Rectifying a twist in a massive tabletop
September 9, 2015 8:28 AM Subscribe
Woodworking Mefites: I have a massive (40"x4"x8') reclaimed fir tabletop made of timbers that were planed and jointed several months ago, which...may not have been stored in ideal conditions.
There's a fair bit of twist to the piece now that the glue is dry and the clamps are off. Fortunately, I have access to a planer that will fit it. Two options below the fold.
Am I better off:
a) Planing it flat, and sealing it immediately, on the assumption that once it's sealed, moisture levels won't change, and it should keep it's shape, or;
b) Bringing it in to my climate controlled apartment for ? years for the moisture levels to sort themselves out, then planing and sealing it?
Am I better off:
a) Planing it flat, and sealing it immediately, on the assumption that once it's sealed, moisture levels won't change, and it should keep it's shape, or;
b) Bringing it in to my climate controlled apartment for ? years for the moisture levels to sort themselves out, then planing and sealing it?
Probably neither. If the twist on such a wide surface is significant enough to notice, I'll bet that you'd have to plane it very thin to flatten it. If the bottom corner of one end is higher than the top corner of the other end, you'd actually run out of table before it was flat. Sealing it won't protect it in any meaningful way from humidity changes. There are internal stresses at play that need to be dealt with.
I'd rip all the glue lines, let the wood rest for a month indoors, re-joint the edges and re-glue.
Lee Valley sells a great magnetic jointing fence for any metal hand plane. It sounds like your boards are thick, so here's a great Paul Sellers tutorial for edge jointing thick stock by hand.
You need to register to watch that particular video but it's free and I highly recommend it.
If the twist is actually very minimal, you can totally do this with a jack plane. Memail me for tips.
posted by bonobothegreat at 9:00 AM on September 9, 2015 [2 favorites]
I'd rip all the glue lines, let the wood rest for a month indoors, re-joint the edges and re-glue.
Lee Valley sells a great magnetic jointing fence for any metal hand plane. It sounds like your boards are thick, so here's a great Paul Sellers tutorial for edge jointing thick stock by hand.
You need to register to watch that particular video but it's free and I highly recommend it.
If the twist is actually very minimal, you can totally do this with a jack plane. Memail me for tips.
posted by bonobothegreat at 9:00 AM on September 9, 2015 [2 favorites]
Whoa! Sorry, I misread the dimensions. If it's 4" thick, I guess you have plenty of thickness to work with. Yeah,... jack plane - working across the grain at the high points and always working INTO the table when near the long grain edges. Then go with the grain for final smoothing.
posted by bonobothegreat at 9:10 AM on September 9, 2015
posted by bonobothegreat at 9:10 AM on September 9, 2015
Mitheral has it. We could make better guesses about what's going on if we knew the storage conditions before and since assembly, but chances are the fir timbers were far too wet to build stable furniture out of, and now you're paying the price.
You should absolutely let it dry out and stabilize before you bother flattening it, or else you'll just have to do it all over again. We can't guess how long that will take without knowing how wet the wood is right now. Once it does stabilize, you will have to flatten one side before running it through a thickness planer. Flattening something that size with a hand plane is a big job and requires a fair bit of skill. The router jig that Mitheral mentioned is the way to go.
posted by jon1270 at 9:27 AM on September 9, 2015
You should absolutely let it dry out and stabilize before you bother flattening it, or else you'll just have to do it all over again. We can't guess how long that will take without knowing how wet the wood is right now. Once it does stabilize, you will have to flatten one side before running it through a thickness planer. Flattening something that size with a hand plane is a big job and requires a fair bit of skill. The router jig that Mitheral mentioned is the way to go.
posted by jon1270 at 9:27 AM on September 9, 2015
I would first bring it to the apartment and watch it over the winter. Then come next May (or whenever the leaves come out and humidity goes up), wait another two weeks, monitoring very closely the pattern of change. Then make your marks and use that jack plane (sharp, and often re-sharpened).
posted by Namlit at 9:28 AM on September 9, 2015
posted by Namlit at 9:28 AM on September 9, 2015
You can see a pretty minor twist on such a large piece easy. I had to joint my 8 ft cabinet bench top (flat glued 2x4s so 3.5" thick) to take out about an 1/8th of twist plus 1/4" unevenness and I've still got more than 3" of thickness. I used a router jig for rough flattening and then finished with a hand jointer.
If your glue up was properly aligned with all the growth direction going the same way it really isn't all that hard to do this with a jointer plane though, just a serious workout. My bench was all over the place and knotty to boot which is why I did the heavy lifting with the power tool. It's such a large casting though that new ones are pretty pricey which is one of the reasons the router jig is so popular.
Though wow, I wonder how horrible the Grizzly H7568 plane is.
posted by Mitheral at 9:47 AM on September 9, 2015
If your glue up was properly aligned with all the growth direction going the same way it really isn't all that hard to do this with a jointer plane though, just a serious workout. My bench was all over the place and knotty to boot which is why I did the heavy lifting with the power tool. It's such a large casting though that new ones are pretty pricey which is one of the reasons the router jig is so popular.
Though wow, I wonder how horrible the Grizzly H7568 plane is.
posted by Mitheral at 9:47 AM on September 9, 2015
Yes, definitely wait until it has dried before doing anything. A moisture meter is pretty cheap and a useful thing to have.
Then hand plane or using a router flattening jig. Fastest may be to use a router jig on the underside, then plane the top.
posted by ssg at 9:54 AM on September 9, 2015
Then hand plane or using a router flattening jig. Fastest may be to use a router jig on the underside, then plane the top.
posted by ssg at 9:54 AM on September 9, 2015
The other thing to consider is that, assuming this fir is reclaimed from large beams and depending on the timing of your resawing, jointing and planing, the issue may just be a release of tension within the wood, without moisture being a major factor. That's another good reason to get a moisture meter.
posted by ssg at 10:34 AM on September 9, 2015
posted by ssg at 10:34 AM on September 9, 2015
Response by poster: It had spent about a year indoors, but it was bridge ties before that (8x4), so it was probably far too wet when I got it planed and jointed. (Fairly) inexpensive lesson learned, I guess. I'll seal the ends and find somewhere to put it for a while before I break out the winding sticks and the router jig.
Would I need a moisture sensor that'll take nail probes to get an accurate measurement on something this thick?
posted by Kreiger at 10:39 AM on September 9, 2015
Would I need a moisture sensor that'll take nail probes to get an accurate measurement on something this thick?
posted by Kreiger at 10:39 AM on September 9, 2015
Best answer: Would I need a moisture sensor that'll take nail probes to get an accurate measurement on something this thick?
You need to get probes deep into the wood, but it doesn't require a special meter. If you can drive 2 nails parallel and the same distance apart as the meter's probes, you can just touch the meter to those and that'll work well enough.
posted by jon1270 at 10:54 AM on September 9, 2015
You need to get probes deep into the wood, but it doesn't require a special meter. If you can drive 2 nails parallel and the same distance apart as the meter's probes, you can just touch the meter to those and that'll work well enough.
posted by jon1270 at 10:54 AM on September 9, 2015
Though wow, I wonder how horrible the Grizzly H7568 plane is.
I don't want to know. Especially when deals like this are available.
posted by jon1270 at 11:00 AM on September 9, 2015
(Nevermind that particular plane I linked to on eBay. It looks nice at a distance, but there are more functional choices available. Memail me if you want help picking one.)
posted by jon1270 at 11:21 AM on September 9, 2015
posted by jon1270 at 11:21 AM on September 9, 2015
Kreiger: "it was bridge ties before that (8x4)"
Assuming they were several years old then the wood is probably as dry as it is going to get. Acclimatizing the wood to your interior conditions for several months and then flattening would probably be safe.
posted by Mitheral at 1:02 PM on September 9, 2015
Assuming they were several years old then the wood is probably as dry as it is going to get. Acclimatizing the wood to your interior conditions for several months and then flattening would probably be safe.
posted by Mitheral at 1:02 PM on September 9, 2015
This thread is closed to new comments.
No coating is 100% vapour proof so sealing the wood won't prevent continuing movement if the wood still needs to dry.
PS: a planner won't take out a twist. You need to flatten one side first. Unless you have access to a 20" jointer you'll have to do it by hand with a jointer or with the aid of a jig and a router.
posted by Mitheral at 8:55 AM on September 9, 2015 [3 favorites]