Wainscoting Out of 3/4" MDF How to Glue It Up

[Bob Feeser]

I'm redoing the main bedroom and installing Wainscoting all the way around the bottom. I started to joint and plane some boards out of Hickory but it got to be too huge of a job trying to get much finish wood out of "barkey" Hickory. So I bought a bunch of high grade 3/4" MDF. It's all perfectly 3/4". So I am doing raised panels using cabinet making router bit set.
I am at the glue up stage and was wondering what everyone felt was the best way to glue it up. I have 2 test pieces curing in the shop right now using Titebond III and clamped.
I tried using dowels in addition to the cabinet rail and stick contours, but it resulted in some splitting of the MDF. So I glued up some test samples without dowels.
I read up on someone who was using pocket hole screws but his tolerances were too narrow. He was predrilling and mentioned if it was off by only a little bit it would split.
Then I read where someone put a thin coat on first, and then came back and put on a second coat on quickly before assembing, thereby offsetting the problem of the MDF soaking up the glue and creating a dry joint. I have one with a single coat, and a second one with a dual coat. Tonight those joints will have cured 24 hours so I plan on putting them to a reasonable stress test. I don't plan on using a vise on them though. If they can hold up to all that I give them, that is sufficient.
I know I am posting this in a sea of people who have experienced wainscoting glue ups, so I am curious as to what you think works best? What kind of glue works best?
I ruled out Gorilla glue because I don't want the foam cleanup.

[Frank Drew]

Bob,

I'd buy extra MDF and use solid, unglued pieces for the panels. Too much work the other way, IMO.

[Clint Olver]

You should be fine. I wouldn't bother with dowels or pocket holes. Gluing the stiles to the rails should be sufficient.

C

[Bob Feeser]

Bob,

I'd buy extra MDF and use solid, unglued pieces for the panels. Too much work the other way, IMO.

I agree with you there. That is why I bought MDF. When I thought of the hassle of gluing up the Hickory I went with MDF. I have a few hundred board feet of hickory, but even the pieces I jointed and planed had a lot of bark mixed in, not to mention the various other problems like cracks and splits on the ends. I should have coated the ends when I had the sawyer first saw them.

[Bob Feeser]

You should be fine. I wouldn't bother with dowels or pocket holes. Gluing the stiles to the rails should be sufficient.

C

Thanks Clint. I was on my way down to the shop and thought why don't I stop into SMC and see what others thought.
I have those 2 sample pieces that are glued and have been cooking for 24 hours, so hopefully they will withstand my strong pulling to pull them apart. I'll let you know how they did. Thanks again.

[Bob Feeser]

Well that settles that one. I went down into the shop and both seams the single and double coated stile and rail panels, edge glued together held so well I doubt I could very easily get them apart with a big hammer. I bent the one piece over the edge of a workbench right up to the seam, and pressed down on it hard. It didn't budge.
So all of the discussion that is going on over the web about the difficulties of gluing up MDF forget about it. Make tight joinery and use TiteBond III, gently clamp it, let it sit for 24 hours and your all set to go. ;)

[Peter Quinn]

No problems with MDF glue ups here Bob. Use enough glue and move quickly. If the set up is too quick you can bump a little water into the titebond III, up to maybe 10%, to retard it a bit. On a long complicated assembly it can help to have extra time. And keeping the glue "cool", like 60 degrees, slows it down.

For wainscot in MDF cope and stick should be fine, I don't usually use dowels. If using dowels sand them down a bit so the fit is looser. You can chuck them in a drill press to act as a mini lathe and hit them with some 80 grit! No more splitting. I like MD lite like "Truppan Ultralite MDF" for making raised panels, it mills better and doesn't weight nearly as much, so look out for that too. Has a better milled surface texture too. Good luck with your project.