Friday, November 18, 2011

Rocker table upgrade

First things first, I had to get my rocker table sorted because parts of the last one I used were cut up in the course of the camper van fit out I was working. So this was a good chance to customise the table a bit to make it easier to use and stronger.

I stuck with the original Brokite style design because it just has so many benefits and that the setup that BoardOff's jigs are designed around.

The setup is two matching steel frames one each for the top and the bottom and made out of 40x40x3 mm angle iron. Then use middle and out rocker / concave jigs straight out of BoardOff and clamp easily to the angle iron frames. The top and bottom jigs then come together to bend the rocker table surface over the center jig to get the right compound curves into the table surface (which going to be the same 4mm ply and 4mm acrylic as I used previously. I checked with the plastic supplier I bought it from and they said that the plastic won't deform until it reaches 100 degrees so 50 degrees is no problem. Even if it was a problem, the plastic is supported on the 4mm ply.

Although the table's not tweakable like tables with individual slats that adjust, changing the set up is just a mater of cutting out the new jigs from scrap wood (MDF) and it seems there are no shortage of old cupboard doors thrown out on the pavement that suit the purpose nicely.

So here's the revised table with all the jigs clamped in place with a single G-clamp for each.

I was lucky enough to find a single bed frame at our local St. Vincent de Paul op shop. It has casters and the fold out legs you can see on the bottom section. Its handy for a number of reasons including being at a better working height and will make it easy to place heat lamps close to the work so that I can post cure it at 50 degrees.

The bed slats are pretty solid and I think that they should solid enough to support the load of the center jig without bending.

For the top frame I bought 40x40x3 mm angle iron from Edcon steel which cost about $17 for all c. 6 m of it (compared to $25 for 2m from bunnings). I welded it together and also welded some long bolts in each corner top and bottom to be used to pull the frames together.

My idea is to use ratchet straps around the bolts to clamp it together. The ratchets for both sides can be done simultaneously to help make the clamping action uniform so that it doesn't spill the rocker table surface out one side like it did last time.

The snap below shows the center jig. You can see it in the shadow but the center jig is clamped to a piece of angle iron. This will help keep it straight when its loaded up and also distributes the load across all the bed base slats which should limit bending further.

Next step is to work out how to turn it into an oven. Dean in WA cure his board using standard 100W bulbs. He said that its important to have a fan circulating the hot air and also to make sure you're measuring the temperature at the board surface and not in the top of the oven where the hot air will collect. I also spoke to Dave who runs the engineering show at maxi yacht building facility and he said they put temperature sensors right inside the work so they get exact temp measurements. I'm still working through some ideas for this one.

After that its on to doing the actual board!! Yeah fucking ha!!!

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