jmack77 Posted April 27, 2016 Report Share Posted April 27, 2016 Looking for some advice. This past weekend I milled some 4/4 walnut that I've had for about a year down to 3/4. Got them all nice and flat. I edge glued two boards together and clamped them for about 12 hours. For a total of four boards. All four were done gluing by Monday afternoon. Today I went out to start sanding when I saw that all four have cupped. I live in Martinsburg, WV, and yesterday we had a front move in. Over the weekend we had nice warm sunny days. Today it's been cool and cloudy with slight rain. My shop is in our garage with no AC or heat. Could this cupping being caused by the weather? Quote Link to comment Share on other sites More sharing options...
shaneymack Posted April 28, 2016 Report Share Posted April 28, 2016 Best chance of having flat straight lumber for a project is mill in 2 stages. Rough mill taking just enough to get both sides flat and parallel trying to take the same amount of material from both sides. Sticker it for a couple days and then final mill. The other big thing is to only mill the pieces you will be working on. You dont want to final mill and then have it sit there for weeks. Even doing this doesn't always guarantee the boards will behave how you want but its best to take all the precautions you can. Sent from my SM-N910W8 using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
jmack77 Posted April 28, 2016 Author Report Share Posted April 28, 2016 I made sure to flip the boards over during the milling process to try and take the same amount from both sides. And I haven't had any issues with the joined boards bowing. The middle of the cup is at the joint. I guess I could split the boards at the joint. Which is a bummer cause the glue lines are practically invisible. Then re mill the boards and try again. I have some wiggle room with the thickness, as this is for a bread box for Mother's Day. Quote Link to comment Share on other sites More sharing options...
Coop Posted April 28, 2016 Report Share Posted April 28, 2016 Were the individual boards themselves cupping or is it at the glue line? Did you use cauls when you had them in the clamps? Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 28, 2016 Report Share Posted April 28, 2016 Yeah I think Coop is on the right track. I bet your joints weren't perfectly square. Check your jointer fence. Quote Link to comment Share on other sites More sharing options...
davewyo Posted April 28, 2016 Report Share Posted April 28, 2016 Are you 100% sure your jointed edges are 90 deg.? Did you check them for flat when you clamped them up? Could be your jointer fence isn't dead on. Could be the weather. Could be the lumber. I know, that's not much help. 1 Quote Link to comment Share on other sites More sharing options...
gee-dub Posted April 28, 2016 Report Share Posted April 28, 2016 Just to clarify, are you saying that the assembly is cupped or that each board cupped individually leaving you a scalloped surface? Terminology check : If the whole assembly is cupped across its width due to bad edge jointing I would expect you to see this during assembly. A note on clamping, it is to hold things together while the glue dries, not for forcing things into position. Did the boards lie flat and true prior to gluing/clamping? Quote Link to comment Share on other sites More sharing options...
jmack77 Posted April 28, 2016 Author Report Share Posted April 28, 2016 Thanks everyone for the feedback. Before gluing, I played around with the board for the best grain match. I was pleasantly suprised that just about every matching had a nice seam. So when it came time for glue up, I didn't have to bear down on them clamping pressure. I used parallel clamps, and made sure that the board were lying flat. One thing that I did not do, and talk about a rookie mistake, was use cuals except on one. I assumed that since the board were lying flat that everything would be okay. In the end, I guess not. I cut the four boards along the glue lines last night. And have stickered them over night and all day today. I did take a look at them this morning, and most were okay as far as cupping. The others I will put through the jointer. And then send them all through the planner to I also went and looked at the edge that was joined. Those were all looking good as well. For the edges that got glued, I used the edges that were formed on my TS. I guess the next step is to make sure my blade is set at the 90°. Quote Link to comment Share on other sites More sharing options...
Eric. Posted April 28, 2016 Report Share Posted April 28, 2016 9 minutes ago, jmack77 said: I also went and looked at the edge that was joined. Those were all looking good as well. For the edges that got glued, I used the edges that were formed on my TS. Why? You have a jointer, use it. I'm not saying that's the cause of your problem, but the jointer was made to, uh...joint. Get your fence dead at 90* and you'll have much nicer joints than what you get off your table saw. Table saw joints are for guys who don't have a jointer. If you find that all your machines are set up dead square, I'd start looking at your lumber next. Was it kiln dried and purchased from a reputable hardwood dealer or did you get it from Uncle Cletus? Quote Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2016 Report Share Posted April 28, 2016 Also did you lay the panel flat on a bench after taking the clamps off? You need to sticker a glued up panel. If more air/humidity hits one side then entire thing might cup. If I need to let a glued up panel sit around for a while, I usually clamp a caul to each end (just put the clamp in the center so the panel can expand) and make sure I keep it stickered. This will help keep the panel flat while you store it. Quote Link to comment Share on other sites More sharing options...
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