Blasting cabinet troubles.

[dobbslc]

Hopefully you guys can help me with some advice getting this blasting cabinet working properly.

I bought it a few months ago and haven't had any time to play with it until now.
I fitted a new bigger led light as the one it came with was not very bright and had some slightly dodgy wiring!





No earth connection to the metal cabinet itself

These are the bits it came with,


I've got it working but I'm not convinced the pipes were on the gun the right way round, I think the air goes on the top and media at the bottom, is that correct?
The hole in the nozzle is about 6-7mm in diameter, is this worn out?

Any ideas more than welcome .
Thanks

 

[dieselsamurai]

Hi yeah air at top media from the bottom

I think that gun is way too big for your compressor though , I have 300lts and 15cfm but sometimes have to switch in the back up compressor which is 12cfm +150lts if im doing wheels or bigger stuff

i use a 5mm nozzle and swap it out when it gets to 7mm as its really noticeable performance drop

whats the compressor you have?

 

[brightspark]

-dont expect too much of it its a suction gun 14cfm is the bare minimum cfm required and will drop in pressure in use the 6 to 7mm nozzle isnt the air blast nozzle size its at the rear of gun and a lot smaller
heres what it looks like inside grit nozzle on left blast air nozzle on right

 

[dieselsamurai]

I think hes saying the ceramic nozzle is 6-7mm the air blast nozzle is much smaller mines 3 or 4mm i cant remember exactly

my friend uses a gun like that with 25fm and its about right

 

[brightspark]

just connect the airline of your comp to the gun and run it see what pressure it will run it at constantly .its preferable it runs at 90 psi without dropping. hardly likely on a 14cfm

 

[dobbslc]

I think hes saying the ceramic nozzle is 6-7mm the air blast nozzle is much smaller mines 3 or 4mm i cant remember exactly

my friend uses a gun like that with 25fm and its about right

Yes 6-7mm is the media nozzle. Sounds like this gun is a bit big for, y compressor then.

whats the compressor you have?

It's the one in the photo above, 150 litre and I think 8cfm.

 

[MetalMonkey]

Well it’s not going to work very well with that kink in the media tube

Media tube goes in bottom, air in the back of the gun - you want about 3 to 4 threads exposed past the lock nut (or about 6 - 8 threads into the gun body) , which should set the nozzle distance correctly - also check inside for any blockages and that the oring is in place and nothing looks worn.

On the media mixer valve at the bottom of the cabinet you need to unscrew the air bleed to allow it to pull in some air otherwise it will struggle and surge a lot. Try about halfway past the hole and adjust from there.

With the compressor you have, it should be possible to get some reasonable results if you aren't in a hurry - but you want to size the nozzle, air jet and media to suit.
These are clones of the Clemco BNP blast guns, parts are readily available. https://www.hodgeclemco.co.uk/wp-content/themes/Hodge Clemco/images/photos/744.pdf

I'm using a boron carbide, which IIRC is the smallest #5 and that is really a bit too big for my compressors (two 10CFM, but will run for a short while on one) - however they last a lot longer than the ceramic, but the ceramic are cheaper to buy to experiment with.
You also need the maximum possible flow from your compressor to stand a chance- so no restrictive fittings, nice large pipes etc.

 

[AVI_8]

Cabinet looks similar dimensions to mine, lighting is 12v DC hence no earth wire to the cabinet.
I‘ve upgraded the hose going to the gun from the mixer valve to 16mm ID

 

[dobbslc]

This was wired with a 240v led light with the inner cores hanging out and no stuffing glands
I'm now wondering what the switch is rated at!

Media tube goes in bottom, air in the back of the gun - you want about 3 to 4 threads exposed past the lock nut (or about 6 - 8 threads into the gun body) , which should set the nozzle distance correctly - also check inside for any blockages and that the oring is in place and nothing looks worn.

On the media mixer valve at the bottom of the cabinet you need to unscrew the air bleed to allow it to pull in some air otherwise it will struggle and surge a lot. Try about halfway past the hole and adjust from there.

Thanks for this.
The "bolt" in the back of the gun was wound all the way in which I think put the air nozzle past the point the media comes up, I thought that wasn't right.
I did wonder about that hole in the mixer valve! I think it was fully open.
There was a load of crapè in the gun, looked like parts of a plastic bag and an electrical crimp connector!
Thanks for all this advice guys! I've always wanted to have a blaster but until now never got the chance, I have tons of stuff to blast up and paint

 

[AVI_8]

I bought some led strip lights 12V and have them wired to a spare car battery through the original switch, they’re very bright, I‘ve seen people use a powerful light resting on the external glass shining in and that seems to work also.

 

[dobbslc]

Stick a wire mesh on that screen

It's a bit scratched up already, looks like it's got another layer on it inside but I don't know what it yet.

 

[not done it yet]

My first thought? That is being run on a compressor with a 13A three pin plug (so no more than about 10cfm, at tops - and quite likely less).

I’m no expert on these things but they are usually touted to do rather more than most can reasonably expect - and require rather more air than they claim.

 

[bricol]

My biggest issue with a similar cabinet was the crap it knocked off whatever item I was blasting, then fell down and got sucked up with the media - which the blocked the system somewhere. A couple of cheap bonsai gardening riddles allowed me to filter out the crap.

Second was the dust prevented me seeing what I was doing - the extra lights I added, reflected off it just as bad as the original - two bathroom fans blowing into one side, vented out the other via cyclonic separator helped.

 

[MetalMonkey]

Just to give you some idea of what is possible with this set-up.
I use that same style of gun (genuine clemco), that exact foot-pedal and media valve in a home made cabinet with a wood-chip extractor to control the dust.

I've had these in to blast and refurbish this week:

These were done with aluminium oxide media - I could have spent a lot more time on them and got more of the pitting out, but it is good enough for treating with phosphoric acid.
I did "pre-treat" with a needle scaler and wire brush to get the worst of the flaky stuff and all the mud and crap off so it doesn't end up in the bottom of the hopper and block the gun.

Before:

After:

I find the cabinet very useful for small stuff like this, and brackets and components - anything much bigger like a wheel or large suspension component I send out, as it is too much effort to try and do.
I don't need to do a lot now, otherwise I'd consider buying a pressure pot for the larger stuff.

You could do all this on one compressor - I often do just use one for small bits, but you can find yourself waiting for it to catch up - which is why it is nice to have the second one available to assist.

Next project is to build a cyclone for it to try and reclaim the media that is currently being distributed over the garden.
Good extraction makes or breaks it IMO.

 

[brightspark]

My biggest issue with a similar cabinet was the crap it knocked off whatever item I was blasting, then fell down and got sucked up with the media - which the blocked the system somewhere. A couple of cheap bonsai gardening riddles allowed me to filter out the crap.

Second was the dust prevented me seeing what I was doing - the extra lights I added, reflected off it just as bad as the original - two bathroom fans blowing into one side, vented out the other via cyclonic separator helped.

if im using the suction gun in mine i let the media drop in to a bucket

Just to give you some idea of what is possible with this set-up.
I use that same style of gun (genuine clemco), that exact foot-pedal and media valve in a home made cabinet with a wood-chip extractor to control the dust.

I've had these in to blast and refurbish this week:

These were done with aluminium oxide media - I could have spent a lot more time on them and got more of the pitting out, but it is good enough for treating with phosphoric acid.
I did "pre-treat" with a needle scaler and wire brush to get the worst of the flaky stuff and all the mud and crap off so it doesn't end up in the bottom of the hopper and block the gun.

Before:


View attachment 417159

After:

View attachment 417160


I find the cabinet very useful for small stuff like this, and brackets and components - anything much bigger like a wheel or large suspension component I send out, as it is too much effort to try and do.
I don't need to do a lot now, otherwise I'd consider buying a pressure pot for the larger stuff.

You could do all this on one compressor - I often do just use one for small bits, but you can find yourself waiting for it to catch up - which is why it is nice to have the second one available to assist.

Next project is to build a cyclone for it to try and reclaim the media that is currently being distributed over the garden.
Good extraction makes or breaks it IMO.

i have a big fine filter up the inside of cabinet going out to a woodchip extracta decent media just drops back down and just fine crap goes out the filter .i use a rubber mat in the cabinet with just a 1 inch gap all round . the media falls down and it stops the media been blown back up cauising a dust storm

 

[dobbslc]

I've found another gun!
It's a bit smaller so hopfully works better.

 

[dobbslc]

I finally had a go at some blasting tonight!
I've adjusted the bleed screw and gun and unkinked the media pipe then tightened up all the air hoses as one blew off ! Made me jump a bit
Not bad as a first attempt.


The hoses look knackered and the black air feed one feels very thin, it's got RPVC marked on it, is this the right stuff?

Stick a wire mesh on that screen

Doh!


Although this was because I dropped something on it

 

[dobbslc]

There is no mesh. It seems thes a piece of glass and perspex in there.

 

[dobbslc]

I'm still getting nowhere with this
I've tried a new blast gun with smaller nozzle but it just won't work. I've tried a pressure pot I bought a long time ago but I'm still getting no grit coming out of the gun
I'm only getting 35 psi at the pressure pot gauge so I'm now wondering if the compressor is knackered!
It's a SIP 150 liter 3HP one that has done very little work since I've had it, how long should it take to fill to up?



Any help appreciated.

 

[MetalMonkey]

What is the pressure guage on the tank reading when you turn the regulator to max?
If it isn't showing you something like full tank pressure (probably around 10 bar) then you have a problem.

Thread discussing pump up times here:
https://www.mig-welding.co.uk/forum/threads/how-long-does-your-compressor-take-to-fill.111381/

If you aren't getting anything much out of it, then it could be an issue with the regulator on the compressor - looks similar to a clarke one I had which wasn't great at all.
Or the pressure pot gauge might be knackered and giving a false reading.

Lots of variables, so go back to basics and fault find it logically.

One option would be to get a pressure gauge that you have some confidence in and screw an airline fitting on it, then take a reading at the tank reg, make sure they agreed, then move to the end of the hose and check there.
That way you have eliminated the regulator, hose and couplings. You would expect a few psi pressure drop, but it should be minimal over a short hose.

However just because you have pressure doesn't necessarily mean you have flow.
Another option would be to remove the regulator from the tank, stick in a reduction bush, put your hose directly on it, and then see if you have an improvement in performance, that would show if the regulator was the issue.
Make sure the pressure pot is rated for whatever the tank pressure is though.

Its just going to be a process of working through it methodically until you find the issue.
Do you have any other air tools, a tyre inflator? Anything that might give you an indication of if you are getting the correct pressure and performance.