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Author Topic: cheap gothic arch solar kiln  (Read 2430 times)

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Offline grouch

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cheap gothic arch solar kiln
« on: April 30, 2017, 01:07:10 pm »
The title is more flowery than the contraption. I'm hoping this thing will reach that magic 133F/30 minutes mark that WDH and others on here have mentioned, but if it fails, it will at least be temporary shelter for my growing lumber stack.

I was so tickled to be able to saw lumber for myself that I've neglected what it takes to dry and process it. Time to try to pay that piper, now. This time I'm going to be a little smarter about a project and post it while it's unfinished in order to hopefully reap the benefits of some of the experience, knowledge and creativity amongst folks on here.

First here's a link somebody posted on here somewhere and it bears repeating:
Forest Products Laboratory Wood Handbook (509 page PDF) Chapter 20, I think, is the one about the 133F for 30 minutes standard.

Ok here's the proof of concept (hey, it's still standing), a boat "house" I built to keep the snow and leaves out of my son's bass boat:


If I put something like that up with black plastic as a sort of inner wall and clear plastic on the outside, it should heat up in the sun. A gap in the black plastic at the ridge and one at the floor should turn that into a plenum and convection should provide circulation. Win, lose or draw, I'm trying it.

Here are my highly technical blueprints:


Ok, so maybe not so highly technical but at least no engineers were harmed in their making.

Here's the progress so far:
1-1/4 (nominal trade size) EMT arches:


1-1/4 EMT is close enough to actual 1-1/2 inch O.D. to fit nicely in one set of dies that come with the harbor freight tubing roller. I just drew 9ft-6in radius arcs on the garage floor and rolled the EMT until it matched.

Spent yesterday welding connectors I had previously cut and fishmouthed, in spite of wire feed issues, wind issues, operator wardrobe issues, heat and humidity issues, and carpenter bee issues.

Using a magnet and a little c-clamp for a jig:



Some T's tacked:


A pile of T's tacked:


Using a complex alignment device to start tacking the crosses:


Bunch of crosses tacked:


Before going any further, I should point out that me and MIG (MIG and I?) are barely on speaking terms. Toss in pipe-like and thin and it's a downright adversarial relationship.

Oh, and the wardrobe issue. Ever been welding and suddenly get reminded that *you're wearing sneakers not workboots, dummy!* Globules of molten steel are hot stuff. This is why you don't throw away the old welding gloves, so you don't have to take time out for a change:


All connectors (over-) welded up:


I am not suffering from an infestation of mutant mud daubers; this is just my artistic impression of MIG welding:


(And that's probably the best bead in the bunch).

That's how it stands so far.

Offline Gearbox

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Re: cheap gothic arch solar kiln
« Reply #1 on: April 30, 2017, 01:43:43 pm »
For covering you can get used billboard tarps . The ones I get are 14 X 48   $ 50.00 . I get 3 or 4 years covering wood piles . Google used billboard tarps . They have a envelope to slip in a 1x2 and then  strap it down . They come with a white or black back .
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Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #2 on: April 30, 2017, 02:05:00 pm »
Thanks Gearbox! I'd never heard of those before.

Offline Gtodoug

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Re: cheap gothic arch solar kiln
« Reply #3 on: April 30, 2017, 02:46:01 pm »
If you have a local billboard company just ask them if you can have few for free, especially if you tell them what you are doing.  We have gotten four or five for free that way.  They are usually just concerned that you don't tarnish the image of the company who's advertisement you might get.
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Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #4 on: May 01, 2017, 12:12:33 am »
I'll be watching this to see how it turns out.
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Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #5 on: May 01, 2017, 06:59:30 pm »
I'll be watching this to see how it turns out.

You like slow motion train wrecks, eh?


Cold and gusty winds today but I did a little site prep.

South side of the same old barn that currently houses my sawmill:


I do not like this stuff at all:


But I do like this young feller:

Have to try to avoid hurting that.

After some mowing and picking up some scrap wood:

(What? You were expecting grading, gravel and concrete?)

This stuff is still there. I want it to die by slow cooking.


Preliminary site prep done! Black plastic stapled to the barn (hence the compressor and generator) with a few concrete blocks to hold it in place. The wind rolled the blocks over by this afternoon so I'll be putting a few battens on the barn before the arches.



I need to cut some 4x4s for a base for a stack of lumber. Don't trust my felling abilities in gusty winds like today, so I just caught up on some mowing the rest of the day.

Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #6 on: May 01, 2017, 08:56:16 pm »
As long as my train of thought is involved in the slow motion train wreck, we'll be fine!

 :D :D :D :D :D
1992 LT40HD

The winds of change are blowing at hurricane force and I don't like it but good shall come even though I see not how.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #7 on: May 03, 2017, 10:35:08 pm »
Yesterday was a bust. Went walking through the woods scouting for likely trees from which to make a good base for drying lumber. Found a couple...

An oak, dead and standing near the base of a pond dam:


It's about 17 inches DBH.


Just down the hill about 30 ft, the top of a tulip poplar:


And the tree it came from:


That's about 19 inches DBH.

Both in this picture, the oak is partially obscured behind greenery to the right of that bleached looking tall stump:


Both tops (sweet gum obscuring the broken top of the poplar):


Angle showing a crook at about 8.5 ft up the poplar:


Even with the crook, I think those two would provide suitable lumber to frame up a base. The poplar looks to have a good 10 ft log above the crook. It would be a bear to get them up that steep slope.

By the time I got back to the house to eat breakfast and catch up on the Forum, the wind was gusting 30 mph. I'm not a lumberjack. When the tops of trees are randomly dancing around, I don't cut trees.

Don't think I should delay any longer, so, time for plan B...

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #8 on: May 03, 2017, 10:54:29 pm »
Here's plan B:



That's what Lowe's calls "whitewood". It's from my store-bought cache of lumber earmarked for my garage extensions. Now this thing has bought EMT, bought plastic, and bought lumber. Should have left "cheap" out of the title.

Heckuva lumber truck:


Might not look it, but that's level in both directions:


Close enough:


It's sitting on concrete blocks and various bricks and treated 2x stuff at the 4 corners, only. I'm not worried about frost heaving but I do think it will need supports at mid-span for each 2x6.

I'm only going to try to get up half of the thing. Rain is supposed to roll back in tonight and hang on for a while.

Oh, by the way, if you have mud dauber wasps, a tire valve cap frustrates 'em when they try to take over your air tools:


I had a choice: use 1/4-20 x 2 inch carriage bolts on hand, or spend half the day going to and from a town to get suitable hex head bolts. Carriage bolts went in the ridge connectors.
Doesn't take up much room like this:


Easy way to get the 3 arches to cooperate:


Welders like to believe that their work holds the world together. The rest of us know it's Duck tape and baling twine:


Roll it over...


Set it on the wood:


Add some stop blocks to the wood frame, and add the girts to the arches:


I think it will sit there without attaching it to the wood frame, as long as I leave off the plastic. Don't want it becoming a strange parasail.


Have to wait and see what the weather does now.




Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #9 on: May 03, 2017, 11:21:45 pm »
That's gonna be one nice green house I mean kiln!  Lookin good 8)
1992 LT40HD

The winds of change are blowing at hurricane force and I don't like it but good shall come even though I see not how.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #10 on: May 03, 2017, 11:39:06 pm »
Oops! I was so caught up in making sure to get the pics in order I left out a bunch of details.

The arches were assembled on the porch. They like to twirl around if you don't put them on a flat surface while drilling and bolting them to the ridge connectors. Simple jig: two wood blocks screwed to the porch right against the house siding, spaced 9 ft. 6 in. apart. (Don't tell my wife they're there). I used a couple of retainer wall blocks to hold the conduit flat.

Holes were drilled by just eyeballing about 3/4 in. from the end of the connector; step drill bit in my impact driver made the initial hole, 1/4 inch twist drill bit in a cordless drill pushed through to the other side. 1/4-20 x 2 carriage bolts, 1 per leg, tightened until the end of the bolt was flush or 1 thread protruding. Actual O.D. of 1-1/2 (nominal trade size) EMT is 1.740 +/- .005. (All connectors are made from 1-1/2 EMT, the rest of the arches, ridge, girts are 1-1/4 EMT).

The two rim joists are 2x6 x 10 ft. Regular joists are 2x6 x 9 ft. 3 in. at 24 inches on center. All crowns up. Shot with 3-1/4 x 0.131 (16d short) coated nails via pneumatic nailer (where were those when I was building my house and garage?!), 3 per end per joist.

Ridge pole is 10 ft EMT (minus whatever they short ya). Girts are 57-3/4 inches. If I was putting up the whole 20 ft structure at once, only the end girts would be that length and all others would be 58-1/2.

Other than the bolted ridge connectors, the only things holding that structure together right now are Duck tape and gravity.

Let me know if I've left other stuff out.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #11 on: May 03, 2017, 11:40:12 pm »
That's gonna be one nice green house I mean kiln!  Lookin good 8)

Thanks! That's why I have it *behind* the barn. If she sees it, it will be filled with cacti and weird green stuff.

Offline ChugiakTinkerer

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Re: cheap gothic arch solar kiln
« Reply #12 on: May 04, 2017, 02:19:40 pm »
I like this, and see a way to make use of it at my place.  I have the tarp from a "portable garage" that collapsed from snow weight.  I can rebuild the frame using EMT ala grouch.  Is the ridge angle around 120 degrees?
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Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #13 on: May 04, 2017, 06:49:54 pm »
Somewhere up there is a photo of my working sketches. I drew the arch out full size on my garage floor before ever making the first one. The ridge angle is exactly 118 degrees, based on that.

There's quite a bit of wiggle room; 1-1/4 EMT has an O.D. of 1.510 inches and 1-1/2 EMT has an I.D. of 1.610 inches. I cut the connector legs about 5-7/8 inches long but they could be shorter and still work well.

[Edit to add:]
I used a 1-3/4 inch hole saw in a milling machine to cut the fishmouth joints for welding. No pilot bit in the hole saw, several teeth missing (prior use in a drill press but poorly clamped part).

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #14 on: May 09, 2017, 10:48:49 pm »
Malfunctions, disruptions and interruptions make for a fine day. Probably should've stopped after the 2nd broken drill bit, but I never claimed to have good sense.

Got the frame blocked up including an oak 4x4 running under the middle, resting on 3 concrete blocks. Each 2x6 now only has to carry a 5 ft span.

Started putting some 1/2 inch x 1-1/2 inch oak strips on the arches to have a place to staple plastic. That's where all the frustration came in. Only got 3 up this afternoon, using some coarse thread 1 inch drywall screws I had on hand.



Clamps and twine pulled the oak up to the EMT for drilling and screwing.




That shadow of that cedar tree starts touching the frame at about 3 pm and has it covered by about 4 pm. Might affect how much heat this thing can absorb in a day.

At least there was something nearby to perfume the air (besides the red oak in use):


May have to revise my original plan for stapling plastic on the bottom of the floor joists. That could let too much air get back to the heating side without passing through the lumber stack first. I'm mostly guessing at everything in this experiment anyway, though.

Offline ChugiakTinkerer

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Re: cheap gothic arch solar kiln
« Reply #15 on: May 10, 2017, 01:46:25 am »
Sounds like you're maybe like the eagle in the video that was posted in a POSTONLT40HD thread.

http://www.forestryforum.com/board/index.php/topic,96078.msg1482455.html#msg1482455

Sometimes a fella gets an idea, jumps in with both feet, and just has to ride it out to its conclusion.
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Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #16 on: May 10, 2017, 07:15:26 am »
That eagle must've been real hungry or in need of glasses.

Don't think I've had that rough a ride, yet. The day's still young though.

 ;D

Offline Jemclimber

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Re: cheap gothic arch solar kiln
« Reply #17 on: May 10, 2017, 11:03:40 am »
Very nice project!! How much of a hassle was it to bend the pipe?

 Can you explain your thought process of stapling the plastic to the bottom instead of the topside. It seems like it would pull on the staples and tear more easily on the bottom versus the top.  I'm curious.
lt15

Offline pineywoods

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Re: cheap gothic arch solar kiln
« Reply #18 on: May 10, 2017, 11:12:53 am »
Jem, I think he's using 2 layers of plastic, clear on top and black on the underside. 2 inch gap between. I use a similar system on my kiln, except the underside is black metal roofing.  Works well..
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Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #19 on: May 10, 2017, 05:27:05 pm »
Very nice project!! How much of a hassle was it to bend the pipe?

It's thin wall conduit -- 1-1/4 trade size (1.510 inch actual O.D.), 0.065 inch wall thickness. I used the HF tubing roller which comes with a set of 1-1/2 inch dies that fit this size conduit closely enough to work. It takes rolling 'em back and forth through the roller multiple times, but is not hard work.

Quote
Can you explain your thought process of stapling the plastic to the bottom instead of the topside. It seems like it would pull on the staples and tear more easily on the bottom versus the top.  I'm curious.

This:
Jem, I think he's using 2 layers of plastic, clear on top and black on the underside. 2 inch gap between. I use a similar system on my kiln, except the underside is black metal roofing.  Works well..

Except in my case it's 1/2 inch wood + 1-1/2 inch tubing + 1/2 inch wood, so a 2-1/2 inch gap. Plus or minus the waviness I cut into the wood. :)

Maybe I'll get lucky and the curvature of the wall will help with efficiency of gathering heat.

Storms are headed this way. Stuff keeps interfering with my playing.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #20 on: May 10, 2017, 10:18:05 pm »
Didn't get much time to work on it today, but I did make some clamps.



Those are clamps. Trust me.

The wooden parts are 1/2 x 1-1/2 x 8 inches oak with 1/4 inch holes bored 1 inch and 4 inches from each end, centered (eyeballed) across the width. 1/4-20 x 3 bolts go in the holes.



Part of the frustration of drilling and screwing the oak strips to the tubing is getting them to stay still and flat on that rounded surface. These clamps make that easier.



The space between the end bolt and that one shoved through the middle holes is 2-3/4 inches. Tube + 2 oak strips is 2-1/2 inches. Put the clamp on, yank the tails to take up the slack, and the friction of the side pieces is usually enough to hold everything in place.

Where the strips try to slide over to one side, just put a nut on the bolt in the middle and tighten both until it lines up:



Sorry about the focus. These cobbled-up clamps hold the strips centered over the tube so a C-clamp or bar clamp can also be used without slipping off the side.

Offline Jemclimber

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Re: cheap gothic arch solar kiln
« Reply #21 on: May 11, 2017, 09:23:16 am »
Thanks!  Nice project, thanks for the very descriptive pics!!!
lt15

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #22 on: May 17, 2017, 01:21:27 pm »
The good news is that it's ready for plastic.

The bad news is my wife saw it with the oak strips on it and said, "Oh, that would make a really nice greenhouse!" (Darrel jinxed me).

Been grabbing a little time here and there to get the oak strips screwed on. Had to take time to cut a bunch more. I sawed these from what would otherwise be junk boards, so it's been piecemeal. Probably should be pine for stapling, but the only pine I have is bought dimensional lumber.

Used a ratchet tie-down strap to pull things together before screwing the strips to the girts.










The ridge was the most fiddly. Didn't have the arches spaced evenly, either, so I had to mess with pushing and pulling them in place in spite of Duck tape that's been cooked on.

Had more time today to work on it than any since first raising it. Clouds went away and the sun chased me in.

Speaking of the sun -- it clears the trees by 7 am but doesn't hit the arches until 8. I may have to move this thing out in an open field before loading it with lumber.

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Re: cheap gothic arch solar kiln
« Reply #23 on: May 17, 2017, 03:51:50 pm »
Sure is going to be a nice greenhouse!  I'm sure the wife will cook you an extra large serving of burgoo stew and maybe a derby pie.
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Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #24 on: May 17, 2017, 04:23:59 pm »
The good news is that it's ready for plastic.

The bad news is my wife saw it with the oak strips on it and said, "Oh, that would make a really nice greenhouse!" (Darrel jinxed me).


All I can say is that you had better get your drone forwarder fired up and sticker stacking lumber in there before your wife comes back loaded down with flower pots and the like.  :D D D D D
1992 LT40HD

The winds of change are blowing at hurricane force and I don't like it but good shall come even though I see not how.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #25 on: May 17, 2017, 04:28:47 pm »
Hmph. She'll more likely give me lunch meats and chips until she has a greenhouse that looks like this. She had my son and I running out into the boonies 40 miles away to bring home a dinky HF greenhouse she found on craigslist for $25 (about a tenth what they sell for new). I told her that was too much, but she had to have it. It was almost intact and complete, but even she agrees it wasn't worth the time or gas. She just stores flower pots in it now.

If this doesn't get hot enough for a kiln, I'll just rip the black plastic off the inside and move it where ever she wants it.

If it does work, I'll still have to build one for her. ;)

All I can say is that you had better get your drone forwarder fired up and sticker stacking lumber in there before your wife comes back loaded down with flower pots and the like.  :D D D D D

Troublemaker! It's all your fault.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #26 on: May 18, 2017, 03:49:06 pm »
I couldn't stand it. There was sunlight hiding behind the corner of the barn in the morning and behind a cedar tree late in the afternoon. So I loaded up my trap and I moved to sunny fields.



Cedar tree had to give the sun trap a little goodbye hug:




Hmm. Maybe I should put my mill in that, put canvas over it and go mobile. Think the D.O.T. would be thrilled to see me?

Guess it would need either Conestoga wagon wheels or Michigan Logging Wheels instead of those dinky 12s.



It will be hotter to put the plastic on there, but the whole idea is to capture heat. There was too much getting away where it was before.

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Re: cheap gothic arch solar kiln
« Reply #27 on: May 18, 2017, 05:59:27 pm »
For your sake (and mine too), I hope it is far enough away and hot enough so that your wife will leave it alone. Then my jinxing will be counteracted and I will once again be able to sleep at night.
1992 LT40HD

The winds of change are blowing at hurricane force and I don't like it but good shall come even though I see not how.

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Re: cheap gothic arch solar kiln
« Reply #28 on: May 18, 2017, 09:32:44 pm »
It should be hot enough where it's at. But you don't get off that easy. She saw where I parked it and said, "Is that for me?"

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Re: cheap gothic arch solar kiln
« Reply #29 on: May 18, 2017, 11:34:31 pm »
DanG
1992 LT40HD

The winds of change are blowing at hurricane force and I don't like it but good shall come even though I see not how.

Offline grouch

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Re: cheap gothic arch solar kiln
« Reply #30 on: May 19, 2017, 04:23:45 pm »
Between thunder showers and thunder storms passing through today, I managed to block the contraption up at the 4 corners and get the trailer out. The lowest corner is sitting on a dry stack of concrete blocks 3 layers high. That's 22-1/2 inches. I measured the height of the engine on a push mower and it's 17 inches. I should be able to keep the grass under the platform mowed so that if this thing is a complete flop, I can take it down and not have a big bare spot in the field.

Looking at it, I'm wondering if maybe a better design would be to have semi-circular arches oriented north-south. The north end of the half cylinder would be elevated to an angle matching the latitude. The platform on which the lumber is stacked would remain level. The inner wall of the half cylinder would be black and the outer wall transparent. From sunrise to sunset, the sun's rays would be nearly perpendicular to that inner wall -- passive tracking.

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Re: cheap gothic arch solar kiln
« Reply #31 on: May 19, 2017, 04:30:45 pm »
Oh, almost forgot.

For your sake (and mine too), I hope it is far enough away and hot enough so that your wife will leave it alone. Then my jinxing will be counteracted and I will once again be able to sleep at night.

Sleep easy, Darrel. I'm sitting here eating a t-bone steak. If she's gonna try to butter me up to get that kiln for a greenhouse, I may owe you.  ;D

Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #32 on: May 19, 2017, 07:12:06 pm »
Oh, almost forgot.

For your sake (and mine too), I hope it is far enough away and hot enough so that your wife will leave it alone. Then my jinxing will be counteracted and I will once again be able to sleep at night.

Sleep easy, Darrel. I'm sitting here eating a t-bone steak. If she's gonna try to butter me up to get that kiln for a greenhouse, I may owe you.  ;D

Now I can enjoy my BBQ chicken and sleep. Thanks.
1992 LT40HD

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Re: cheap gothic arch solar kiln
« Reply #33 on: May 22, 2017, 02:26:12 pm »
The sun trap has settled into its new nest in the field.

Up on blocks and the little trailer out from under it:


Got so hot while I was working on it that I decided to add some shade:


See those clouds in the background? Knew it was too hot. Had to go release that big blue sail because nothing anchors that contraption to the ground.

Following the wind came the rain:

There are squirrels who travel across my garage, through a redbud tree to the right, into and then down the walnut tree just left of center, and across the ground to a bird feeder hanging in a grapevine at the left edge of that photo. The little black dog thinks it is his duty to get the squirrels. He outran 1 so far and is determined to get the rest.

After the off-and-on showers, nice and cool this morning:


Such artistry! People pay big money to see wrinkles like those, don't they?
The black plastic was kind of raggedy so I put it on in 3 strips, eliminating the biggest tears.


Don't know if these ~3/4 inch holes will be significant or not:


And it was clouding up as I came in for lunch, so...



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Re: cheap gothic arch solar kiln
« Reply #34 on: May 22, 2017, 11:47:53 pm »
I screwed up. Got two rolls of 6 mil plastic, 10 ft (ha!) x 25 ft, but they are closer to white than clear. Don't have any confidence in them being more transparent to IR than they are to visible light, so I ordered a 54 inch x 75 ft roll of plastic that's reputed to be clear as glass. ~$60.

"Cheap" just keeps getting whittled away. I think I'm going to be close to $300 for about 500 cubic feet of enclosed space.

Well, there are other things that can be done while waiting for delivery. I'll just have to keep that tarp on until then. It got hot in there very quickly in spite of cool breezes and cloudy sky.

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Re: cheap gothic arch solar kiln
« Reply #35 on: June 04, 2017, 12:34:13 pm »
Need to bring this up to date. Will post photos later.

Hit 128F by 11:11 am this morning. Had to rescue my remote temp probe because it's only rated for 120F. Was 76F in the shade at the time. The outside layer of clear plastic doesn't even come all the way down -- it's open to the outside -- so it is heating even with sucking outside air into the space between layers of plastic.

Now I need to worry about it melting the black polyethylene, which is drooping really badly right now.

More later.

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Re: cheap gothic arch solar kiln
« Reply #36 on: June 08, 2017, 09:49:14 am »
Switching from barely translucent polyethylene plastic at 10 ft wide to very clear vinyl at 54 inches wide required some changes.

The only long (about 14 ft) 2x6 I was able to salvage from my stinky oak had to be sacrificed to make tack strips for the narrower plastic.





This little critter was waiting when I pulled the tarp off:


Treefrogs don't need to be cooked in a kiln, so I moved him to an old apple tree.

Each tack strip is let in so that meant more pilot holes and screws. I cut the notches with a hacksaw to keep from dulling any teeth on a wood saw. Mark, drill x 2, screw x 2, cut, clamp, drill, screw, and repeat for 4 strips on 3 arches.




Weather made it more appropriate to work overnight.

That black plastic on the ridge is there to keep the raw edges from wearing through the clear plastic when it gets installed.



 

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Re: cheap gothic arch solar kiln
« Reply #37 on: June 08, 2017, 10:06:13 am »
In the light of day:


Those tack strips were too thin to be spanning 5 ft and holding plastic flapping in the breeze, so I added strongbacks to them, swiped from my too-small pile of stickers.


Ok, so it's not a real consistent cut. It made 'em stiff enough for the job.



There's a bit of figure in that oak:


Wish I could've salvaged enough to make something pretty from it.






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Re: cheap gothic arch solar kiln
« Reply #38 on: June 08, 2017, 10:25:41 am »
The roll of clear plastic was sold as "4 gauge". I have no idea what gauge they use (US Steel? Brown and Sharp? AWG? Railroad?) but it feels like about 4 mil (whatever that is).



I got it through Amazon. It arrived from:


Clear enough for me:


My tack strips are on 48 inch centers. The plastic is 54 inches. Gives me 6 inches for folding to reinforce where it gets stapled. So, fold it under 1-1/2 inches along each edge, then double it over to make it 3/4 inch wide, that makes for sandwiching the plastic with 2 layers above and 1 below for stapling.



Heavy dew:




I sprinkled the staples pretty heavily:


Putting the plastic on in the cool of night keeps from having it sag too much in the heat of day.

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Re: cheap gothic arch solar kiln
« Reply #39 on: June 12, 2017, 02:28:44 pm »
Not caught up yet. :(


Folding the plastic. It was about this time I realized I could count on the lines on the green paper backing and not have to use a permanent marker to draw a 1-1/2 inch border.


2nd fold:






2 layers of heavy tape where the plastic gets stapled to the center arch:










Conestoga wagon needs wheels.





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Re: cheap gothic arch solar kiln
« Reply #40 on: June 12, 2017, 02:40:07 pm »
Black plastic. Old vampire rushing to stay ahead of the sun.
















Offline Darrel

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Re: cheap gothic arch solar kiln
« Reply #41 on: June 12, 2017, 03:11:33 pm »
It may be a bit unconventional but it will get hot, and you'll soon know how hot.
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Re: cheap gothic arch solar kiln
« Reply #42 on: June 17, 2017, 04:48:32 am »
It may be a bit unconventional but it will get hot, and you'll soon know how hot.

Yep. It hit 128F by 11 am one morning. That was with the outside layer incomplete; it had and has about 6 - 8 inches open to the outside all along the bottom of each side.

I still haven't loaded it with lumber, though. Stuff keeps eating up time.

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Re: cheap gothic arch solar kiln
« Reply #43 on: June 24, 2017, 03:30:44 pm »
Oops. Forgot to post the photos of closing the ends ahead of some rain. This was June 5. That was the day it hit 128F and I had to run and rescue my 120F rated remote temperature sensor. Rain rolled in shortly thereafter.













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Re: cheap gothic arch solar kiln
« Reply #44 on: June 24, 2017, 03:47:16 pm »
After that bout of rain, I spent 2 (partial) days in the hot sun (off and on, between spells of panting in the shade) loading that thing with what lumber I have on hand. Then it turned cool and rained until today.





The sag was just right for unloading.



That load didn't fill it very much.



Thoughtful old Dodge kept rising to make it easy to unload.



2nd load.



Rarin' to go.







Needs about 3 more loads, but I don't have 'em.



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Re: cheap gothic arch solar kiln
« Reply #45 on: June 24, 2017, 04:04:52 pm »
Somewhere around here, GeneWengert-WoodDoc pointed out that convection alone is never going to move enough air to dry a stack of lumber in a solar kiln. My original intention was to have intake flaps along the floor in that inner wall black plastic, and exhaust flaps at the ridge. The idea was to use a chimney / venturi effect to increase air flow. I don't think that would work simply because the temperature differential between floor and ridge is going to decrease as the whole thing heats up. Serendipity may have come to the rescue.

Those gaps in the outside plastic at about floor level suck in outside air, heat it up on its way up the wall, and blast it into the kiln at the ridge. If I understand correctly, the elevated moisture capacity of the heated air is the key to using it to dry the lumber. Moving that heated air through the lumber stack sucks the moisture from the wood, and then you have to get rid of it without putting it back into the wood.

I'm going to try making the lumber stack the muffler in the exhaust system. I'll drape plastic over the stack like a blanket, with the edge just even with the end of the stack nearest the closed, west end of the arches. The sides will be sort of tucked in. The other end of the plastic will be loosely draped over the foot of the lumber stack, then the edge brought up and stapled to the east end arch. A second sheet of plastic will go over that end, also. This makes the lumber stack the only way for air to exit the kiln. That's where I'll monitor the temperature.

The path then becomes: Ambient temperature air enters through that gap at the base of the outside wall, gets heated between the clear outer wall and black inner wall, passes into the kiln at the ridge, mucks and mills around inside looking for the exit, then gets crowded through the lumber stack to exhaust to the outside at the east end near the floor, if the outer end plastic there isn't closed up to force more heating.

Being a hobbyist and not depending on this lumber to pay the bills, I can experiment like this.

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Re: cheap gothic arch solar kiln
« Reply #46 on: June 24, 2017, 06:00:22 pm »
Check out E-bay for solar powered camper fans...

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Re: cheap gothic arch solar kiln
« Reply #47 on: June 27, 2017, 02:12:26 pm »
Check out E-bay for solar powered camper fans...

Thanks, but that's too conventional. :)

All the wind in the world, from gentle breezes to monster hurricanes, comes from just sunlight. I want to avoid converting light to electricity to convert to rotary motion via an electro-mechanical device to make wind.

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Re: cheap gothic arch solar kiln
« Reply #48 on: June 27, 2017, 02:29:37 pm »
I've read reply number 45 several times and I'm just not going to read it anymore because every time I read it I become more clueless as to what Grouch has in mind. Then I read reply number 46, sounded good to me. Then when I read reply number 47, the grouch kinda put the kibosh on that.

Now I'm sittin here with this big grin on my face anxiously waiting to see what happens next!

 :)
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Re: cheap gothic arch solar kiln
« Reply #49 on: June 27, 2017, 02:45:50 pm »
I've read reply number 45 several times and I'm just not going to read it anymore because every time I read it I become more clueless as to what Grouch has in mind. Then I read reply number 46, sounded good to me. Then when I read reply number 47, the grouch kinda put the kibosh on that.

Now I'm sittin here with this big grin on my face anxiously waiting to see what happens next!

 :)

Bwahaha! My evil plan is working! Today, Darrel, tomorrow THE WORLD!!1

Let me see if I can make this more confusing. Take a big funnel. Lay it on its side and fill the throat with lumber (properly stickered, of course) such that the ends of the boards are even with the narrow end of the funnel.

Put the whole thing into a jug whose opening is the same size as the big end of the funnel. Cut some narrow slits in the side of the big jug near ground level. Air can get into the jug through those slits, but can only get out by coming out the funnel (backwards to the way a funnel is normally used).

Hang a big sheet over the big end of the funnel so you can control how fast air gets to come out. The heating of the air between jug and funnel throat is what drives air flow.

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Re: cheap gothic arch solar kiln
« Reply #50 on: June 27, 2017, 04:55:42 pm »
I think even I understand your evil plan now.  Might the lumber pile offer too much resistance to get good flow?  I suppose there's at least one way to find out...
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Re: cheap gothic arch solar kiln
« Reply #51 on: June 28, 2017, 12:15:17 am »
I've read reply number 45 several times and I'm just not going to read it anymore because every time I read it I become more clueless as to what Grouch has in mind. Then I read reply number 46, sounded good to me. Then when I read reply number 47, the grouch kinda put the kibosh on that.

Now I'm sittin here with this big grin on my face anxiously waiting to see what happens next!

 :)

Bwahaha! My evil plan is working! Today, Darrel, tomorrow THE WORLD!!1

Let me see if I can make this more confusing. Take a big funnel. Lay it on its side and fill the throat with lumber (properly stickered, of course) such that the ends of the boards are even with the narrow end of the funnel.

Put the whole thing into a jug whose opening is the same size as the big end of the funnel. Cut some narrow slits in the side of the big jug near ground level. Air can get into the jug through those slits, but can only get out by coming out the funnel (backwards to the way a funnel is normally used).

Hang a big sheet over the big end of the funnel so you can control how fast air gets to come out. The heating of the air between jug and funnel throat is what drives air flow.

Well why didn't you say so?!? ;D
1992 LT40HD

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Re: cheap gothic arch solar kiln
« Reply #52 on: June 28, 2017, 07:39:04 pm »
You mean you're no longer confused?

Curses; foiled again! Should've kept quiet.

I haven't had a chance to try it out yet, so the lumber I put in there has just been baking at whatever temp it gets to in there. The end is not sealed but there's nothing to force the exhaust air to pass through the stack. It could be warping the wood and growing mold in the center by now.

Need to get a meat thermometer with a remote probe or two.


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Re: cheap gothic arch solar kiln
« Reply #53 on: June 29, 2017, 06:29:38 pm »
Look on E-bay...
They sell a Thermometer Hygrometer meter for under $10.00

 

 
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Re: cheap gothic arch solar kiln
« Reply #54 on: June 30, 2017, 05:58:09 pm »
Look on E-bay...
They sell a Thermometer Hygrometer meter for under $10.00

 

 (Image hidden from quote, click to view.)

Thanks! That oughta do it. Ebay doesn't like me, though. Might be because I haven't logged in and bought anything there in ten years or so.

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Re: cheap gothic arch solar kiln
« Reply #55 on: June 30, 2017, 07:36:57 pm »
Look on E-bay...
They sell a Thermometer Hygrometer meter for under $10.00

 

 (Image hidden from quote, click to view.)

Thanks! That oughta do it. Ebay doesn't like me, though. Might be because I haven't logged in and bought anything there in ten years or so.

Amazon also sells it for $9.99.
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Re: cheap gothic arch solar kiln
« Reply #56 on: July 01, 2017, 04:15:46 pm »
You're a procurement officer. Thanks Kbeitz!