6" to 8" Conversion at the seacow

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6" to 8" Conversion at the seacow

Postby mannytheseacow » Mon Feb 17, 2014 11:32 pm

So I'm ramping up to start the conversion effort on my RMH. I'm getting the form put together and I want to do everything right this time. I've been lost over on the donkeyboards for about an hour now.... Can anyone point me to how to implement the tripwire correctly on an 8" j tube? I've read between 5mm and 8mm deep, but need some solid details on how far down the burn tunnel should the arrow begin and how far down should the point of the arrow be?
"Knowledge is power. Arm yourself."
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Re: 6" to 8" Conversion at the seacow

Postby matt walker » Tue Feb 18, 2014 5:26 am

I wish I could help, I haven't built one. It would definitely be a good idea to ask over there. I just got lost for an hour looking for an answer for you!
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Re: 6" to 8" Conversion at the seacow

Postby Bobwieser » Tue Feb 25, 2014 11:29 pm

http://donkey32.proboards.com/thread/48 ... #post-4280
Is this what your looking for? There is a lot of info here. They say to use the p-chanel in conjunction with the trip wire. I know there is another post with mrre details and dimentions. If I find it I'll do post it here.
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Re: 6" to 8" Conversion at the seacow

Postby Bobwieser » Wed Feb 26, 2014 12:11 am

http://donkey32.proboards.com/thread/355?page=5

This might be what you are looking for.
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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Wed Feb 26, 2014 2:37 pm

Thanks for posting those links, Bobwieser! I posted the same inquiry over on Donkey's site they referred me to the same links. After a little inquiry, the info I got was that there aren't really too many specifics on angles and such and it probably won't matter much in the long run. I've got the mold built and just did a basic 30* angle 2" back from the the feed, about 5mm deep. I can't wait to see how it works!
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Re: 6" to 8" Conversion at the seacow

Postby Bobwieser » Thu Feb 27, 2014 1:21 pm

Glad I could help.
In the second link Peterberg says. "The trip wire could be at right angles to the flow direction, but it's better at an angle of 10 to 15 degrees as an arrow pointing to the heat riser. The right angle trip wire will work nevertheless, only not as efficient."
Are you planing for a "P-chanel" in the feed tube? Good luck. I'll be waching for your results.
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Re: 6" to 8" Conversion at the seacow

Postby mannytheseacow » Fri Feb 28, 2014 2:33 pm

You know, I remember seeing this and my head was spinning by that point I guess I didn't absorb it. Well, I went with 30* but I'm sure it will be ok.

I've given some thought to the P channel. I'm keeping this one in my back pocket and figure at some point I'll be in some old boy's garage drinking beer and he'll have some steel and a torch and a vise and we'll throw one out without burning ourselves. We'll cross that bridge when we get there!
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Re: 6" to 8" Conversion at the seacow

Postby Prescott » Sun Mar 02, 2014 12:23 am

Hey Manny.

I have been very busy and not on the boards much, but hear you. I am likely going to upgrade my RMWH to an 8".

My bench is a lot smaller than yours so does heat up, but I am gone for 10-14 hours a day and the little burn chamber that could needs more attention than that. So I am with you on the 'sigh' business. Essentially I built a working prototype that functions well but I'd like to step it up!

My bench isn't clay (it's field stone and sand) so it'll be easy to disassemble (albeit messy, I'll likely wet it first) and my chimney will not need to be modified. Sorry to hear that about yours... :(

Looking forward to seeing your new core construction. I look forward to refining my first core, realistic trip wire and a bigger better turbulator, and like you, hope a p-channel manifests from some garage beer drinking creation!

Thanks for keeping us posted! It has been a brutal winter but I am amazed at how little wood I've burned. I'd be burning more if I were home more but it's good to have the work to pay the bills and such.

Steady on, oh one more thing. Did you see the original thread where the p-channel and tripwire were essentially "invented"/created? I book marked it a while ago as I kept going over it. It's pretty amazing, watching it evolve. It takes a bit to read it all through but that helped me get my head around it all...

http://donkey32.proboards.com/thread/355?page=1

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Re: 6" to 8" Conversion at the seacow

Postby Oddmar » Mon Mar 03, 2014 7:33 am

I remember Peterburg saying that the tripwire actually Reduces burn efficiency when used without the P-channel. The tripwire Needs the extra oxygen provided by the P-channel. Otherwise the tripwire just introduces drag.

The P-channel gap should be 5-7% of the feed opening. Basically 3/8" gap between the plate and the face, and sticking down 3/8" below the ceiling of the burn tunnel to properly siphon fresh air in along the ceiling, and over the turbulence-creating tripwire.

Somewhere i saw he refined his feed opening also, making a cool-air chamber around the feed that the P-channel gets it's air from. This steel box armors the feed opening against Matt's abuse... :) , cools the feed opening to reduce flame creep on thicker pieces, and pre-heats the air going into the P-channel.

I'll create a descriptive illustration...
Darrell "Jake" Jacob, Oddmar on all the forums, KC9PZN to all you amateurs.
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Re: 6" to 8" Conversion at the seacow

Postby Oddmar » Mon Mar 03, 2014 9:08 am

Image
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