Thanks Jason.....
Hope I don't upset anyone, but here's a few replies....
engineer one":5gmg4ung said:
Wonder why he and so many American magazine articles use dado so much on plainboxes?
I think it is because the Americans have been a lot slower on the (manufacturing) uptake of MFC and MDF and still use a lot of plywood. American homes are still predominently timber frame, so their forest products sector is a lot larger than ours in Europe. Things are changing gradually, though. Notice that he (Norm) doesn't dado MDF or MFC very often, if ever - a dado head would probably rip MFC to pieces and chip all the edges, too
engineer one":5gmg4ung said:
I have to say that I think with MFC you need to remove the facing where you are aiming to biscuit otherwise you will get no glue up strength, not sure the facing is strong enough in shear strength to allow for gluing. If you check out all store bought MFC wardrobes and cabinets, they are screwed together, the biscuits or other fixings only locate. So maybe that is the idea biscuit and then screw.
Shop-bought furniture is either flat pack (mainly cam and dowel) or dowelled and glued construction because of the production equipment used to manufacture it. Line borers came in in the early 1970s to be followed by PTPs (point-to-point borers) then finally a European speciality called the PTP router, a cross between a CNC router and a PTP borer. All this equipment excels in gang boring vertical and horizontal holes on 32mm (or multiples thereof) centres. The resulting components can be put together very quickly and accurately by relatively unskilled staff. Biscuits require a greater skill level to use ad so have been taken up by small shops in the main.
The best quality MFC kitchen carcasses
are actually dowelled and glued, but extra strength and rigidity can be achieved by inserting a tight-fitting back into a groove and adding a few spots of glue and by adding cross braces at the rear of the carcass top, bottom and if necessary in the middle. The glue should be a good quality D3 (exterior grade) PVA (as noted by Jason). I buy mine from a company called
Strongbond in Bury, but they only really do trade quantities I'm afraid. I've had success in the past with EvoStick blue (exterior grade, D3)
One thing you sometimes have to watch with biscuits is that they are a good fit in the slot. Oversize slots or undersize biscuits can seriously weaken the carcass.
johnjin":5gmg4ung said:
As far as I am concerned I use Evo-Stik on melamine and it seems to do a pretty good job. It also sticks pretty good to the chipboard. I believe that that is what the melamine is stuck on with in the first place.
Actually the melamine facing is generally bonded onto the core with something like a melamine or phenol resin, not a contact adhesive. I'd avoid contact adhesives like the plague for construction joints - the glue joints always creep and have little strength. They work well for laminating Formica onto chipboard in situations where the surface will be subjected to no shear forces (e.g. horizontal work surfaces), but I cannot think of many other areas where they do work.
As George says carcass screws work pretty well, although personally I'd add a bead of PU glue to the joint, the type sold in 300ml tubes and dispensed using a mastic or "skeleton" gun, to beef up the joint. Makes it more waterproof, too, which for a kitchen or bathroom is a must.
Scrit
