Getting my sand blasting set up right - It's driving me crazy !!

[dannyp]

a 90cfm- screw comp runs a 6mm jet no problem. ive run one for -years

the 130 cfm is well onto of the 6mm jet. the problem isnt with the compressor running it, it's just i'd like a bigger jet.

then you end up with a poorly 600 cfm unit been abandoned on you well it'd be rude not to fix it to play with, and hopefully work it

 

[tedmagnum]

Well I've had an interesting morning.... Very frustrating.

My new Nozzles arrived today. Totally the wrong size. They're for blast pots not cabinet guns. Bugger.

So I tried pulling my big Orange blast pot out and gave that a go. What a waste of f**cking time... It's just terd. The nozzle clogs all the time and I can't seem to maintain any pressure in it. Maybe the media is too coarse. I just don't know. I tried every single setting on it. Cleaned it out 20 times etc. The only way I can get air and media to come out at the same time is to remove the nozzle entirely and that obviously just doesn't work.

I also tried linking up two compressors to my airline to see if it will get my blast Cabinet working again.

I used a Y-piece. All that happened is that my bigger compressor ended up pressurising the smaller one and blowing it's safety valve. Am I missing something here ???


If anyone knows what they're doing and lives locally to the Wirral, I will happily invite you in and fill your car with beer if you can get my set-up working reliably.


I have been totally static all week with this problem now. I've got work stacking up, no cash to pay anyone else to do it and winter drawing in fast.

Do I just bite the bullet and buy a new 28 CFM Compressor on my credit card ???

Why did I become self employed again ?????????

 

[rtbcomp]

I used a Y-piece. All that happened is that my bigger compressor ended up pressurising the smaller one and blowing it's safety valve. Am I missing something here ???

Sounds like the big compressor is working at a pressure greater than the smaller one's safety setting. Either install a non-return valve to stop air going from the big compressor to the smaller one or reduce the cut-off pressure of the big one to about that of the smaller one.

Is the blast hose punctured? Sometimes this can allow the pressure to drop in the hose so the pressure difference between the top & bottom of the pot is increased, this will cause too much grit to be introduced into the air.

What are the sizes of the compressor you're using?

The way I set mine up is

1) close all valves
2) open the bypass valve
3) open the main valve and wait for any residual grit to clear
4) open the bottom valve a SMALL about at a time, it can 20 seconds or so for it to stabilise

When you can just see the grit coming out of the nozzle with a decent blast of air the mixture is about right.

 

[tedmagnum]

My main compressor is a Clark 150L , 14CFM.

The smaller one is much smaller. 1.5HP , 7CFM. Obviously a big difference there...


The problem started about 10 days ago on my cabinet. The nozzle in the gun kept clogging but the media was getting old and I was blasting grimy parts. It was working, but clogging up every 5 mins.

So I bought some new media which was a medium grit. I cleaned everything out and now I get almost nothing out of the gun.

I'm guessing that the media I bought is too coarse. Too heavy for the vacuum. It is 0.2 - 1.5. I thought it would speed things up.

Before I go out and buy a new compressor, I need to make sure I need one.

Today I've bought online:

A brand new gun (only £18).
25kg of Jblast Supafine (I know this works well, i've used it in the past)
A selection of nozzles.
New perspex screens ( At £10 a pop and last about 5 hours before they're opaque).

I'm going to be scratching my **** for 4-5 days until they're delivered so I'll report back when I've got it all done.


I've found a 28CFM Clark for under £1000..
http://www.tool-net.co.uk/p-343342/clarke-se29d270nd-240v-270l-air-compressor.html


I'm learning that sandblasting is like my Italian girlfriend. Expensive and temperamental.

 

[rtbcomp]

The J-Blast should work , if a little dusty.

The perspex screens fit on the OUTSIDE of the glass in case it shatters, these are the sort of things you want for the inside, there are a variety of sizes & prices

http://www.ebay.co.uk/sch/i.html?_f...en.TRS0&_nkw=blasting+cabinet+screen&_sacat=0

I'm intending to modify my cabinet to take a roll of acetate film, feed spool at the top of the window, bring the film through under the glass and out the bottom. Just pull a fresh piece through when you can't see through it anymore.

 

[500e]

The thing is you want reliability & you need it know ! not in 7\10 days find some one who does it for a living.
no mess No running out of media\jets hose \compressors

 

[tedmagnum]

My screen is 600x300. It's too expensive to keep buying the glass and throw away screens.

I had been replacing the lot with 3mm perspex which does the trick. It lasts about 5-10 hours of good blasting.

A film roll would be nice....

From that link I've just bought 10 screens for £32. I'll try them and see how I go..


Once I get down a reliable nozzle, media and screen set up then I'll buy spares so I can keep going.

 

[rtbcomp]

Don't follow - you keep the glass and change the screen, I would have thought that was cheaper than perspex.

 

[tedmagnum]

When I bought the blaster the glass was broken and there were no screens. I just assumed there was a piece of glass and a sheet of perspex for safety. Like I said, I'm learning everything the hard way..

I threw the glass and bought a piece of perpsex just to keep going. I did look for disposable screens but I could only find expensive ones so kept the perpex.

I'll give these eBay ones a go..

Thanks for all the advice.

 

[clarkey31]

I take it you are sieving your media even the new stuff

 

[jackojacks]

looking at the link That blast pot you have should work fine and it shud work fine with your 14cfm compressor all be it a bit short of air ie taking a bit long to do the job but it shud be capable of doing the blastwork ok i know this because this is pretty much my set up . and i have been doing it for years also using j blast supa fine its all down to your ball valve settings and nozzle size. the only mod i did to stop pot clogging was to bungie strap an old electric drill to the side of the pot with an offset cam in the chuck to work as a pot shaker that transformed my blast set up keeping the media flowing untill the pot is empty. yes a bigga compressor would help but its not your problem at the moment.

 

[jackojacks]

As above you must seive your media thats rule number 1 in blasting in my book.. dont try to save time on this job it has to be done especially when using such small nozzles.

 

[paceman1]

what are you blasting and what media are you useing

 

[paceman1]

I bet the media is damp

 

[tedmagnum]

I've never sieved it no... I didn't know I had to :/ its always seemed okay !!!!

What's the benefit ???

 

[brightspark]

new grit wont need sieving its dry and --consistent just coarse sieve and fine sive the dust out if u re use

 

[paceman1]

well I would have thought you needed the media at a reasonable size to go through the nozzle what are you blasting

 

[jackojacks]

yes as above its consistant and ok when new but when re used it needs the crap paint ect siving out of it you must do this or you will get nowhere never put it in the pot without

 

[brightspark]

also using ballvalves on the cheaper pots have a tendancy to clog up easily. spend about 70 quid on a good one and there more consistent and hardly block up

 

[slim_boy_fat]

new grit wont need sieving its dry.....

Assuming it hasn't sat in the back of the Courier's wagon, sloshing about in water/damp .............like some parcels I've had delivered.