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Joining boards along their length

8054 Views 39 Replies 8 Participants Last post by  graeme.c.payne
Hi folks

I'm going to start building a 1600mm long buffet in the coming weeks, but am having difficulty sourcing the laminated wood sheet for the base of the cabinet in the dimension I want. So, in order to give me plenty to work with, I'm considering joining two pieces along their length and cutting off what I don't need.
I can only get 405mm wide, and I need 450mm wide in the pre-laminated sheets I want to use for this. The manufacturer won't make a custom sheet. Both boards would be 18mm thick.

Given I have limited tools and (at this stage) experience, I was thinking to join them by cutting a rabbet along the edge of both boards and gluing them together. Then, because there will be supports in the middle of the underside, making the join about halfway across the width and cutting the sides off to make my 450mm wide baseboard. This seemed a simple solution to me, and as the laminated sheets have proven very stable, I don't anticipate movement to give me any real grief.

This to me seemed a better option than having the possibility of the boards just side by side, as they would have a tendency to shift independently. I have no biscuit joiner, or dowel alignment jig, so have no confidence in going down that track (and they're not in the budget). I also have no tongue & groove bits for the router. Strapping them underneath by putting small bracing strips doesn't meet with approval from my client (wife).

I'm just posting this as a curiousity, wondering how you might suggest other methods that may be achievable given my sparse fit-out of equipment. If you have any other suggestions, I'd love to hear them so I can learn other possibilities. I've tried to give it some thought, but I'm all for learning other methods.

Thank you in advance.
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2
spline it instead of rabbeting...
better face alignment. stronger, easier and less waste..
use BB for the spline...

,

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use a slot cutter for the spline...

.
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Okay, what's BB?
Hadn't thought of a spline. That would be a long spline, almost 1600mm long. Have you ever done that?
Would you cut both slots at the same time, i.e. have the boards both clamped and cut just the once running the cutter up the middle?
@1fizgig, Stick probably offers the best solution, but I notice you say you do not have tongue-and-groove bits. Do you have a slot cutter? If not, take a leaf out of JOAT’s book, and make yourself a very simple dowelling jig. Instructions on the internet.
Provided you register the jig against the “bookmatch” faces of both boards (as opposed to face of one and back of the other), the faces should be well-aligned. Do a dry-fit before glue-up, and re-drill any dowel that is problematic. A slight longitudinal discrepancy will not matter, since you will be trimming to length anyway.
In my humble experience, the “affordable” dowelling jigs are not better than homemade.

Regarding the position of the glue-line,
1. Will it be visible inside the cabinet?
2. Will the board be weight-bearing?
3. Are there any other structural members to give support?
4. Exactly what material are you using? If by laminate you mean melamine-faced, it is darn difficult to get an invisible glue line. In that case, you might want to position the glue line as far towards the back as possible. Also, the factory edges will possibly be more chip-free than you or I can achieve by cutting. Ditto for the edging. If the laminate is wood veneer, it may not matter so much.

Perhaps post a sketch?
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Okay, what's BB?
Hadn't thought of a spline. That would be a long spline, almost 1600mm long. Have you ever done that?
Would you cut both slots at the same time, i.e. have the boards both clamped and cut just the once running the cutter up the middle?
BB = Baltic Birch...
how about 40 feet...
been making splines since I was kid...

nothing says you have to have a continuous spline... segment it...
blind it if you don't want it visible at the ends...
a Slot cutter is the most effective simplest easiest (least amount of work) and economical way to get where you need to be...

I'd cut one edge at a time and all from the face/show side...
when you assemble the joint the face pieces will auto flush...
make one from some scrap...
it will all come together and make sense to you...

FWIW..
a tongue and grove bit is a different fit up vs the spline...


spline...



T&G...

.

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You are asking how to make the boards longer not wider. The way it is done is with finger joints. You can buy a bit or do it on a saw.

https://woodgears.ca/box_joint/fingerjoint.html
You are asking how to make the boards longer not wider. The way it is done is with finger joints. You can buy a bit or do it on a saw.

https://woodgears.ca/box_joint/fingerjoint.html
Evidently the material available is equivalent to maybe our 4' stock where his needs call for 1600mm (62.99213") length boards. Stick certainly gives you the methods best to use and as he stated the splines don't need to be continuous but need to be at both ends to be concealed. As Biagio asks, more information is really needed to determine what if anything else should be considered.
I splined 2 seven plus foot birch boards together once for a mantle top using a 1/2” wood spline. You need to get the glue in as fast as possible at that length so more hands can be an asset.
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You are asking how to make the boards longer not wider. The way it is done is with finger joints. You can buy a bit or do it on a saw.
/QUOTE]

I understand it to be that he wants a board 1600mm long and 450mm wide, but the standard width is only 405mm. Hence he wants to join two boards of 405mm along their long edges, and then cut off the extra. The question is whether to have the joint in the middle of the board, or to one side (i.e. one of the joined boards would land up being only 45 mm wide).
If this is the base of the cabinet, and not particularly visible from the inside of the cabinet, I would opt for the simplicity of the unequal widths.
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Hadn't thought of a spline. That would be a long spline, almost 1600mm long.
You are asking how to make the boards longer not wider. The way it is done is with finger joints. You can buy a bit or do it on a saw.

https://woodgears.ca/box_joint/fingerjoint.html
to build for length an FJ butt joint is the way to go..
but I believe he wants to go wide...
I splined 2 seven plus foot birch boards together once for a mantle top using a 1/2” wood spline. You need to get the glue in as fast as possible at that length so more hands can be an asset.
use a slow set glue...

https://www.garrettwade.com/slo-set-glue-pt.html
Titebond Slow Set Wood Adhesive - Franklin Adhesives and Polymers

switch from yellow woodworkers glue (like Titebond or Elmer's Carpenters' glue) to a white all-purpose glue (such as Elmer's Glue-All).
Another option is to use a hide glue or a powdered plastic (urea-formaldehyde) resin glue.
Both of these glues set up slower than yellow glue and are just as strong.

go w/ an RF welder/curing...
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You are asking how to make the boards longer not wider. The way it is done is with finger joints. You can buy a bit or do it on a saw.
/QUOTE]

I understand it to be that he wants a board 1600mm long and 450mm wide, but the standard width is only 405mm. Hence he wants to join two boards of 405mm along their long edges, and then cut off the extra. The question is whether to have the joint in the middle of the board, or to one side (i.e. one of the joined boards would land up being only 45 mm wide).
If this is the base of the cabinet, and not particularly visible from the inside of the cabinet, I would opt for the simplicity of the unequal widths.
he could FJ the length..
that would make for a ferociously strong connection...

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Given the sizes, I'd considr getting a 1/4 inch slot cutting bit--not expensive, cut the slot face down, or if you must do it freehand, face up with as wide a base as you can get on your router or at least an edge guide. This string has been very thorough.
Given the sizes, I'd considr getting a 1/4 inch slot cutting bit--not expensive, cut the slot face down, or if you must do it freehand, face up with as wide a base as you can get on your router or at least an edge guide. This string has been very thorough.
might want to think a bit more on using an RT... the board is a bit long for one and could easily become unwieldy...
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use a slow set glue...

https://www.garrettwade.com/slo-set-glue-pt.html
Titebond Slow Set Wood Adhesive - Franklin Adhesives and Polymers

switch from yellow woodworkers glue (like Titebond or Elmer's Carpenters' glue) to a white all-purpose glue (such as Elmer's Glue-All).
Another option is to use a hide glue or a powdered plastic (urea-formaldehyde) resin glue.
Both of these glues set up slower than yellow glue and are just as strong.

go w/ an RF welder/curing...
Using a slower glue helps but even then the water in the glue can cause the wood to start swelling after a few minutes which can make a tight fit turn into too tight a fit. I think if I were to do boards that long again I would use a polyurethane glue (provided it has a long enough open time) and then spritz on the water needed for it to set and clamp it right away. I think the p u glue is less prone to make the wood swell than water based.
Using a slower glue helps but even then the water in the glue can cause the wood to start swelling after a few minutes which can make a tight fit turn into too tight a fit. I think if I were to do boards that long again I would use a polyurethane glue (provided it has a long enough open time) and then spritz on the water needed for it to set and clamp it right away. I think the p u glue is less prone to make the wood swell than water based.
PU glues has been discontinued here...
I like weldbond or RF...
PU glues has been discontinued here...
I like weldbond or RF...
Interesting. Why has PU been discontinued? Environmental concerns or more basic reasons?
Interesting. Why has PU been discontinued? Environmental concerns or more basic reasons?

discontinued in my shop, not in general..

Parts being glued with polyurethane need to have a tight fit to be strongly joined. polyurethane is not a good gap filler at all which compromises strength.
As it sets it froths up and the froth hasn't any strength.
In very dry areas (low humidity like here) it requires moisture to set or it can set very slowly and not reach it's full potential.
Because it is sensitive to humidity in the air and the wood's MC, setting times are all over the map.
Because it tends to foam and squeeze out. If not tightly clamped everywhere the parts can be forced apart by the foam, weakening the joint.
The foam gives the illusion of gap filling, but there is no strength.
I believe that it hasn't the strength of PVA glues......

After its cured it is very chemically inert and safe but the intermediate phases are it is toxic and an irritant. cause allergic reactions. This begets polyurethanes have to be handled carefully, kept off your hands and not breathed in too much. do a search for the MSDS's of various brands to get more information.

Read the warning label: Contains isocyanate containing polymers. Contact causes eye irritation. Prolonged or repeated skin exposure may cause allergic reaction, irritation and sensitization. Contact may stain skin. Do not allow eye contact. Avoid prolonged or repeated contact with skin.

short shelf especially after opening and they are EXPENSIVE...
It is messy and sticky to use and always seems to get on everything.
Polyurethane is difficult to clean off hands, (gloves are highly recommended).
it takes Acetone or lacquer thinner to clean tools while still uncured.

it's not worth the extra work and hassles so I stopped using it all together...

this does does apply to construction adhesives such as PL Premium which I'm a die hard fan of......
and I'll stick w/ Weldbond...
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We used to see people on the forum say they used p u glue because it would foam up and fill the joint but you are correct when you say that the foam has no strength. It must be a tight fitting joint for it to work. The websites about it used to say as much but they removed those parts because people believed otherwise and they were selling more glue as a result. If you have a tight fitting joint then the foaming action is supposed to drive the p u glue into the wood grain making a stronger joint. But if it isn’t a tight fitting joint it won’t be a good idea. Then you need a glue with high solids content which I think might be be Titebond 3 but I’d have to check that to be sure. Lee Valley makes a GF glue (gap filling with high solids content) but if you use it on tight fitting joints you risk splitting them. Or having glue push out end grain on something porous like red oak from the hydraulic pressure in the joint. (VOE speaking here). This once again reinforces the statement that no one glue solves every problem and you need to use the right glue under the circumstances you have. I keep about 6 around that I consider essential but I might keep more if I could focus on woodworking all the time.
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