Technical Blast cabinet help

Hi need some help. I have an older cabinet it's a scatblast. I turned it into a gravity feed. It has all new parts. Using a new pedal controlled gun. Have no kinks in the lines, sand is new and dry. Air is dry. You can see the sand come up the tube to the bottom of the gun then it stops. Any help would be greatly appreciated. Thanks for your time

 

Did you replace the ceramic nozzle in the gun, there are different sizes for different grits of sand,

My gun just has one hose. HRP

 

It has the nozzle it came with. I am using black beauty sand through the gun.

 

I've worn out the brass fitting for the media intake in the gun (air leaked by it) and had to replace it. From your description the air traveling through the gun is not "vacuuming" the abrasive properly that would leave me to conclude there is an issue within the gun itself, I assume you get lots of air coming out of the nozzle. There are times trash got in mine and I would just put the palm of my hand over the nozzle and hit the pedal to blow air back through the abrasive supply line.
For what it's worth I am having problems with the media not flowing to the intake I am thinking of getting a vibrator of some kind to keep the media moving. Be sure to check to make sure that is not a problem.

 

When you press the pedal does any air blow out of the gun?
If the gun is new have you taken it all apart to see if there may be a hairball in there?

 

I had it apart ones but will do it again just to double check it. It is a new gun that has never been used.

 

You need a siphon tube for the sand supply

 

Is that small ball valve open? Is it supposed to be?

 

I have tried it all the way open and all the way closed and everything in the middle. It's all most like it does not have enough suction. You can see the sand moving but its not doing anything

 

You have it hooked together like a Pressure Pot. That isn't going to work, PEROID

 

If you don't have good media, it can have clumps in it that will impede the flow to your nozzle. Here is a helpful article.

https://www.guyson.com/guyson-blast...e/suction-blast-basics-optimizing-media-flow/

 

I am trying to convert it to a gravity feed from a siphon I have seen done to many cabinets. I just don't know what is screwing up. You can see the sand coming out but it's not doing anything. Here is a pic on how somebody else did the same thing I may just go back to the siphon feed if I can't get it to work

 

I have a siphon tube in the hopper and it works great. You are changing it to gravity feed what’s the advantage of that? The old siphon/5 gal. Bucket never too well.

 

They say it makes the sand flow more consistently and the gravity feed gives a steady flow of sand to the pick up. So they say not working to well for me. Worked well as a siphon feed just had to keep kicking the cabinet so the tube would stay full.

 

Maybe if the air is drawn in on the other side of the hopper feed it would work.

 

I have the HF cabinet and have done a couple of mods to the pickup tube to get the airflow through the media feed tube. works well, except the flow is erratic, stops or slows a lot occasionally. What I've found makes it free up is holding my finger over the end of the gun and pulling the trigger. That sends a blast of air down the pickup tube and it starts flowing. Maybe try that with yours? If there is a clog that should free it up.

 

It is possible that you might have a chunk of rust or paint that has blocked the feed where the sand flows out of the hopper into the line. You could take a rod or piece of wire & poke it down thru the expanded metal floor into the sand to the bottom of the hopper & work it around & see if that starts the flow. We had a Kansas Instruments bead blast cabinet at work that would do that constantly.

 

I wouldn't put my finger over the tip if the air valve was open on the bottom.

 

I see no advantage in doing this.

I have a Trinco Dryblast 36, and I have been using it for almost 20-years. It was used when I got it. I replaced the pickup tube with a piece of conduit about 7-years-ago. Zero issues after that. It works great. I use everything from Black Beauty to 180-grit glass.

I have a refrigerated dryer and a monster compressor. I can blast at a 100% duty-cycle until the window protector is to cloudy to use.

 

Those guns work by venturi effect. The tip has to be in the correct position in relation to the feed tube outlet and the end of the feed tube has to be positioned so that the media can be drawn into the air stream. Before I did anything at all to the gun I'd dump the media out of the hopper and only put in a coffee can's worth of media in the hopper and try that. Gravity feed units are picky about how much weight is pushing down on the media. I'd you dumped a 20 lb bag in that is most likely the issue.

 

There are some good tips here that may help solve my inter-mitten media flow problem.

 

Could we see a pic of your setup and modifications?

 

You don't have the tapered orifice turned around do you?

 

You mentioned your using black beauty. I’ve used it with large pressure pot blasters and it was very large media. I’m not familiar wether there is different sizes but the stuff I used would probably not pass through your set up. Cabinet media is much finer.

 

I use #6 glass beads. It leaves a better finish, and it is not as bad as sand, health-wise.

 

To get good media flow with the plumbing done as in your photo you need to be able to pressurize your cabinet. Blast Cabinets aren't built to work that way.

 

I use the Black Magic and one thing I found is that I needed the "Extra Fine" grade they sold. The next size up clogged the gun but the finer stuff works pretty well. I buy mine at Tractor Supply.

Also if you look up on Utube the modification that people do to the suction tube on HF units and others, it helps a lot. Last thing is the air supply. I use the fittings with larger holes in them to insure there is plenty of air flow. You need volume as well as pressure.

 

No modifications.

What I replaced with conduit was the pickup tube. I made a duplicate of what was there, just without the rust holes.

 

Air volume is more important than line pressure and you need plenty volume. Pressure may very pending job at hand.

 

Have you seen the YouTube 'right way to dial in your harbour freight blast cabinet metering valve upgrade' ? Might help. Some insights in the questions too.

Seems like 45 to 65 psi is what required. 3/8 air line. 1/2 on the media.

I've been contemplating this conversion, backyard style, like the op has. If the YouTube are to be believed it has to be a good move!

Edit. Also, take a look at the YouTube 'direct comparisons of 3 harbour freight blast cabinet metering valve upgrades' (longest fucking YouTube title ever?). The guy is saying the plumbing parts version is a flip a coin matter with his improved product! Comparing the plumbing version shown with what you've pictured (all YouTube extracts) yours necks down prior to the air inlet whereas the one shown in the 3 comparisons necks down afterwards and the guy stresses the importance of a voluminous swirl area where the media gets picked up, which looks to me to be much greater than that in your version, by virtue of where the necking down occurs. I'm trying to learn too!!

Chris