Sand blast cabinets...

[Gc33]

G'day all. Over the past year I bought a sandblast cabinet. Exactly the same as what you guys in US call a harbour freight unit. I've made a few modifications along the way. Better lighting, a gravity feed with a metering unit, dust extractor, castor wheels on legs so it can be moved about easily. I also put a small sheet of stainless mesh in the bottom of the hopper as a filter to stop large pieces of crap that have blasted off from recirculating and blocking the gun.
I've learnt a few things along the way.
High pressure doesn't mean better or faster blast, just means more dust in cabinet!
Different media for different applications
Standard vacuum cleaner is too efficient so need to make a control for it.
And now I'm putting mine up for sale on gumtree as I'm going to upsize to a more commercial unit. Comes complete with dust extractor. I will still need to modify it in a couple of areas such as making it a gravity feed. It her wise they recommend 50 kg of media in the hopper. With a gravity feed unt I can get away with 2-3 cups of media so it then becomes very easy to swap out and change over blast media.
And I'll put castor wheels on it as well. I'll also have it set up be able to use as a vapor blast or wet blast unit.
The unit I'm upgrading to I can then fit wheels in as well.
The siphon set ups don't work very well so this will be removed and replaced with gravity feed.

Metering valve be fitted to trap door.

 

[DaveKamp]

Yep, GC- your experience is exactly same as mine... and I'll throw in my sixpence on it:

Having an industrial-grade setup grants a substantially more 'trouble-free' experience, which in a shop, means you walk up, open the door, put in the part, close the door, and do the job, and aside from changing media every so often, and a new nozzle, mebbie a pair of gloves, and the glass, it just keeps goin'.

Most think the advantage of a large cabinet is just interior volume... and it's not. Being able to MOVE your arms, and workpiece, and not be crouched over a little box, trying to see and work. Being able to stand at a height that doesn't cramp you... in a NATURAL position...

And...

The glass. Small blast cabinets go through glass like pretzels in a pub on game day. Media that bounces off the interior, comes up and strikes the glass, abrading it away. There's film sheets, polycarbs, and silica glass that are available to make them last longer, but having a LARGE cabinet means that deflecting media has to travel farther before hitting the glass, and in that travel, it loses much of it's velocity, thus, energy (Energy = Mass x Velocty ^2, right?). As a result, smaller blast cabinets NATURALLY wind up with faster glass abrasion.

Interior lighting and dust control... ALWAYS important. My first cab just used an ordinary shop-vac. The fine dust choked the filter and ruined vac bags, vac motor bearings. Of course, an average home shop-vac isn't particularly robust... but the big win, is adding a cyclonic dust separator BEFORE the vac. After seeing how well the cyclonic did it, I vowed that my new shop building will have a cyclonic separator integrated into the whole-shop ventilation system, so that when it's all shut up tight in middle of a cold winter, and I gotta take a wire-brush to something big and crusty, it doesn't result in a cloudy haze amidst all the machinery. My woodworking shop's sawdust collector is getting a large cyclonic, too.

A blast cabinet is TOTALLY dependant upon the air supply. Pressure for the cab NEEDS to have a dedicated regulator. My air system is 110psi on, 135psi off (that's 7.6bar and 9.3bar for the metrified populus... I'd use kilopascals, but those numbers are big'nuff to scare me). I feed it to all buildings that way, then place reguators at dedicated machines so it's properly suitable AND locally adjustable.

The air MUST BE DRY... no oil, no moisture. Even the best blast media turns into clumpy cat-litter when it gets contaminated, and NO system pulls media worth pooh when it does. I have a refrigerated dryer on my primary compressor (a 4-cylinder Brunner built in 1940)... but the primary reservoir is 300 gallons (I mean US gallons... we can't afford UK gallons here) so around 1000L. Gravity and nature do a really good job of drying it right there, and in fall and wintertime, the refrig isn't necessary... but spring and summer it gets a workout. I've got my main compressor in a climate controlled environment, from there, air pipes out underground to the other buildings. They all have reservoirs (mostly around 20 gal (75l) with heated automatic drain valves on the bottom., sometimes, during high demand, they'll strip a little more moisture there, but by time it gets to the regulator on the wall by the blast cabinet, it's damned dry.

I didn't nix my old HF cabinet when the new one took over. The big one has aggressive abrasive, but the little one is reserved for alternatives... like if I want to use sodium bicarbonate or fine steel shot. Small hopper means quick/easy media change.

 

[Gc33]

DaveKamp » Today- 8:18[/url]":3in3j5l8]
Yep, GC- your experience is exactly same as mine... and I'll throw in my sixpence on it:

Having an industrial-grade setup grants a substantially more 'trouble-free' experience, which in a shop, means you walk up, open the door, put in the part, close the door, and do the job, and aside from changing media every so often, and a new nozzle, mebbie a pair of gloves, and the glass, it just keeps goin'.

Most think the advantage of a large cabinet is just interior volume... and it's not. Being able to MOVE your arms, and workpiece, and not be crouched over a little box, trying to see and work. Being able to stand at a height that doesn't cramp you... in a NATURAL position...

And...

The glass. Small blast cabinets go through glass like pretzels in a pub on game day. Media that bounces off the interior, comes up and strikes the glass, abrading it away. There's film sheets, polycarbs, and silica glass that are available to make them last longer, but having a LARGE cabinet means that deflecting media has to travel farther before hitting the glass, and in that travel, it loses much of it's velocity, thus, energy (Energy = Mass x Velocty ^2, right?). As a result, smaller blast cabinets NATURALLY wind up with faster glass abrasion.

Interior lighting and dust control... ALWAYS important. My first cab just used an ordinary shop-vac. The fine dust choked the filter and ruined vac bags, vac motor bearings. Of course, an average home shop-vac isn't particularly robust... but the big win, is adding a cyclonic dust separator BEFORE the vac. After seeing how well the cyclonic did it, I vowed that my new shop building will have a cyclonic separator integrated into the whole-shop ventilation system, so that when it's all shut up tight in middle of a cold winter, and I gotta take a wire-brush to something big and crusty, it doesn't result in a cloudy haze amidst all the machinery. My woodworking shop's sawdust collector is getting a large cyclonic, too.

A blast cabinet is TOTALLY dependant upon the air supply. Pressure for the cab NEEDS to have a dedicated regulator. My air system is 110psi on, 135psi off (that's 7.6bar and 9.3bar for the metrified populus... I'd use kilopascals, but those numbers are big'nuff to scare me). I feed it to all buildings that way, then place reguators at dedicated machines so it's properly suitable AND locally adjustable.

The air MUST BE DRY... no oil, no moisture. Even the best blast media turns into clumpy cat-litter when it gets contaminated, and NO system pulls media worth pooh when it does. I have a refrigerated dryer on my primary compressor (a 4-cylinder Brunner built in 1940)... but the primary reservoir is 300 gallons (I mean US gallons... we can't afford UK gallons here) so around 1000L. Gravity and nature do a really good job of drying it right there, and in fall and wintertime, the refrig isn't necessary... but spring and summer it gets a workout. I've got my main compressor in a climate controlled environment, from there, air pipes out underground to the other buildings. They all have reservoirs (mostly around 20 gal (75l) with heated automatic drain valves on the bottom., sometimes, during high demand, they'll strip a little more moisture there, but by time it gets to the regulator on the wall by the blast cabinet, it's damned dry.

I didn't nix my old HF cabinet when the new one took over. The big one has aggressive abrasive, but the little one is reserved for alternatives... like if I want to use sodium bicarbonate or fine steel shot. Small hopper means quick/easy media change.

Dave... Awesome info there. My compressor is OK at present but I'll need to up size in that as well soon

 

[DaveKamp]

I actually 'cheat' a bit. If I'm running the cabinet, or doing something ELSE that wants LOTS of capacity, I have two other compressors in the outbuildings that I can enable. I generally DON'T have them enabled, as they're not in conditioned spaces... they're in areas that get bitterly cold in winter, so they wouldn't survive long rolling over with oil being cold enough to roll into a ball... oh2:

 

[pidjones]

Let me add a few things from my experience. At work, my uses were very critical for cleanliness. We did not permit our cabinets to be used for other purposes (they were kept padlocked). So much so that I switched to and recommended a hand-held spot blaster for our most critical parts. We used them outside and let the media go. Glass bead is popular, but the glass shatters on impact and creates very fine glass dust that when inhaled lacerates nasal tissue. After years of infections and even pneumonia caused by this, I switched to aluminum oxide. Aluminum oxide also cuts faster, and if you use fine enough grit leaves a better surface with almost zero inclusions of media (a killer in our process). In a cabinet it is reusable much longer, too. I have a tub of garnet here at home (another Aluminum Oxide crystal) that works pretty well, but seems softer.

NEVER USE SILICA (PLAY) SAND! It causes silicosis.

A cabinet MUST be located in an area separate from anything that you don't want the grit in! At ORNL, the owners of the cabinet that I used had placed it in an area with sinks, non-moving machinery, etc. Not bad, but we had to vacuum the area carefully after each use because even with separators, vaccum attachment, foam door seals, etc., when the door opened dust came out. That dust is super-abrasive! We knew it was there because the slick-finished concrete floor became almost too slick to walk on each time until vacuumed and mopped.

My home compressor is just too small to consider using a cabinet, so for getting those nooks and crannies that wire/abrasive wheels won't reach, I use a hand spot blaster outdoors. Obviously if my need was greater, an industrial compressor, cabinet with associated separators, and separated blasting area would be needed.

My first bike was a Triumph chopper that the shop building it had blasted to bare metal at a monument company. Their blast cabinet was a room with windows and long gloves. Must have used a fine grit, because the surface finish was beautiful before priming.

 

[DaveKamp]

A cabinet MUST be located in an area separate from anything that you don't want the grit in!

AMEN!!!!

My new shop building will be separated such that not only will the welding, grinding, and blasting be separated from the machining areas, the ventilation flow will progress from cleanest, to dirtiest, so as to protect the sensitive machines. The only 'gotcha' is the surface grinder, and I'll need to figure out a slick way of handling that, too...

 

[Gc33]

As luck would have it, I saw a blast cabinet for sale at one of our second hand machinery yards on the weekend. I checked theur website.. No price. So I emailed them.. $850.
Needs a couple of things... Gun, foot pedal actuator, gloves and glove mounting kit.
What ever the person before was was using it for... Holy crap. Some real sticky gooey stuff... Was using it for like a spray booth or something. Any way.. A bit of elbow grease... It's coming up OK. Still beats $2200 for new..

(fixed pic orientation, df)

 

[dan filipi]

Nice find!

 

[Gc33]

dan filipi » 59 minutes ago[/url]":1nkg7ab1]
Nice find!

Dan... How the blazes do I change how the pics are? Been trying to figure it out..
Blast cabinet... Yeah.. Pretty happy. Stripping it down a bit to clean all the gooey crap off. Once I have it reassembled I'll then do my mods to it. Better lighting, filter screen at bottom to stop the chunks blocking the gun, make a metering valve for a gravity feed system, then finally....ill make it so as to use it as a wet or dry blast cabinet. I have a design in my head... Pretty basic... Needs to be coming out of my head haha.

 

[Rednaxs60]

Good score. Opportunity knocked, and you went for it. If you hadn't probably would not have been there when you would go back. Karma

 

[DaveKamp]

Gotta LOVE that front-access arrangement. Side access cabinets mean you can't put 'em in alongside other stuff, or in a corner... and every part you put in, is an acrobatic exercise trying to support the weight in an off-balance reach.

Normal swing-up fronts either leave the ledge with gloves, or swings the whole works up on a radius, which hangs out overhead, and risks dumping the cabinet forward onto you. This double-hinge setup (and the groovie gas-spring over-center linkage) is SWEET! Hopefully, it seals down snug, DO keep us posted!

 

[Gc33]

DaveKamp » Today- 18:26[/url]":1kfcskdj]
Gotta LOVE that front-access arrangement. Side access cabinets mean you can't put 'em in alongside other stuff, or in a corner... and every part you put in, is an acrobatic exercise trying to support the weight in an off-balance reach.

Normal swing-up fronts either leave the ledge with gloves, or swings the whole works up on a radius, which hangs out overhead, and risks dumping the cabinet forward onto you. This double-hinge setup (and the groovie gas-spring over-center linkage) is SWEET! Hopefully, it seals down snug, DO keep us posted!

I've got new door seals coming. I've just done all the hatch seals and extractor seal. Putting led lights in... Re-sealing all joins and any other holes that may be around. Has to be good for wet blast too...which reminds me... Gotta go to hardware shop for parts for metering valve...

 

[dan filipi]

Gc33 » Yesterday, 4:57 am[/url]":egmucljq]

dan filipi » 59 minutes ago[/url]":egmucljq]
Nice find!

Dan... How the blazes do I change how the pics are? Been trying to figure it out..

The way I fix the orientation is I first download the pic then I rotate and save on my computer using just the basic preview app, then I go to edit your post and delete and replace your pic with the one I corrected.

 

[Gc33]

dan filipi » Today- 5:36[/url]":1iecokt5]

Gc33 » Yesterday, 4:57 am[/url]":1iecokt5]

dan filipi » 59 minutes ago[/url]":1iecokt5]
Nice find!

Dan... How the blazes do I change how the pics are? Been trying to figure it out..

The way I fix the orientation is I first download the pic then I rotate and save on my computer using just the basic preview app, then I go to edit your post and delete and replace your pic with the one I corrected.

Yeah I've tried deleting photo, editing it then reposting a still ends up sideways...

 

[Gc33]

Bit more progress today. Extra LED lighting fitted and wired in.. Functioning. Installed my crude but functional metering valve. Added an isolation tap for when wet blasting.
Just need to fit the filter screen at the bottom of the hopper and it will be just about ready to rock n roll!

 

[Gc33]

Another day done and the unit is almost a go.... I'm now just waiting on the new door seal, glove mounting kit, the correct gun and the foot pedal actuator.
I bought a pump from our local hardware giant bunnings and got that all set up. Just need hosing for that... Ozito brand is a cheap brand... The pump is designed to pump dirty water so it won't be working anywhere as hard as it's designed to. And at $69aus, with 3 years warranty... Hell... Got nothing to lose.
Im happy with how it's come up and once all the bits get here I'll be able test drive it... When I do I'll post some samples up..

 

[dan filipi]

Looking good :good:

 

[DaveKamp]

I LOVE the over-center (er... under-center) geometry of that gas-spring. I'm gonna steal that idea!

I'm seriously considering building a new cabinet that has a laminar airflow path across the glass to reduce erosion. I go through windows just wayy-too-fast for my liking, and always find myself struggling to see my workpiece. If age isn't bad enough, right??

 

[Gc33]

DaveKamp » 2021-04-22- 4:28[/url]":1tb43lnr]
I LOVE the over-center (er... under-center) geometry of that gas-spring. I'm gonna steal that idea!

I'm seriously considering building a new cabinet that has a laminar airflow path across the glass to reduce erosion. I go through windows just wayy-too-fast for my liking, and always find myself struggling to see my workpiece. If age isn't bad enough, right??

Ha... Yes indeed. Age is a bitch... That comes to all of us.
If you need more pics of the cabinet design let me know and I can email you pics...

 

[Gc33]

Finally... Wetblast cabinet up and running. Gonna have to up size my compressor tho... Which means having 3 phase put in to the house... And I need a new gun... One I'm using is OK for dry blast but need a good one for wet blast.
So far I've found that if I dry blast things that have had paint or heavy rust the wetblast comes up mint after.
I've been working on the rear wheel of my 75. I'm pretty darn happy with it too.
Did my front rim and now setting to and polishing. It has had a bit of pitting in it so I've been wet sanding with 3 different grades and then polish... One side is looking good, just the other to do... Then it's on to the rear rim and hub... Front hub has come up good also..