I would appreciate any suggestions given on how to minimize twist in a dh kiln. I just took out a load of poplar from my nyle 200. 20% mc going in and laid pretty flat but had some twist in a fair amount of boards coming out. I know poplar can be prone to twist bu am wondering if I'm drying to fast or maybe doing something I'm not aware of.
Also I have a load of fresh cut hemlock to go in that will be T&G afterwards and it has me a little concerned. I 've never dried any hemlock. Any suggestions and thanks in advance.
What board sizes are you drying?
What size logs are you sawing?
Can you narrow down the twist to certain logs, or certain board characteristics?
How would you describe the stacking and stickering? Weight on top of the stack is?
This lumber came from decent logs. All 12 ft from the butt or second log. All FAS. I separated for grade while sawing and stickering. stickers two ft apart while air drying and in the kiln. Also saved a 6x6 cant from each log for other purposes so no heartwood. Boards are anywhere form 6 to 14 inches wide. No weight on top of the load may be the culprit but they were twisted through out the pile with most near the top. I didnt see any twist when loading the kiln and I load it a board at a time. thats what makes me wonder if it was something I did. (drying too fast etc.)I have been dryin in a smaller kiln for years and it is a lot slower than the 200 although i primarily dry red oak.
During shed and kiln drying I hold the stickered stack under tension via ratchet straps and peroidically re-tension as the stack shrinks. If I leave the heart in the board then I will get cupping so I've begun cutting that out but I have not seen twisting. Like you, I dry mostly oak.
Bob
if the wood is at 20% m.c going in the kiln ,then your not drying to fast, maybe not enough air flow. the moisture realesed is not moving from the stickered rows fast enough causing the lumber to reabsorb at differant rates
Along red oaks' line, I don't think the wood was 20% going in. Like he said, if it was 20%, you couldn't dry too fast. But, if it was wetter, at least some boards, then you may have caused twisting by drying too fast.