Choice of blasting nozzels, marginal air supply

[ElderWelder]

Hi,

been looking at available nozzels on ebay for first try with large tank 3 HP compressor.


Tungsten carbide 2.5 or 3.5 bore 55 mm long 10 mm dia £20

Silicon carbide 3.4 bore 100 mm long 10mm dia £23
better wearing?
will length reduce power of media ?
cut in half with abrasive wheel and get two nozzels ?


Fixing collar to 10 mm dia to hold in gun, braze or shrink ?
(Gun from 22 mm T fitting)

Worth turning sacrificial tapered funnel entry for nozzel ?, should increase efficience +40%

Any tips appreciated.

 

[rtbcomp]

If you have a 10mm hose just hold the nozzle in place with a Jubilee clip. If the I.D. of the pipe is greater reduce it with a bit of rubber pipe.

The larger the nozzle bore the slower the media speed if the compressor can't keep up. You can compensate for this by using glass grit rather than J-Blast as glass is sharper.

 

[Wendelspanswick]

I have used old spark plugs as nozzles, drill out the centre electrode and machine an adapter to screw in the plug to your handheld gun or clamp threaded portion into hose.

 

[Julian_P]

Hi,

been looking at available nozzels on ebay for first try with large tank 3 HP compressor.


Tungsten carbide 2.5 or 3.5 bore 55 mm long 10 mm dia £20

Silicon carbide 3.4 bore 100 mm long 10mm dia £23
better wearing?
will length reduce power of media ?
cut in half with abrasive wheel and get two nozzels ?


Fixing collar to 10 mm dia to hold in gun, braze or shrink ?
(Gun from 22 mm T fitting)

Worth turning sacrificial tapered funnel entry for nozzel ?, should increase efficience +40%

Any tips appreciated.

2.5 maximum. Piston compressors are hoplessly inefficient, so call yours 9cfm. for 2.5 nozzle you need 13cfm for 100psi. You mustn't let the pressure drop or else you just waste grit like there's no tomorrow so you'll be spending at least 1/2 the time stopped while the compressor catches up with you.

Years ago I used to use three electric compressors with the outputs all commoned up, 3hp, 2 hp & 2.5hp, and still not nearly enough to keep a bigger nozzle working all the time. Now I have a Diesel engined (Atlas Copco) screw compressor and that's just what's needed.

I'd not waste money on a tungsten nozzle until you determine exactly what you need as the ceramics are cheap enough off ebay - just chuck em out when they wear away.

http://www.theblastshop.co.uk/Sandblast/Nozzles.htm

Julian.

 

[rtbcomp]

I blast scooter frames &c and use a 3 and a 2 hp compressor which run a 2.5mm nozzle just fine, although towards the end of the day the air gets a bit hot and the grit stream looses some of its force.

Glass grit will work down to 40 psi, 100 psi is too much when you're holding the workpiece in your hand!

If you're blasting buildings or car bodies then you must have a road compressor and a bigger nozzle or it'll take forever.

I make my own grit and use a 4mm nozzle first, recycle the grit then use a 3mm, recycle again and then use a 2.5mm nozzle until all the media disappears as dust in my extraction filter.

The different sized nozzles all started out as 2.5mm and wore down over time.

 

[ElderWelder]

Choice of nozzels, marginal air

Thanks for the responses,

RTB- Interested in glass grit, how do you crush it to usable size? I have seen the stone crushers on ebay for reducing stone, two ribed plates in V with heavy crank.

Wendel- Yes, must try the spark plugs, down to the garages tomorrow, must have thrown the last lot out ! Looks a good dia for turning to fit the T fitting of the gun. Is it a drill out or twist and punch job to remove centre pin?

Julian- this is a trial before committing to a Compair 6000 package compressor, (three phase) to which I am proposing to fit a petrol (diesel ?) engine. (Due to lack of reasably priced (or any) road compressors locally)
I am hoping the package, rated about 65db will be down to about 55db outside the double brick garage. Would be interested in your first hand practice in operating larger (100cfm +) engine driven screw compressors.

This is for my own metalworking projects in a cabinet about 1.5 meter cube.

 

[rtbcomp]

It's a bit of pain to crush on a small scale, but I smash the bottles in a souped up waste disposal unit, basically a steel bar whizzing round inside a cylinder, then crush it in a mangle on steroids, 2 more cylinders driven via a Belle mixer gearbox. The rollers are the same size as pub gas cylinders

The final process is a sieve, the big bits go through the mangle again and again until they are the right size.

Have you a link to an Ebay stone crusher?

 

[KemppiFrog]

Just getting into blasting, but a while back I adapted a rock crusher to size down pine bark for mulch. The rotor was several discs with hinged hammers around them, that welted the rocks until the gravel sized bits fell through a sieve (row of spring steel bars spaced to grade the gravel. OK, this was seriously big, with a 75HP electric motor, but the principle might come down to bottles?
KF

 

[Julian_P]

Thanks for the responses,

RTB- Interested in glass grit, how do you crush it to usable size? I have seen the stone crushers on ebay for reducing stone, two ribed plates in V with heavy crank.



Julian- this is a trial before committing to a Compair 6000 package compressor, (three phase) to which I am proposing to fit a petrol (diesel ?) engine. (Due to lack of reasably priced (or any) road compressors locally)
I am hoping the package, rated about 65db will be down to about 55db outside the double brick garage. Would be interested in your first hand practice in operating larger (100cfm +) engine driven screw compressors.

This is for my own metalworking projects in a cabinet about 1.5 meter cube.

The answer for crushing glass grit is to get someone else to do it for you! I buy the 25kg bags for £5 either medium or fine (crushed bottles) and have decided that it's simply not worth the hassle of trying to make your own. If you blast at a minimum of 100psi, as I do, the £5 of glass will go further than you would imagine. Try to blast at lower pressures and the efficiency drops off like sheep falling off a cliff!

My compressor is an Atlas Copco road compressor, it's a two tool machine, screw compressor and would be about 75cfm at a guess. It's ample for the small pot type blasters with the ceramic nozzles, but of course the real machines that you would do the side of a house with all need huge six cylinder engines to power up and they are very expensive. Still, the 75cfm compressor is blummin marvellous in comparison to electric jobbies, unless you had some humdinger of a three phase hydrovane or screw machine!

Julian

 

[rtbcomp]

That's a good price, how much do you have to buy at a time? Does that include VAT & Carriage? My local Hodge Clemco doesn't stock it so I have to pay for delivery and haven't got enough room to store a significant amount.

The glass does go a long way, although it breaks up easily it still remains sharp.

Scrounging bottles from neighbours and crushing it myself works fine, just do the crushing during quiet spells (although they don't stay quiet once you start!)

 

[Julian_P]

I have to get it myself and I normally buy about 10 bags or so. Much more than that in one go starts to make my Astra van look a bit low at the back and I always thing that gives PC plod an excuse to pull you over :-(

Julian.

 

[ElderWelder]

Choice of nozzels.

Will have to find a source of media, I like the glass option.

I have attached a cutaway picture of "Mini jaw crusher" Clever bit is the material drops down between the jaws and can only exit when at the bottom when small enough, presumably it is an adjustable gap.

Yes a road compressor would be easy to collect and resell. The engine powering of a package is daunting and possibly overkill but apart from fabrication hours fairly cheap and accoustically clad.

 

[rtbcomp]

That's clever, but a bit too sophisticated for a home build (for me anyway). The biggest drawback my mangle is that you have to keep circulating the grit via a sieve until it's all crushed.

 

[Julian_P]

That's how they've been building rock crushers for decades. Go to a vintage show and you'll maybe find one belted up to a stationary engine, steamer or tractor crushing limestone for a road making demo!

Julian

 

[Ja99a]

Blaster nozzle

Hi, for what it's worth, I am using the 2.5mm nozzle from ACE on the bay and its fine with a clarke compressor / motor retro fitted to an old receiver setup.

Just can't run at 10 bar needs to be less otherwise the compressor is running all the time and working the pressure down.

I used a large bolt bored it out to take the nozzle and run a 3/8 bsp thread on one end to mount it in a gas tap (this is on off and not used for metering).

Seems great so far, here are some pictures of my pot and nozzle.
I was hoping to use the gauges so I could see the pressures so that they were easy to dial in, these are not needed as the pot can be set by feel save yourself £30...

http://www.fr10ker.co.uk/FR10KER/Si...-PressurePot/Gallery - PressurePot/index.html

http://www.fr10ker.co.uk/FR10KER/Si...ot/Gallery - PressurePot/images/IMAG0457.html

 

[Mode1]

The answer for crushing glass grit is to get someone else to do it for you! I buy the 25kg bags for £5 either medium or fine (crushed bottles) and have decided that it's simply not worth the hassle of trying to make your own. If you blast at a minimum of 100psi, as I do, the £5 of glass will go further than you would imagine. Try to blast at lower

Julian

Where are you getting glass at £5 /25kg?Im paying £200 a pallet.My blast pot has a 3/4" hose and 8mm nozzel,so I can use half a pallet in a days blasting..expensive.

 

[captain-destructo]

Where are you getting glass at £5 /25kg?Im paying £200 a pallet.My blast pot has a 3/4" hose and 8mm nozzel,so I can use half a pallet in a days blasting..expensive.

erm how many kg on the pallet tho?

 

[rtbcomp]

40 bags = 1 Tonne usually

 

[captain-destructo]

If one tonne on the pallet thats 1000 kg 40 bags @ £5 each £200
so you are getting the same deal

 

[rtbcomp]

That's what I paid for J-Blast Supafine (copper slag), crushed glass was more expensive.