Sandblasting cabinet problem

[Ian ParkinParticipant @ianparkin39383]

I needed to be able to blast a few smallish components so bought a bench top blasting cabinet and some crushed glass as media

it all works great but a after a few seconds…20-40 or so the pickup tube is in free space and i have to shake the media to get it to pool around the open end of the tube..

Ive ordered a vibrator off amazon

GT6 Pneumatic Air Turbine Vibrator, Pneumatic Vibrator, Air Turbine Oscillator 1/8in Thread Industrial Vibrating Platform Supplies, for unloading silos, Vibrating Platforms, Filter Screens

 

i was wondering about fastening this to the base of the cabinet to vibrate the media to keep it moving?

 

or any other ideas?

[Charles LamontParticipant @charleslamont71117]

Mine does that. I have supposed that putting in more glass beads would cure it, but as yet I have been too mean to try it, as they are not cheap.

[mike TParticipant @miket56243]

I fitted a tall, narrow, storage hopper (made from a plastic kitchen container) on the side of my cabinet. This provides a constant feed of glass media to the gun. The flexible feed pipe goes from the bottom of the hopper, through the cabinet wall to the gun. When the hopper is empty I transfer the glass beads from the cabinet floor, back to the hopper.

[BazyleParticipant @bazyle]

Don’t quite know the design but could you tilt the whole cabinet and clip the feed tube in the bottom corner.

[peak4Participant @peak4]

How dry is your air supply?
I fitted a desiccator to the one I bought from you which does help.
Also added a vacuum cleaner to the rear air out port, running via a cheap cyclone filter off eBay.

Bill

[Graham MeekParticipant @grahammeek88282]

When I built my small parts Blasting cabinet,

 

 

I relied on a gravity feed for the media, the pick-up pipe is anchored vertically above the sump. The end of the pipe is cut off at an oblique angle to help stop blockages.

 

 

Regards

Gray,

[Dave HalfordParticipant @davehalford22513]

1. Not enough media, the gun needs more (add some) or is taking too much (gun tends to pulse and needs the tube restricting) You could try less pressure.
2. the pick up tube should be free floating with a breather tube.
3. move the pickup tube to where all the media is collecting or point the gun toward the pickup.
4. crushed glass is cheaper than glass beads.

The black stuff Graham is using looks like J Blast AKA copper slag which is heavier than glass and would flow down hill to the pickup easier.

[Ian ParkinParticipant @ianparkin39383]

Well the vibrator arrived a small less than 2 inch square and 1/2 thick device

coupled up to an air source and it vibrates like mad but gobbles air

bolted it to the base where the glass collects and connected it to a foot switch

so when blasting i can see if the pickup tube is visible i give it a quick press of the pedal and it vibrates all the glass level..

So thats that sorted for now

On another thought i wondered about putting the bare cleaned bmw heads in the dishwasher

i dod remember putting a bare alloy pan in once though and it came out blackened?

is that the action of the dishwasher tablet?

[Ian Parkin]

On Ian Parkin Said:

…
i dod remember putting a bare alloy pan in once though and it came out blackened?

is that the action of the dishwasher tablet?

 

Amongst other things, dishwasher tablets usually contain a mild alkali.  Alkalis convert oil and grease into a soluble soap that can be washed down the drain, leaving mostly clean dishes ready to be finished off with few rinse cycles and a dry.

Don’t put Aluminium objects into a dishwasher because alkalis dissolve it.  The blackening is a thin layer of corrosion left behind, not good.

What happens to Aluminium is related to the process used to beautify it by which the dull surface layer of Oxide is stripped off and regrown extra thick in combination with a dye.  Accidentally creating ‘Dishwasher Black’ is ugly and unpredictable, whilst anodising  controlled by electrolysis is predictably attractive.

Gun Bluing and Steel Blackening processes are even more similar, though not done in a dishwasher!   A layer of corrosion is deliberately applied to protect the metal underneath, and/or to look pretty.   Cold gun-blue potions aren’t nearly as effective as industrial bluing processes, the best of which boils parts in molten Nitrates and other hairy chemicals.

Dave

Dave

[duncan webster 1Participant @duncanwebster1]

I reckon you could make a fairly good vibrator from a door bell. Mine has just an armature on a spring inside a coil, the coil is fed via a diode from a transformer. No doubt the mass/spring combination is tuned to 50 hz?

Take the bell off and make the armature hit the cabinet.

[VicParticipant @vic]

I was gifted a Clarke sandblaster and it’s great for what I paid for it! 😆

I have the same issue though. The media gets evenly distributed around the whole base of the cabinet and although sloped much of it refuses to fall to the bottom. Even if it did though the opening for the pickup pipe is at one end.

Better designed (but larger) cabinets seem to have more of a funnel shaped base with the pick-up right at the bottom. I have contemplated cutting a hole in the base of my cabinet and fixing a round container below it into which the pickup pipe can sit.

Other things to do though so I keep a small paintbrush in the cabinet which I use to “sweep” the media towards the pickup opening.

[Ian ParkinParticipant @ianparkin39383]

Vic

for the £20 that the vibrator cost me its a great thing almost makes the media like a fliudised bed just a blast of air to it every 20 seconds or so keeps the media round the pickup tube

[Dave Halford]

On Dave Halford Said:

1. Not enough media, the gun needs more (add some) or is taking too much (gun tends to pulse and needs the tube restricting) You could try less pressure.
2. the pick up tube should be free floating with a breather tube.
3. move the pickup tube to where all the media is collecting or point the gun toward the pickup.
4. crushed glass is cheaper than glass beads.

The black stuff Graham is using looks like J Blast AKA copper slag which is heavier than glass and would flow down hill to the pickup easier.

Hi Dave,

You are right in your observation. I have however successfully used Glass Beads, Crushed Glass and Soda. The latter I tend to use only outside, but still with PPE.

I have found a lot depends on the shape of the pick-up pipe. I started off with a square end on the tube, but found this would clog seconds after clearing. Cutting the tube at an Oblique angle cured this straight away and blockages are now a thing of the past.

Regards

Gray,

Edit, I do not know what has happened to the Text in the above quote, it is not of my doing.

[John MCParticipant @johnmc39344]

Not sure if the following will be of any use to the OP.   I have an ancient Guyson blast cabinet (and dust extractor) that I struggled to get working reliably.  I use steel grit.

It would pick up and blast for a couple of minutes then stop picking up.  Initially I thought it was a lack of air pressure.  Air pressure was not the problem, it now works well between 40 – 80psi.

Stirring up the hopper with a length of steel bar would get it going again, for a couple of minutes.

I played with nozzle sizes, made no difference.

On advice, I then emptied the hopper and refilled with a lot less grit.  That made a difference but would still not blast for more than a few minutes at a time.

I then found the American Guyson website.  Very much more helpful the the UK one.   It described a way of making a very simple regulator to control pickup by bleeding air in to the suction pipe.  Now, I can blast for as long as I like.

I find that I need to sieve the blast media fairly frequently, the suction side will pick up some big lumps of whatever I’ve blasted off that will block the nozzle

 

[BazyleParticipant @bazyle]

I’d be interested to see before and after’ examples of some work to see if it is something I should consider. The Men’s Shed were thinking of getting the kit but don’t have room at the moment.

Also a couple have mentioned air bleed – perhaps more detail please. Is it something one could route to a regulating tap outside the cabinet? I can see it would help in ‘diluting’ the media/air mixture.

Cutting tube at oblique angle – then do you place the long side up, side or down, or doesn’t it matter?

[Graham MeekParticipant @grahammeek88282]

Hi Baz,

If you look further up the post you will see in my post the pick-up tube enters the sump vertically and is firmly anchored to the side of the sump.

Regards

Gray,

[VicParticipant @vic]

Can anyone help with media? I’m currently using:

CLARKE 7.5KG ALUMINIUM OXIDE ABRASIVE POWDER – 60-80 GRIT.

https://www.machinemart.co.uk/p/7-5kg-60-80-grit-aluminium-oxide-powder-2/

Which works great but I could really do with something a bit coarser. I’m not wanting to buy too much or spend a lot though. Shipping can be a deal breaker as well.

[VicParticipant @vic]

In case it’s of help to anyone else. This is the Guyson Blog on media flow:

SUCTION-BLAST BASICS: OPTIMIZING MEDIA FLOW

Guyson Pickup tubes mentioned in the Blog.

[VicParticipant @vic]

I don’t have a welder or any steel tube so it’s going to be fun for me trying to fabricate a pickup tube with similar functionality! 😆

[John MCParticipant @johnmc39344]

This is a (poor) photo of the air bleed on my Guyson cabinet I made from the guidance given on the US Guyson website.  Works very well, wish I had come across the US site sooner, would have saved a lot of frustration.  The tape was a very quick way of blocking the lowest pair of holes to stop grit leaking out.

The gloves Guyson supply are “industrial” Marigolds (I kid you not!) that are sealed by rubber muffs in the door.  Neither muffs or gloves lasted very long, the gloves split and the muffs went horribly sticky and fell apart.  Something like £80 to replace so I bought some thick long sleeved rubber gloves from the bay and fitted them into the door.  They have outlasted the Guyson supplied gloves and muffs.

[Vic]

On Vic Said:

Can anyone help with media? I’m currently using:

CLARKE 7.5KG ALUMINIUM OXIDE ABRASIVE POWDER – 60-80 GRIT.

https://www.machinemart.co.uk/p/7-5kg-60-80-grit-aluminium-oxide-powder-2/

Which works great but I could really do with something a bit coarser. I’m not wanting to buy too much or spend a lot though. Shipping can be a deal breaker as well.

Why Vic,

80 was the largest size I used cleaning car chassis etc. Smaller is better for getting into pits, a mix of worn 80/60 and new grit is the best for shifting big flakes of rust (the 80 is heavy and hits harder) and still get the pits cleaned out with the much smaller used grit.

Aluminium oxide breaks down exposing fresh sharp edges so it keeps cutting unlike sand which just goes blunt.

Steel shot is for girders and ships hulls and damaging lighter steel.

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