gun with trigger for bead blasting cabinet

[pgrbffParticipant @pgrbff]

I have a small blasting cabinet, cheap from China which I use with glass beads to clean up bits and bobs.

I have always wondered if getting a proper gun would improve the performance?

My compressor is the biggest I can manage on the 5kW single phase supply the Italian electricity board allows me. In theory, it gives me 10.1 CFM free air.

Any suggestions?

Edited By pgrbff on 31/03/2021 18:42:08

[pgrbffParticipant @pgrbff]

[Dave HalfordParticipant @davehalford22513]

Even the small Guyson gun is not very good.

The now not so cheapy chinese pressure pots will give you the most improvement, if you get a 2mm carbide nozzle and mount it direct in the hose you can ignore the CFM ratings . The on /off valve on the end of the hose only lasts minutes if you keep it.

All you need to do is rig up a spring to close the air inlet valve and some kind of foot switch/lever to over come the spring to open it.

I'm sure you can find a nearer supplier than Belgium.

Edited By Dave Halford on 31/03/2021 19:14:39

[old martParticipant @oldmart]

There are lots of guns with triggers and a set of nozzles on ebay, you will have to blast in short bursts with any gun if the air supply is low volume.

[pgrbffParticipant @pgrbff]

Posted by Dave Halford on 31/03/2021 19:13:45:

Even the small Guyson gun is not very good.

The now not so cheapy chinese pressure pots will give you the most improvement, if you get a 2mm carbide nozzle and mount it direct in the hose you can ignore the CFM ratings . The on /off valve on the end of the hose only lasts minutes if you keep it.

All you need to do is rig up a spring to close the air inlet valve and some kind of foot switch/lever to over come the spring to open it.

I'm sure you can find a nearer supplier than Belgium.

Edited By Dave Halford on 31/03/2021 19:14:39

I have one just like that. The compressor just about copes for 10-20 seconds. What I need is a gun that will work in my cabinet.

The guyson 400 with trigger, hoses, pickup etc will cost somewhere around £200. Too much if it doesn't work.

The std valves will work fine with the cheap Chinese pots if you make sure you open and close it fully every time.

Edited By pgrbff on 31/03/2021 21:38:30

Edited By pgrbff on 31/03/2021 21:41:29

[pgrbffParticipant @pgrbff]

Posted by old mart on 31/03/2021 20:02:38:

There are lots of guns with triggers and a set of nozzles on ebay, you will have to blast in short bursts with any gun if the air supply is low volume.

There are lots on eBay. Probably all just like the one I have already. I'm trying to find something that might improve performance.

[Phil PParticipant @philp]

I am afraid there is no substitute for more air capacity, most blast guns will only give mediocre results if you are trying to use a small compressor that cannot keep up with it.

The comment about the Guyson 400 not being any good is a bit unfair, that gun performs extremely well if it is set up correctly and has an appropriate air supply. The design goes back many decades and despite many attempts to come up with a better design over the years, it still remains one of the core products for Guyson's. In fact many people buy a Guyson gun to upgrade other makes of blast cabinet.

Phil

[not done it yetParticipant @notdoneityet]

Another air receiver would lengthen the time you can operate without losing pressure – presumably below 6 Bar?

It would, of course, not increase the total work-time – but it would allow a longer stint before having to stop (and wait longer while the pressure rebuilds in the receiver(s).

How many kW is your compressor? Is its rating in free air deliverty or air displacement? Mine is 2.2kW and used to keep up reasonably well when I grit blasted with a copper slag grit. My compressor operates at 10 Bar. There is, as stated above, no substitute for a copious air supply at a good pressure.

[Dave HalfordParticipant @davehalford22513]

Posted by pgrbff on 31/03/2021 21:37:26:

Posted by Dave Halford on 31/03/2021 19:13:45:

Even the small Guyson gun is not very good.

The now not so cheapy chinese pressure pots will give you the most improvement, if you get a 2mm carbide nozzle and mount it direct in the hose you can ignore the CFM ratings . The on /off valve on the end of the hose only lasts minutes if you keep it.

All you need to do is rig up a spring to close the air inlet valve and some kind of foot switch/lever to over come the spring to open it.

I'm sure you can find a nearer supplier than Belgium.

Edited By Dave Halford on 31/03/2021 19:14:39

I have one just like that. The compressor just about copes for 10-20 seconds. What I need is a gun that will work in my cabinet.

The guyson 400 with trigger, hoses, pickup etc will cost somewhere around £200. Too much if it doesn't work.

The std valves will work fine with the cheap Chinese pots if you make sure you open and close it fully every time.

Edited By pgrbff on 31/03/2021 21:38:30

Edited By pgrbff on 31/03/2021 21:41:29

In which case if you spend 15 to 20 Euro on a 2mm carbide nozzle ( it's just a straight tube – no flanges) fit it straight on the end of the hose with a motor type hose clip though it will need packing out with a bit of garden hose. A 15cfm 3hp compressor will keep up with a 3mm one. I had a Guyson 2000 cabinet fed with 25cfm and it was very slow.

If that's too much trouble perhaps your cabinet pickup size needs reducing you can make the paint pot suction type trigger guns work better by restricting the amount of media they can suck. It also helps if there's a tube that allows air down to the very end of the pickup.

[Phil PParticipant @philp]

Dave

You are spot on with your comments regarding air to the pickup.

The operation of the gun relies on the fact that a vacuum is generated in the gun body and it is that vacuum which draws media up the hose and entrains it out through the nozzle.
But unless the correct ratio of air and media is travelling up the hose it will never perform correctly, most people tend to have an over rich mixture and that causes the gun to pulse, the media never gets up to full speed and the performance drops off, if the mixture is too lean it will probably be exiting the nozzle with enough velocity, but there will not be enough of it to be very effective. It is a fine balancing act to get it just right.

At the point where a Guyson pickup fits, it can be adjusted in and out of a mixer box which sets the mixture to the correct ratio, it will need re-adjusting if the media type changes significantly. glass bead performs very differently to say a steel shot or other heavy media.

The condition of the actual media being used also has a great bearing on the performance of a blast cabinet as well.

Phil

[pgrbffParticipant @pgrbff]

Posted by Phil P on 31/03/2021 22:05:22:

I am afraid there is no substitute for more air capacity, most blast guns will only give mediocre results if you are trying to use a small compressor that cannot keep up with it.

The comment about the Guyson 400 not being any good is a bit unfair, that gun performs extremely well if it is set up correctly and has an appropriate air supply. The design goes back many decades and despite many attempts to come up with a better design over the years, it still remains one of the core products for Guyson's. In fact many people buy a Guyson gun to upgrade other makes of blast cabinet.

Phil

ABAC in the UK say I have 10.1 cfm free air, that should be enough for the Guyson 400 which can operate as low as 8cfm.

[pgrbffParticipant @pgrbff]

Posted by Phil P on 31/03/2021 23:14:56:

Dave

You are spot on with your comments regarding air to the pickup.

The operation of the gun relies on the fact that a vacuum is generated in the gun body and it is that vacuum which draws media up the hose and entrains it out through the nozzle.
But unless the correct ratio of air and media is travelling up the hose it will never perform correctly, most people tend to have an over rich mixture and that causes the gun to pulse, the media never gets up to full speed and the performance drops off, if the mixture is too lean it will probably be exiting the nozzle with enough velocity, but there will not be enough of it to be very effective. It is a fine balancing act to get it just right.

At the point where a Guyson pickup fits, it can be adjusted in and out of a mixer box which sets the mixture to the correct ratio, it will need re-adjusting if the media type changes significantly. glass bead performs very differently to say a steel shot or other heavy media.

The condition of the actual media being used also has a great bearing on the performance of a blast cabinet as well.

Phil

Guyson said the pickup was important. They don't have images on the website of their pickup, but they promised to send me some images with a quote.

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