Home Made Sandblaster

[Tazza]

As most of you will already know, I'm re-building a 751. I needed to get it all sandblasted but to get it "professionally" done they wanted about $1,000. With the help of some of the members of this board they gave me all the info i needed to build one.
I ended up using an old LPG cylinder from a fork lift and some old gas pipe and fittings i had. So far it has only cost me the sand i put in the pot. I haven't gotten around to mounting it on wheels, i mainly wanted to set it up so i knew if it would work, which it does!
The biggest problem is the air it requires! i have 2 compressors setup in parallel for a total of 28CFM. With a 1/8" nozzle i can maintain 90PSI, the compressors run flat out at that pressure. I have an old 2 pot V style compressor here, but i need to hook it up to an engine. I don't know what sort of flow it would provide, but it looks pretty big.
Piccies, i know it doesn't look great, but it sure does work!

If interested, higher rez pictures are available here: http://users.tpg.com.au/tazza_/sblaster/

 

[perry]

Good job Tazza, tell me, how do you load the sand?. The pots I've seen the sand is dumped in the top.

 

[Luthor]

Good job Tazza, tell me, how do you load the sand?. The pots I've seen the sand is dumped in the top.

Good one Tazza. How long did it take to clean the wheel, what type of media are you using?

 

[Tazza]

Good one Tazza. How long did it take to clean the wheel, what type of media are you using?

I'm using ilminite (spelling) basically black sand. Filling is a bit of a pain in the butt, i'm using a port on the top that is used for the fuel gauge. Its a square block held in place with 4 screws. I figure i won't be loading it up all that often so the minor inconvenience of removing and installing the 4 screws isn't THAT bad.
The top side of the wheel took maybe 5 minutes? probably less. The paint on the hubs isn't that tough. Even the *good* paint still gets eaten up pretty easily.
I really need more air, the 1/8" nozzle holds the pressure around 90 PSI but the spray is a little narrow. A larger nozzle would help cut the paint and rust much easier but you need to keep the pressure up. Light rust and paint disappears really fast, you just wave it over and its clean!
I did pay a tarp down to catch a bit of the media, and it does work. Just sweep it up and run it through fly screen to get the chunks out.
I may try and get a small video of it running, see how it turns out.

 

[Land-Tech]

I'm using ilminite (spelling) basically black sand. Filling is a bit of a pain in the butt, i'm using a port on the top that is used for the fuel gauge. Its a square block held in place with 4 screws. I figure i won't be loading it up all that often so the minor inconvenience of removing and installing the 4 screws isn't THAT bad.
The top side of the wheel took maybe 5 minutes? probably less. The paint on the hubs isn't that tough. Even the *good* paint still gets eaten up pretty easily.
I really need more air, the 1/8" nozzle holds the pressure around 90 PSI but the spray is a little narrow. A larger nozzle would help cut the paint and rust much easier but you need to keep the pressure up. Light rust and paint disappears really fast, you just wave it over and its clean!
I did pay a tarp down to catch a bit of the media, and it does work. Just sweep it up and run it through fly screen to get the chunks out.
I may try and get a small video of it running, see how it turns out.

Pretty cool setup. I have a small gravity fed hopper that runs a 1/4 " nozzle and I've never had enough compressor. I would hook it up to my dump truck and the extra tank capacity seemed to help.Do you have a large tank you can plumb in maybe?
My hopper is open on top but I think it works differently than yours. My neighbor has a a pro model mounted on a tandem axle trailer. Compressor is run by a 4 cyl Deere. He let me use it to do the box on my dump. took 4 hr and 500 lbs of glass beads. $30 per 100# bag. His machine had a pressurized pot and was kind if a pain to load. It had maby a 6" port and a funnel to load it with. retail would have been about $1000 Scott

 

[Tazza]

Pretty cool setup. I have a small gravity fed hopper that runs a 1/4 " nozzle and I've never had enough compressor. I would hook it up to my dump truck and the extra tank capacity seemed to help.Do you have a large tank you can plumb in maybe?
My hopper is open on top but I think it works differently than yours. My neighbor has a a pro model mounted on a tandem axle trailer. Compressor is run by a 4 cyl Deere. He let me use it to do the box on my dump. took 4 hr and 500 lbs of glass beads. $30 per 100# bag. His machine had a pressurized pot and was kind if a pain to load. It had maby a 6" port and a funnel to load it with. retail would have been about $1000 Scott

I do have another LPG tank i guess i could use but i really don't know if it would help much. With both compressors hooked up and running flat out, it will hold at 90PSI. I can run it for say 5 mins and its still at 90.
I could always make a smaller nozzle and see if that holds a higher pressure but the smaller the nozzle the less cutting it will provide. But i can only try it i guess.
I cheated with the nozzles, they are simply old pieces of steel bar that i drilled a hole in and threaded one end to fit the hose to. When i work out what works best i'll make a bunch and heat treat them. When they wear out simply make a new one.

 

[jerry]

I do have another LPG tank i guess i could use but i really don't know if it would help much. With both compressors hooked up and running flat out, it will hold at 90PSI. I can run it for say 5 mins and its still at 90.
I could always make a smaller nozzle and see if that holds a higher pressure but the smaller the nozzle the less cutting it will provide. But i can only try it i guess.
I cheated with the nozzles, they are simply old pieces of steel bar that i drilled a hole in and threaded one end to fit the hose to. When i work out what works best i'll make a bunch and heat treat them. When they wear out simply make a new one.

Good job on that. I especially liked the homemade nozzle, that is a machine most people could build with stuff they already have and use your photo for a guide. Is there a valve on the bottom of the tank to meter sand flow into the air stream? I have seen blasting cabinets built from oil tanks and chest type food freezers maybe I will get motivated now and make one for our little blaster.

 

[Tazza]

Good job on that. I especially liked the homemade nozzle, that is a machine most people could build with stuff they already have and use your photo for a guide. Is there a valve on the bottom of the tank to meter sand flow into the air stream? I have seen blasting cabinets built from oil tanks and chest type food freezers maybe I will get motivated now and make one for our little blaster.

I need to mount it to a trolley and give some more detailed pictures. The only cost so far was the sand, i had all the other pieces ad *junk*. There is indeed a ball valve at the bottom to adjust the amount of sand that is allowed out of the pot. Other units have 3 or 4 valves, but honestly they aren't needed. You can turn the air off to the unit by un-plugging the air supply. Simply shut the sand off first. If you shut it off at the nozzle the sand builds up in the T piece at the base of the tank. I always turn the sand valve off first, then when the sand is clear of the hose un-plug the main air supply. A ball valve may be installed one day, but not really required.
I have a siphon style blaster too, its great for small jobs like spark plugs but on a job like this I'd be old and grey before i finished! I'll try and take a pic of it too, very handy unit.

 

[perry]

I need to mount it to a trolley and give some more detailed pictures. The only cost so far was the sand, i had all the other pieces ad *junk*. There is indeed a ball valve at the bottom to adjust the amount of sand that is allowed out of the pot. Other units have 3 or 4 valves, but honestly they aren't needed. You can turn the air off to the unit by un-plugging the air supply. Simply shut the sand off first. If you shut it off at the nozzle the sand builds up in the T piece at the base of the tank. I always turn the sand valve off first, then when the sand is clear of the hose un-plug the main air supply. A ball valve may be installed one day, but not really required.
I have a siphon style blaster too, its great for small jobs like spark plugs but on a job like this I'd be old and grey before i finished! I'll try and take a pic of it too, very handy unit.

Tazza, the ilminite might be the same as I use to buy, it was called 'black diamond' and sold through 'Northern Tool'. It's now called 'AmberBlast', $10 for 50 lbs. which ain't too bad.

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200343777_200343777

 

[jerry]

Tazza, the ilminite might be the same as I use to buy, it was called 'black diamond' and sold through 'Northern Tool'. It's now called 'AmberBlast', $10 for 50 lbs. which ain't too bad.

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200343777_200343777

Mine is a 20 lb cap from harbor freight and it works ok, much smaller nozzle though. If I had a cabinet large enough to do things like a wheel rim in it would be nice, that is why I was thinking a fuel oil tank or larger.

 

[Tazza]

Mine is a 20 lb cap from harbor freight and it works ok, much smaller nozzle though. If I had a cabinet large enough to do things like a wheel rim in it would be nice, that is why I was thinking a fuel oil tank or larger.

If its the same stuff, i paid $11 per bag for mine in 25kg bags. Thats close enough to being 50lb. Its all i have ever used in my hand held gun too, works pretty well i found and won't kill me from silicosis.
Even with a smaller pot, if you can get enough air there is no reason why you can't use a larger nozzle. You will find you spend more time re-filling the pot with sand (naturally).
I hope i can get time to set it all up better, its tied to a post where i store my bobcat! I have a trolley ready to mount it to, all i need to do is find time to drag out the welder!

 

[skidsteer.ca]

I'm using ilminite (spelling) basically black sand. Filling is a bit of a pain in the butt, i'm using a port on the top that is used for the fuel gauge. Its a square block held in place with 4 screws. I figure i won't be loading it up all that often so the minor inconvenience of removing and installing the 4 screws isn't THAT bad.
The top side of the wheel took maybe 5 minutes? probably less. The paint on the hubs isn't that tough. Even the *good* paint still gets eaten up pretty easily.
I really need more air, the 1/8" nozzle holds the pressure around 90 PSI but the spray is a little narrow. A larger nozzle would help cut the paint and rust much easier but you need to keep the pressure up. Light rust and paint disappears really fast, you just wave it over and its clean!
I did pay a tarp down to catch a bit of the media, and it does work. Just sweep it up and run it through fly screen to get the chunks out.
I may try and get a small video of it running, see how it turns out.

More tanks help if you are starting and stopping, but what you always need to blast is MORE AIR. I think 75 to 100 cfm would be needed to run a 1/4" nozzle. And of course they wear out and get biggers which just makes it harder to keep the pressure up.
With a relatively small nozzle like you using I can get by with one 27 cfm 2 stage compressor (note that is actual rating at 175 psi, not at free flow or 0 psi) Pressure will fall below 90 when the nozzles begin to wear out. Twinning it with another 18 cfm 2 stage compressor will maintain @ 125 if I don't let the nozzle get too worn.
Of course you can start and stop, but unless you shut off the sand metering valve at the bottom of the pot, your hose fills with sand and that gets wasted when you start back up as there is no air flow in the hose until the sand clears. (you could shoot it into a pail)
Blasting a 16' TA car trailer is a all day job with a blaster this size. So by the time you add up your media and electric bill, wear and tear it does add up. But it sure is nice to see everything get all cleaned up.
Ken

 

[Tazza]

More tanks help if you are starting and stopping, but what you always need to blast is MORE AIR. I think 75 to 100 cfm would be needed to run a 1/4" nozzle. And of course they wear out and get biggers which just makes it harder to keep the pressure up.
With a relatively small nozzle like you using I can get by with one 27 cfm 2 stage compressor (note that is actual rating at 175 psi, not at free flow or 0 psi) Pressure will fall below 90 when the nozzles begin to wear out. Twinning it with another 18 cfm 2 stage compressor will maintain @ 125 if I don't let the nozzle get too worn.
Of course you can start and stop, but unless you shut off the sand metering valve at the bottom of the pot, your hose fills with sand and that gets wasted when you start back up as there is no air flow in the hose until the sand clears. (you could shoot it into a pail)
Blasting a 16' TA car trailer is a all day job with a blaster this size. So by the time you add up your media and electric bill, wear and tear it does add up. But it sure is nice to see everything get all cleaned up.
Ken

I got the specs on a V twin pump i have here, its rated at 30CFM but no doubt its rated at free air like most compressors are these days.... Either way, it will add to the compressor bank and hopefully give me a higher blasting pressure or i can use a larger nozzle.
Do you find much difference between say 90 psi and 125?

 

[TriHonu]

I got the specs on a V twin pump i have here, its rated at 30CFM but no doubt its rated at free air like most compressors are these days.... Either way, it will add to the compressor bank and hopefully give me a higher blasting pressure or i can use a larger nozzle.
Do you find much difference between say 90 psi and 125?

I have found that pressures above 100 will significantly increase the wear in inexpensive ceramic and cast iron nozzles. The nozzles will wear away quite quickly. Too much pressure can also destroy the media by causing it to shatter when it strikes the surface. Silica Sand has sharp edges that will break away to expose a new sharp edge. However you can shatter the grains turning them to dust if the pressure is set too high. I can usually get 3-4 uses from Silica Sand before I pitch it, if I keep the pressure below 100 psi.
Higher pressures normally will require a Tungsten/Boron-Carbide nozzles. You can get the smaller ones for less than $50. I have tried making my own steel and cast iron nozzles. They may be cheap, but they don't last very long. I even made one out of a hardened pressure washer nozzle. It wore away pretty quick also.

Remember blasting is abrading away the surface and increased pressure does not always mean increased performance. Increasing the volume of sand and air will increase the cutting speed. You also need to pay attention to the angle the abrasive is striking the surface. Change the angle of attack to find the best cutting action.
A friend of mine worked as a commercial blaster. They used big screw compressors that only put out about 100 psi but they were pushing over 400 cubic feet per min. That is well over a ton of sand per hour. You should see how fast they cut, it is all about the volume. He has one of their old compressors and sand pots out at his farm. He is using sand right from their field. The sand is nothing special but at that volume it still works well.
This Blasting Chart will give you approximate air requirements and square feet per hour for different size nozzles.

 

[Tazza]

I have found that pressures above 100 will significantly increase the wear in inexpensive ceramic and cast iron nozzles. The nozzles will wear away quite quickly. Too much pressure can also destroy the media by causing it to shatter when it strikes the surface. Silica Sand has sharp edges that will break away to expose a new sharp edge. However you can shatter the grains turning them to dust if the pressure is set too high. I can usually get 3-4 uses from Silica Sand before I pitch it, if I keep the pressure below 100 psi.
Higher pressures normally will require a Tungsten/Boron-Carbide nozzles. You can get the smaller ones for less than $50. I have tried making my own steel and cast iron nozzles. They may be cheap, but they don't last very long. I even made one out of a hardened pressure washer nozzle. It wore away pretty quick also.
Remember blasting is abrading away the surface and increased pressure does not always mean increased performance. Increasing the volume of sand and air will increase the cutting speed. You also need to pay attention to the angle the abrasive is striking the surface. Change the angle of attack to find the best cutting action.
A friend of mine worked as a commercial blaster. They used big screw compressors that only put out about 100 psi but they were pushing over 400 cubic feet per min. That is well over a ton of sand per hour. You should see how fast they cut, it is all about the volume. He has one of their old compressors and sand pots out at his farm. He is using sand right from their field. The sand is nothing special but at that volume it still works well.
This Blasting Chart will give you approximate air requirements and square feet per hour for different size nozzles.

Nice, thanks for the info.
I did think pressure would be an advantage to a limit. I then would use a larger nozzle to give more sand and surface area where the sand strikes. I didn't actually give it much thought about the media turning to dust when it strikes. I'd just like to have enough pressure and flow to take a bit of the load off the compressors as i'm sure they aren't rated for 100% duty cycle.

 

[DANNP]

Nice, thanks for the info.
I did think pressure would be an advantage to a limit. I then would use a larger nozzle to give more sand and surface area where the sand strikes. I didn't actually give it much thought about the media turning to dust when it strikes. I'd just like to have enough pressure and flow to take a bit of the load off the compressors as i'm sure they aren't rated for 100% duty cycle.

The sand blaster we have at work is basically the same as you built only the top is inverted so it is concave and you pour the sand in it like a funnel , in the middle of the top is approx. a 3 inch hole the sand goes down through to the tank in the hole is basically around plate that is 1/4 to 3/8 inch bigger and it is on the inside welded to the center of the plate is a solid vertical bar with a tee welded to the top bigger than the hole again to stop it from falling through , around the edge of the plate is a rubber gasket to help seal it . All you do is release the air from the tank and the top falls to the t handle allowing you to pour sand in quickly then you pick up on the handle and apply air and the pressure holds it up until you release it again. Sounds complicated but works well. Don't know if it helps or not but it's an idea.

 

[Tazza]

The sand blaster we have at work is basically the same as you built only the top is inverted so it is concave and you pour the sand in it like a funnel , in the middle of the top is approx. a 3 inch hole the sand goes down through to the tank in the hole is basically around plate that is 1/4 to 3/8 inch bigger and it is on the inside welded to the center of the plate is a solid vertical bar with a tee welded to the top bigger than the hole again to stop it from falling through , around the edge of the plate is a rubber gasket to help seal it . All you do is release the air from the tank and the top falls to the t handle allowing you to pour sand in quickly then you pick up on the handle and apply air and the pressure holds it up until you release it again. Sounds complicated but works well. Don't know if it helps or not but it's an idea.

I have seen that setup, one set of plans was essentially the same. You get a large LPG tank and cut the top off, invert and weld it it in place. It had the same seal setup as you said but his also had a bolt and nut to hold the cap in place. The static pressure would be more than enough to hold it there though as you said. Filling it with sand isn't THAT much effort but the inverted lid would speed things up a lot.
I was in a bit of a hurry to build it as i was a little skeptical that it would actually work and didn't want to spend too much time on it.