In this post I wrote about my gap filling tests. I decided to go with the resin/mortar combination. I ordered some resin from Screw-fix because it is relatively cheap and because I had spoken with a structural engineer last summer and he had recommended it. The problem is, it comes in a proprietary tube that doesn't fit in a regular caulking gun. I had already decided that I would make a custom tool to help me apply it to the bricks, but I never imagined the tool would require so much effort to make.
Here's what I've come up with. It is based on the same principle as the clay extruder I made last fall.
The first problem was the extreme amount of pressure that is applied to the pieces. Initially, the notches on the vertical post were pieces that I attached with screws, but the force of the bar was ripping them out. So instead, I notched out the post itself. As well, the plate where the tube rests had to be re-anchored with extra support.
The second problem was the shape of the resin tube.
It has a stem in the middle that doesn't slide. So I needed an extruding stick that was tube-shaped. Luckily, the workshop has a bunch of random bits and pieces, so I found a PVC pipe. I thought I had this working well, but then I noticed that the resin wasn't mixing properly. Normally, there is a white resin and a black hardener and they mix in the nozzle to produce a grey substance. I wasn't getting any of the hardener. I puzzled over this for a while until I realized that there is another sliding part inside the stem. My extruding stick needed to have two parts- a tube-shaped part for the outside, and a rod for the inside.
The workshop pulled through again. I found a smaller PVC pipe and a cable tightener that I could jam in the end. Above is the assembly: the small tube goes inside the big tube and all the parts are threaded onto the bolt.
It still takes a lot of strength to pull down on the bar. I have to keep reminding myself to hold it closer to the end because I can really feel the mechanical advantage with a longer lever arm. My hand just keeps sliding down because I want to see how the resin is coming out onto the brick.
The Screw-fix resin is relatively cheap, but their proprietary gun costs £30 (when a normal caulking gun is under £5). They know that anyone who buys their products will also have to buy their tools. I think I've managed to thwart their plans...for now.
The first problem was the extreme amount of pressure that is applied to the pieces. Initially, the notches on the vertical post were pieces that I attached with screws, but the force of the bar was ripping them out. So instead, I notched out the post itself. As well, the plate where the tube rests had to be re-anchored with extra support.
The second problem was the shape of the resin tube.
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