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Old 10-02-2017, 06:08 PM
berntd berntd is offline
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Default Sanblasting pressure pot. I always have trouble. Can someone help?

Hello

I have this cheapish pressure pot on wheels for blasting.

My problem: It blasts for a bit (like a few seconds) but then it is just air until I shake the pot. This repeats all the time. I am mostly blasting with one had while shaking the pot with the other hand to keep it going. Not ideal and it is getting on my nerves.


I use washed riversand from Bunning hardware.
I let this dry for about a year in the sun and when adding it to the pot, I run it through a mosquito metal grit.
The sand is bone dry and pours real well

I run 6 - 8 bar air pressure on the pot.

The pot has a valve at the bottom and I adjust this but then I suddenly get way too much stuff coming throuigh and then nothing again.

I only ever add a few handfulls of grit to the pot.
The nozzle is not getting clogged.

The compressor has a moisture trap AND the pot also has a moisture trap.

What am I going wrong?

Best Regards
Bernt
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Last edited by berntd; 10-02-2017 at 08:42 PM.
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Old 10-02-2017, 06:38 PM
steve.murphy steve.murphy is offline
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Hi Bernd,
Try strapping a electric sander to the side of the pot and leave it on when blasting . The vibrations might help the sand settling.
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Old 10-02-2017, 08:35 PM
berntd berntd is offline
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Thanks but should that even be necessary in the first place with this type of blaster? Mine has has always been like this.

BTW it looks the same as those Harbour freight and others that you see everywhere.
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Bernt
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Old 10-02-2017, 08:57 PM
CaptonZap CaptonZap is offline
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One of the problems with the low end pots is that the suction tube is not sized correctly, nor is an air tube used to aerate the sand before it goes into the pickup tube.
Try placing a 3/8ths tube along side of the pickup, with the bottom end situated so that the air coming down the 3/8ths tube is blowing on the sand being picked up at the entrance to the pickup tube.
What you are trying to do is keep the sand from clumping as it is drawn into the pickup tube.
A sort of analogy is the old time insect sprayers, where the air going over the pickup tube drew fluid up. In this case, the fluid, sand, is drawing air in to mix with the sand, keeping the sand grains separated with air.
Another possible problem is a change in inside diameter of the pickup path anywhere between the sand and the nozzle. If it decreases, (pipe and hose fitting joints ), the sand can pack up.
If you fix the problem, let us know how, if you don't mind.

CZ
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Old 10-02-2017, 09:03 PM
berntd berntd is offline
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Quote:
Originally Posted by CaptonZap View Post
...Try placing a 3/8ths tube along side of the pickup, with the bottom end situated so that the air coming down the 3/8ths tube is blowing on the sand being picked up at the entrance to the pickup tube.




Hey Jerry, I am hoping someone else has already encountered this and will let me know what the problem is or if it is finger trouble from my side.

I have to admit that I do not fully understand what you suggested.
There is a hose going down tha back of the pot and that meets the left arm on a T under the pot. The T's leg goes into the pot underside and the other arm is the output. There is also a valve in the T's leg to control sand flow.

Looks like this but with anopther valve in the tube going to the mixing valve.


I only use this pot ever few months and every time I get annoyed but then it is parked again untill next time because of more pressing things.
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Bernt

Last edited by berntd; 10-02-2017 at 09:29 PM.
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  #6  
Old 10-02-2017, 10:21 PM
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Steve Hamilton Steve Hamilton is offline
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Berndt
A few things to check
Blasting material needs to be very dry.
Air supply also needs to be free of moisture.
The blasting material has to be able to flow , if it clumps due to moisture or too fine like a powder it will not work.

Mine works good until the material level gets down to the bottom 1/4 then I need to shake it.
Setting the valves for air and material flow can be tricky. You need to have enough air pressure to the top of the pot to keep the material flowing. The valve on the vertical pipe controls that.
The valve on the bottom of the tank controls material flow, to much material flow makes a big restriction to the air stream.

How I set mine up
Fill to top with material
Turn material valve off
Turn on main air supply
Slowly turn material valve on just til you get a good material stream
Lastly adjust pot top pressure to keep material flowing.

Good luck
Steve
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Old 10-02-2017, 11:35 PM
berntd berntd is offline
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Quote:
Originally Posted by Steve Hamilton View Post

Mine works good until the material level gets down to the bottom 1/4 then I need to shake it.
I think we are onto it now!!

Like I mentioned, I only ever put a few handfuls of sand into it.
Seems like you have the same problems at those low levels.

Perhaps I just need a higher sand level and the probklem will be sorted.

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Bernt
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  #8  
Old 10-03-2017, 01:20 AM
John Buchtenkirch John Buchtenkirch is online now
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Try mounting this on your tank and Iíll bet your problems are over http://www.ebay.com/itm/Skat-Blast-Sand-Blast-Cabinet-Abrasive-Shaker-6120-10-/352175109688?hash=item51ff45b638:g:tvUAAOSw~oFZzj-0
it worked for me on my blast cabinet. When you mount it donít use continues welds, that could cause tank cracks. ~ John Buchtenkirch
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Old 10-03-2017, 06:54 AM
Jerry Jackson Jerry Jackson is offline
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If shaking the tank restored operation then I agree with other comments that suggest increasing the media level and adding a source of vibration.

I had a different problem. Very often the rubber blast hose (not the nozzle) would become clogged and could only be cleared by removing the hose and shaking it out. Initially my tank did not have a valve to regulate media flow so I added one. I tried to find a valve setting that would prevent clogging and that did reduce the frequency of clogs but they still occurred too often.

I came to the conclusion that the trouble started when the blast air was stopped by release of the nozzle trigger. When the blast air was stopped the media continued to flow into the aspirator & hose until it became full. When the trigger was pulled to start blasting again the over-full aspirator/hose was clogged and the blast air is unable to clear the clog. I reasoned that the way to prevent the clogging was to never allow the media to flow without having full blast air flow That meant I had to open the media valve after starting the blast air and and to close the media valve before stopping blast air.

That procedure is especially inconvenient (to the point of being impractical) when you have to get onto your hands and knees to reach the media valve at the bottom of the tank. I overcame that problem by adding a contraption that allowed me to open/close the media valve using a lever located near the top of the tank. That lever has a pivot point near the top of the tank. The lever actuates a pushrod that leads down to a bell crank and rotary shaft that is inline with the axis of the media valve. The shaft is fitted with a U-shaped member that engages the media valve lever. Raising/lowering the lever opens/closes the media valve.

That modification was successful in curing my clogging problem.

Jerry Jackson
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Old 10-03-2017, 03:51 PM
berntd berntd is offline
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I am with you 100%. I often have the same basic issue as well although the hose does not clog.

Sometimes, when I stop the nozzle and then re-start it, I often get a solid stream of media coming out at reduced speed until the hose has cleared again.

So many issues with such a simple arrangement!


Best regards
Bernt
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Last edited by berntd; 10-03-2017 at 04:06 PM.
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