Converted my sandblast cabinet to pressure blast with foot control

[alloy]

I picked up a nice Skat Blast cabinet and dust collector awhile back to replace another one that was a clam shell design that took up a lot of extra room in my small shop. I had a HF 110lb pressure blast unit on my old cabinet and just transferred it to the new one. I have been using a dead man gun and it's getting tiresome holding it open to blast transmission housings. So I ordered a pinch valve from Richway to add foot pedal control and do away with the dead man gun.

The pinch valve required a separate pressure regulator to adjust the air pressure to about 25 psi above the pressure I'm blasting with. I have the pressure set at about 45 psi for glass beads so I won't shatter them when blasting.

Here is a pic of what I started with on the HF pressure tank.



View attachment 189588
And changed it to this adding a second HF regulator for the pinch valve. I have had pretty good luck with the HF regulators. I have one on my parts washer also.


Here is the pinch valve setup.

I modified the the original "T" fitting. It had a hose nipple on one end, so I milled that off and drilled and tapped it for 3/8" NPT so I could connect the valve directly to it.

On my cabinet I'm using the original hose that came with the HF blaster. I picked up a 3/8" NPT bulkhead fitting for the hose so I could go through the cabinet wall.



I used a foot pedal I got off Amazon to control the valve.



I took the dead man apart and got rid of the handle and body. Just used the nozzle end and put the hose barb fitting on it and put it on the end of my hose. So much easier to handle now and my hand doesn't get tired at all even when doing a complete housing.




If anyone needs links or part numbers let me know. I have about $150 in the mod. The pinch valve was $68, and the rest was the cost of the fittings (not cheap) and the regulator. It sure was worth it to me.

 

[C-Bag]

Hi alloy. I'm a noob here, first post.

I've got a HF bench top blast cab that works off suction and have been contemplating modding it to use a pressure type setup like I think you have done. The stock setup is really a pain. A small pressure tank is only like $60! But I know there would be a lot of details like there always is with anything HF. First off I'd need to make a dump valve from the bottom of the cab to be able to refill the pressure unit. Then the plumbing I'm sure is going to have to be modded. So it sounds like you have done what I'm thinking about.

I'm not familiar with terms like pinch valve etc so I get a little lost in your terminology but I think with some more basic pics and info I should be good to go. Right now the unit is out in my storage shed because of room in my shop/garage and I didnt think I needed the cab until recently when I started wanting to do some machine restoration.

 

[alloy]

Welcome to HM.

I had a large HF cabinet for a very short time then upgraded to a professional quality cabinet.

I don't have any kind of dump valve, just the spring loaded trap door that was in the cabinet. I empty it into a 5 gallon bucket and pour it back into the pressure tank. Not very efficient but with a 110 lb. tank I can go for a long time before having to refill the tank. I am on the lookout on CL for a cabinet that recycles the media. Eventually one will pop up on there.

The pinch valve is a pneumatic shut off valve. It allows me to control the flow with a foot pedal instead of holding a dead man valve open. I do transmission cases and just did a bell housing and holding the dead man open was a pain for anything but very small parts. You don't have to use a pinch valve, you can use a dead man valve. HF sells one, but its completely useless. The one I have I got from Northern Tool. It has replaceable rubber blocks, but the replacements don't fit very well. But its a million percent better than the HF one.

To get the pressure hose through the cabinet I used a 3/8" pipe bulkhead fitting I got off ebay. Then I got 2 hose barb fittings from Ace hardware. I looked at the fittings that Home Depot had and the barb was very short like about a 1/2". Too short to trust while your twisting the hose around for fear it will pop off while your using it. The Ace ones are much more expensive but the barb part of the fitting is much longer. On the hose I just cut the one that came with the pressure tank and attached it to the hose barb fittings. The hose was plenty long for that.

I'm at work now so can't take pics. If you let me know what you need pics of I can try and take them tonight. I'm going out of town tomorrow to a swap meet I don't have a lot of time this evening. I have to load up my display and a bunch of transmissions.

 

[C-Bag]

Thanks. I'm the type who gathers the info, then the parts. So I'm in this for the long haul. And I get you're busy so there's no rush. I've not gotten the cab out of the shed yet or bought the pressure unit either. It's just great to find someone who's done what has been a side project idea for a while.

I've used blast cabs in school many moons ago but never got into the specifics of them. Like how they were plumbed but they were also I think what you are calling a recycling type because there was no separate pressure tank. Besides the inefficient suction setup I also hated the deadman nozzle on the HF because with the big glove it feels like you are wrestling, not working. The foot switch is a great idea, and it happens I have several heavy duty ones I got in a weird batch of pneumatic stuff in a local junk store.

I also looked up pinch valves on eBay and as is often the case, there is a HUGE price range with different specs. Bare with me, but is seems as though your pinch valve is running in the media part of the stream. Is it made to shut of sand/glass beads?

This pressure setup seems to be much more efficient as it seems the pressures are not wide open. I've seen folks say they are running 35/45psi. You also mention "not breaking the glass beads", so over a certain pressure you are blasting too hard and the beads shatter and cause a rough finish? Most of what I would want to be doing with mine is removing paint and cured powdercoat. I would probably put the powdercoat is some stripper beforehand, then blast.

 

[alloy]

I'm never too busy to help someone. You just caught me right before I'm going out of town.

I got the valve from Airpinch. its a 5/8" for $78 plus shipping. Ebay is way too expensuve and didnt have what I needed. And yes it shuts off the media stream. The pinch valve has a Max working PSI of 75lbs. The higher PSI you use it at, the less service life the valve has. But it can be rebuilt. I shoot the beads at 40PSI and have the valve set at about 65-70PSI. The different air pressures are why you see 2 pressure regulators on my setup. The valve has to have greater pressure than the media does otherwise it wouldnt close. And after I had everything done I realized that my pinch valve had air pressure on it all the time and would probably shorten the life of the valve, so I put a ball valve in the inlet line. Which makes the original shut off valve that shut the pressure off to the tank redundant. But I just left it there and added the second valve. Would have had to tear everything apart and re plumb the air to remove it.

The pressure setup is at least for me a dozen times faster. I can clean a part almost as fast as I can move the nozzle.

Actually shooting the beads at a higher pressure gives a great finish, but the beads shatter and turn to dust and they all end up in my dust collector and I have to buy more beads after using them once.

I have removed rust from parts and paint. Just takes a little longer. I think on the powder coat its a good idea to soften it up with paint remover before using glass beads on it. You could probably cut the powder coat with sand, but in my setup I use the beads all the time and would be a pain to switch different media all the time.

 

[C-Bag]

Great info, thanks. That is something I'd want because of running abrasive media, is to be able to rebuild the pinch valve. I'll have to look up Airpinch. It also makes sense that the pinch valve would have to run at higher pressure than the pot is pressurized at.

I've got a lot to learn about the different media too. I'll be honest I'd be terrified to run glass beads on anything that was in a common sump oiling system like an engine or transmission. Even though we were required to bead blast everything when I was in aircraft school. But we pulled all the gallery plugs and were subject to inspection before we could start final assembly. I like the finish, just not how a minute amount can turn an engine into a boat anchor in minutes. But I don't do engine work anymore.

When I used the present cab to take off powdercoat it was not feeding well and I used sand and the finish looked ok, but was too rough when I powdercoated it. It was also hard to find media other than sand. But I was in Tractor Supply and they had stuff called Black Diamond. It's hard to know exactly what it is, but it says it's less than 2% silica. So seems it's not sand, correct? It looks like some kind of mix. It was in two different grits too. I got the finer of the two.

 

[alloy]

I'm not familiar with the black diamond, but I am using black bull glass beads from home depot. They are $26 for 50lbs and if you buy 2 the shipping is free. Tractor Supply has the same thing, but more expensive. I have a thread on here about them, but I can't paste links on the forum from my phone.

I saw on one of the reviews on the black bull being dusty. Well yes if you shatter the beads by shooting at too high a pressure and don't have a dust collect yes there will be dust. I haven't had any problems with that and they give a really nice finish on the aluminum housings I do.

If you were close I would give you my 50lb. HF tank. Its what I started out with and went to the 110lb one so I didn't have to stop so often to refill. It just sits in a corner now collecting dust

 

[alloy]

Here is a link to the Airpinch Valve. A company called Richway sells them.

http://www.richway.com/pinch-valves/valve-selector.html

And here is my thread on the glass beads.

http://www.hobby-machinist.com/threads/good-inexpensive-source-for-glass-beads.55351/

 

[C-Bag]

Seems as though Richway is undergoing some kind of leap into Internet commerce as their site is askew right now. It's ok, I appreciate the link. Still a LOT of options to wade through and I'll be honest, I hate the silly conversion of plumbing silliness to real world dimensions.

Took a look at your thread on glass beads and that made me go back and look again at the stuff Tractor supply sells. In the store it's not clear what it is. But online they say it's something like coal tailings or? The medium grit gets universally panned as garbage, but the fine gets 5 stars. And at $7.99 (I'd forgotten what I paid)for a 50lb bag that's was why I went for it. The medium grit folks said there was weird stuff like wire in it and it really needed to be sifted beforehand. They also complained it clogged nozzles and filtration systems and made a ton of dust. Not so it seems with the fine grit. Still, distressing this could possibly be coal waste being sold as blast media. I don't think I would have bought it if I'd known what it was. This also begs the question are they running it at too high of pressure and shattering it like you said glass beads do? In the specs it says it's one time use.

 

[alloy]

You have to call Richway to order. I had problems with their site also and gave up and called.

I couldn't decipher the pipe sizes on the valves myself they had listed, so I just waited to get the valve and then went and got what I needed to connect it.

Considering what you say about the other media I'm going to stick with glass beads. They do the job for me quite well.

Here is a bulkhead fitting.

http://www.ebay.com/itm/Brass-3-8-x...187006?hash=item43c3d2e47e:g:9BcAAOxyYYlRuHsK