brightspark
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my twin comp can run the 3.omm jet no problems at 100 psi and above pressure. roughly about 28cfm
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julianf
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yep - it was more that i was hazy about when anyone would "want" to use lower pressure? I looked up "walnut shell" and was still getting told 100 psi...
brightspark
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dropping the pressure ratio air to media makes it use a lot more media and hardly any cutting power and a bit unreliable
you can drop the pressure a bit and just hold the jet a bit further away from the article being blasted seems pointless though if your using less agressive media
Erie Fred
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I was doing some work on an automated pressure blasting machine that ran plastic abrasive.
I was told that running above IIRC 60 psi causes the abrasive to shatter on first impact, the
manuf said there is no reason to go above that pressure. Cleaning would not improve at higher pressure.
So it was being run at 100 psi.....
And they were going thru large drums of the stuff so fast, they built a venturi suction device
to load the machine from the barrels....
I was told that running above IIRC 60 psi causes the abrasive to shatter on first impact, the
manuf said there is no reason to go above that pressure. Cleaning would not improve at higher pressure.
So it was being run at 100 psi.....
And they were going thru large drums of the stuff so fast, they built a venturi suction device
to load the machine from the barrels....
julianf
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Sadly, I've not made further progress with this.
I'd arranged with Bond to acquire the hose and deadmans, but I think he has gone AWOL (which is absolutely fine, we had no contract) but I've been waiting / hoping that he would return before doing anything else.
I think I'm probably going to "hard wire" (link) the two ports on the control block that would have had the red and yellow, so the unit is "always on" and just stuck a bit of whatever hose I can find on the bottom and see what happens.
I want to clean up a landrover door frame for hot dip galvanizing and it's just another item in the way at present!
I'd arranged with Bond to acquire the hose and deadmans, but I think he has gone AWOL (which is absolutely fine, we had no contract) but I've been waiting / hoping that he would return before doing anything else.
I think I'm probably going to "hard wire" (link) the two ports on the control block that would have had the red and yellow, so the unit is "always on" and just stuck a bit of whatever hose I can find on the bottom and see what happens.
I want to clean up a landrover door frame for hot dip galvanizing and it's just another item in the way at present!
brightspark
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its no big deal not having the deadman if your working close to the pot .just use of the main airline ball valve on the pot ive managed without one for 45 years and blasted my house car wheels motorbike frames and stacks of of other stuff
Erie Fred
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No problem, the home made pot I built, I used standard 3/4" rubber air hose for the sand hose.
I've poured thousands of pounds of sand thru it, and it's finally starting getting thin.
so you'll be fine.
Don't think hydraulic hose will be better, soft is better here for resisting the sand flow.
julianf
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I ended up taking off the control block. It seemed to work, very briefly, at low pressure, but when I turned up the regulator, something altered and it started gassing out the exhaust violently, and that was that...
Clemco has the repair kit for not a lot of cash, but has a minimum order charge of 75, plus 12 delivery, plus vat... And I don't have a dead man's anyway.
I can't find the 15mm, umm, die (?) for my bender so the mess above will do.
What I then found was that the grit control valve just seemed to dump loads of grit down even in the closed position. I opened it up, and it looked like maybe someone has been in their prior with their welder, so I'm unsure if it's "factory" or not. There was a fair gap between the plate that blocks the hole and the hole, allowing anything to just come around the side anyway.
I lifted the plate with a washer under it, which has improved things, however the unit is still a long way from being controllable : (
I've got an, I think, 3mm tungsten nozzle, in the end of a 12mm tube. Seems I'm very much all or nothing, and then the nozzle blocks at the blink of an eye, despite stealing a sieve from the kitchen.
A load more air (I'm running a 3hp compressor, but I also linked in another 3hp before I deleted the valve block) and maybe it would work, excluding the nozzle blocking frequently.
I've not tried more air since removing the control block. I guess that should be my next thing.
There's no real reason why it shouldn't work now, but I'm dubious if the grit valve is how it should be.
Clemco has the repair kit for not a lot of cash, but has a minimum order charge of 75, plus 12 delivery, plus vat... And I don't have a dead man's anyway.
I can't find the 15mm, umm, die (?) for my bender so the mess above will do.
What I then found was that the grit control valve just seemed to dump loads of grit down even in the closed position. I opened it up, and it looked like maybe someone has been in their prior with their welder, so I'm unsure if it's "factory" or not. There was a fair gap between the plate that blocks the hole and the hole, allowing anything to just come around the side anyway.
I lifted the plate with a washer under it, which has improved things, however the unit is still a long way from being controllable : (
I've got an, I think, 3mm tungsten nozzle, in the end of a 12mm tube. Seems I'm very much all or nothing, and then the nozzle blocks at the blink of an eye, despite stealing a sieve from the kitchen.
A load more air (I'm running a 3hp compressor, but I also linked in another 3hp before I deleted the valve block) and maybe it would work, excluding the nozzle blocking frequently.
I've not tried more air since removing the control block. I guess that should be my next thing.
There's no real reason why it shouldn't work now, but I'm dubious if the grit valve is how it should be.
brightspark
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is the grit valve same as the one i use on mine put a piccy up
julianf
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Yes. In your top photo, the part on the bottom right - the "paddle" on that was some way off from the port above it, so the grit could just leak around the side.
I put the washer between the "paddle" and the shaft, so as to raise the paddle slightly and close up the gap.
The fusion of the paddle to the shaft looked like it may have been repaired at some point, which made me think it may have been meddled with. Either that or it always looked a bit ropey. It wasn't clear cut either way. It's an old unit so they may have been more "hand built" at the time this one was made.
Note - yours is way neater than the one fitted to this unit. I have in mind, but would need to check again, that the shapes are slightly different too, but it's the same otherwise.
I put the washer between the "paddle" and the shaft, so as to raise the paddle slightly and close up the gap.
The fusion of the paddle to the shaft looked like it may have been repaired at some point, which made me think it may have been meddled with. Either that or it always looked a bit ropey. It wasn't clear cut either way. It's an old unit so they may have been more "hand built" at the time this one was made.
Note - yours is way neater than the one fitted to this unit. I have in mind, but would need to check again, that the shapes are slightly different too, but it's the same otherwise.
