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  1. #71
    Thanks Clive, I'll take a look at that one.

  2. #72
    Coming along nicely John. I really looking forward to seeing her up and running. :)

  3. #73
    .
    Last edited by Doddy; 05-07-2020 at 10:50 AM.

  4. #74
    Me too! It's been a long time but we'll get there. I'm actually pretty glad I did the wiring aspect earlier, I think that the thought of tackling that again right now would be overbearing.

    The top is drying well but not as flat as I would have liked, there is an area in the centre where the concrete is 5mm or so lower than the rest, I'm not entirely sure if it was bowing under the weight or just due to some factor related to drying but it's not the end of the world.

    I have sourced the resin, it's here with me, I ended up going to a crowd in Northern Ireland but I'll fill in details later around that.

    Prior to pouring the top I intend to flatten it as much as possible, reason being the resin isn't cheap and I want to have a nice even layer across the surface. To that end I have ordered a Diamond Cup for grinding/polishing concrete that will fit to my 4" grinder. It's on the way so should be here soon. It shouldn't take too much effort to knock down the high spots of the top with this tool to prepare it for the epoxy layer. I might combine the grinding with some filling of the very low area with epoxy/granite to minimise grinding but we'll see how we go.

    I have a good respirator and will likely try to work wet with the grinding if possible, I know silicosis from breathing concrete dust is nothing to toy with. I really would have liked to have avoided grinding the top but those are the breaks, it will all work out I'm sure. As soon as the grinding disk arrives I'll be getting started.

    One thing I'm a little concerned with in relation to the epoxy pour is the temperature in the workshop, looking at the resin data sheet we need to stay above 15 deg. C to avoid issues. I'll have to plan ahead with weather and some external heating source (heat lamp maybe) but I'll have a think, I'm sure we can come up with something.

  5. #75
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 13 Hours Ago Has been a member for 9-10 years. Has a total post count of 786. Received thanks 96 times, giving thanks to others 176 times.
    You might be better off trying self leveling floor compound, it runs like water.
    Regards
    Mike

  6. #76
    Quote Originally Posted by mekanik View Post
    You might be better off trying self leveling floor compound, it runs like water.
    Regards
    Mike
    Thanks Mike, I'm kind of committed to this way of approaching it now as I have all the bits and bobs ordered. The resin I have is really low viscosity so it's really just a case of roughly evening the concrete surface before hand, shouldn't be a massive chore but without doing so the majority of the resin would sit in the centre leaving an overly thin layer at the sides where the rails will sit. It's not far off as it is though, about 5mm in the worst spots so it'll be fine with some gentle massaging. Appreciate the point though, I might source some of that to level any low spots on the floor of the space itself before painting it.

  7. #77
    Are you comfortable that the concrete will have cured sufficiently, and is not gassing, prior to pouring the epoxy? I'm not going off anything other than tales that concrete takes a lot longer than some might expect.

  8. #78
    Hey. I'm not 100% on the curing time but really just playing that by ear at the moment. The grinding process on the top is complete now and that proxess was useful in order to gauge the state of curing. Really messy job but was able to get it within a few mm across the surface. I plan to pour it toward this weekend which should be over three weeks since it was poured for it to cure so my hope is that will be sufficient. Once the epoxy is on top my hope is that any remaining drying will be allowed for by the sides and underneath that will still be open to the air. I'm aware I'm experimenting here though, so it could prove to be an issue, but ill give it a bash to see how it goes. One thing I'm certain of at this point is the strength is there, even with a diamond cup on the grinder I was barely able to grind away the top, slow going. Whether that means a lot in relation to off gasing is beyond my knowledge to be honest

  9. #79
    Today is epoxy pour day (number one)

    I decided to pour the top in two stages. Reason being I wanted to ensure the first layer goes on without a hitch and apparently it's good practice to do it this way.

    Step one: I went through the form and sealed all the edges with a small amount of epoxy, allowing it to fully cure before keying it in with some sandpaper. Reasoning here was to be 100% sure that my expensive resin wasn't going to leak down the side of the form. I'm glad I did this first as I was able to spot a few problem areas that needed a couple of coats to seal.

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    Step two: I was really concerned about the temperature inhibiting curing. The resin I have is documented to work best above 20 degrees C but will cause issues if the temp drops below 15 degrees. Daytime temps at the moment are above 15 so that isn't an issue but nighttime temps are dropping to 11 or so.

    What I ended up doing is buying a garage fan heater and a 13A plug thermostat. By sealing the underneath section of the form with some ply and blowing the hot air in, the idea is to heat the mass of the concrete base and prevent any issues. I'm told the air temperature doesn't matter so much so long as the surface temp is above the threshold. This seemed like the most efficient way of getting the heat where it's needed without breaking the bank on electricity. We'll see if it works.

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    I'm currently in and out of the workshop to pop any troublesome bubbles with a hot air gun, so far so good anyway.

    Best, John

  10. #80
    After 48 hours to cure the first layer of resin is on and cured.

    I'm pretty happy with the result so far. One thing to note is that the concrete, being porous, caused many bubbles during the set up. The resin I have has a very long pot life: >8 hours @ 25C so I was in and out of the workshop every 30 minutes during that period to pop any bubbles as resin sank into the pores. It wasn't much hassle to be honest, the heat gun takes the bubbles out in a flash with a quick pass. Incidentally I should mention I have an adjustable heat gun (designed for reworking PCB's) so that was set to the lowest heat setting in order to avoid overheating the resin.

    After cure I'm quite happy with the results, it's self levelled very well indeed. I have a sensitive Starett No 98 machinists level and it's no more that fractions of a mm off in the worst spots. I'm also glad I chose to do it in two stages, the porous nature of the concrete left some areas with creators as the resin sank into pores during the end of the pot life leaving small craters. At this stage it will be completely watertight so the next layer should even that out nicely.

    I plan to leave it to cure for another day or so as I get on with other things following this I'll key it in lightly with some sandpaper, hoover up the dust and pour the second layer in the same way.

    I've been thinking ahead to mounting the machine and have some materials on order for that which should be here soon.

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