DIY Pressure Pot

[M@tt]

I've just finished my blast cabinet (http://www.mig-welding.co.uk/forum/showthread.php?t=14009) and i had a go today cleaning a few bits up with the syphon gun but i found it really struggled to pick up the media so wasn't really cleaning all that well.

My compressor is a 200l 3hp 14cfm jobbie so should be capable of reasonable results from what i've read. I was getting a good 80-90 psi operating pressure

I tried the pickup tube in various positions ie submerged in media, just on the top of the media but it was still quite hit and miss and miss as to whether it picked up the media. The media is fairly course grit for masonary but on the occasions it would suck up it did remove paint and clean up rust.

I'm thinking the media might be a bit heavy to be sucked up via syphon method so i'm wondering whether i might need a pressure pot instead.

I've seen Stormins thread on converting an old gas bottle into a pressure pot
(http://www.mig-welding.co.uk/forum/showthread.php?t=10682).

I've got a small calor gas bottle which i could possibly use to do something similar but i don;t have the ability to make a flange or anything like that as Stormin did, i just wondered if anyone had any suggestions on other possible methods

Cheers

Matt

 

[brightspark]

blast pot

hope this helps u ive mad 5 blast pots using this method only one bolt to undo the bar swings open refill slide bar back clamp up and away u go normans pot is verry well engineered the same as the clemco bought ones but quite time consuming to make. i used to shotblast houses and classic cars for people with mine the larger pots with mobile compressor this ones based on the clemco minipot without the popup valve

 

[brightspark]

if u are having trouble with suction gun it might be trying to pickup 2 much grit at once .block and pulse i have a small square box under my cabinet where the grit falls into and the suction pipe in from the side so it can be ajusted for its feed in the grit otherwise it piles up on top of picup pipe and blocks

 

[brightspark]

home made gun and cabinet

the gun i sandcast out of alumimium using an old worn gun as the pattern bored it out threaded it .machined the brass end cap and nozzle holder. jets were made and hardned cabinet out of sheetsteel glass front and angle iron welded and riveted .the light in the top are 3 16w 2d bulbs. suction by a woodchip and dust extracta which sucks all the fine dirt and worn grit away leaving the good quality grit to fall to the bottom cost of whole setup cabinet and blastpot 60 quid

 

[stormin]

The pop-up valve type pots require a lot of cfm to lift the valve initially. Not sure it'd work with a 3hp compressor, never tried it with mine.

You'd be better of with a system like brightsparks or a large threaded fiitting. I considered fitting a 1 1/2 bsp nipple and end cap, giving something similar to the Ebay pots.

 

[rtbcomp]

I was wondering about a clamp rather than a screw. My experience of the ACE gritblaster proved that the lid clamping screws didn't last very long.

There is already a ring welded to the bottom of a gas bottle (ie the top of the pot!) and I was thinking of using this to fix a spring loaded lever to, which in turn would hold a flap over the hole in the top of the pot. Being spring loaded it could double up as a safety valve.

 

[brightspark]

blastpots

over 30 years ago none of this sort of gear was available to the ordinary guy . i started by being given the old clapped out guyson gun. my brother and i have a small foundry so away we went cast the guns made the cabinet . made the compressor with twin pump westinghouse. had to make oilpump for it as bearings were pressure fed . the next step i wasnt happy with cfm so went down stanley vickers.pneumatics saw the lad on counter who showed me the clemco minipot £1000 quids worth said it needed min 90cfm to run .50 quid changed hands was given a carbide blast jet and a blast hose and a fee hand to measure a blast pot in pieces then bought a large 90cfm v twin compressor for 60 quid . a 20hp lister twin engine bummed 4 large v belts and away i went .rented a small building on a farm used to blast car wheels and motobike frames every saturday made 200 quid a day now all the gear is readily available and quite cheap . also theres a good pool of knowlege from members in forum for ideas which saves a lot of time experementing

 

[rtbcomp]

......made the compressor with twin pump westinghouse. .........

Anything like this one?

http://www.mig-welding.co.uk/forum/showthread.php?t=8692&highlight=skip

 

[brightspark]

Anything like this one?

http://www.mig-welding.co.uk/forum/showthread.php?t=8692&highlight=skip

simlar il post a few pictures shortly

 

[brightspark]

compressors

small one is 30 years old new motor belts and oilseal . blast helmet of e bay 50 quid home made filter regulator out of soilpipe with a good quality airfilter inside. double compressor rebuilt 140 quid and diesel compressor is 28 years old never been run for 2 years started 1st turn that was 150

 

[M@tt]

cheers for the replies

so whats the best way for a suction pipe to sit to suck up the blast media? should it be completely submerged or sit on the top? and does the pipe need to be smaller or throttled somehow?

brightspark whats that pot from that you've showing in your first pic? doesn't look like a calor gas bottle.

also any suggestions as to the best place to get hold of the appropriate T pieces, pipe and shut off valves if i were to make one?

cheers

Matt

 

[brightspark]

cheers for the replies

so whats the best way for a suction pipe to sit to suck up the blast media? should it be completely submerged or sit on the top? and does the pipe need to be smaller or throttled somehow?

brightspark whats that pot from that you've showing in your first pic? doesn't look like a calor gas bottle.

also any suggestions as to the best place to get hold of the appropriate T pieces, pipe and shut off valves if i were to make one?

cheers

Matt

the gas bottle is a macgas any make will do air fittings and taps crosling potter and cowan but ebay sell them cheap . the grit in the cabinet falls through a 20 mm hole in the bottom of hopper into a square box forming a pyramid of grit the suction pipe comes in from the side which slides in and out to regulate the flow alowing air and grit to enter ,the grit cant pile up on top of it so stops pulsing and blockage try finer grit will help as well my pictiure doesnt show the box underneath wasnt fitted at that time hope this helps

 

[M@tt]

great thanks!!

i think i can picture what you mean. if you have a pic though that would be great

also can i ask what size pipe fittings did you use on your top pic i'm struggling to find any on ebay , i probably searching for the wrong terminology

cheers

Matt

 

[rtbcomp]

............ the grit in the cabinet falls through a 20 mm hole in the bottom of hopper into a square box forming a pyramid of grit the suction pipe comes in from the side which slides in and out to regulate the flow alowing air and grit to enter ,the grit cant pile up on top of it so stops pulsing and blockage ......

That's a good idea - I use a syphon gun occasionally (Clarke SB4, which isn't too bad), but I have problems with the feed pipe blocking, so I'll give this a go.

 

[brightspark]

That's a good idea - I use a syphon gun occasionally (Clarke SB4, which isn't too bad), but I have problems with the feed pipe blocking, so I'll give this a go.

another little bodge i do is drill a hole in the pickup just out of grit this alows air in which helps just experement till get right

 

[brightspark]

the easiest way of explaining is look at a hoover flexipipe it has a sleeve over a square hole which u adjust close completely it sucks to the ground open slightly up it comes

 

[M@tt]

ah i get it

does anyone know what size thread is in a flogas bottle? it is it a special regulator specific only size? or is it a standard thread which would allow easy connection to T pieces etc?

edit> i've measured the hole with my verniers and it reads 0.63" but i've no idea what that equates to in available thread sizes

 

[brightspark]

ah i get it

does anyone know what size thread is in a flogas bottle? it is it a special regulator specific only size? or is it a standard thread which would allow easy connection to T pieces etc?

edit> i've measured the hole with my verniers and it reads 0.63" but i've no idea what that equates to in available thread sizes

3 .8th bsp is 0.65 0d 19 thereads per inch u can get the reducing nipples from machine mart if u want to drop 2 quarter bsp

 

[M@tt]

Excellent

so what would you recommend for the pipework?

The ones in your pic look like they might be larger than 1/4"?

 

[brightspark]

its a small pot using quarter fittings but 3/8 would be fine whatever u can get hold of at the right price u can reduce the bore size at the teepiece underneath to suit the hose