Panel joinery problem.
I have had a problem pop up on occasion when I edge glue boards to make a panel. Red Oak in this case, and it’s kiln dried and has sat in my shop at least 6 months prior to use. I use Titebond II usually, with biscuits. I stain with Minwax oil stain and finish with 4 or 5 coats of wipe-on poly. Everything looks Ok, but about six months later, I can feel ridges where the joints are. It’s as if either the wood shrinks or the glue expands.
What causes this and how can I prevent it in the future?
Replies
Wood movement. Red oak moves more than most any other hardwood, so it's best to glue up in an environment similar in humidity with where the work will be placed or installed; or, a moisture meter will take the guesswork out the equation- the wood should be 6-9% in most environments save extremes like Arizona or the swamps of Louisiana.
The really easy answer, Dan, is do not use biscuits. Rub the joints and set aside to dry, they should hold. The use of biscuits in this situation sometimes hampers creation of a lasting joint by preventing the application of proven techniques, so trust your ability to plane a fitting joint.
One thing, after sitting in your shop for any length of time, timber is not kiln dry, it is acclimatised to the humidity of the shop.
Happy holiday
David,
"...The use of biscuits in this situation sometimes hampers creation of a lasting joint by preventing the application of proven techniques...."
I am tempted to use the "poodlejuice and goosewipe" expression but its probably banned from Knots now. :-)
What evidence do you have for maligning the poor, innocent biscuits in this vicious manner, I prey?
Lataxe
PS Merry Christmas and I hope you get that Lamello you've been wanting from Santa.
Edited 12/20/2006 3:41 pm ET by Lataxe
I agree with you on this one- biscuits have been maligned by some for years. For no good reason. Biscuits are not the culprit in a raised glue line...
And to mufti, biscuits are a proven technique. They've been used successfully for over twenty years.
Edited 12/20/2006 4:33 pm ET by jackplane
I've got nothing against Bis-kits, they are quite good with gravy, though slippery dumplings are better.
I've used bisquites for face frames and cabinet carcass construction and found them to work a treat, but I don't understand what good they'd be in edge jointing? There is too much play in the slots in my experience to be a meaningful route to better alignment (stock prep, clamping, and cauls, or splines seem more promising for alignment purposes), and the joint doesn't need more strength, so is it just a belts and suspenders thing, or what?
In this case, it's to act as a spline of sorts. You're right. As this is edge-to-edge gluing no re-inforcement is truly necessary. But it's sorta like mental insurance, or if one gets used to biscuits, one uses them all the time.
Samson,
Uses for biccies in edge jointing:
* help to align bendy or otherwise unweildy boards (obvious and it work perfectly with no dips or bulges, if the biscuit joiner and biscuits used are proper ones and you are not a cack-handed user).
* allows clamps to be removed earlier - biscuits act as internal clamps, once swollen into place.
* help with oily woods like teak and afromosia. Biscuits offer a mechanical grab on edge joints as well as an increased glue join, in areas where the glue might fail because of excess or leaching oil.
Of course, what would I know, having used only a few thousand of them - presumably unlike the detractors, who have been listening to boogie stories told to them as naive little apprentices, probably. ;-)
Lataxe, who will one day have that Lamello.
Lataxe,
A firm no to each of your assertions.
But go ahead and use them if you want warts to grow on your nose and experience complete failure of any underarm deodorant.
I tell you, biscuits are nasty beasties!
Rich,
Although the warts are as yet dormant I have to confess that you've got me worried concerning the underarm pong-remover. Only the other day in the gym, I noticed sneering glances, muttering and a number of wrinkled noses.
However, I still like to plunge my hands into a box of fresh No 20s now and then - I just can't help myself.
Lataxe, a biscuiter-extraordinaire; and only a bit smelly when damp.
PS. It is a sad thing to see a grown woodworker frightened of a few little friendly biscuits. They are Nice and everyone should have a box or two.
Edited 12/21/2006 7:11 am ET by Lataxe
Frightened of a few bicuits is it!? Nah! Here in rugged Northern Arizona we sprinkle some on our morning oatmeal. Nice 'n' crunchy! Rich
The problem from the original poster has NOTHING to do with clamping pressure-too much or too little - as you have stated.
If he experiences glue creep, that's one thing. But he mentions being unable to keep the tabletop pieces from moving out of alignment while clamping- a product of either a non-flat bench to work on, wood edges not flat, or stock so thin-usually at 3/4" or less that it becomes difficult to keep it flat as the clamps start to bend.
Edited 12/21/2006 8:47 am ET by jackplane
jackplane,
The original poster mentions nothing at all about problems in keeping the pieces aligned.
PVA glue creeping out of joints and forming ridges is more noticeable when clamping pressure is not high enough because the joint then has a gap which is filled with glue, which eventually creeps out onto the surface of the glued piece. A tight joint has a thin glue glue line which is less prone to this problem.
Rich
rich,
glue can't creep out of the joint to form a raised ridge under less clamping pressure.
A tight joint results from properly prepped stock(flat and square), and is not the result of too little or too much clamping pressure.
For example, luthiers routinely use only clothespin clamps when adhering the soundboard to the framing.
"glue can't creep out of the joint to form a raised ridge under less clamping pressure"
I believe they are talking about "creep" that occurs long after the glue is dry and even months out of the clamps. The point as I understand it, is that with less clamping pressure, you are effectively leaving a thicker "ribbon" of glue between the boards, and hence have left more PVA available to "creep."
I love the Lee Valley 2002 Cabinet makers glue, and use is almost exclusively. It is high in solids, has a good working time, and is light brown, so it tends to match the wood better, the extent it's ever seen. I've never had any creep in any project. Could it be that Titebond or other PVA's are more prone to creep? Dunno, but FWIW.
jackplane,
Samson said exactly the same thing I did, in a different way. Maybe you'll understand his explanation better.
Rich
So the suggested glue to use would be?
Doug Meyer
Well,
I had already suggested polyurethane, epoxy, hot hide. I like polyurethane a lot for its very fine glue line and the slightly tan color it dries to. I started using it to adhere lignum vitae to other tropical hardwoods for wooden plane soles. It solved so many problems for me that I just continued using it as a general purpose glue. Like anything else, its personality needs to be learned, then it's a friend.
Richard jones has also recommended urea formaldehyde.
But properly clamped, I think that PVA glue is not a problem.
Rich
>> So the suggested glue to use would be?In the shop I was involved with we changed to a urea formaldehyde adhesive like DAP/Weldwood Plastic Resin for all our panel glue ups. PVA adhesive is still preferred for most other joints.Personally, I don't like poly adhesive. It's messy. If too much moisture is added, the foaming is considerable and the joint is actully weakened. The foam is gap filling but has no strength. It requires tight, long term clamping. I see no advantage except for gluing oily woods.Howie.........
Howard,
Polyurethane keeps getting this rap for being messy and for foaming.
It has a long open time. That's good for a lot of purposes. As with any glue, it's important to apply the right amount. And with this glue it's important for the wood to have enough moisture. That's not hard to do. And it's not hard to avoid too much. Like any process, a little craftsmanship is required. The clamps need to stay on for 12 hours or so. I don't find that a negative.
The glue does not foam within the joint. If that's happening, the joint is not closed in the first place and the clamping technique is all wrong. You're right, there is no gap filling/holding capability of this glue. But that's the point - invisible (tight) glue lines are the goal.
All the foaming takes place outside the joint from squeeze-out. That should be minimal, as controlled by the initial application. The goal should be just tiny beads appearing at the glue line as the clamps are brought up tight. Within a minute or so, those beads turn to a little foam which can be removed mechanically, with acetone, or just left for clean-up later when hard. The dried foam has no structural integrity and comes off easily.
All-in-all, I've found polyurethane a very useful glue.
Rich
I have a very good Elu biscuit joiner and scriber and was not aware I was denigrating the use of biscuits, however they are not a panacea. In edge gluing small panels I have had no failures in rubbing the joints until the joint starts to resist as the glue grabs, and then setting the panel aside to dry. I could not do this and use biscuits, and many folk have written of the risk of biscuits telegraphing through in joining relatively thin stock.
By the way I use any reputable glue in this way, not just hide glue. Generally I do whatever works and people ask questions when they have done something which has not worked.
His problem was not joint failure. It was raised glue ridges. Your statement that biscuits prevent a time honored technique of joinery, suggests the problem is caused by biscuits, and I'd prefer not to see this discussion devolve into the old biscuits v. anti-biscuits thing.
Didn't mean to single you out on this. Happy Christmas.
Glue creep. Can someone explain just exactly what forces are at work on the dry glue to cause it to move out from between two boards?
Not me. But Samson's explanation is close. I still don't see how dried glue can creep, months after the initial glue-up. I do know, as many know, that pva adhesive is not good in some joints, especially bent laminations- but this due to the glue's elasticity and not glue creep as I understand it.
jackplane,
Unfortunately, your inability to comprehend how PVA glue comes creeping out of those joints does not negate the reality that, in fact, it happens. Long after the joints are thought to be, um, quiescent.
I have my own theory as to the cause, but it involves extra-terrestrials, mis-guided terrestrial collaborators and something about unmentionable sexual activities with cattle. You have read the accounts of crop circles, haven't you?
I could tell you, but then I'd have to kill you.
Rich
You have too much time on your hands.
Time to play with your grandchildren.
This thread is getting very interesting, as always, and as always, drives off in it's own dirrection.I'll throw my handful in. I made up a whole bunch of raised panels for my living room walls, and to do it I had to laminate boards for the railes and stiles, as well as edge join 1cm thick boards for the panels. I used ,very succusfully, a plastic resin waterproof glue called Marine Glue, from Dural Ont. in Canada. It is a powder that you mix with water, so you mix what you need, sets up over night (depending), does not move, and the wood will fail before the glue. There is no creep.
I believe a post above explains it, but to repeat what I read as I understood it: the wood expands pulling the dried, but somewhat elastic glue with it; the wood then contracts again, but the glue is apparently not pulled all the way back to its original position, but instead remains slightly proud of the edge joint line with the result being a tiny ridge of dried glue. The glue "crept" out of the joint line. Humidity may play a roll directly in softening up the glue a tad as well as causing the wood to expand. Anyway, that's what I heard the experts above to be saying. YMMV
Well, in my first post in this thread I said this was not a biscuit problem.
jackplane said,
"I'd prefer not to see this discussion devolve into the old biscuits v. anti-biscuits thing."
Oh why not? It's such fun! And biscuiteers get sooo defensive.
Anti-biscuits.
Never thought of that! Are they like negative-energy thingies that go around zapping biscuits out of existence? Sort of like anti-matter vs matter?
Cool!
Rich,
I have put your name on Lamello's blacklist and a small, nondescript chap in a worn black suit and wire-rimmed glasses will be around to remonstrate with you in due course. Be afraid.
Meanwhile I compliment Willie on his posting - experience backed up with a clear explanation. When I consider your own pathological and totally illogical hatred of the poor little biscuits, in contrast, I can only surmise that your eating them for breakfast has made you queasy and put you off.
It's that or you were frightened by one as a baby.
Or maybe its because they're Swiss.....
Lataxe, amateur psychoanalyst.
Lataxe,
"a small, nondescript chap in a worn black suit and wire-rimmed glasses "
Poor, unsuspecting Lataxe! They have you duped. I know all about them! That's just one of their disguises.
I've been avoiding the aliens for years! They find us by our brain waves. It's simple to fool them. I use an aluminum foil skull cap. It attenuates the brain waves and they can't be picked up at all.
But there's a secret. You gotta use the heavy duty Reynolds Wrap. The thin stuff is junk. And you have to get it tight down, all around your ears, or your brain waves will leak out and they'll get you. Take it from me, you don't want that!
I wear mine all the time. It just drives them nuts!
I found that walking around with your mouth open when you wear you hat,helps as well.
Hey ptu, Thanks. You're right! This place rocks! Always picking up good stuff. I've been walking around all morning with my mouth open. I never pay attention to the advice on those other sites 'cause a lot of the stuff they tell you to do makes you look stupid. Not this place! Don't want to look stupid. Here's a fashion tip - red or green paint on the aluminum foil, for the season, doesn't affect it at all. Rich
Edited 12/23/2006 4:30 pm ET by Rich14
Thanks for the tip! I'm going to try LED, hope they don't find meMC&HNY
Sorry guys. This is my first original posting. I didn't mean to get everyone so riled up! But I did get an answer that makes sense. I won't use Titebond for edge joing glue ups. I'll try the poly glue.
Seriously, thanks to all for your comments.
Dan,
It doesn't usually get this silly! It must be the season.
Have fun!
Dan, Howard Acheson provided the answer to your original question at this link http://forums.taunton.com/fw-knots/messages?msg=33256.18 earlier in the thread. Funnily enough I recognise the text as I wrote it some time ago when I lived in Houston, ha, ha.(I certainly don't mind you using it Howard if you happen to revisit this thread.)
It seems to be the case (from discussions I've had and threads in forums that I've read) that many woodworkers have never seen the 'row-of-pimples' creep in joints assembled with PVA as you described. However, this type of creep does happen as you are able to testify.
There are many alternative glues that do not suffer from creep-- hide glue, urea formaldehyde, polyurethane, epoxy, etc.. Any one of these will work. However, it's my experience that the glue most likely to fail with a clean break right on the glue line itself (as opposed to mostly tearing of the wood fibres) is polyurethane type.
I'm not sure why this is the case, but I suspect it may be to do with the foaming nature of the glue. This tends to push joints apart unless very firmly clamped. If the glue foams and the joint can move apart even a miniscule amount due to the foaming the foam in the gap between the parts being glued is not in itself strong, i.e., the foam is not structural, hence the clean break line if a break occurs. That's my theory on polyurethane glue failures. I've not tested it scientifically, but it's the gut instinct theory I've come up with.
On another topic, there is nothing fundamentally wrong with using biscuits for panel or slab glue-ups. I tend not to use them which means, obviously, that very occasionally I do. If you do use them and glue the panel up with a water based glue you do have to take into account that water is added to the wood at the joint. That means water is added to the edge joint, and also added to the biscuits and grooves element of the joint. Not only this but the biscuits are essentially manufactured flakes of wood that at some stage of their making are hydraulically compressed . They are meant to swell when glued into their matching grooves to form a tight joint. This swelling of the biscuits coupled with the addition of water to the general glued up area raises the wood slightly all along the mated edges and either side of the biscuits.
As the water dries out of the wood the wood shrinks back again, and this applies to the glue line, and even to a small extent (I believe) to the biscuits used in the biscuit joint. I've found that it's prudent to leave edge joints, particularly biscuited edge joints to settle for about a week or ten days after gluing up to let the wood dry out and do all its shrinking before final surface preparation and polishing happens. This reduces the chance of rugby ball (oval) shaped depressions showing up later. (Also, waiting this long reduces the chances of what's known as furrows or furrowing in the spaces between the biscuits showing up, described in the next paragraph.)
If there are no biscuits in the edge joint and it's a plain edge joint with a water based glue used in the job I still recommend you wait a few days after unclamping the glue up before you get busy with prepping and polishing. In this case what can happen if you don't wait a bit is you'll later see a slight depression or furrow along the length of the glue line.
I've whittered on long enough. That'll do for now as I've beers to go and drink, ha, ha. Slainte.
Richard Jones Furniture
Edited 12/21/2006 4:36 pm by SgianDubh
Richard,
Ooooooh! Gen-yew-ine woodworking knowledge!! I have sucked it up, verbatim.
All that you say chimes with my experience, such as it is - except perhaps that rugby-football effect, which I have never suffered. That must involve either biscuits too close to a suface or soft timber, I feel.
I wonder if you could be persuaded to follow-up concerning one remark you made:
"There are many alternative glues that do not suffer from creep-- hide glue, urea formaldehyde, polyurethane, epoxy, etc.".
I used to use Cascamite (urea formaldehide) a lot but Humbrol (the makers) seemed to change something about it so that it mixed up all porridge-like rather than into a smooth paste. It also seemed to dry up and go solid a lot faster than it used to do, in the glue pot.
As a consequence I began to use various PVA - Titebond and the like - which now and then throws up those damned glue lines. I loved Cascamite but they knackered it for me.
Do you have any info or experience on this Cascamite formula change and its consequences for how the glue should be applied? I e-mailed Axminster (the retailers I bought from) and Humbrol thenselves, with no success.
Lataxe
Lataxe, you might have a point about the positioning of the biscuits and the softness or hardness of the wood being a contributory factor in revelatory oval depressions showing up later.
I don't know for sure, but your theory has intuitive common sense attached to it. That doesn't mean it's right of course, but it's a point certainly worth considering. I will say that I've witnessed these depressions and furrowings in a wide variety of timbers, both soft and hard, regardless of the position of the biscuits too. Lastly on this topic, the depressions usually don't show on vertical surfaces due to way the light normally strikes them. They do tend to show on horizontal surfaces, again due to the angle of light reflecting of them.
As to your Extramite (Cascamite) question I don't know if the formula has changed. I do know that since moving back to the UK three years ago I've returned to using the stuff after a ten year absence. As far as I can tell it mixes up and performs the same as it used to back in the very late 60's, 70's, 80's and early 90's during my previous life and work in the UK.
Perhaps your mixing technique is failing you? If I recall off the top of my head, the proportions by volume are 1 part water to 3.5 parts powder. Dump all the water in a non-metallic container. Add all the powder and stir briskly until you have a creamy consistency. Double cream consistency is a bit too thick. Milk consistency is a bit too thin for most jobs. I like to use quite sturdy cylindrical plastic pots and pieces of 12 mm or 9 mm dowel for the mixing. Slainte.Richard Jones Furniture
Thanks, Richard. This makes a lot of sense. I probably rushed the finishing too much after glue-up and I'm sure that aggravated it. I have never seen the dimples form from the biscuits, but as I said before, I rarely use them for gluing panels anymore. It's too easy to cut off a panel and find you exposed part of the biscuit. Now that's hard to fix!
So I will try the poly glue next time. How long should I have it clamped to know it's fully cured? In the winter, I usually keep the temps down to about 55deg when I'm not out there, but I can keep it warm overnight when glue is curing.
I'm not sure about the clamping time Dan. There are fast setting and slower setting glues available. The makers of the polyurethane glues usually state on the container how long to leave a job clamped up at a particular temperature, say 70ºF or 20ºC.
If your conditions are cooler you'll usually need to extend the time allowed, and if warmer you can normally shorten it. Certainly if you leave the job clamped up overnight between about 60º- 80ºF that will normally be plenty of time to cure-- but do check the side of the container for instructions.
Watch out for a minimum temperature that your choice of glue can be used at and, of course, if there is a minimum temperature stated, pay attention to it. Slainte.Richard Jones Furniture
Nah, I only mean exactly what I say, and no other interpretation applies. I was not aware there has in the past been controvesy on the subject so perhaps I live on a different Planet
Best wishes, David
Give me the chance to rage against biscuits and I can rant with the best. But this is not a biscuit problem. (BTW, don't use biscuits, ever, in any kind of application).
It's not a red oak movement problem either.
The problem has been discussed before here. It is probably a problem of glue creep out of the joint, most frequently caused by PVA type glues and inadequate clamping pressure at glue up. That leaves enough excess glue in the joint to creep out later and give a raised ridge at the glue line.
Problems with biscuits are that the biscuits swell from moisture in the glue and raise the wood above them. If the joint area is sanded too soon after gluing (a week is often too soon), the raised wood is removed, then as the biscuit shrinks, a hollow forms. Biscuits add no strength to an edge glued joint and they are the work of the devil. Don't use them. Go ahead if you insist, but you will go bald, blind, get fat, your children will hate you and all your investments will go south.
Did I mention? Don't use biscuits.
Edited 12/20/2006 5:30 pm ET by Rich14
I've used biscuits to help align the boards. I know they aren't necessary for strength. But I found that when just edge gluing, the boards tend to slip when I clamp them.
I'm making some raised panel doors and have been using an edge joint router bit to give a tongue and groove joint which is perfect once you get the bit height correct. It gives the best results I've ever had as far as aligning the boards.
So apparently it's the PVA glue. That's what I suspected. So what kind of glue should I be using for these panels?
Dan,
I recommend using cauls, rather than the router joint. But if you can form the joint without problem, great. I can't. With a shaper, yes. But not with a router.
BTW, a good way to align for edge gluing is a few well-placed dowels using a center-finding doweling jig and a milling bit. One board gets holes. The other gets slightly elongated slots at the approximate position of the corresponding holes. Just a few dowels does the trick, aligns the surfaces and completely avoids the problems with biscuits. But cauls are the best way. They assure the whole assembly is flat.
PVA is ok if you use enough clamp pressure. That means plenty of clamps. And plenty of force. The frequently-given advice that you can starve the joints of glue with too much pressure is, in most cases, just wrong.
Almost any other glue will avoid the glue creep problem. Polyurethane, epoxy, even hot hide. I like polyurethane for a number of reasons. But well-clamped, the PVA glue line should not be a problem.
I think I am going to have to agree with Rich on all points. A buddy of mine was so proud of his new biscuit jointer that he used it on the edge gluing of a cherry tabletop. I assume he worked it too soon ( 2 days) because you could see every football shape in that top when he applied a gloss urethane finish. He panicked and called me and all I could do was to tell him to rub it out with 0000 steel wool to se if that cut the refraction of light. It helped a lot , but I still notice them so I keep my mouth shut because he thinks he does'nt see them anymore. I think the only real solution is to strip it and run it through a wide belt sander and refinish it. According to FWW biscuits actually weaken an edge glued board(slightly). Rich is right on the money!
Dan,
I tend to agree with Rich about the glue creep...as I'm having the same problem as you with two tops I glued up a couple of months ago. In my case I clamped the boards with cleats & wedges on the workbench and put about 60 lbs of cast iron on top to keep them flat. After about 2-3 weeks I re-flattened the boards (per Franklins recommendation). I can't figure out what else it could be..lack of clamp pressure is about all that is left to blame. I did notice that Stickly uses a tongue and grove as you are doing.
in a pinch i used the kreg jig to make a red oak dresser top and i was actually impressed, i personally would use pocket holes, depending on circumstances over biscuits myself but then again i am a super novice and that wouldn't be fine woodworking
Dan, I don't know what's causing your problem. But I've made lots of panels and used thousands of biscuits and have never experienced it. I've clamped really tight and sometimes not so. Sometimes I apply edge banding using only masking tape as a clamp. That's not much pressure. I don't think the problem is PVA glue. The only remotely similar experience I've encountered is on my oak floor. We filled and finished in early spring, everything was beautiful. The floor perfectly smooth. (for a floor) Then came summer and higher humidity. The floor swelled and pushed the filler out from between the boards. We now live with gaps in the winter.
I think you're on to something. Maybe the OP can tell us how he attaches the tops. If he doesn't use a method allowing for expansion and contraction - buttons or figure 8 hardware, he may be seeing ridges from expansion that has no where else to go?
Raised gluelines are a long well known problem with PVA adhesives. It's function of what is known as "creep".
It has been discussed here and on other forums for years. Here is one of the best explanations I have seen. It was written by a frequent contributor to this forum.
************************************
Creep has been known about for many years, perhaps even centuries. It's nothing new and has already been defined precisely, so no need to reinvent the wheel here. PVA is the classic and renowned creeper. Meaning it has relatively low shear strength. In other words, it slips.
The tendency of the glue to ooze out of joints is one form of creep. A classic example is in a slab edge to edge glueup, such as a table top. When ambient humidity rises the timber and the the glue swell. When the ambient humidity goes down the timber shrinks again, and so does the glue, but the glue doesn't all shrink back into its original place resulting in a line of pimples disfiguring the finish. Actually, under sustained high humidity my anecdotal observations are that the glue keeps on absorbing moisture and creeps out of the joint without the need for the timber to shrink. The symptoms can also be seen sometimes at the shoulder line of other joints such as mortise and tenons.
Another cause that I've witnessed several times is to make a solid timber slab with edge joints in a fairly humid workshop without climate control using PVA as described before. Then right away get to planing and preparing the surface ready for polishing with scrapers, sanding, etc.. Right after that apply the polish, whether it be varnish, pre-cat, or another finish, and take the piece into a drier house, either heated or air conditioned. Three to five days later the rows of pimples will be apparent as the timber shrinks.
Somewhat related to this is using an aid for edge glue alignment, such as biscuits with PVA. These jobs need time to settle. If you are in too much of a hurry and prepare for and polish it all as soon as you get the piece out of the clamps, the chances are you'll see a row of rugby ball shaped depressions telegraphing the position of every biscuit a couple or three weeks later, although I've seen them appear as much as a year, or more, later. The moisture in the glue swells the wood either side of the biscuit, and it takes a week or two for this moisture to work its way out of the joint properly. My advice then is to not rush into the preparing for and polishing stages after this type of glueup, particularly table tops and the like which show off every flaw. I don't use PVA for this specific kind of glueup at all anymore here in hot, humid Houston. I tend to reach for the hide glue nowadays, either out of the pot, or the liquid stuff.
Slainte, RJ.
In the shop I was involved with we worked with our adhesives supplier for a couple of years trying to resolve the problem. The ultimate resolution was to change to urea formaldehyde adhesive for panel glueups.
**************************
Go to:
http://www.fpl.fs.fed.us/
Then click on:
General Info
Then click on:
Wood Handbook
Then download:
Chapter 12 -- Drying and Control of Moisture Content and Dimensional Changes
Hope this helps,
dlb
.
i'm not sure if u mean there is a ridge line of glue, or a difference in the thickness of the wood as compared to the piece next to it. if it is the latter, it is called glue steps. it occurs when flatsawn and radial grain are glued up together.IF this is your problem, then try to only glue up flatsawn to flatsawn, radial to radial etc....if it is a glue ridge line, well, there are a ton of good posts here to help...good luck
I was just about to post something similar to what you did. To go further, flatsawn, will expand/contract across its thickness and can become thinner as it dries or thicker as it absorbs moisture. Radial sawn (quarter sawn) will expand/contract across its width and it's thickness will be more stable.
"I cut this piece four times and it's still too short."
i may be mistaken, but i believe radial grain is more prone to its thickness being the greater tendancy to shrink/expand and flatsawn to expand/ contract accross its width.dont want to start an argument here, but i do beleive i am correct. cheers, mike
What were rings, get thicker and thinner but radial sawn is AKA quarter sawn and if the quarter sawn grain is perpendicular to the face, the length or width will change more. Flat sawn will get thinner and thicker. We can look into this and post whatever links we find, OK with you?
"I cut this piece four times and it's still too short."
gossamershavings and highfigh, click on the image thingie below for what happens. The sketches and text should explain what goes on adequately enough. Slainte.Richard Jones Furniture
Nice drawing.
It seems that the problem could be glue creep or it could be board layout or both.
I've also heard it recommended that even using strictly quartersawn wood to glue up a panel, it is best to keep the growth rings matched, that is, glue the bark side to the bark side, the pith side to the pith side and so forth.
The thought is that the outer rings of the tree expand and contract more than the inner rings.
Monte
MonteB, you mean as illustrated in this sketch. Slainte.Richard Jones Furniture
Sgian,
I went backed and checked my end table tops...uneven shrinkage appears to be the culprit as I mixed flat sawn with rift sawn lumber. With winter comming on the boards shrunk different amounts, hence a raised seam. Not much I can do now except paint it orange and put a " Watch your step" sign...sigh!
I certainly didn't start this thread but now I am thoroughly confused. I have experienced 2 tables with what I will call "joint raise." And a whole bunch that have stayed nice and even. Have read about a half dozen glues; clamping pressure; mating differnent wood grains. Too much to process. I'm just gonna keep doing what I have been: PVA glue, clamping pressure that seems right, and a couple of "table stabilizers" (boards under table screwed at joints) to prevent cupping, glue creep, whatever.
PMM
Unfortunately PMM, just closing your eyes to the subject of timber technology, including understanding the characteristics of the glues used, and hoping any problems won't occur or will just go away seldom works.
To deal with such problems you have to become knowledgeable and skillful and it does require an investment in time and study. For instance, your proposed '"table stabilisers" (boards under table screwed at joints) to prevent cupping, glue creep, whatever' may not work as you intend if they're used carelessly or set-up incorrectly.
Maybe you're not closing your eyes at all, and your post was intended as a humorous tongue in cheek one? If that's the case and I picked up the wrong meaning I apologise for perhaps coming across somewhat heavy handedly. Slainte.Richard Jones Furniture
The check (or is it cheque?) is in the mail to you as payment for years of sage and wise advise (or is is advice?) here on knots over these many years....Jimmy...(or is it Jimmie?) Check also in mail for C stanford and l grindinger...
Edited 12/23/2006 8:36 pm ET by Jimmy
Extremely large unsolicited cheques (five or six figures seems about right) for doing almost nothing are always welcome, Jimmy, ha, ha. Slainte.Richard Jones Furniture
Slainte,
Sorry that it took so long to reply. I've been on extended holiday.
Yes, this drawing is exactly what I meant. It opened my eyes to the greater-than-I-thought extent of wood movement when I first saw this.
Monte
Now that you know what causes it, you can prevent glue creep by using polyurethane glue instead of PVA. It's a better color match for red oak, anyway. You can also use epoxy, but that's expensive.
Dan,
I'm the lone ranger around here, and know this as I have posted on the subject before.
The only way I glue up boards is with a joint bit in most cases using a shaper. There is some skill to this, but once the tricks are learnt and the process is understood, it is very forgiving. By forgiving, I refer to when it is not possible to match similar grain properly, or when gluing species such as Teak which is naturally oily, or Congolo Alves where glue does not penetrate the fibers. The process takes care of alignment, creep and adds tremendous strength to the joint. During the clamping process there is no concerns regarding both alignment, or keeping the boards parallel, as the joint takes care of both. The only strength the glue adds, is to prevent horizontal separation, and the typical vertical forces a table top is subjected to is actually sustained by the joint construction.
Most avoid this method, because when using a shaper, the boards must be perfectly flat, otherwise the results can be disastrous.
If the latter is a problem, I use a joint bit on a router, with a straight edge. In this case I have been able to get a straight top, using bowed boards and matching bowed areas as opposites. This works where one gets exotic figured lumber which is not straight and it's worth the effort.
The fix for this is easy and you don't have to quit using PVA glue if you don't want to. I think hide glue is better and is more rigid at the glue line, however.
You don't need biscuits. What you need to do is glue up your stock at full thickness - don't plane to final thickness and then glue the panel. Scrub enough off both sides to match color and grain and finish joint the edges and glue up the panel. Let it sit a few days. Always use stock that has been in your shop at least three weeks. After a few days, finish plane both sides until you reach desired project thickness. Or thickness the panel over a period of a few days taking the final passes right before you put the piece into the project.
What you need to do is glue up your stock at full thickness - don't plane to final thickness and then glue the panel.
I do this when I can, but it's hard to squeeze a 16" wide panel or table top into my 13" planer.
Seriously, thanks to everyone who has offered their opiions. I am now in the middle of making raised panel doors to reface my kitchen cabinets. I am making the panels from Red Oak but gluing them up with polyurethane glue and just using butt joints. I'll let you know in a few months if the problem persists.
All of the oak has been in my shop for over a year, so I know it is acclimatized. My house has a similar environment, so I hope everything works well.
Process your wide panels by hand.
You're letting your machinery dictate terms to you.
My intentions are not to be troublesome or picky, but.... If a woodworker has chosen his equipment, how can it be said the equipment is dictating terms to the woodworker?
I have some curly maple pieces that I want to glue the edges together. However, I understand that each piece should be reversed with opposite grains. With Curley Maple it is hard to even see the grain. Also, when I am planing it, the planer takes out pieces of the curls. Any help for this?
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