Sandblasters & cabinets

[inchpincher]

Definitely a bit weird that you have to keep shaking the pot. I blasted my scooter last week, the first time I've used the 20 gallon pot and I did the whole job in one 'hit'. I had to shake it once or twice when it was getting low but I was blasting for an hour.
I had sieved 50kg into the pot, maybe they work better when a bit full.
Big thanks to rtbcomp for his sage advice!

ps. I replaced the 3/8 ball valve at the bottom of the pot because it got broken in transit, don't think it's significantly helping the media feed through though.

 

[rtbcomp]

One point I would add, once the media appears to be running out I top the pot up rather than mess around trying to squeeze the last bit out. This means I have a "dead" quantity of grit in the pot.

 

[philip979]

Thanks for the reply. I've only really had about 10kg max of media in the pot at any one time. Perhaps that isn't enough? Does it also need the action of gravity and the weight of the media above to force it through?

Is there any problem filling it, only using it a litle, then leaving the media in the pot for a while? Much risk of it getting damp? Cheers

 

[rtbcomp]

Thanks for the reply. I've only really had about 10kg max of media in the pot at any one time. Perhaps that isn't enough? Does it also need the action of gravity and the weight of the media above to force it through?

Is there any problem filling it, only using it a litle, then leaving the media in the pot for a while? Much risk of it getting damp? Cheers

That could be the problem. The instructions say fill it 3/4 full, but I always cram as much as possible in. What happens when the pot is nearly empty the air blows a hole through the grit. To confirm if this is happening close the bypass valve. If you still get air out of the nozzle it is blowing through. If you get a really thick discharge of media it isn't.

I always leave the media in the pot, never had a problem.

 

[malcolm]

I've actually read a thread before asking a question. Bad move - many more questions that I hadn't thought of.

rtb - Nip down to Machine Mart and look at their free-standing cabinet and copy it. Those guns that suck up the grit (syphons) are no good, they use a lot of air, clog. and the nozzles don't last very long. I use tungsten carbide nozzles from these people http://www.acegrit.co.uk/acegrit/gritblaster/page7.html

Which size nozzles do you use? Our CFMs will be similar - can you get away with 3mm?

1 - did you sieve the J-Blast? There are some big bits in there that can cause clogging.

Ahhhh. This was the question I was going to ask. My nozzle is the ceramic one that came with the eBay 20 gallon sand blaster. It's quite small, maybe 2mm, and it is getting blocked by the bigger bits of J-Blast Supafine.

With sieving - you start off sieving the big bits out, then when it gets worn sieve the dust out and the big bits that have been picked up? Of always just the big bits? What type of sieve do you use - I've checked the kitchen but the holes seem a bit small in that sieve.

I'll try and post details of my nozzle mod later.

I half remember something about this - was it in another thread?

 

[rtbcomp]

I'm using worn 2.5 & 3mm nozzles, for Supafine you need the 3mm, as the grit wears down the 2.5 is OK. I suspect siphon guns will need larger nozzles to get the airflow through the venturi to suck up the media.

I just sieve the big bits out. Do this every time as you end up with bits of paint, nuts, washers in the media. I don't bother sieving the dust out, I just let the dust extractor do the job in my blast room. It may be a good idea with a cabinet though as there isn't as much room to disperse the dust, on the other hand a good vacuum cleaner should shift quite a bit. Make sure the air inlet to the cabinet isn't blocked. I quite like having a mixture of media sizes, its a good compromise between shifting paint quickly and getting into tight corners.

Basically I squeeze a 10mm olive onto the centre of the nozzle. On the sandblaster change their nozzle holder for a double 3/8 BSP brass nipple, put nozzle in the nipple and secure with a 3/8 compression nut (Nut & olive can be got from 10mm microbore fittings).

The idea of putting the olive in the middle of the nozzle is to allow some of its length to fit inside the nipple, this stops the media getting in contact with the nipple and wearing it out.

Hope this helps.

PS I'm experimenting with making my own blast media out of crushed glass - Google Blastglass

 

[malcolm]

Thanks for that - will check the fitting arrangement in the morning and order bits. Only need to blast an inaccessible corner of a boot floor that's due for a fiddly repair in the short term and I'll do that between clogging. Hopefully in a week or two I'll do the inaccessible bits of my chassis - it's surprisingly speedy this shot blasting setup (between clogs).

What type of sieve do you use to filter the stuff? My kitchen sieve seems to have 1mm square holes which seem a bit small.

 

[rtbcomp]

I'm not sure of the mesh size, I went round the shops and bought a few.

If you do want to filter out the dust, try the fluff filter off a tumble drier.

You can do a serach on Sieve on ebay in Business & Industrial, Lab equipment. A guy there sells various mesh sizes.

 

[malcolm]

Turns out some of the spare ceramic nozzles that came with the eBay blaster were about 3mm. That's sorted out my blockage. Should keep me going until I organise some tungston nozzles.

The blasting is impressively quick. I'm planning to wheel my chassis outside next sunny day and do the whole lot.

 

[AndyHR]

Turns out some of the spare ceramic nozzles that came with the eBay blaster were about 3mm. That's sorted out my blockage. Should keep me going until I organise some tungston nozzles.

The blasting is impressively quick. I'm planning to wheel my chassis outside next sunny day and do the whole lot.

No time soon then.....

 

[malcolm]

No time soon then.....

I'll wait until both of the ceramic nozzles have worn out first of course. Not going to spend £15 until I really need to.

 

[13ad13oy]

Sorry to dig this up but I'm planning on buying one of the 20gal basters from eBay this week and would like all the bits so I can switch to a tungsten nozzle.

I'm going to get the 3mm tungsen nozzle from ACE, and use JBlast

Also these parts - Just to confirm

replaced the nozzle holder with a 3/8 x 3/8 BSP male/male nipple (The original has an odd thread where the nozzle fits).

No. 2?

Got a 10mm straight compression coupler (B&Q, Screwfix) and squeezed the olive on the TC nozzle (it's 10mm OD) about 2mm from one end.

Like this?

Thank you very much

Al

 

[rtbcomp]

No 2 looks like the one, make sure it's 3/8 BSP.

The last 10mm fitting I bought from B&Q had a funny thread that fell between 3/8 and 1/4, most likely metric.

To be on the safe side I bought some proper BSP nuts from Duncan Rogers

http://www.airlines-pneumatics.com/webcat/product-index.asp

You need J-Blast Supafine.

 

[13ad13oy]

Wow! Quick reply!

Many thanks and wish me luck!

 

[rtbcomp]

Forgot to mention.

When you squeeze the nipple on the end of the nozzle make sure it's flush with the end. You can then slide a piece of steel tube inside the brass fitting, it will last much longer.

Cut the steel tube slightly longer than the fitting and sligfhtly flare the ends to stop it moving.

On my machine I have completely removed the nozzle valve and fixed the nozzle straight to a 3/8 BSP x 14mm hose tail.

 

[13ad13oy]

Have just ordered a raft of fittings and a 20 gal blaster

Any idea of the diameter of steel tube please?

 

[rtbcomp]

Any idea of the diameter of steel tube please?

I'd wait until you get your fittings and measure up - they may be different to mine.

You need fairly thin wall though, if you speed the air & grit up too much it will wear the tube faster.

I actually used a bit cut off the spacer tube used to mount washing machine motors, as I have a supply of dead washing machines!

 

[13ad13oy]

Sorry, Back again!

So I ordered up these parts....

And was thinking that they should be installed something like this:

So I tried the olive on for size... but then its pretty tight so I just thought i'd check....

Coz the nozzle doent fit through the nut either

Would it be OK to wack it all together so it ends up like so...?

Thanks Again..

Btw really impressed with the delivery of the blaster, so quick and although I haven't used it yet, it looks good quality!

Where is the best place for J-Blast?

 

[rtbcomp]

That's a slightly different olive to mine, I wouldn't wack it one - I don't know how strong the nozzle is!

The olive I used was out of a compression fitting, it slid on OK then I used the compression fitting it came with as a tool to compress the olive.

Try warming the olive up and you'll have to drill the nut, it can be a loose fit.

I mentioned earlier about using a bit of steel tube. If you do then the olive has to be at the end of the nozzle, however if you omit the tube move the olive up so the nozzle protrudes into the fitting, this should discourage the grit from whizzing past the softer fitting and wearing it out.

Look up Wolverhampton Abrasives or Hodge Clemco for a local stockist or try this guy on ebay Click

 

[Wedg1e]

I use this bunch for my blast media as they're just down the road from me:

http://www.vixen.co.uk/

Helpful staff, lots of media choice from crushed walnut shells to lumps of granite

For cabinet-specific parts such as tungsten nozzles I go and have myself a new bumhole reamed by Guyson:

http://www.guyson.co.uk/

as I use a DBH2 with matching extractor. I keep meaning to make an extension box for it so I can get longer parts in...