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Forum topic by Matt posted 03-07-2016 01:13 PM 502 views 1 time favorited 8 replies Add to Favorites Watch
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Matt

28 posts in 1060 days


03-07-2016 01:13 PM

Topic tags/keywords: end grain end grain problems stupidity cutting board cutting board question cupping

Good Morning Lumberjock world,

I have recently found a love for creating end grain cutting boards, I am very new to these but have turned out 4 so far, all becoming larger in size as I go. My question goes back to how to glue up these boards without creating a ton of warping.

I should have taken some pictures of what I am talking about but I will do my best to explain my issue. I begin as every end grain does by making a long grain board, run that board through my planer to get consistent thickness. Next I run the board through my table saw on my cross cut sled, the most recent board I made the blocks were cut at 1.75 inches. After cutting the blocks I left them in my shop overnight, my shop is heated and I try to keep it consistent. The wood has been in the shop for well over 6 months so the climate hasn’t changed much. The next morning when I begin to line up the blocks with an alternating pattern I realize that all the blocks have about an 1/16 inch crown in them. This creates quite a pain when trying to line up my blocks to get the nice alternating pattern that I set out for. Once I finally achieved the pattern after much cussing and a large pot of coffee I began my second glue up. When it was all said and done the board is a total of 13×20x1.75, as I know I am going to lose some of it in the flattening process I left my self with plenty of extra.

I built myself a Router sled as I have heard many horror stories about running an end grain board through the planer. This sled works great but it does take a considerable amount of time to use when you have a cutting board of this size. I was told that a Bowl and Tray works well to flatten and so far have had good success. My problem lies in the fact that in order to get a board of this size flat I ended up removing an 1/8 of an inch from both sides. The good part is I took that into account with the 1.75 starting thickness but I realize there has to be a better way.

Is it possible that it all goes back to when I’m gluing up my strips in the beginning I am tightening the clamps too much?
Is it just normal and I am new to this?
Is it the wood just reacting to not being cut and cupping to follow the grain?

FYI the wood types Ive been using, Maple, Cherry, Apple, Mahogany.

I have read one article about clamping and that you shouldn’t over tighten your clamps as you end up squeezing the majority of the glue out. I find that while that makes sense sometimes when you just need that extra 1/4 turn to really feel comfortable. Many times when I come back to my project 12-24 hours after the initial glue up my clamps are almost loose, almost as if they backed off a little or the wood shrunk. (I am kicking myself for not taking pictures!) I am also sitting here saying to myself this could sound really dumb to a lot of people. I have been teaching myself in this trade and have used many of the helpful tips from the lumberjocks world to help me through a project but this one has me ready to scream.

I am sorry that I dont have a picture to really show you what I mean but I think you very intelligent people will have a reasonable answer for my stupidity.

I look at these YouTube videos and their glue ups seem much easier than mine, my guess is time, talent and patience has a lot to do with that.

Looking forward to your intuitive wisdom!

-- The more sawdust I make more I dont want to go to work! Is it worth it?


8 replies so far

View FancyShoes's profile

FancyShoes

506 posts in 826 days


#1 posted 03-08-2016 01:53 AM

Do you have the issue when gluing other projects together?

View jerryminer's profile

jerryminer

528 posts in 903 days


#2 posted 03-08-2016 04:30 AM

Two things:

1. How are you storing these blocks overnight? Are they sitting on a solid surface so that one side is open to the air while the other side is not? If the material has a different moisture content than the surrounding air, and only one side is open to the air, you can expect warping.

2. Don’t worry about “over-clamping”. You can NOT starve a joint with too much clamp pressure. That is a myth (which you can disprove yourself by clamping the snot out of a sample joint or 6)

View JBrow's profile

JBrow

818 posts in 382 days


#3 posted 03-08-2016 05:55 AM

Matt,

I am not an end grain cutting board guy, but I have some experience with glue-ups. My comments assume the project went ok until you sliced up the long grain glue-up into strips for the last glue up that, when complete, reveals end grain on the top and bottom of the cutting board. It was these slices from the long grain glue-up that cupped.

I do not believe the cupping is due to clamping pressure. Also I personally do not believe a joint will fail if glue is properly applied to both mating surfaces, the mating surface make full contact under clamping pressure, the joining surfaces were recently milled exposing fresh wood, and the glue remains active. Contrary to conventional wisdom, I do not think you can starve a glue joint by clamping pressure

In your case where the first glue-up is spliced to lengths of 1-3/4”, I cannot see how internal stresses in the wood led to the cupping you observe. I suspect you are observing moisture either enter or leaving one surface more than the other surface. Even in a stable shop environment and fully acclimated lumber, freshly milled surfaces will allow moisture to enter and leave the lumber at a greater rate than lumber that has set for some time. Also, moisture does not remain in the wood. Moisture is constantly on the move, entering and leaving the wood at all times. Wood is stable because the moisture exchange occurs evenly everywhere in the wood. The wood will move as in a cup, when moisture has a hard time entering or leaving the wood in one area. This happens if one surface is not milled while the other is or the work piece set on a solid surface.

Whether your problems are the result of doing something wrong is hard to say. But I can share my method for glue-ups. Glue-ups look and sound simple, but to get near dead flat and flush glue-up is a challenge, requiring proper milling, preparation/planning, and then execution. I have pursued the near perfectly flush and flat glue-up for a long time and have just recently gotten close. My last one turned out well, requiring about 1/64” of total material removal to achieve both flat and flush surfaces on three glue-ups flushed up with a drum sander.

Lumber is first cut to manageable lengths. Then it is flattened on one face. The opposite face is planed to achieve boards with parallel faces of the same thickness. One edge is jointed straight and the last edge cut parallel to the jointed edge. The milling operation is complete. During the milling operation an effort to expose fresh wood on both faces and both edges is made so that the lumber can take in or release moisture evenly and thus keep the board flat. In the case of a first glue-up for an end grain cutting board, the boards in the glue-up should be cut to the same width. It is best to sticker milled stock so air can move around all surfaces if it is to be stored. I like to proceed to glue-up soon after milling to take advantage of freshly exposed wood grain. Fresh wood takes glue better.

Before spreading glue, getting the cauls and clamps ready and doing a dry run saves some time when glue is applied and reveals any problems before the glue is spread. A pair of curved center cauls can apply pressure at the center of the glue-up, crown sides against the glue-up faces. The end cauls can be straight since multiple clamps can flush-up the ends of the glue-up. Cauls can be prepared by applying wax to the caul’s surface and running some packing tape or cellophane tape over the waxed surface. The wax makes removing the tape from the reusable cauls an easy task. The tape keeps the cauls from sticking to the glue-up. I also like to apply masking tape to the bar clamps wherever glue squeeze-out can contact the clamps, stopping short of the clamp jaws.

After protecting the workbench from glue squeeze-out drips, I apply the prepared cauls across glue-up, beginning at the center and working to the ends to achieve even top and bottom surfaces. Then applying pressure to the bar clamps is last. With the lumber in the glue-up position, I check that the glue-up will be flush. There have been times when I have re-milled a board because it would not flush-up with the other boards. Once satisfied that a flush and flat glue-up will result, the clamps and cauls are released.

Glue is applied to both surfaces that will be glued together. The glue is spread evenly and thoroughly and in sufficient quantity that it will squeeze out of the clamped glue-up. I set each board on the clamps and continue until all the boards have received glue or I run out of time (before glue on the first board begins to tack and dry). If I run out of time, the remaining boards go into the clamps with no glue – to be glued later. When the boards are set on the clamps after applying glue, I keep them separated just enough so that the adjoining glue surfaces do not begin to bond.

The cauls are applied as in the dry run. Then the bars clamps squeeze every together. This can require some force to overcome the downward pressure of the cauls. The glue-up is left to cure at least an hour or longer before the cauls are removed – otherwise the boards in the glue-up can slip out of position. Once the cauls are removed, the glue squeeze-out can be easily removed with a paint scraper without damaging the wood. The glue-up is left clamped until the glue is fully cured.

After the clamps are removed, the glue-up is stickered or flushed-up. Once flush, it remains stickered. Otherwise moisture can enter or leave one side of the glue-up more than the other causing cupping.

View McFly's profile

McFly

188 posts in 489 days


#4 posted 03-08-2016 05:58 AM

“Left them overnight” <—-well tha could be your problem right there.

I would wrap projects in plastic overnight to eliminate air/moisture movement.

Also consider your grain orientation. If the grain all curves to the same side, it can magnify warpage.

View rwe2156's profile

rwe2156

2190 posts in 942 days


#5 posted 03-08-2016 01:04 PM

When youd did all the Xcuts, fresh wood was exposed.
McFly’s ^^ suggestion is a good one.

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

View Matt's profile

Matt

28 posts in 1060 days


#6 posted 03-08-2016 04:13 PM

So I have a couple more questions and thank you very much for everyone’s knowledge.

FancyShoes – I have not run into these issues when gluing up anything else no.

jerryminer – The glueups I make are always left in the bar clamps overnight, usually for about 12 hours or more. They always have 2 bar clamps on top 2 on the bottom. The over clamping is a relief, its one of the only workouts I get trying to tighten those things.

JBrow – Thanks for all the info, I will have to work on making a set of cauls, I have used them when doing my panels but I have not made a set for my cutting boards yet. Sounds like a good reason to make a set.

McFly + rwe2156 – The air movement makes sense but wrapping it in plastic would only make sense after I make my cross cuts. Is that what you are saying?

If I were to wrap it in plastic overnight wouldn’t that prevent the glue from properly setting up? I almost always allow my project to dry for 12+ hours in clamps before working with it again. Am I waiting too long?

The grain movement makes sense, so how would I prevent this? Is it as simply as after I make my crosscuts to try and go right to aligning the pieces to glue them together again? It would make sense that if I were to do this and re-glue it quickly all of the movement would have to counteract the piece that its glued to but wouldn’t that create more splitting?

My thought is that no matter how careful you are there is always going to be some flattening I just think that an 1/8 inch on both sides is excessive.

Now that I have it flat I just have to put a quick sanding to finish it off before lathering the mineral oil to it but I am already trying to figure out how to make the next one easier.
It seems as though I have to pay closer attention to grain orientation and plan this out a little better.
I was one of those people that thought this was going to be easy….... shows how much I know. I’ll post a picture of it when I am all done, but thanks again for the information it makes sense. I think.

-- The more sawdust I make more I dont want to go to work! Is it worth it?

View bigblockyeti's profile

bigblockyeti

3668 posts in 1182 days


#7 posted 03-08-2016 06:08 PM

As for wrapping the slices in plastic after cutting, I usually go the other way. I’ll set them on a pair of thin sticks to allow air movement all around usually for a couple days in the shop before gluing them all together. If there is excessive movement (which I’ve not yet experienced) I’d rather deal with it on each slice before the glue up vs. risking having the whole thing blow apart as it continues to dry after the work is all done. Using cauls is a must, I use the beam from the parallel clamps covered with masking tape to serve as cauls on both the top and bottom of the glue up, for me this method has worked well. I always have a little flattening to do, but it’s just a little. I don’t yet have a drum sander so I use a belt sander usually staring around 60 grit and working up from there until somewhere between 150 and 180 depending on how things have been going. At that point I’ll switch over to a ROS and run it through 240 which works out to be very smooth if I’ve taken my time with each grit.

View splintergroup's profile

splintergroup

827 posts in 684 days


#8 posted 03-08-2016 10:47 PM

When I do end grain boards, I get the same effect. Usually I just compensate like you did with extra material.

After a final glue up, i’ll let the board set for a few hours then run though the drum sander w/36 grit to clean off the excess glue and get an initial flattening.

After a week (next weekend), I’ll do more sanding to flatten with 80g and 120g. The next day I find that when I run through the sander again (120g), the board has a slight bowl shape (maybe 1/32” to 1/16” deep on an 12×20” board).

All of this I attribute to moisture. If I was concerned about maximizing wood, the advice above is great to minimize wood movement. As it is, I loose at most 1/4” between the glue up misalignment to the final sanding.
Typically you can expect to let dry wood ‘rest’ a week for each inch of thickness after you make any surfacing cuts.
This resting is with the wood stickered in your shop environment. 1-1/2” thick board strips probably should wait 1-2 weeks before undergoing the final glue up.

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