I often get myself into places where I think I must have been nuts to let myself get into. Today I started on some highly figured walnut gunstocks. Am I nuts? :D These things are 2.75" thick. I'm going to try a 12 day schedule that I used back in 2009 and it worked on similar material. Of course, in 2012 I tried a modified schedule on walnut gunstocks and ended up with some beautiful firewood. If the 2009 schedule doesn't give me good results, I'll try the White Oak schedule that dried 3.5" WO in 13 days. It had some surface checks but the WO is maybe more prone to checking. The next few weeks will be interesting.
I'm using a little computer that is about the size of a couple decks of cards. For some reason, it doesn't like jpeg. The forum doesn't like png so I'll try bitmap. Nope. How about gif?
(https://forestryforum.com/gallery/albums/userpics/10317/2_75.gif)
They will look great. I am sure that you have forgotten more about drying than most of us will ever know.
Geoff
Thank you. That's why I keep tons of records. Who can remember 30 years of experience? Paper, computer logs and pictures help an old man along. :)
Are you starting from green? I just finished a load of blank that the guy air dried for eight years.Had to cull a bunch before I started because of cracks or miscuts but it looks like what came out behaved.
Keep us posted Den!
Looks like a lot of fun.
woodbutcher, these are freshly cut. They came with zero cracks. Sure hope I can keep them this way!
I can breathe easy. They are dry in 12 days with practically zero checks. I saw a couple that you can't get a fingernail into. It takes the customer 7 months to dry these things dry.
(https://forestryforum.com/gallery/albums/userpics/10317/dry_gunstock.gif?easyrotate_cache=1463677592)
8)
I am definitely impressed. It could take me considerably longer than 7 months to dry it using my DH Kiln. I sure wish I had one of your kilns!!!!
I'm sure Den will sell you one :D
Like I've said a thousand times, I wish we could build a kiln cheap enough that everybody could buy one. My son and I kick it around at least once a week.
But then, maybe it wouldn't be as effective? ;)
No the problem is manufacturing cost. Pumps, heat exchangers and such are scaled to kiln capacity. If I cut capacity in half, manufacturing cost is not cut in half. You end up with a little kiln that cost way too much.
I need to talk with you Den, I'm getting quite tired of degrade in red oak. Do you make a 1000 bdf kiln that will do 16-6"?
Please email me at dsocling@vacdry.com.
We have a little kiln that holds about 1100 BF of 8/4 but I hate it because it's so expensive. Our most popular kiln holds about 2900 BF of 8/4.
I was just documenting a schedule I originally wrote back in 2005. A guy brought me some 12/4 Red Oak flitches that were badly cracked. This schedule really closed a lot of cracks. In the picture, the red crayon marks show how far the end checks reached before they went into the kiln.
(https://forestryforum.com/gallery/albums/userpics/10317/closed_end_checks.gif?easyrotate_cache=1463937114)
In the picture below, there were so many surface checks that I laid a crayon on it's side.
(https://forestryforum.com/gallery/albums/userpics/10317/surface_checks.gif?easyrotate_cache=1463937292)
The cracks are still there but you can't see them.
You know, you're going to end up selling me one of them things. Be a couple of years yet before we can justify it - but between the high quality product and the sheer outright speed that would let us respond to customer demand without holding huge amounts of stock - I wants me one of them.
About twenty years ago my first first customer told me how great it was to not need a log pile and guessing what the market would be months down the line.
Quote from: Den Socling on May 22, 2016, 06:54:06 PM
About twenty years ago my first first customer told me how great it was to not need a log pile and guessing what the market would be months down the line.
For us its a different scenario: about 25% of our volume is rainforest species, but they generate 50% of our turnover. Theres about 130 commercial species of timber in the FNQ rainforest, but 95% of the area got locked up under a world heritage listing 25 years ago. Some of the super high value species are getting scarce in the privately owned land that we can still harvest to the point where I take the order then go cut the tree: where I can we buy the standing trees of those and leave them standing so I can go back for them later because the one thing you can guarantee is that if I cut it into 8/4 the order will be for 6/4. If I really got to take them on the initial harvest I try and hold them as flitches so I've got some flexibility.
It'd be nice to be able to take an order and say ready in 4-6 weeks, not ready in 4-6 months.
I ran across some out of the square but off the shelf components that made me think "affordable small vac kiln" a while back - I'll PM you a link
John,
Thanks for the link but here is why I don't think the idea would work. WoodMizer used to build a small vac kiln that used electric blankets. When the blankets were near wet wood, evaporation would hold the temperature down. Meanwhile, right next to the wet spot might be a dry area where evaporation was low and temperature would get high. WoodMizer tried to control blanket temperature with one sensor per blanket. If the sensor was in a wet area, it would call for heat. If it was near dry wood, it would shut the heat off. As you can imagine, you could end up with some mighty bad results. However, if you learned how to control them, they could work. I used to dry 3.25" Red Oak newel post in a WoodMizer VK2000 with good results.
Den
Here we go again. 5"x5" Red Oak post.
(https://forestryforum.com/gallery/albums/userpics/10317/5x5.gif?easyrotate_cache=1464112744)
I like Precheck when we are going through TSA but not so much here. This load will be walnut gunstocks, the Red Oak post and 10/4 Red Oak flitches with which I will run a two week White Oak schedule. Should be interesting. :)
Looks like it will really need your expertise. ;D
Quote from: Glenn1 on May 24, 2016, 03:28:32 PM
Looks like it will really need your expertise. ;D
And a lot of luck!
Den,
I just wonder about stuff y'know. Can't spend all my time at work thinking about fishing.
I wonder about a small unit with a single tier chamber say 4'x 4'x 6". Put an oil chamber over the heat pad to disperse the heat like my wifes hideously expensive saucepans have. Targeted at the market for the small high value pieces that fit into that sized chamber - gunstocks, musical instruments, turning blanks etc. There are no shortage of high end commercial vac pumps that can do that volume available off the shelf, and given your cycle times its still quite a productive unit. Whether the depth of market is there to justify the R&D I dont know, but I suspect if you can use off the shelf pieces from other industries you might be able to keep the price attractive.
I also wonder if its possible to put a few more valves and fittings on the larger chambers so that it can be a regular vac kiln by day, but turn into a pressure treatment plant on fridays. For us, and I suspect a lot of smaller mills, putting $100k into a kiln that you're going to struggle to run at capacity is not totally impossible, but its pretty hard to justify. But putting $120 k into a kiln that can also pressure treat (if that could be done) might just be a bit more attractive. A lot depends I guess on the market demand for treated timber. I know the US market isnt treatment mad like we are here, but I dont understand the depth of that. And I dont understand the engineering differences between a vac kiln and a treatment vessel. I do know that if I had a choice of one machine that works hard or two that are under utilised which pays its way better.
I really appreciate your being here, and taking the time to share your expertise with us. I dont want you to think I'm telling you how to build a kiln or be a nuisance with dumb questions you've answered before, but the only way I can learn is by asking.
You're an acknowledged expert in your field and having guys like you willing to share what they know is what makes this place sorta unique, and I appreciate the time you spend educating us.
John,
I'll reply to all of this the next time I have the time. I went to college to be a school teacher so I don't mind explanations. ;) One quick answer is this. With vacuum kiln chambers, pressure is pushing in. With pressure treatment, pressure is pushing out. However, I have worked a little with a PT company that wanted to do drying also. I also have those people who want to do the thermal modification of wood. A couple years ago, we built three 30,000 BF vac dry kilns that the next went to the next step of thermal treatment. There are a lot of things I could do.
Den
John,
If you could successfully dry wood just by heating it in a vacuum, the Italians would have been successful 50 years ago. Instead, IMO they still don't understand the process. They have the basic equipment. Here are a few particulars.
Water has a property called vapor pressure. Vapor pressure is directly proportional to temperature. Water boils when vapor pressure equals ambient pressure. So, if you precisely control temperature and precisely control pressure you can precisely control drying. There is more to it than that but I don't want to make everything public.
Now you need humidity control. Sometimes you need RH higher and sometimes lower. That's a trick in itself.
Now operating procedures. I could give you one of my kilns and you could probably ruin wood for the rest of your life. We have to support every kiln we put out there at least for a couple months. Can you imagine selling 50 troublesome low-cost little kilns? The world would drive me nuts! :D
Den
Hi Den,
You have showed us some wood before going into the kiln that needed emergency care. Can you show us some quality boards or slabs before and after drying. Will there be any checks at all after it comes out of the VK or will they be absolutely beautiful?
I don't know about this one, Glenn. 5"x 5" oak would be tough even if it was in good shape. I just hope to close the checks as in the pictures in reply #13 I think it was. The 12/4 Red Oak with the crayon marks show that two major end checks closed completely and at least half of the third end check was closed. The real goal with the current test is to see how the gunstocks turn out. The oak post and the 10/4 are just along for the ride.
BTW the cracked 12/4 oak in reply 13 was actually dried with a load of baseball bats. The oak was just along for the ride. :) I was depending on the water from the maple to raise humidity and it did. I did have humidity back-up and I had tweaked the schedule for both products.
The first test wasn't as good as I thought. The potential customer found some bottleneck checks or honeycomb. Still, he said it's better than they normally get but it was a small test. The next one comes out next Monday.
I unloaded the second test today. This one ran for 11 days. The post with pith split as expected.
(https://forestryforum.com/gallery/albums/userpics/10317/dry_post_1.gif?easyrotate_cache=1465150701)
I told the customer this would happen. He said the post would be from a huge tree. Look at this one. It actually looks like a crotch.
(https://forestryforum.com/gallery/albums/userpics/10317/dry_post_2.gif?easyrotate_cache=1465150798)
The walnut looks pretty good.
(https://forestryforum.com/gallery/albums/userpics/10317/6_5_16_1_reduced.gif?easyrotate_cache=1465150874)
(https://forestryforum.com/gallery/albums/userpics/10317/6_5_16_3_reduced.gif?easyrotate_cache=1465150909)
I'll send samples to the customer tomorrow for destructive testing. I sure hope there is no honeycomb. 11 days was PDQ!