Blasting Pot Mods

[mylesdw]

I'm sure fair few of you have one of these pressure pot blasters. It's the standard Chinese n gallon pot that all the tool marts seem to sell.

It works,but only after a fashion so I have been trying to improve mine and thought that I would post some progress.

So what is wrong with the base unit?

1. It frequently stops flowing sand. You get it all working, get all the gear on, climb under the car and after a few minutes - no sand!! Shake it, adjust the valves, take it apart; you get the picture. Very frustrating.
2. The frame is very weak, especially when the tank is full and the unit very heavy.
3. The wheels are not suitable for anything but a pretty flat surface.
4. The ceramic nozzles last a matter of a minutes.

 

[rtbcomp]

1) Dont' use sand - use the proper stuff, crushed glass would be best for your application. Make sure it's dry. Keep the pot within kicking distance.
2) Not had an issue with the frame on a 10 gall pot, the 20 gall pot tends to strain the short leg.
3) You could fit bigger wheels, but you'd have to extend the leg, putting more strain on it.
4) Switch to tungsten carbide nozzles from ACE engineering, they sell them on Ebay, in the UK at least.

Mods I've found useful:

My 20 gall pot is used in a static position so I've removed the handles and leg and made stronger ones without wheels.
The mixer at the bottom wore out so I replaced it with a malleable iron T-piece.
I've replaced the bottom hose connector with a Hodge Clemco claw connector - this doesn't wear out. You'll need different blast hose though.
I've removed the pressure gauge and replaced it with a ball valve so I can de-pressurise the pot before removing the top.
I've turned the short hose that feeds the mixer the other way round so the swivel connector is at the bottom - this makes it easier to remove the mixer.

I'm proposing to change the fittings to 1/2" BSP because valves are easier to get and cheaper than the 3/8" ones. The Hodge Clemco connectors are 1/2" so I can get rid of the 1/2 - 3/8 adaptors.

 

[SmartWerks]

Couple of useful vids that should help you out

http://m.youtube.com/results?q=pressure pot 101&sm=1

http://m.youtube.com/results?q=pressure pot 101&sm=1

 

[brightspark]

the main let.down on cheap pots are the blast nozzle and they use a ball valve for metering the grit . there tepremental and eratic a decent hodge clemco one is the best if u can aford to get one or make your own like i do

 

[mylesdw]

To improve the frame I cut the old one off completely

and bought one of these, only about $20 from the local motor factors

New brackets welded on

and a trial fit

I extended the base slightly to improve the balance

and added a bracket for the air fittings

Needs plumbing up but much easier to move about now

 

[mylesdw]

1) Dont' use sand - use the proper stuff, crushed glass would be best for your application.

I call it sand but its real name is grade B garnet. I haven't tried glass but I believe it is cheaper so I will give it a go.

 

[Piero]

Bit like triggers (only fools and horses) broom and handle lol

 

[mylesdw]

One obvious problem with the flow of sand is the tiny 3/8" BSP fitting in the bottom of the pot, another is the shape of the pot - it needs to be much more cone/funnel shaped or there will always be some sand left inside. The outlet is so small that even when all the fittings are removed the flow of sand stops several times before the tank is empty.

The tank shape I'm stuck with but the bottom of the pot was cut out and a larger (1 1/4" BSP) fitting welded in.

Being a pressure vessel I didn't trust my amateur efforts and paid a real welder to do the job.

Then I bought one of these abrasive valves -

It's on a camlock quick release coupling so that the valve can be removed easily for blockages and for emptying the pot.

 

[Piero]

I do like the abrasive valve, were did you get it and how much was it if you dont mind me asking

 

[rtbcomp]

This is looking quite serious now!

With the amount of work you're doing it would have been cheaper to start off with a propane gas cylinder.

 

[mylesdw]

I do like the abrasive valve, were did you get it and how much was it if you dont mind me asking

From a local supplier here in NZ, not sure of the make but looks very much the same as this -

http://www.ebay.co.uk/itm/MINOR-VAL...279?pt=LH_DefaultDomain_3&hash=item54151d573f

Although I'm pretty sure I paid nothing like that much!

 

[mylesdw]

This is looking quite serious now!

With the amount of work you're doing it would have been cheaper to start off with a propane gas cylinder.

Yes, you're right but I already had the pot and quite a bit of the work, for example the filler cap, is already done.

 

[Piero]

Thanks

 

[rtbcomp]

You'll be fitting a bigger filler cap when you start using very fine grit - it takes ages to fill through a funnel!

 

[mylesdw]

All plumbed up ready for testing.

 

[captain-destructo]

looking good but now the work begins

 

[Wendelspanswick]

All plumbed up ready for testing.

View attachment 63424 View attachment 63425 View attachment 63426

What kind of valve is your grit valve, is it a ball, butterfly, disc etc?

 

[mylesdw]

It's pretty much like a gate valve. The knob you see moves a piston up and down a bore which is at an angle to the flow of sand. Does that make any sense?

 

[Wendelspanswick]

It's pretty much like a gate valve. The knob you see moves a piston up and down a bore which is at an angle to the flow of sand. Does that make any sense?

That makes sense but I can't see the advantage over a normal gate valve?

 

[mylesdw]

A good question and my best guess is that

1. The piston shape means there is no flat area for the sand to collect on
and
2. The cylinder is not at right angles to the incoming sand flow; again no flat 'shelf' for the sand to collect on.
3. The piston is shiny: like a hydraulic ram

We shall see whether it works but I did notice on my last trip to the blasters that he has something VERY similar (although must bigger) on his pot.