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Jointing long boards with a bow

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Forum topic by mspain77 posted 04-01-2016 11:01 PM 1054 views 0 times favorited 27 replies Add to Favorites Watch
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mspain77

26 posts in 253 days


04-01-2016 11:01 PM

Topic tags/keywords: milling jointer question

Hey guys,
I’m milling my Doug Fir 2×4’s for a Jay Bates inspired table top and I’m having a heck of a time getting them flat. My jointer is dialed in now (thanks to all of your help) since I got the Snap-Check and got my blades to within .002 of the outfeed table.
The boards are rough cut to about 59” in length, and my 6” bench jointer has a 30” overall table length. I have two roller stands that I set up on both sides of the jointer to help keep the board as flat as possible across the table. I used a long straight edge to make sure both roller stands were on the same plane as both tables. The straight edge stands flat on each table while being supported by the roller stand on that side. I hope this gives a good visual as to what I’m working with.
I’m concerned about taking too many passes to try to wear down the high spots. My depth of cut is set at 1/32” right now. It seems like I hear the same amount of material being cut away throughout the length of the board, and I am putting ZERO downward pressure on the boards. I’m letting their own weight bring them down over the cutter head.
Has anybody else ever tried milling down dimensional lumber like this? Is it normal if I need to make 25-30 passes, or does that mean there’s something I could’ve done differently to get there quicker? Please let me know what you think. Thanks guys.

-- It's a BEAUTIFUL day to go cut some wood & build something!


27 replies so far

View WhyMe's profile

WhyMe

612 posts in 1022 days


#1 posted 04-02-2016 01:55 AM

I straighten out long boards by double face taping on a straight edge and rip cut it on a table saw. Then clean it up on the jointer.

View JohnDon's profile

JohnDon

61 posts in 631 days


#2 posted 04-02-2016 02:48 AM

Yeah, I’ve gone through the process of flattening 2×4’s. There’s a reason they’re called construction grade! You just have to accept the fact that unless you’re really lucky, you’re going to lose a bunch of board thickness in getting construction lumber flat and straight. Just to clarify the specific warp that your board(s) has, I assume that by “bow” you mean the curve as in the attached diagram

While WhyMe’s suggestion is good for a crooked or kinked board, I think it’s hard to do with a bowed board. If you indeed have a bow, in my experience, FWIW, using a jointer is the best way of straightening it. You’ll get it straight more efficiently if you orient the board on the jointer convex side up (that is, the leading and tail ends of the board are in contact with the bed- and cut first, and the gap is in the middle (cut last). While a longer jointer bed would make it easier, you go with what you have, and with your setup you should be able to get good results.

Depending on how out of whack the board is at first, it can take a lot of passes to straighten. You mentioned that by sound is seems that you’re removing the same amount of wood along the entire length. An easy way to check on where the jointer is cutting is to make cross hatches on the board surface with chalk, and see where the chalk is removed after jointing. Good luck!

View Ger21's profile

Ger21

1047 posts in 2592 days


#3 posted 04-02-2016 02:52 AM

30 passes at 1/32 is 1 inch?

If the cutterhead is removing material the full length of the board, it should be flat.
You want to apply pressure over the outfeed table after the board passes the cutterhead, provided it’s actually cutting.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

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JBrow

817 posts in 381 days


#4 posted 04-02-2016 03:10 AM

mspain77,

I have run 4/4 stock across a 36” Craftsman jointer up to 60” long with a feed roller even with the outfeed table. I get the board flat enough to run through the planer to produce flat stock having made no more than 10 light jointer passes. Occasionally, I remove too much material but mostly end up with stock that can be ultimately milled flat to ¾”. Some of these bad results are due to poor technique while other bad results are from trying to use lumber too far from flat.

From the sounds of your setup, you should be able to get a flat face in less than 30 passes; yet your post suggests you are not getting this result. I assume that you are paying close attention to the board as it is run across the jointer to ensure that it is not rocking or shifting as it is face jointed. With your set-up and if the lumber does not shift or rock as it is jointed, then perhaps it is flat but the means by which you determine flatness is failing.

There are some additional things that could be tried. The first is to only face joint the lumber until it sets flat. There could still be some areas on the jointed face that have not been cut, but the board will rest on both straight edges along the length of both edges without rocking. With stock over 1” thick, I think that planning the unjointed face first with the partially jointed, but setting flat, face down will make the unjointed, but planned face flat. Running the freshly planned flat face down through the planer would clean up the partially flatten face.

The second idea is to mark the face that is to be jointer. The pencil marks on the face will be progressively cut away as the face nears flat. Pencil marks left on the face after running the board across the jointer indicate areas that have not been cut. When all the pencil marks on both edges are removed, it is ready for the planer.

That last suggestion is to run a cupped board across the jointer with the crown up. If the board has a twist, run whichever face sets flatter across the jointer.

View bruc101's profile

bruc101

1077 posts in 3003 days


#5 posted 04-02-2016 03:32 AM

I straight line all my boards on the table saw, especially long boards for table, cabinet and island tops. I have several length and width jigs to get the job done for me.

You can see one of my straight lining jigs here.

http://lumberjocks.com/projects/63970

-- Bruce Free Plans http://plans.sawmillvalley.org

View mspain77's profile

mspain77

26 posts in 253 days


#6 posted 04-02-2016 03:34 AM

Thanks for all the input guys! I feel I need to clarify what I’ve got going on. The board definitely has a bow, and it’s maybe 1/2” from end to end if you were to measure the dip in the middle with a straight edge along the length of the board. Secondly, it IS getting better, and I haven’t made 30 passes yet. I’ve made about 9 or 10, but I was being proactive with this question because I feel it may take 15 or 20, and that seems excessive to me. When I run it at any more than 1/32” depth, I get some chattering. Idk if that’s because of the type of wood or what causes that. I’ve slowed down when that happens, and it helps a bit, but it still seems to chatter at the same parts of the board. I just dialed in my knives with a Snap-Check to within .002 on all sides, and triple checked that so I’m sure my knives are not the issue with the chattering.
The marking along the face to see where I’m taking material off is a great idea, and though I’ve seen that on YouTube, it escaped me for some reason, so I will definitely do that tomorrow. Idk if you guys are familiar with Jay Bates on YouTube (Jay’s Custom Creations), but he make some amazing things with dimensional lumber, and seems to pass his boards on the jointer 2-3 times max (though his huge Grizzly jointer is much nicer than mine). I was extremely particular when selecting my boards. I chose all the quarter-sawn boards, and I ripped that lumber stack up getting them. I put it back nice and neat though.
Well I think I covered all that stood out to me in all of your responses, and I appreciate the heck out of you guys chiming in. Please keep it coming. After all, I’m new to this, and I would love to keep learning from some of you veterans as much as I can.

-- It's a BEAUTIFUL day to go cut some wood & build something!

View Aj2's profile

Aj2

687 posts in 1259 days


#7 posted 04-02-2016 03:36 AM

I’m thinking that if your confidant in your technique then your set up is off. Setting up outfeed rollers on short jointer beds is fussy to get great results.
Are you able to produce two edge jointed boards with the machine without the extensions?
Even something 3 ft long would be a good way to test.
Everything about a jointer is how flat the tables are and coplane.

View Ger21's profile

Ger21

1047 posts in 2592 days


#8 posted 04-02-2016 11:57 AM

If you’re face gluing these together, I would not joint them first. Run them through the planer to clean up the faces, and then glue them up in groups of 3, preferably clamping to something fairly straight and flat. Once the glue-ups are dry, then run them on the jointer. You’ll be working with much flatter, and more stable material, and not jointing away half of your wood.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View rwe2156's profile

rwe2156

2190 posts in 942 days


#9 posted 04-02-2016 01:41 PM

What’s your finished dimension?

A 1/2” bow in a 59” board = unusable wood or cut it shorter and use for something else. You’ll be down to a 3/4” thick board before you know it. Keep in mind this amount of bow is probably stress in the wood, not moisture related and is very likely to re-bow by the next day.

A word of advice: If you’re taking a lot of wood off one side trying to joint it, you will almost always end up with a re-bow because of unbalanced moisture.

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

View Nubsnstubs's profile

Nubsnstubs

826 posts in 1191 days


#10 posted 04-02-2016 03:25 PM

A 1/2” bow in a piece of wood 59” is a slight problem, but not as bad as some have mentioned. The op is going to glue this wood to other pieces of wood to make a table top.A good flat glue table, a bunch of clamps, glue and a hammer is all that is needed to straighten any wood, except cupped boards. Twisted wood can be glued if you know how to correct while in the clamps. As long as the edges are equal, even with a bow, 3 pieces will straighten any wood if the glue holds like it is supposed to. Just do it, and show the finished product when done.

Too many people agonize over non existent problems. ........... Jerry (in Tucson)

-- Jerry (in Tucson)

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MadMark

977 posts in 914 days


#11 posted 04-02-2016 03:32 PM

Use a wood other than fir. Its stringy an leaks sap. Yecch.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

View WhyMe's profile

WhyMe

612 posts in 1022 days


#12 posted 04-02-2016 07:14 PM

Referencing the picture of bow vs crook the use of straight edge and ripping on table saw was for crooked boards.

View mspain77's profile

mspain77

26 posts in 253 days


#13 posted 04-02-2016 09:32 PM

I’ve reached out to others that make nice stuff out of dimensional lumber and they said Doug Fir would work, so that’s what I’m going with. I will be joining the boards together on the edges; probably 5 or 6 across depending on what my final dimensions are. I’m jointing one face and one edge to have a flat reference surface so that once I get all 6 done, I can send them through my 12.5” planer to equalize the size based on the smallest board I have at that time. That’s why I want them all done now. I can still glue up in 2 or 3 smaller batches and them glue those up but I’ll tackle that when I come to it. For now, I just want to get one face and one edge flat so I can plane them all down, then rip the last edge on my TS and glue them up right away.

-- It's a BEAUTIFUL day to go cut some wood & build something!

View rwe2156's profile

rwe2156

2190 posts in 942 days


#14 posted 04-02-2016 10:19 PM



Use a wood other than fir. Its stringy an leaks sap. Yecch.

M

- MadMark

B.S. (broad strokes)

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

View jdh122's profile

jdh122

879 posts in 2279 days


#15 posted 04-02-2016 10:23 PM

You probably know that you need to run the concave side through the jointer and not the convex side, but just in case: if you run through on the convex side it’s easy to simply keep buzzing off wood without making much of a dent in the bow.

-- Jeremy, in the Acadian forests

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