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Post by Deleted on Sept 10, 2009 12:34:04 GMT
Ok, I'm now back from sunnier climes and raring to get at the Brit boiler. For this task I will need to build a hearth. A couple of questions for the old sages out there: 1. Does anyone have any pictures or designs 2. I keep reading about using coke, but only the nasal variety seems to be available these days: I propose to use vermiculite instead. I've seen 3.5 cu ft bags of loft insulation at £11.50 each, but perhaps the grain size will be a little small? 3. Any other sources or types of insulation? Thanks in anticipation JB PS. A search for vermiculite knocked the ProBoard over!
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Post by drumkilbo on Sept 10, 2009 13:32:37 GMT
Here's a basic smiddy made one JB. A ruler and a Rob Roy are strategically placed to give you an idea of size. I did the Rob Roy boiler in this but obviously your Brit boiler will need a bit more room, however this one is portable enough to carry outside for brazing ops. The top just sits in the angle iron stand anyway. Ian.
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Post by Deleted on Sept 10, 2009 13:38:15 GMT
Thanks Ian, I like the ballast weight...... JB
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Post by Deleted on Sept 10, 2009 17:03:08 GMT
Did you know that 300hp Suzuki outboards are delivered on purpose-made steel frames? And that these frames are dumped in the marina? And that if you spirit them away they succumb to a disc grinder to make pretty good brazing hearths that can be knocked up in a couple of hours? Well, You do now! Folds up partly too, and yes, I removed the wooden jaws from the Workmate.....
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Post by spamcanman on Sept 10, 2009 18:18:48 GMT
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Post by havoc on Sept 10, 2009 19:15:35 GMT
Are you serious? ??
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Post by Deleted on Sept 10, 2009 19:41:05 GMT
Are you serious? ?? I'm reminded of a consultancy assignment some 12 years ago at a large crematorium. A hearse would pass my office window every 20 minutes: now THAT was serious! I didn't notice any trade in fire bricks though...... JB
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Post by maninshed on Sept 10, 2009 19:53:38 GMT
Hum, I'm not sure if vermiculite might not be the stuff you want to use in a hearth for brazing, far better to use Refractory bricks. The hard ones are better for long life, but the softer silicone ones are light and reflect the heat better as they are not so dense, they can also be cut with a normal wood saw. We use thousands in our electric and gas furnaces at work operating up to 1125 deg C. For a hearth how about going along to B&Q to the end of summer sale and getting one of those half oil drum type barbie Qzzz, ideal shape for a boiler, either that or cut an oil drum in half, and stick some legs on it. No point going for a design council job as they soon go rusty and look a mess.
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Post by Deleted on Sept 10, 2009 20:10:50 GMT
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Post by AndrewP on Sept 10, 2009 22:31:01 GMT
I suspect the vitcas firebricks are the heavy,dense type and the Cupalloys low thermal mass blocks. The blocks I use are from my last kiln rebuild, a 225 x 98 x 75 block weighs 845g - so about one quarter as dense as the cheap one. The lightweight blocks reflect more heat and absorb less.
Andy
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Post by spamcanman on Sept 10, 2009 22:32:34 GMT
Hmm, look like what I bought from Cupalloys I would go for your one's a lot cheaper!
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simonwass
Part of the e-furniture
Cecil Pagets 2-6-2 of 1908. Engine number 2299. Would make a fascinating model....
Posts: 472
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Post by simonwass on Sept 10, 2009 23:12:33 GMT
Just by looking at the photo of the cheap blocks you can see that they are dense blocks. They are heat resisting but they absorb heat. The lightweight ones reflect heat to a large degree, I have both types. The dense ones stay very hot for ages meaning they have absorbed a lot of the heat I was trying to put into the job. The light blocks also get hot but within a few minutes of them being white hot I can pick them up to put back in their plastic storage trays. Both types are fine for our purposes but the light blocks are far superior but do need careful handling to keep them in one piece.
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Post by drjohn on Sept 12, 2009 6:17:56 GMT
Hi again simplyloopyoco
get the guts out of old night storage heaters - for your tiddly wee 3 1/2 boiler they will do fine - yup I'm back!!
DJ
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Post by Deleted on Sept 12, 2009 7:37:25 GMT
Nice to see you back DJ, so am I! You want to watch the Alzheimer's though, I'd have thought you knew my name by now..... JB
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Myford Matt
Statesman
There are two ways to run a railway, the Great Western way, and the wrong way.
Posts: 621
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Post by Myford Matt on Sept 13, 2009 11:34:15 GMT
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Post by Deleted on Sept 13, 2009 11:37:51 GMT
That's a great idea Matt, why didn't I think of that! JB
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kwil
Part of the e-furniture
Posts: 383
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Post by kwil on Sept 13, 2009 14:14:10 GMT
drjohn. Unfortunately those night store heater blocks absorb heat, because thats what they do in their real use. OK for the base of a brazing hearth if you want the shelf underneath to be protected.
If you want the cheapest, use builder's CELCON blocks, make sure they are dry first, they reflect the heat well and do crumble eventually, but they are CHEAP, when they break or crumble throw them away. Being 18 x 9 you do not need so many.
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Post by Deleted on Sept 13, 2009 15:44:06 GMT
If you want the cheapest, use builder's CELCON blocks. Kwil: funny you should mention CELCON blocks. This was how it was set up using bits and pieces. There is a round refractory disc from our kiln covering up the hole in the base. It seemed to work OK but wait 'til we test it all.......
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Post by drjohn on Sept 13, 2009 22:17:33 GMT
drjohn. Unfortunately those night store heater blocks absorb heat, because thats what they do in their real use. That's why they work quite well - they store the heat from a usually inadequate torch and make a nice oven - reflective bricks just throw the heat away. DJ
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Post by Chris Kelland on Sept 14, 2009 16:24:02 GMT
Hi S L,
Do Celcon work as well as Thermalite blocks? Must say they look the same. I saw them up to make whatever size I need. When I want more I just go skip diving.
Have tried coke, but it gives off nasty gasses when it starts burning, I try to stay with something inert and FREE.
Chris K.
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