thoughts? That ceramic glass can take an awful lot of stress. Even a full tea mug breaking on the overly hot neoceram top of the 8" batch box at Paul Wheaton's wasn't able to break this glass. See also a video of the DSR cooktop, the same location. They are using a casserole door, two others has been exploding before. Those were bigger round ones with a metal knob on it. So if one wants to use a casserole lid for a door, make sure it's all glass.
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Post by wisc0james on Jan 5, 2020 5:15:48 GMT -8
We'll that's encouraging. Can someone hypothesize about the differences I might see between having 8 inches and 16 inches between the top of the riser and the glass cooktop? I'm assuming that, at some point, more space will result in lower temperatures on the glass.
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Post by peterberg on Jan 5, 2020 6:06:25 GMT -8
We'll that's encouraging. Can someone hypothesize about the differences I might see between having 8 inches and 16 inches between the top of the riser and the glass cooktop? I'm assuming that, at some point, more space will result in lower temperatures on the glass. The DSR in the video is a 6" version, space between the port and glass is 6" as well. A rule of thumb: minimum space above the riser of a straight batchrocket is the same as system size. Do you want about the same temperatures as the Allerton Abbey build for your 6" version? In that case it need to be 6", when you're aiming for a lower level 8" or maybe 10" is advisable. No hard figures at this stage, sorry.
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Post by martyn on Jan 5, 2020 7:24:38 GMT -8
We'll that's encouraging. Can someone hypothesize about the differences I might see between having 8 inches and 16 inches between the top of the riser and the glass cooktop? I'm assuming that, at some point, more space will result in lower temperatures on the glass. The overall hight might play a part if cooking is your aim.
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Post by wisc0james on Jan 5, 2020 12:07:25 GMT -8
Thank you peterberg and Martyn. That makes sense. With every system, there's a different sweet spot for hottest at the stovetop. In this instance, in addition to cooking temperatures, I was also concerned with not having a catastrophic failure of the glass. What are the limits of this stuff? I reckon blasting it with an eight inch BBR at a foot above the riser would be a real test of the material. The little one at Wheaton's place is a four incher, correct?
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Post by wisc0james on Jan 5, 2020 12:32:57 GMT -8
If the glass can handle it, I should probably be maximizing the stovetop temperature, as my bell is undersized due to space constraints.
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Post by peterberg on Jan 5, 2020 13:57:59 GMT -8
What are the limits of this stuff? I reckon blasting it with an eight inch BBR at a foot above the riser would be a real test of the material. The little one at Wheaton's place is a four incher, correct? No, that isn't correct, it is a six incher. All the high heat of the afterburner function is happening at the other side of that dark glass. I am not surprised they measured 1000 ºF at the hottest spot, this material can take much more. Specifications say not expanding upto 900 ºC (1650 ºF), which means it won't break with uneven heating. Highest temperature I've measured coming out of a batchrocket riser has been just over 900 ºC, so there won't be any problem. By the way: melting point of a glass ceramic is much higher than normal glass.
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