Sandblaster

[Stephen FollowsParticipant @stephenfollows82099]

Does anyone know if I could get away with running a sand blasting cabinet on a 9 cfm 50 litre compressor?

[Stephen FollowsParticipant @stephenfollows82099]

[peak4Participant @peak4]

I have a small bench top blast cabinet with a 3HP 50l 12cfm V twin belt driven compressor.
One of these, and it only just copes.
It runs more or less continuously, and in hot weather the motor overheat trips occasionally, though it is a bit close to a wall.

Bill

Edited By peak4 on 19/05/2022 01:46:15

[Peter KroghParticipant @peterkrogh76576]

Air consumption is dependent on pressure and air passage sizes. 50 years of messing with media blasters has taught me that high pressures and big nozzles aren't at all required for most work. It's surprising how much air and media will go through a 2.5mm hole at 40 psi! My compressor is 2 HP and like 9 cfm @ 100 psi. If I recall correctly.

One just needs to take more time….

Pete

Sorry for the units mess….

[Paul LousickParticipant @paullousick59116]

I have a hand gun type blaster running on an 8cfm compressor and it is very slow and barely scratches the surface on steel.

I have also used a decent blaster, running off a diesel powered compressor (used to run a jack hammer) with lots of volume and higher pressure and it will cut its way thru sheet steel if not careful.

[not done it yetParticipant @notdoneityet]

Firstly the 50 litre spec is just marketing hype, little more.

Next, is this air displacement or free air delivery? I suspect it is the former which may bear little resemblance to the real (true) capacity of the machine.

As an aside, don’t use sand. Use the proper grit abrasives. The fine dust from sand is carcinogenic (it can, at least, cause serious respiratory illness if not cancer).

Of course you can get away with it, but your run time (feeding abrasive) will likely be seriously restricted and/or your compressor motor may exceed its run factor, the pump may well overheat and generally shorten the useful life of the compressor – particularly if the machine is a cheap budget machine.

Depends a lot, too, on the size on the cabinet and hence the nozzle diameter – details of which we are not privy to.

Overall, I think you are simply hoping replies to justify an under-sized machine. That is not coming from me, I’m afraid.

[Ex contributorParticipant @mgnbuk]

I have a small bench top blast cabinet & a 2hp 50 litre compressor. The compressor is not able to operate the blaster continuously – it cannot supply enough air. What I do is let the receiver fill, then use the blaster for about a minute / minute and a half then stop & let the receiver refill. For bigger jobs I have taken the cabinet to work & used the 7.5Kw rotary compressor, which has no problems keeping up with air demand.

Another vote for not using sand if you want a longer life – my grandfather died of silicosis contracted while working in sandstone quarries & I would not like to go that way.

One of the bigger issues I have with my cabinet is the media (glass beads in my case) getting damp, as a standard water trap isn't enough to dry the air. I used a hot air gun blown through the media when it stopped flowing towards the pick-up & through the gun. Dust extraction is also an issue – difficult to do the job when you can't see it ! A small cylinder vac at home isn't really enough, but is better than nothing. Hooking the outlet up to one of the industrial extractors at work is noticably better.

Really depends on what you want to blast. The occasional small bracket / casting isn't too much work & it does a reasonable job. For bigger projects / lots of parts / larger parts I would sub the job out to a professional. I have done an aircooled BMW motorcycle engine cylinders / heads / outer covers in a small cabinet & would not choose to repeat the experience. Likewise did the frame for another bike with "disposable" grit using a dip-tube blast gun outdoors – it did the job, but really not much fun & very messy & the media wasn't cheap. For the next frame I sent it out and had it blasted & powder coated.

Nigel B.

[JasonBModerator @jasonb]

Posted by not done it yet on 19/05/2022 07:06:12:

Firstly the 50 litre spec is just marketing hype, little more.

Next, is this air displacement or free air delivery? I suspect it is the former which may bear little resemblance to the real (true) capacity of the machine.

50lts – That's the tank size

He has said it is 9cfm which is most likely displacement

A lot will depend on what you are blasting, I manage OK on small silver soldered fabrications and the odd bit of bead blasting of small components allowing my 50lts tank to recharge if needed. If it's larger parts that need a lot of rust/paint removed then it may struggle.

[Dave HalfordParticipant @davehalford22513]

Posted by Stephen Follows on 18/05/2022 23:18:35:

Does anyone know if I could get away with running a sand blasting cabinet on a 9 cfm 50 litre compressor?

This is in fact a 5cfm Free Air Delivery (FAD) compressor. The 9cfm is is a calculated figure based on the piston swept volume assuming no losses of any kind.

Peaks cabinet link requires a constant 9cfm as a minimum.

Hand held guns that look a bit like spray guns will work on that size of compressor if the pickup tube is restricted, otherwise they choke up.

The 10 gallon £100 blast pots have improved and will work a lot better on an under size comp. if you buy the smallest 2mm nozzle.

Sand, as in kiln dried block paving sand is useless anyway, being not sharp enough, nor heavy enough to work. It's cheapness does nothing to improve it.

Heavy media like Aluminium Oxide is as said heavy, sharp and breaks down into smaller particles that are still sharp. You get a better effect with used grit as the smaller grit size gets into the little pits that rust makes in steel.

[Stephen FollowsParticipant @stephenfollows82099]

Thank you for the replies. I would like to sandblast, ( maybe I should say grit blast), rust and old paint from small bits and pieces occasionally. I don't want to buy a new compressor, not so much the cost but a lack of space, the present one just squeezes in.

Looks like I'l have to stick to a wire brush!

[Engine Doctor ( Phil )Participant @enginedoctorphil]

Hello Stephen. Another consideration if you have limited space is the cabinet with a vacuum set up or your workshop willend up covered in dust and blast media .

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