Sand blasting

Ive just been using the DIY sand blaster cabinet that Len from this forum kindly passed on to me a while back.

Its done a good job of cleaning up the gearbox crossmember for my MGB project car.  This metalwork had been doing its thing since 1979 so you can imagine the levels of dirt and surface rust that needed shifting. 

This was my first time with any sort of sand blasting so today was more about learning than efficiency.   I used the sand that was still in it and sieved each time I collected and refilled the hopper. 

Is there a limit on how many times the sand can be reused before it has to be discarded ?

As there isnt a large quantity of sand with it Im thinking of buying some more or some other media.  A lot of people seem to be using glass beads, is that good for general purpose use ?

 Crushed glass is a first class media for “sand” blasting. I bought a tonne of superfine glass media and apart from the whole of the GT rod friends used it to clean up a 30 foot fibreglass hull prior to some repairs and repainting and about half of the topside of a classic Mini. If I was doing it again I would use either fine or medium grade. I am sure that the sand is like the glass in that it does break down to finer and finer particles. I probably recycle about four times, using the last usage for less demanding areas. The upside of crushed glass is that there is zero risk of silicosis. The photo shows the GT on the rotisserie after being blasted. 

 

Thanks Philip, 25kgs of medium glass now on order.

What size compressor are you guys using?
Having the ability to do sandblasting would make some of the jobs much easier for me, just small stuff like calipers and hubs. 
 

The ruling parameter is air supply in CFM, cubic feet per minute. Too little & you’ll be forever waiting for the compressor to get its breath back. Although a compressor should be able to run constantly, I fear many of the (many) Chinese offerings are simply not man enough. A drier is an imperative with blast media, especially if you use walnut shells, any dampness will cause clogging.
M

Im using a 2.5hp DIY type air compressor with a tank. Its strong enough for paint spraying , running an air DA sander, pumping up tyres and now some small bits of sand blasting but id probably need something bigger if i was using it with an air wrench regularly or doing larger areas of sandblasting. .

My understanding is a minimum of around 15 CFM to run a sandblaster, my compressor is only 7.5.

Here is what I use:

  Chicago Air HUSH150 Silenced 150L Air CompressorFeatures:

• OFD3 technology: Faster pumping, High Durablity, Oiless operation
• Air receiver tank compliant with Australian Standards, Workplace Health and Safety Regulations
• Dual Handled 150 litre tank design
• At 105kg dry weight comes with with solid wheels it is easy to transport on the job. Critical for a unit of this size
• High Durability Steel Tank
• Minimum footprint wheeled design eliminates rust marks on driveways and other surfaces
• Fully automatic on-off motor control and built-in overload protection
• 4 durable 1.1 running HP motors produces maximum air flow without cutout. Perfect to run any pneumatic application you can throw at it
• 8 Direct Drive pistons for continuous operation for any use
• Easy-to-read Tank & Compressor twin gauges
• Fitted with quality brass male coupler and water filter regulator
• Rubber Dampeners
• Oil-free pump delivers long lasting, maintenance-free reliability - Look after your tools for longer

Suitable for:

• Spray painting
• All air brushing
• Multiple framing and fixing applications
• Most pneumatic tools which require higher air flow
• All sanders and pneumatic tools

Specifications:

• Power: 0.78kW*4
• Motor Speed: 1440RPM 
• Voltage: 220~240V/50Hz
• Current: 13.56A 
• Working Pressure: 8bar
• Tank: 150L
• Intake Volume: 548L/min
• CFM: 14.02
• FAD: 397L/min
• Hazard Level: C
• Noise: 71dB
• Dimensions (L x W x H): 1310mm x 480mm x 820mm
• Weight: 119kg

I've yet to find it out of breath!
You can switch off the individual motors and pairs of cylinders when the airflow demand is light.
It is wonderfully quiet.
It is however not cheap!
 

Do remember to fit a good quality filter/regulator near the point of application, particularly when working in a cool area.
The air leaving the compressor is warm and holding moisture, as it cools it will drop water in the air line, an air drier helps but the simple water spinner in a filter or filter regulator will take out any further droplets as the air cools downstream.
You don't need to be too fine with the filtration, 25 micron will do and the word spinner is a misnomer, the black plastic disc in the filter does not spin, it is static and spins the air in a vortex and its serrated edges pull out the water droplets, forcing them to the side of the bowl and down to the automatic drain, which is preferable over a manual drain.
Size it correctly, if the airline is 1/2" bore, fit a 1/2" bsp filter reg.
Otherwise a pressure drop occurs, creating a restriction equalling friction losses and loss of pressure/power, meaning the compressor is beating its heart out for nothing.

Hi what litre capacity is the tank? Thanks. G.

D4KGP wrote:

Hi what litre capacity is the tank? Thanks. G.
 

What mine? 150 litre

All this compressor talk has got me wondering where my big unit has gone.
How can you loose a great big bloody compressor? My Thorite unit in the garage is fine for everything except sandblasting & my little one in the workshop blows no harder than a maiden farting, I must retrieve the big bugger.
M