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Forum topic by hjt posted 02-16-2016 04:41 AM 1152 views 0 times favorited 23 replies Add to Favorites Watch
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hjt

822 posts in 2606 days


02-16-2016 04:41 AM

Topic tags/keywords: join flat warp cup

While I do not do much real wood working, I do enough to be frustrated. Today’s frustration is warped and cupped boards.

So one goes out to the lumber yard and buys some boards and you pick out those with the least amount of warp and cupping. Somehow, by the time you get it home – shazam! It’s warped more then you thought, the cup is greater than you remember.

So what do you do?

Is it best to run the whole board through your planner OR do you generally cut it to the size you need and run each cut piece through the planner at that point? I can think of benefits and issues with both methods.
Recently I have made some boxes out of 1×12 boards. So the board was actually are ¾ by 11 ¼ . The cup was about as much as 1/8 of an inch at some parts of the board. Running the boards through the planner on both sides, I shaved them down to 5/8 and still had considerable cup, so I stopped.

I hope to make a table next and will be marrying several boards together via a biscuit joiner. I would think the table top should be no less the ¾ thick. What would you suggest I do so that when I put all the boards together to make the top it is actually level and flat?

-- Harold


23 replies so far

View TiggerWood's profile

TiggerWood

271 posts in 1074 days


#1 posted 02-16-2016 05:04 AM

Buy more wood. Do you have a jointer, machine or hand?

View David Taylor's profile

David Taylor

326 posts in 554 days


#2 posted 02-16-2016 05:07 AM

Well, it depends. Sorry, but that’s the way of it sometimes. Quartersawn stock helps, but is hard to find in wide boards.

I generally get rough sawn stock, thicker and generally larger than needed, let it acclimate in the shop for weeks or months (I buy ahead :) before I try to do anything with it. At the point of needing it, I do cut it to rough, oversize dimensions for each piece needed, and then joint, or if too wide, plane with a hand plane and then run it through the planer to still about a quarter inch oversize, then let it sit at least a day. After that time, I bring the pieces to final dimension, and then, and this is important, get them together as quickly as possible. If you leave them after getting them to final dimension, wood will be wood and it will move again. It will move after assembly, too, but you build with that in mind, raised panels in grooves, table tops with bread board ends, things like that.

As you’ve found, if you run a cupped board through the planer, you’ll get nothing but a thinner cupped board. Before the planer, one face has to be at least relatively flat. I figure you probably, like me, don’t have a 12” or better jointer, so what I do like the case you describe, with a cupped 1×12, is take a hand plane to the edges that are cupped up. Get them close to the level of the center, and then run them through the planer, first with the side I just planed facing down, then flip it and run it through again after I flatten the first face with that side up, to finish what I didn’t get with the hand plane. This generally gets a flat board that doesn’t lose too much thickness.

For your table top, if you want to end up with 3/4” thickness, I would start with 5/4 or even 6/4 stock. You’ll probably end up thicker than 3/4, but you’ll end up flat.

-- Learn Relentlessly

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Timberwolf323

67 posts in 310 days


#3 posted 02-16-2016 05:10 AM

You need to face and edge joint the board before passing it through the planer. If no jointer you could have them surface it at the mill. I always mill my boards down close to final dimension and let them sit in the shop to acclimate to the humidity change for awhile. Then mill them to final right before assembly.

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bandit571

14651 posts in 2151 days


#4 posted 02-16-2016 05:14 AM

For WIDE boards that will stay wide…I’ll rip them down a bit. Narrower boards will stay flatter, then glue up a flat panel using the same boards, in the same order as they came off the saw. Add a caul to help keep it flat while the glue sets up.

-- A Planer? I'M the planer, this is what I use

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fuigb

404 posts in 2425 days


#5 posted 02-16-2016 06:04 AM

+1 to the need to joint remarks, especially the suggestion to rip wider boards and then blue them back up.

What do you mean by “lumberyard? ” if it’s a big box then borrow one of their carpenter’s squares to do an even better job of culling the crap.

-- - Crud. Go tell your mother that I need a Band-aid.

View Timberwolf323's profile

Timberwolf323

67 posts in 310 days


#6 posted 02-16-2016 06:32 AM



+1 to the need to joint remarks, especially the suggestion to rip wider boards and then blue them back up.

What do you mean by “lumberyard? ” if it s a big box then borrow one of their carpenter s squares to do an even better job of culling the crap.

- fuigb

Leave a mess for them to clean up too. Job security.

View rwe2156's profile

rwe2156

2200 posts in 948 days


#7 posted 02-16-2016 01:01 PM

Your best bet is to glue up narrower boards this will make a more stable top.

As you now know, the wider the board the more prone to this problem.
Acclimation and moisture content very important but not the whole story. There is also stress in some wood that when you start milling or ripping become more obvious. Common feature of wood with large knots like pine. This type wood is for the fire bin IMO.

I have had wood warp or bow within 20 minute drive from lumber yard to shop just in back of truck on a sunny day. Usually just turning board over and putting in sun will even out.

Therefore I always cover my wood when transporting.
Hope this helps.

-- Everything is a prototype thats why its one of a kind!!

View eflanders's profile

eflanders

87 posts in 1318 days


#8 posted 02-16-2016 01:11 PM

One other idea to avoid issues before you buy is to use a moisture meter. You can get one for under $50 then use it when you go lumber shopping.

View hjt's profile

hjt

822 posts in 2606 days


#9 posted 02-19-2016 03:27 AM

Ok, guys, just getting back to my post. Thank you for the info, some of which surprises me or is otherwise beyond my understanding.

Bandit: you state 9and other agree) to rip wide boards into narrower strips. Ok I get that. Where I was surprised was to read the I rebuild and glue them in the same order? I guess you know what you are doing, but that is just baffling to me that putting back in the same order would help solve the issue.

Fuigb: Yes – I get most of my lumber from HD or Lowes.

RWE: Since you do not care for pine, what do you use for non furniture types projects.?

-- Harold

View bandit571's profile (online now)

bandit571

14651 posts in 2151 days


#10 posted 02-19-2016 03:34 AM

You can glue the pieces back into the “board” they came from. But now they will act as smaller boards glued up into a panel….that just so happens to have the grain matching all the way across…..it will “look” like the same board, minus the saw kerfs, but will behave like a collection of narrower boards. If the glue up is done right, it will stay flat.

-- A Planer? I'M the planer, this is what I use

View bbasiaga's profile

bbasiaga

759 posts in 1462 days


#11 posted 02-19-2016 04:17 AM

If you have a big board that is cupped or warped, and you plan to cut it to a shorter board, cut it before you joint and plane it. Obviously, the pieces still need to be big enough to run through your machine.

But cutting the boards to length, plus a few inches for snipe, takes a lot of the warp out. You’ll end up with more usable lumber and less sawdust machining 3 2’ pieces of a 6’ board that is warped, than you will if you try and flatten the whole board first.

Make sense?

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View ColonelTravis's profile

ColonelTravis

1194 posts in 1361 days


#12 posted 02-19-2016 04:21 AM

After using pine to make my workbench I swore I’d never use that stuff again for anything but hidden framing. Poplar has become my cheap-o non-furniture wood of choice.

View Timberwolf323's profile

Timberwolf323

67 posts in 310 days


#13 posted 02-19-2016 04:45 AM

Harold

Try this sawmill for your lumber. They are in Cocoa. . If they don’t have what you want I know a guy near Orlando that’s got cheap walnut, cherry and oak, maple etc. And some tulip and monkey wood I think. It’s all kiln dried, f&s

http://www.doubleeaglesawmill.com/index.html

Lumber from Home Depot and Lowe’s is junk. :).

View rwe2156's profile

rwe2156

2200 posts in 948 days


#14 posted 02-19-2016 12:33 PM



RWE: Since you do not care for pine, what do you use for non furniture types projects.?

I didn’t say that I didn’t care for it, just beware of its drawbacks. I made all the face frames and drawer fronts for my shop cabs out of premium pine.

For any painted wood project, drawer sides or inside carcase components I use poplar almost exclusively.

-- Everything is a prototype thats why its one of a kind!!

View RossCapolupo's profile

RossCapolupo

10 posts in 340 days


#15 posted 02-19-2016 01:11 PM

A machine planer alone will NOT flatten or square boards; it will not flatten cupped or bowed boards because planers have a pressure bar before the knives – before the board is planed, the pressure bar more or less forces the board flat… So it is temporarily flattened, then planed, and then springs back to its warped/bowed shape once it exits the machine. A planer also wont square a board on its own, because it basically indexes the cut off the bottom face of the stock (which is sitting on the table) – if the bottom face is not square, it will sit on the table off square, and so too the top face will contact the knives off square.

To truly flatten a board with a machine, you need a jointer. A jointer indexes off the surface it is actually cutting, which is the bottom face that rides along the tables. If a board is cupped, each pass will take stock off the high points only, until it becomes flat and starts taking stock off the whole surface evenly.

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