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foy9999
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Wow. I didn't realise you got nozzles that big (for DIY pots).
My new pot (Mattis SB5) came with a 3.5 fitted and I did have some success with it but assumed it was too big so moved down to 2.0 and that's when the blockages started.
Previously I used a pot which had a tubular tungsten(?) nozzle with quite a small orifice
3.5 nozzle
previous type of nozzle (size not known)
Mattis SB5
daedalusminos
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Mine will only 'clog' if left for a while with the nozzle valve not seated properly - the 'clog' clears in a few seconds of using. I've only got a 50l tank, it would be a right ball ache to keep flipping the air ball valve on the tank.there rubbish and clog the blast hosejust use a strait through blast nozzle and operate the pot from air ball valve on the pot supply line
chrisg3103
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I was actually going to post the exact same question earlier today! Stripping and blasting a Freelander 2 and cant find a supplier of blasting media within reasonable driving distance (central belt) the delivery is as much as the media. Ended up buying from here https://problastingsupplies.com/ £30 delivery for £32 of crushed glass 
If I'd read this earlier could of suggested going half in on a half pallet load or whatever you needed, sods law!
If I'd read this earlier could of suggested going half in on a half pallet load or whatever you needed, sods law!
daedalusminos
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You need to be aware of two 'clog' issues with those guns, as described previously, the blast hose can 'clog' if left for a while with the nozzle valve not seated properly - the 'clog' clears in a few seconds of using again but wastes grit and poor performance. The second is nozzle blocking, I found the nozzle tended to block using fine iron silicate at 2.5mm, a gentle tap of the gun would clear it, all was OK at 3mm.
brightspark
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a 6mm nozzle takes a 85 cfm comp to run at 90 psi
Erie Fred
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I'm not familiar with that, do you have a mesh size ?
Dcal
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I use J Blast Supafine all the time.
3mm nossle, and a single 3hp compressor.
It's slow but would blast the amount you've shown in about 10 seconds.
The problem is your set up, not the media.
Dump the toy "dead man" gun and get a 3mm tungsten nossle.
Then, if you are going to do any serious amount of blasting, buy or make a proper media valve.
If you don't want to spend a lot of time waiting on your compressor building up air, buy another (or a bigger) compressor.
Also make sure your air is dry.
I just plan to be doing something else while the compressor is filling back up.
I run the compressor tank at 150psi and the blast pot at 90psi.
When the tank drops to 90psi (in about 5min) go and have a cup of tea.
I suspect your nossle is far too big for the air supply and pipework you have.
A good 3hp compressor should be able to keep a 2mm nossle going at 90psi, if the media is small enough to pass.
This is less than half the size of a 3mm and will do much less than a quarter of the work in same time, but you would be able to blast for longer.
3mm nossle, and a single 3hp compressor.
It's slow but would blast the amount you've shown in about 10 seconds.
The problem is your set up, not the media.
Dump the toy "dead man" gun and get a 3mm tungsten nossle.
Then, if you are going to do any serious amount of blasting, buy or make a proper media valve.
If you don't want to spend a lot of time waiting on your compressor building up air, buy another (or a bigger) compressor.
Also make sure your air is dry.
I just plan to be doing something else while the compressor is filling back up.
I run the compressor tank at 150psi and the blast pot at 90psi.
When the tank drops to 90psi (in about 5min) go and have a cup of tea.
I suspect your nossle is far too big for the air supply and pipework you have.
A good 3hp compressor should be able to keep a 2mm nossle going at 90psi, if the media is small enough to pass.
This is less than half the size of a 3mm and will do much less than a quarter of the work in same time, but you would be able to blast for longer.
Stuff you have fixed today
My water butt has old fire bricks under it (they were free), same tap placement as @dobbslc . The shed which it catches the run off is under a Yew tree so at the weekend I put a lower "total drain" tap in it as the old water in the bottom was a bit smelly, after the weekends' rain it is now...
www.mig-welding.co.uk
foy9999
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I'm a bit confused about the mesh sizes as different sellers seem to use different descriptions. some give grit number, some say mesh size, some give actual size of grains
This is listed as 0.2mm to 0.7mm.
What mesh size is that?
Dcal
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Last photo in the post below.
This is for a pressure pot so not sure it's what you are after.
I use the pressure pot in my blast cabinet as well and it works a treat.
https://www.mig-welding.co.uk/forum/threads/grit-valves-for-cheap-pots.28960/post-1382646
Dcal
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foy9999
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so what mesh sizes are 0.2 and 07? The other person asked me what mash size J-blast Supafine was. I don't know so I give size of the grit and now am told it's 2 mesh sizes. Does that mean all abrasive is sold with more than 1 mesh size in the spec?
foy9999
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This thread wasn't supposed to be about the blasting process so I didn't put full information in the initial post.
I have 4 compressors. Plan is to hook them all together to get more air. At present I've got 2 on the pot and it's better than 1.
main compressor is 3.0HP/150L
2nd compressor is 2.0HP/100L
I've also found (I think) the grit I had more success with years ago. It's from Scangrit and is Olivine (magnesium-iron silicate) from what I can see so am just going to order it online.
Also had a bit more success with the blasting and I found the single-most useful way to keep the grit flowing is by rocking the pot back & fwd or side to side. Don't know why it works and it's obviously not practical if you are far away from the pot but it's working for me
want more of this
I have 4 compressors. Plan is to hook them all together to get more air. At present I've got 2 on the pot and it's better than 1.
main compressor is 3.0HP/150L
2nd compressor is 2.0HP/100L
I've also found (I think) the grit I had more success with years ago. It's from Scangrit and is Olivine (magnesium-iron silicate) from what I can see so am just going to order it online.
Also had a bit more success with the blasting and I found the single-most useful way to keep the grit flowing is by rocking the pot back & fwd or side to side. Don't know why it works and it's obviously not practical if you are far away from the pot but it's working for me
want more of this
brightspark
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if your having to give the pot a kick the media is either damp or its not flowing down through the ball valve properly in to the blast hose . they are rubbish and clog up easily unless the grit is verry consistent in size which is hardly likely unless you sive it from new .fitting a proper reg overcomes that and is verry forgiving. i can fill m,y pot up regulate it and not touch the reg at all once set to the finishThis thread wasn't supposed to be about the blasting process so I didn't put full information in the initial post.
I have 4 compressors. Plan is to hook them all together to get more air. At present I've got 2 on the pot and it's better than 1.
main compressor is 3.0HP/150L
2nd compressor is 2.0HP/100L
I've also found (I think) the grit I had more success with years ago. It's from Scangrit and is Olivine (magnesium-iron silicate) from what I can see so am just going to order it online.
Also had a bit more success with the blasting and I found the single-most useful way to keep the grit flowing is by rocking the pot back & fwd or side to side. Don't know why it works and it's obviously not practical if you are far away from the pot but it's working for me
want more of this
Dcal
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Yes, because otherwise you end up with everything that would pass through the bigger size sieve and that would includes all the dust and bits smaller than 0.2mm which you don't want.
What you do want, is a range of grit particles which are about the right size for the job they are designed to do.
Too big and it will clog and won't go through the nossle, too small and it won't have enough energy (inertia) to do the work and will just create a load of dust.
As grit gets reused (and I reuse it) it gets less effective and becomes more dusty and in fact more like what you would get if you bought a grit which was graded with just the larger size mesh.
You end up with very fine (light weight) grit, which might still work ok and be fine for light work but not for removing mill scale or heavy coatings. I find rust is surprisingly easy to remove.
On your second point, I used to rock my pot all the time and was considering getting a shaker like the ones used on proper soda blast pots, but then I made a media valve and all that nonsense stopped.
I now just set the valve and forget about it.
brightspark
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brightspark
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