Building Logs

First doorways uni roped

Posted by Paul

After a blistering Tuesday, Wednesday and Thursday cooled to winter like conditions again. I thought the opportunity too good to pass up. I have been avoiding doing the uni ropes in the doorways for a couple of reasons. First it looms as a difficult task given that I need to defy gravity to get the ropes up into the de-cored doorway upside down for more than half their way. And given my apprehension I thought the heat was the last thing I needed adding urgency to the mix. As has always been the case with the build, the jobs I feared the most turn out to be the easiest and go off relatively without drama.

I have a method set out for jobs like this. It requires me to transform from my usual take it as it comes laid attitude to one of studied organization. I have to plan the routine, and each step is in order. So with this in mind I started by cutting a piece of plastic strip long enough to wet out the already cut to length and width uni. I did this last week, by taking a small offcut of uni and rolling it up to see how wide the piece needed to be to neatly fill the slot, it turned out that 400mm would be pretty close and given I have 1300mm wide rolls 430 would be just perfect. The length speaks for itself, but having said that I ended up with a rope 10mm too long that needed to be squeezed into the trench to fit, 10mm less would have been ideal but it worked out in the end. Why didn’t I just cut the 10mm off, well I hadn’t done my planning quite well enough and did not have the scissors close at hand at the time! and my hands were full!!

I then screwed 45mm screws through the bulkhead at about 200mm intervals about 100mm from the edge. I had elastic bands at the ready and I had pre ripped 40mm strips of a sheet of 3mm mdf and covered them in clear packing tape (epoxy doesn’t stick to it). I then wet the uni out by pouring epoxy on it and spreading it with a squeegee, by far the best method of wetting out glass in my opinion. It is fast and enables you to squeeze excess resin out as you go. Then once wet, I used the remaining resin in the pot to mix up some coving compound (glue works equally well) and I put it into a plastic zip lock lunch bag, sealed it and cut the corner off to make a piping bag. I ran a thick bead of the mix into the slot. Ideally you ought to brush some epoxy into the balsa edge too but as the balsa is not really what holds the uni in, it is the glass sides that it really adheres to I am not sure this makes all that much difference and I skipped that.

I then went back to the wet out 3.6 meter length of uni and rolled it into a rope. It is a good idea to do this last and not earlier because the tight roll could start going off faster than a laid out sheet of glass. Anyway, the rope was still cold to touch so it was not yet close to going off. I had been working fast and it was only 5 to 10 minutes since I finished wetting it out so I felt confident I had at least another 15 minutes open time. So I rolled the rope up as if it were a length of rope and took it to the doorway.

I already had the start of an mdf strip held against the doorway by an elastic band stretched from one side of the screw around the front edge to the other side. I deliberately started the uni rope down one of the long sides of the doorway about halfway down. 2 reasons for this. First it is just easier to start and finish along a straight section and leave the upside down section to near the end when most of the rope is now in the trench. Second but far more important is that the uni rope is unbroken through the entire radius of both curves. The reason for the rope is to strengthen the doorway and prevent it being a weak point where cracks or tears in a bulkhead can occur, so it stands to reason that these would be more difficult along a straigt section, that is why I chose to put the uni join along a straight.

I pulled the mdf strip away from the door edge and put the start of the uni rope under it and let the elastic bands pull it in tight again to hold it in place and started threading the uni rope into the trough onto the bed of coving already in the slot. The combination of the rope and the coving compound was a bit more than the trough wanted so it fills every cranny and then oozes out the edges. Doing about 500mm at a time I then, using one hand, the other hand holding the uni rope not yet in the trough, lined up the mdf over the edge and started stringing elastic bands over the mdf from one side to the other pulling it all down as I went. This pushed the excess cove and resin (resin oozes out of the wet rope) out of the edges wherever it is just too full to be pulled down by the mdf. A quick scrape to clean remove the glue and I repeated until I had all the rope in the slot and under the mdf. I then had 2 free hands so using a screw I poked any rope bulging out of the sides back under the mdf and then ran extra elastic bands all the way around, this time running them from one screw to the next adding even more tension to the mdf as I went and pulling it all down a little tighter.

Today, I removed the mdf and elastic bands (and the screws) from the first doorway and it came out ok. I have a few kinks in the rope here and there causing holes that will need back filling but other than that it worked really well. You need to avoid kinks in the uni as it also weakens it but the kinks I had were not too bad and I think the strength will be ok.

To finish I will sand some of the low spots to key them then back fill them to flush and while at it I will fill all of the screw holes. A reader suggested I use clamps to push the mdf down but it would be just too difficult to get the clamps on while holding the uni and mdf in place while still holding the rest of the uni in one hand all with just one pair of hands, way too hard. Once the screw holes are back filled and sanded flat we are back to good as new.

Flushed with the success of the first attempt and mindful that I have a little more working time so as to take a little more care rather than rush I set to doing the second doorway. It seemed at lot less rushed but surprisingly, it took much less time to finish the second one than it did to do the first. Yesterday it took me about an hour and a half, today I had the second one done in just over an hour.

That gave me some time rough in the robe cabinet. At this stage it is just sitting in place. I also discovered that my attempt to make the drawer after first making the front, sides and base did not work, the back simply pulled the front out again. I am quite surprised but perhaps the front had not fully set when I pulled the back down. Anyway, the solution is to cut the twisted front off and glue it back on again without the twist gluing it between the sides instead of to the edge of them and ensuring it is square and plumb. Ironically I had misjudged the depth or got my measurements wrong and the draw was too deep for the cabinet meaning I would have to cut the drawer down anyway.

robe cabinet rough inrobe cabinet rough in 1robe cabinet rough in 2draw front twisted

Hopefully I will get a few more cool days (the forecast is for about a week of cooler weather) to finish the uni ropes at the pace I go and unflustered. I want to get them all in because the longer I go without having them dont the more chance of forgetting not to stand on them and damaging them. Once the uni is in the doorways will be as strong as they could ever be.

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