Monday 21 April 2014

The pros and cons of my blasting rig

After a lot of research I decided to go for Aluminium Oxide (60 – 80 grit) as my blasting media. I was able to pick up a 20kg tub locally and added the whole lot to the hopper. I blasted these small inspection hatch pieces to get a feel for it:

I was delighted with the results as the surfaces are amazingly clean and it seems to be gentle to the healthy metal under the rust. Plus, the embossed factory numbers are preserved in amazing condition, something that a wire wheel would have no doubt damaged or partially erased. For a before/after comparison, here is a vent cover from one the heater channels with a thick layer of paint and crud all over it:

After a quick sandblast:

And finally everything gets the usual lick of primer:

However, not all is as good as it seems. There are a couple of annoying problems with my current set-up. Firstly, my little 2.5Hp compressor cannot keep up with the air demands of shot blasting. It has a tiny 24L tank and it is just not enough to hold a sufficient volume of air. In fact, I can only blast for about 8 seconds then I have to wait for it to re-pressurise and this recovery time gets frustrating after a while. Having looked into my options I have identified 3 possible solutions:

1. A more powerful compressor – this would be ideal however for a hobbyist like me this does not make good economic sense because a big compressor that has the spec required is a LOT of cash!

2. Add an expansion tank – I could link a receiver tank to the compressor to increase the overall volume of compressed air at my disposal. This would allow me to a much longer blasting time, but on the flipside the recovery time would be equally longer.

3. Link two compressors in together in tandem – this I feel is the ideal solution. Basically I need to get another little cheap compressor and join it together with my current one with a ‘y’ connector. This would increase the overall tank size and recovery time. Best of all I could set the compressors to kick in at slightly different times (e.g: one starts when the pressure hits 90psi and the other when the pressure dips to 80psi).  

The second issue that I was encountering was the amount of dust being generated which obscured vision a lot quicker than I had anticipated. I think I will rig up a vacuum extraction system at the time I add a 2nd compressor. In fact, I have an old vacuum cleaner that would be ideal for the task! Stayed tuned...

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