I was asked by a fellow Lumberjocker to further detail the process of bent lamination. I am sure that there are many of you FAR more qualified to document this then I but in the spirit of sharing knowledge and to honor a request I have blogged this process in a more indepth manor. Please note that I have included pictures from two separate projects.
I start by building forms from MDF. I prefer to use light weight MDF if you can find it but the standard stuff works well too albeit alot heavier. Since I will be laminating stock that is 1-1/2” thick I will need to build my forms out of two layers of 3/4” MDF. I like to work directly off my CAD drawings using them as a template. I print the CAD drawing on letter size paper at full scale. This take several pieces of paper so I create a 6”x6” grid so that I can easily tape the pieces togetherr to get a complete template.
Once I have the template together I then just spray mount the paper template directly onto the mdf. At this point I screw my MDF layers together making sure not to drive any screws near the lines that I will be cutting out. I cut these templates out on either the band saw or jig saw cutting just shy of the lines. Keep in mind that you will be making two cuts to account for the thickness of the lamination. I smooth the lines using an oscilating sander. To finish off the forms I use clear packing tape along the edges to seal the mdf. This will prevent the glue up from sticking to the form.
The finished form looks something like this. You will want to mark a center line on the two forms so that you can align your forms during glue up.
I then set up to cut my own veneer on my bandsaw. I set up to resaw anywhere between 3/32” – 1/8” thick veneer. You will want to make sure that you have your BS dialed in for this. I cut a test piece and place it in my form to make sure that the piece can be bent at the desired radius without splitting or cracking. Satisfied with the thickness. I joint the edge of the first piece as this will be the show face. Using a piece of chalk I mark a triangle on my stock so that I can keep it in order as I resaw. I then proceed to resaw the stock until I have enough veneer cut. Since I am doing a 1-1/2” thick lamination and am resawing to 1/8” I need 12 pieces. For those of you who have a thickness sander you will want to cut your veneer over size and bring to final thickness with the sander. Since I don’t have one yet I skip this step and cut to the 1/8” thickness. Here I have just cut my veneer and have kept it in sequence for the glue up. You will notice that I cut a few more extras just in case. I also make the glue up longer then needed as you will encounter the veneer sliding in the form. You can cut the lamination to final length when you take it out of the form.
Now I am ready to start the glue up. Note: If this is your first time laminating or using a new glue I highly recommend doing a test piece. You will save yourself some frustration in the long run. At the vary least do a dry run each time before you mix your glue making sure that everything is ready. I usually will put a long board down over a pair of saw horses and clamp some wax paper to the board since you are about to make a huge mess. You will want to protect your floor as well.
Now my experience is with Better Bond Ultra-CAT veneer glue (available through Veneersupplies.com which I have NO affiliation with) but Unibond 800 also works well from what I have read. Depending on the color of the wood you are bending you will have to add the optional lightening agent. Reading and following the directions I measure out the correct amount of glue (it comes in powder form). I use my wife’s food scale (don’t tell her!). I also measure out the necessary amount of water. I use distilled water but I am sure tap water will work too. I also use a respirator while I am working with the glue in powder form and while I am mixing it. Once it is mixed to proper consistancy I am ready to start glue up. I have found that the easiest, fastest and most efficient way to apply the glue is to use a roller. With your stack of veneer in order I flip the first piece over so that the show side is down and I roll the glue on making sure that I apply an even coat. I take the second piece of veneer and turn that over stacking it onto the piece I just glued and repeat the process. I do this for all the pieces that will make up the lamination being carefull not to put any glue on the show side of the last piece. Carefully move your glue and veneer “sandwich” to where you have your form and clamps set and ready to go and place the lamination into the forms. Starting at the middle slowly tighten the first clamp making sure your center line marks that you drew on your forms align. working your way from center out continue to clamp and tighten. You may have to go back to the first few clamps and tighten down as you progress outward. It helps if you clamp one of the forms to your table or bench so that it doesn’t move on you. This will also assure that the form is flat on the surface. You will want to also use wax paper below the glue up so that nothing sticks to your surface or bench that you are working on. Once satisfied that the lamination is properly seeded in the form and that you have used your entire collection of clamps you will want to let the lamination cook overnight until the next day.
The next day you can remove the lamination from the form. Be sure to wear gloves as the shards of glue are as sharp as glass and will cut you (I know this from experience). Once out of the form you can clean up one edge with the a belt sander before you joint the edge.
Once one edge is jointed you can then pass the other side through a bench planer. If there are any small voids you can fill them. At this time you will want to cut to final length. Sand, Scrape, and finish as desired.
Here are two examples of finished projects using this technique.
Note: On the tea cart I used commercial veneer that was 1/42” thick due to the complex curve involved.
-- Brian, Folsom, CA http://www.brianfullerdesigns.com