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When assembling very large frames, a few other considerations come to mind. One is the pressure plate of the Underpinner is not going to work as effectively because of the depth of the molding. You can see the large gap I have here as compared to what I have when I pull the frame into this position. There is what I consider a proper gap. So we need to use something to fill in that space. I have already pinned together the two L sections as you saw on the previous movie, and what we're going to do now is just assemble the final two corners.
So to protect the frame, I'm going to slide this piece of cloth in, and then I have just got this plywood corner that I'm going to use as a spacer, and I'll slide that in. The other thing you may notice is I have got this table that the molding is resting on. In the smaller frame that we put together earlier I was able to stand back and keep it directly in front of me. It was very easy to manage. What happens when you get to these larger frames is the weight of the legs is fighting to pull apart the joint, and so you really need to support it as you go from assembling the two L-shape sections to the final assembly of the frame.
So I made this table to exactly match the height of my Underpinner, made a little cut out, so there is room for me to stand in the middle, and now I have already applied the glue here, I'm going to carefully line up these two corners, hold it tight and press down, and you see how the pressure plate hits the plywood quickly, and then I'm just going to go through as I did before and put in a series of V-nails wrapping up with direct contact to the outer edge of the frame, and you see we have got a nice clean joint there.
And then I'm going to carefully rotate the frame to the opposite corner. Once again, I have already applied my glue there. But you notice how I kept the frame flat on the table surface? That was in order to place as little strain as possible on the joints that already glued. Then we'll just repeat what we just did, we'll put in the fabric to protect it, put in a little plywood spacer. You can see here, too, I have got a little overspill with the glue. I'll clean that up in just a little bit with a damp paper towel.
Once again, apply pressure for that first nail and then slide your guide back, and I have several of these spacers that I use with different depths of frames that I just keep where my underpinner is in the shop. Okay, so now we have completed our joint there, I'm going to get that glue cleaned up in just a second, and then to get out of here I just lift the frame and then the table is on wheels, so I can step back, then I'm going to set the frame down. We're down with the Underpinner for now, so I'm going to set it out of the way.
I want to show you one more tool, it's really handy on a large frame like this, it's called a Band Clamp, and you can see here is the band. It has four special little braces that go on the corners, and you can see this crank here. This great big spool is always webbed banding, and so what I'm going to do is pull out enough of the band so that it will completely surround the frame, I am going to set kind of the handle unit there, and then I'm going to make sure I have enough slack to go all the way around.
Maybe just a little bit more. And then these four corner pieces, I am going to start just taking this one. They slide, you can also pop them off, they go along, you see you have got these two legs and the band slides into those two legs like that, and you want these two little pressure points to line up the flat sides on the corner.
I have got the second corner, and you want to do this on a table that will support these. Once they are in tension, they'll stay in position, but until you put tension on the Band Clamp, they would just slide off. So once again, I'm going to slide this back a little bit so that, that one is supported, and now I have got all four corners placed, I'm going to use this crank and wind it tight to take up some of the slack and the band, and as it gets a little bit tighter, I'm going to double check that all my corner clamps have that flat side in and stayed in position.
Sometimes they'll shift as you're applying the initial tension of the clamp. So now I have all four corners where they are supposed to be properly aligned, and you can see here I'm already starting to generate some tension in the band, so it's already pretty tight, I have got as much as I can with this crank. Then I shift over to this one, and what this does, if you watch that you can see how that's moving, pulling it tighter and tighter, and you can inspect the corners, and you can see that the little joints have been pulled very tight.
And what I'll do, I'll give this a couple more turns, you can see how much more tension is on that now. You have got to be careful. This tool--you can put on enough pressure to actually dent softwood frames, so you have got a kind of find the fine line, and I usually find it by inspecting the corner to make sure I have got a good seal. And now that the clamp is on here, I'll leave it until the glue is completely set, which usually takes about 2 hours. I suggest the Band Clamp on any molding with this kind of depth. I use them almost always on Shadow Box Moldings.
Sometimes they are handy even on small frames. If you have had a little bit of warpage due to humidity or other things, they can help pull the frame more tightly together. And remember, the glue is as important as the V-nail in providing the strength in the corner joint. On a frame of this scale, the glass starts to get pretty heavy, so you really want to make sure the frame is secure at the corners.
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