Damp Media

[Pollys13]

The water traps arn't collecting any water, that said can the grit still become damp and clog in the pot and the traps remain dry?
Cheers.

 

[Country Joe]

Maybe your air supply & nlasting media are already dry to begin with?

CJ

 

[Pollys13]

Maybe your air supply & nlasting media are already dry to begin with?

CJ

Maybe, the grit seems to clog and spurt.

 

[brightspark]

Maybe, the grit seems to clog and spurt.

its probably getting 2 much media through and blocking the jet is it a suction gun or a blast pot if suction the pickup needs more air introduced . if blast pot only let a small amount through in to the blast pipe

 

[Pollys13]

its probably getting 2 much media through and blocking the jet is it a suction gun or a blast pot if suction the pickup needs more air introduced . if blast pot only let a small amount through in to the blast pipe

Is a pressure pot and had the bottom valve fully open. I'm very new to all this.If I close the valve down some, so less grit comes through, will it still come through at the pressure I set on the regulator?

 

[Country Joe]

I was just going to say that maybe @brightspark or @rtbcomp would be better placed to answer, as they do a fair amut of blasting.

But I was too slow!

CJ

 

[brightspark]

also what size jet and what media is being used

 

[Pollys13]

also what size jet and what media is being used

Black SC 120 mesh oriface size I'll check later

 

[Pollys13]

3mm tungsten carbide tip

 

[Dcal]

If you are running the media valve full open a 3mm nozzle will certainly block.
Too much media is less effective than too little.
The idea is to introduce the right amount of media into the air stream. Too much media and the air isn't able to accelerate the particles up to a speed so they can do their work, even if it could get through the nozzle.

 

[fizzy]

I always use a sieve before I fill my pot. Takes out bigger bits.

 

[Pollys13]

If you are running the media valve full open a 3mm nozzle will certainly block.
Too much media is less effective than too little.
The idea is to introduce the right amount of media into the air stream. Too much media and the air isn't able to accelerate the particles up to a speed so they can do their work, even if it could get through the nozzle.

Um I think I'm getting the picture, so any clogging is not, because the grit is getting blocked at the valve and grit exit at bottom of pot? Is too much for the nozzle. So if I have a play with the valve on the bottom of the pot, trying it at various openings through a bit of trial and error I should be able to get a satisfactory result

I always use a sieve before I fill my pot. Takes out bigger bits.

Thanks I looked into this a while back, as only etching glass that has a vinyl mask on it, no bits of this resist come off, so seems no contaminants getting into the grit.

 

[Pollys13]

I have have nother problem I might be able to get some advice on here. On the wall board, have uploaded photo of it. If the pot valve is set to 40PSI the gauge on the pot valve is not the same. Also I have contrived an off off pedal air activated foot pedal using a pinch valve. The design is here https://www.instructables.com/id/Footswitch-Operated-Sandblasting-System/
The pedal itself is connect sort of back to front, the vent and P port. When press pedal air comes from the 2nd regulator on the board and forces the pinch valve shut allowing the grit to flow.
That said there is some latency, the on/off, the grit continues to flow for a second or two.
Will have the system on Tuesday and will post the different gauge readings on the wall regulator and the pot gauge.

 

[Dcal]

I wouldn't get too hung up on the different readings you are getting.
Cheap pressure gauges are always a bit approximate but more likely the readings are a function of the flow rates and pressure drops at different points in the system.
If the regulators and pipework can't supply enough air you will probably have a lower reading at the outlet end compared to the gauge just downstream of the compressor.

If you get settings that work for you, the relative readings on the gauges shouldn't matter.

A bigger issue might be the settings changing as the air pressure in the compressor drops (assuming it's not able to keep up with the blast pot) and as the grit level in the blast pot lowers. The later issue can be greatly improved by installing a proper media valve. The former by taking breaks from blasting or getting another and / or a bigger compressor.

 

[fizzy]

Um I think I'm getting the picture, so any clogging is not, because the grit is getting blocked at the valve and grit exit at bottom of pot? Is too much for the nozzle. So if I have a play with the valve on the bottom of the pot, trying it at various openings through a bit of trial and error I should be able to get a satisfactory result

Thanks I looked into this a while back, as only etching glass that has a vinyl mask on it, no bits of this resist come off, so seems no contaminants getting into the grit.

I wasn't thinking of contaminated grit. Even new grit can have the odd bigger clumps in it which will clog the nozzle. I sieve NEW grit!

 

[Pollys13]

I wasn't thinking of contaminated grit. Even new grit can have the odd bigger clumps in it which will clog the nozzle. I sieve NEW grit!

Ah OK, thanks for the tip I'll get on it.

 

[brightspark]

if its a 3mm jet

I wasn't thinking of contaminated grit. Even new grit can have the odd bigger clumps in it which will clog the nozzle. I sieve NEW grit!

worth doing because if it has a ball valve for regulation its critical to have uniform media .the Clemco ones with flat regulator are more forgiving that's what I copied mine off I have tried a ball valve one on a pot I made and it was useless always blocking and needed re setting

 

[Pollys13]

I wouldn't get too hung up on the different readings you are getting.
Cheap pressure gauges are always a bit approximate but more likely the readings are a function of the flow rates and pressure drops at different points in the system.
If the regulators and pipework can't supply enough air you will probably have a lower reading at the outlet end compared to the gauge just downstream of the compressor.

If you get settings that work for you, the relative readings on the gauges shouldn't matter.

A bigger issue might be the settings changing as the air pressure in the compressor drops (assuming it's not able to keep up with the blast pot) and as the grit level in the blast pot lowers. The later issue can be greatly improved by installing a proper media valve. The former by taking breaks from blasting or getting another and / or a bigger compressor.

Not saying I'll get one, "The later issue can be greatly improved by installing a proper media valve " Which would be? I have a 20 gallon pot in which I've put 25Kg of 120 grit SC. I have another 25Kg bag. Have I put the correct quantity in?

 

[Pollys13]

if its a 3mm jet
worth doing because if it has a ball valve for regulation its critical to have uniform media .the Clemco ones with flat regulator are more forgiving that's what I copied mine off I have tried a ball valve one on a pot I made and it was useless always blocking and needed re setting

Dcal said, " "The later issue can be greatly improved by installing a proper media valve " Is this Clemco the one Dcal refers to or would I have a choice of makes, Clemco sounds expensive? The pot I have is an 20 gallon one from Ebay for 80 quid, with a ball valve. Will upload photo of base ball valve with connected pinch valve assembly on Tuesday.

 

[Pollys13]

I love this forum, always get sensible, rock solid, straight advice, on compressors, air related stuff. Right from the horses mouth, sort of like, why deal with the monkey, when you can deal with the organ grinder direct I love it