advice on sandblasting equipment

[michaelp94]

hey everyone, i'm looking to sandblast the engine bay and floor pan/interior of an old mercedes i'm working on to have a better idea of the extent of rust i'm dealing with. I've removed all the sound deadener on any metal i plan to work on and am at the stage of buying the equipment.

I have a 300Litre/Minute (roughly 10.6 cfm ) air compressor ( http://www.tradetools.com.au/products/HD300) and was wondering how effective it would be using an ebay unit such as this http://www.ebay.com.au/itm/281070939544?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

I'm not too worried about if the air compressor needs a break every 3 or so minutes, but if if doesn't have enough pressure to clean the material then there's obviously a problem.

also would it be safe to use a respirator such as this http://www.ebay.com.au/itm/Anti-Dus...894?pt=AU_Protective_Gear&hash=item460ecf626e cheap one from ebay along with the mask supplied by the sand blaster?

any tips for someone attempting their first go at sandblasting are also welcome

thanks,
michael.

 

[Julian_P]

That's the pot blaster I have. It's works OK, but you'll find that the little 3hp compressor will struggle to keep up on all but the smallest of nozzles if you want to blast at a good pressure of 90psi. So you'll need to take breaks while the comp catches up.

The face mask will last 5 minutes before the visor starts to get eaten by the sand. So I use a 3M 'bug' style repirator, and some goggles + ear defenders + wolly hat + welding gautlets.

The 1/4 turn ball valve by the nozzle doesn't last long (gets eaten alive from sand) and the ceramic nozzles don't last long (tunsten carbide ones available off ebay)

For semi-serious DIY it's good value and works fine - but if you could find another compressor to run in tandem you'd do better.

Julian.

 

[rtbcomp]

The hood supplied with the pot is pretty useless. If you use goggles or similar protect the clear plastic with clear film or a cut-down drinks bottle taped in place.

Bear in mind your eyes need protecting against items that may fly out of the muck you're blasting away.

 

[500e]

http://www.mig-welding.co.uk/forum/forumdisplay.php?f=40
Huge amount of info

 

[michaelp94]

thanks for the help Julian and rtbcomp, i had a look at tungsten carbide tips on ebay and found one with a tip of 2.5mm which appears to be the smallest you can buy, but that claims to only do 70psi with a 300L/min compressor? I'm new to all this but does that mean it just flat out won't do the requried 90 psi i need to blast metal or it won't be able to continuously supply 90psi and i will need to let the compressor catch up?

I can't seem to find replacement turn ball valves on ebay. I'll have to have a look at a local tools shop.

Are you saying the sandblasting helmets in general are pretty useless? There wouldnt be much of an upgrade in a cheap $20 one off ebay? (http://www.ebay.com.au/itm/360598970029)

 

[rtbcomp]

but that claims to only do 70psi They're saying it works well at 70psi, there's nothing to stop you giving it more.

If I were you I'd get the pot and hitch it up to the compressor you've already got and see how it goes before spending any more money. How well it works also depends of the type of paint you're trying to shift.

The best helmets are the air fed ones like the Scorpion and the Apollo, but they cost £200-£300 and need their own air supply.

The fabric ones vary enormously, get the heaviest one!

 

[Julian_P]

thanks for the help Julian and rtbcomp, i had a look at tungsten carbide tips on ebay and found one with a tip of 2.5mm which appears to be the smallest you can buy, but that claims to only do 70psi with a 300L/min compressor? I'm new to all this but does that mean it just flat out won't do the requried 90 psi i need to blast metal or it won't be able to continuously supply 90psi and i will need to let the compressor catch up?

I can't seem to find replacement turn ball valves on ebay. I'll have to have a look at a local tools shop.

Are you saying the sandblasting helmets in general are pretty useless? There wouldnt be much of an upgrade in a cheap $20 one off ebay? (http://www.ebay.com.au/itm/360598970029)

Yes, in effect you just utilise the storage capacity of your compressor's tank. When the pressure has dropped, then you just have to stop and wait (a cup of tea is handy!) the ebay is awash with 1/4 turn ball valves - 3/8th BSP.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=171036201167

I'd just stick to ceramic nozzles maybe for now - I got spares from ebay. The blasting hose will eventually wear through and so will the hose nipple and 3/8-3/8 BSP male adaptor - but they're all cheap to buy, so don't worry.

 

[merckx]

I would disagree with Julian and recommend buying a 2.5mm tip to use with the pressure pot like you have already mentioned.

You don't have that much air with a 3hp compressor and you'll need to supply a lot more even if a ceramic tip was to wear to just 4mm which doesn't take long at all.

 

[Julian_P]

I would disagree with Julian and recommend buying a 2.5mm tip to use with the pressure pot like you have already mentioned.
.

Well I'm not sure what you're actually disagreeing with. But anyway, I wonder if you could take a length of bolt shank (say metric grade 8.8) and drill a 2.5mm hole in it. I wonder what sort of life you could expect?

Julian.

 

[rtbcomp]

^^
I'm sure I tried that, I've certainly tired thick walled tube and it didn't last for any useful length of time.

Same with the ceramic nozzles supplied with the pot. They're OK for bead blasting with though.

 

[brightspark]

even a hardened carbon steel nozzle only lasts a while and when it wears it uses more air .just shell out and buy a carbide nozzle

 

[merckx]

Well I'm not sure what you're actually disagreeing with.

Julian.

You said "I'd just stick to ceramic nozzles maybe for now".

I'm saying buy a tungsten carbide nozzle straight away, they're well worth it.

 

[Julian_P]

You said "I'd just stick to ceramic nozzles maybe for now".

I'm saying buy a tungsten carbide nozzle straight away, they're well worth it.

I think you're right. I've just been using a 3.5mm TC nozzle and it is good. Somehow it seems more effective and I'm not sure why. Maybe the fact that it's about twice as long as the ceramic nozzle gives the sand more time to better accelerate up to the speed of the air?

Julian.

 

[Shox Dr]

Male PCL fittings work a treat, and if you are on the ball: swop them out before they have worn too much to use as an air fitting. I have now gone through all mine so I might look at a Carbide end, but at less than a £1 a time for a PCL I'll be in no hurry

 

[rtbcomp]

Male PCL fittings work a treat, .....

Yes they do, but only for bigger jobs as they need a lot of air.

 

[Julian_P]

Male PCL fittings work a treat,

Perfect! I shall be trying that one day.

Julian.

 

[merckx]

I think you're right. I've just been using a 3.5mm TC nozzle and it is good. Somehow it seems more effective and I'm not sure why. Maybe the fact that it's about twice as long as the ceramic nozzle gives the sand more time to better accelerate up to the speed of the air?
.

I think it's only when you actually switch to the tungsten carbide nozzles yourself that you actually appreciate how much better they are in being able to have a nozzle which maintains its size for much longer which is so very important when you haven't got a massive amount of air to use them with. I had persisted with the ceramic nozzles and making my own from steel bar for some time before I thought I would try a tungsten carbide nozzle and I cannot recommend them enough now I've used one.

I have now two 14cfm, 3hp compressors and with a 2.5mm nozzle, they do run continuously but the pressure remains more or less constant and I don't have to pause at all and wait for them to catch up which is great.

 

[Julian_P]

I think it's only when you actually switch to the tungsten carbide nozzles yourself that you actually appreciate how much better they are in being able to have a nozzle which maintains its size for much longer which is so very important when you haven't got a massive amount of air to use them with. I had persisted with the ceramic nozzles and making my own from steel bar for some time before I thought I would try a tungsten carbide nozzle and I cannot recommend them enough now I've used one.

I have now two 14cfm, 3hp compressors and with a 2.5mm nozzle, they do run continuously but the pressure remains more or less constant and I don't have to pause at all and wait for them to catch up which is great.

Well I'm a bit spoiled as I treated myself to a 2 tool diesel road compressor a few years ago. With the 3.5mm nozzle it maintains 110psi just on tickover with the unloading valve merely cycling

One thing that I did discover with these cheap pot blasters is that if you use a really big nozzle (ie a knackered ceramic one) the airflow through the 1/2 inch blast hose picks up to the extent that the sand wears through it too and you end up with that bursting a fair bit. And the work rate doesn't increase much.

I gave up using proper 1/2 inch blasting hose and now just use cheap 1/2'' rubber (heater) hose as it's so cheap and still lasts a fair while.....

Julian.

 

[brightspark]

Well I'm a bit spoiled as I treated myself to a 2 tool diesel road compressor a few years ago. With the 3.5mm nozzle it maintains 110psi just on tickover with the unloading valve merely cycling

One thing that I did discover with these cheap pot blasters is that if you use a really big nozzle (ie a knackered ceramic one) the airflow through the 1/2 inch blast hose picks up to the extent that the sand wears through it too and you end up with that bursting a fair bit. And the work rate doesn't increase much.

I gave up using proper 1/2 inch blasting hose and now just use cheap 1/2'' rubber (heater) hose as it's so cheap and still lasts a fair while.....

Julian.

if u wore out a proper half inch blast hose u must have been doin a hell of a lot of shotblasting. mine lasted a few years and i was doin car wheels and motorbike frames every week and sandblasted a few houses before it wore out . either it wast the proper stuff or it was cheap rubbish

 

[Shox Dr]

I use aircon tube, it has a plastic liner, it has only worn out where is constantly bent