Panel glue-ups using old flooring...biscuits necessary?

[Josh Reet]

I hear conflicting advice on this.

I'm going to be using some old maple gym flooring to create a small bookshelf for my baby nephew's room. His parents are "green" folks who will love the reclaimed lumber aspect of the project.

Anyway, I'm going to take off the t&g with the table saw and glue the boards up into aprox 12in wide panels. Do I need biscuits for alignment or not? These aren't junk boards and seem fairly straight and non-bowed/warped. But I don't have a biscuit joiner at the moment, and if I'm going to buy one I'd like to do it while the dewalt is still on sale at Lowes.

In case it wasn't obvious, I've never done a panel glue up before.

[Mark Warwick]

Everyone has an opinion. that's why you got conflicting ones. I'd use a glue joint router bit and nothing more. Glue holds what 3000 pounds per square inch? If they are nice and flat you won't have any trouble lining them up.

[Greg Hawthorne]

Try dry-clamping the boards using the existing T&G an see whether the join is acceptable. In addition to aligning the boards, the T&G significantly increases the glue surface area, which is what you would be trying to achieve if using a router bit.

Glue bits are good if you can machine the boards after glue-up, as perfect alignment is not all that easy to achieve.

Panel clamps are also an option, e.g. http://www.veritastools.com/Products/Page.aspx?p=136

[Doug Carpenter]

I would think the existing T&G would be good with one exception. I wonder if the joint is intentionally loos to allow expansion. This could be solved by using that Gorrila glue and the like because it expands like crazy. I would think that since the wood has aged it will be nice to work with and should behave well.

[Harold Burrell]

Funny you should ask...

I just recent used some old flooring to make panels for drawer veneers. Some I biscuited...some I did not. Both ways glued up fine and are (IMHO) equally strong. I took cut offs pieces of the "nonbiscuited" panels and tried to break them. They did not break at the glue joint.

[Josh Reet]

Using the existing t&g seems like it would be a good place to start. But I had sort of nixed the idea because there was a lot of cruded up old finish that seeped in the joints when the flooring was in a gym. The gunk isn't in the t&g, but without a lot of sanding/prep, I'm not sure how nice the joints will be.

I will see if I can get the gunk off cleanly with the sander though and maybe that will answer my problems. Alignment is a lot easier with the t&g, that's for sure.

[Bill White]

Ain't gonna catch me usin' 'Rilla Gunk :mad: for anything except glueing wood to rocks (sure, I do that all the time). I use the biscuits all the time, and have had good results.
Bill

[Larry Rasmussen]

Gluing up a walnut desk top recently I found on the initial glue up the boards were not quite as straight as I thought (dry fit, what's that?. Luckily at that point I could still get the pieces through the planer. Next I punched some dowel holes since my jig was out from my last project. Better but they were a pain to work with at glue up I thought. Next I used a spline applied both on my router table or by running a router and slot bit along the boards to make slots for the spline, much easier. I don't bother to use this approach much but it was easy to set up and gluing went like a dream. And cost literally nothing once you get a bit.

Luck, Regards,
Larry R,
Seattle

[Josh Reet]

Next I used a spline applied both on my router table or by running a router and slot bit along the boards to make slots for the spline, much easier. I don't bother to use this approach much but it was easy to set up and gluing went like a dream. And cost literally nothing once you get a bit.


That's an interesting thought. What did you use for spline material?

[john bateman]

According to Wikipedia, biscuit joints were invented in 1956. That means all the glued up panels for a couple hundred years prior didn't require them. And most panels in the last 53 years don't have them either.

I don't see why a shelf hanging on a baby's room wall would need them at all.

[Joe Jensen]

I have never used any joint between boards for a glue up and I've never had a joint fail. I do use C-clamps with small clamp blocks to align the boards. A pad goes on each face and the C-clamp squeezes the board faces into alignment. I used to use scraps of wood with wax on them so they wouldn't stick to the glueup. Now I have small pieces of high density plastic.

Having said that, I've used a Dewalt biscuit jointer for years and I never felt that it gave truely precise alignment. The Festool Domino does. If you don't have a biscuit jointer, try clamping without glue. You can always glue in several rounds, gluing only a few pieces at a time to keep it managable. At times with unruly boards I've done one board at a time.

[Josh Reet]

Just to be clear, as there seems to be some confusion here, I'm not talking about using biscuits for strength. I am well aware of the strength of glue and how much strength biscuits do or don't add. I'm just talking about biscuits as an alignment aid to make the process as easy and good looking as possible.

However, that having said, posts like Joe's above have pretty much convinced me that I should just give it a go and see what happens without anything for alignment. I may try and sand the gunk off as I mentioned earlier and see if I can get a nice join with the existing t&g. But if not, or it proves to be too much work for not much gain, I'll just glue them up a few boards at a time and see how it goes.

[Frank Drew]

Josh, biscuits can help with alignment but certainly aren't necessary for a successful glue up. Just do a dry run first, have a flat and level table for working on, enough clamps, and alternate them above and below the work. I'd clamp from the center out towards the ends.

Work quickly but carefully and you'll be fine.

I think you made the correct decision to cut off the old tongues and grooves.

[Pete Bradley]

I wonder if the joint is intentionally loose to allow expansion. This could be solved by using that Gorrila glue and the like because it expands like crazy.aged it will be nice to work with and should behave well.

Expanded Gorilla Glue has almost no strength. If you want gap filling and strength, thickened epoxy would be a better choice.

Pete

[Chip Lindley]

Go *DarkGreen* and use the existing T&G joints as-is! Unless the T&G are so loose-fitting as to be difficult to pull together for a tight-fitting joint, why go to the extra effort??

A child's bookcase from recycled flooring should look like something recycled IMO! It will impress the green-conscience parents and be much less work for you.

Biscuit joints are only good (IMO) for alignment! I would bet it takes longer to rip off the T&G and cut the biscuit slots, than to adjust the boards of a butt-jointed panel in the clamps. It takes Much less time to just use the T&G as-is!

[Josh Reet]

Go *DarkGreen* and use the existing T&G joints as-is! Unless the T&G are so loose-fitting as to be difficult to pull together for a tight-fitting joint, why go to the extra effort??

A child's bookcase from recycled flooring should look like something recycled IMO! It will impress the green-conscience parents and be much less work for you.

That is actually a very good point for this particular project. Because it is "recycled" and because the people getting the gift will value that aspect, it doesn't have to be perfect. And in fact, may have more value by not being perfect.

Like I said before, I'll see about sanding the gunk off and find out what kind of a joint that gives me. But I may still end up having to cut off the t&g.

[Myk Rian]

Using the existing t&g seems like it would be a good place to start. But I had sort of nixed the idea because there was a lot of cruded up old finish that seeped in the joints when the flooring was in a gym. The gunk isn't in the t&g, but without a lot of sanding/prep, I'm not sure how nice the joints will be.

I will see if I can get the gunk off cleanly with the sander though and maybe that will answer my problems. Alignment is a lot easier with the t&g, that's for sure.
Get a T&G bit set and re-do the boards. That would get rid of the goo.

[Josiah Bartlett]

Using the existing t&g seems like it would be a good place to start. But I had sort of nixed the idea because there was a lot of cruded up old finish that seeped in the joints when the flooring was in a gym. The gunk isn't in the t&g, but without a lot of sanding/prep, I'm not sure how nice the joints will be.

I will see if I can get the gunk off cleanly with the sander though and maybe that will answer my problems. Alignment is a lot easier with the t&g, that's for sure.


I think you will find the original T&g won't work. Flooring grooves are milled so the bottom is loose so they are always tight on the top. This will make the glued up panel bow. I would just rip the tenons and grooves off, joint them parallel, and glue them up. The biscuits are optional. They don't add any strength, they just make it really easy to align the glued up panels. You can always drive a brad into the edge of the board and snip off the head to help keep the glue up from skewing apart if you are having alignment problems, or just clamp cauls on the top and bottom.

[Harold Burrell]

just clamp cauls on the top and bottom.

+1 on cauls.

[Doug Carpenter]

I din't know that the expanded glue wasn't strong. I guess I thought it would fill the slight gap just perfectly.

I also didn't think about the bottom part of the joint not touching at the same time the top does. I think it will curl under clamping pressure because of that.

My bad.:o