need some help with a sandblasting project

[bjcsc]

More than likely it's the sand you're using. We use a small pressure pot type blaster. The smaller nozzles of these units don't like even medium material (slag). Go to a sandblasting supply place and either get some fine slag or medium starblast (both are inexpensive). Take your nozzle with you if you have any doubts. You should be able to take the nozzle off the gun, hold it like a funnel, and pour the medium through it with your other hand. If it hangs up at all, it won't blast. Make sure you're using the largest nozzle size, use the right medium, and when you start blasting, open the nozzle, start the air first, then open the sand valve just to the point where you're getting continuous sand. When you want to stop, turn the sand valve off first, let the line blow clear, and then turn off the air valve. If your nozzle has a shutoff, don't use it. Leave it open. It's for emergencies and will not work to start/stop the blasting.

 

[andrewj]

What kind of sand are you using now? If it is from your kids sandbox, it may have other larger particles that are messing your feed up. As mentioned a few times, it also needs to be DRY. Go out and buy a bag or two of dry blasting sand and try that. Make sure the feed hose is not linked and is layed out as straight as possible with any bends being as larg a radius as possible. Having the non pressure feed hopper up above you gets gravity in on the feed process.

Get a large sheet of clear plastic to layout and put the planter on, then pull the sides up as walls to try and contain the blown sand. If you are carefull, you can recover quite a bit with broom and dustpan, and a fine mesh screen to filter out the paint and rust chips will allow you to re-use a good ammount of the sand.

The CFM and recovery time of that small compressor are going to be the limiting factor on how fast you can go. It will work great for the first minute, then be mediocre for the next few till you stop and let the compressor recover. A bigger compressor will really speed things along and allow you to work till you need to collect, filter and refill the hopper. If you have the time, it will work eventually, but it will be a matter of how valuable your time is to you. A larger rented air compressor will really speed things up.

Wear a good respirator. That old impliment paint probably has lead in it, and the dust from pulverised blast sand is none to healthy either...

Good Luck

Thanks, Ron - yeah, it was regular sand so sounds like that is one of my problems..takes a long time = OK. I have about thirty years left to live I think, so an extra hour or two is ok!!!

 

[andrewj]

Hi
I believe the problem might be the moisture the compressor is producing. A cheap filter/air dryer from harbor freight might be the answer along with very dry sand. Works for me.

Charlie

I will try that, I have never heard of an air dryer for a compressor...the filter in the unit is small and I don't see how it can stop moisture. I drained the petcock this morning and tried it again with same results. there was a lot of water in the bottom of the tank. so play sand, plus moisture equals my problem.

 

[MrJimi]

I will try that, I have never heard of an air dryer for a compressor...the filter in the unit is small and I don't see how it can stop moisture. I drained the petcock this morning and tried it again with same results. there was a lot of water in the bottom of the tank. so play sand, plus moisture equals my problem.

There are many different names for this filter, here are a few
http://www.harborfreightusa.com/usa/itemdisplay/displayItemList.do
and to do any good, they have to be mounted away from compressor NOT at the tank end like most people do.
Picture wet sand in your hand, squeeze it and it will keep it's shape but not dry
Cheap sand can be bought at a place that sells dirt etc. make sure you screed it out real good
sandblasting is NOT fun

 

[ray66v]

It is the sand that is the problem. You need to buy media made for and blasting. Osha got involved in this, and now it all costs a lot and does not work as well.

You need a compressor about 5x bigger than what your using. On top of it taking forever, your compressor is going to heat up and produce a lot of water vapor. You will then be blasting the newly cleaned metal with moisture. Then you will have built in rust on your new paint job.

Forget about any filters or traps. The filter won't trap the water vapor. Filters only trap water that has condensed into liquid. The vapor will pass right through.
Fixing this problem requires a dryer and that starts at $300.

Easy way out: Buy some wire wheels, preferably a couple of different sizes and types, and for a couple of different tools, (i.e. 4" angle grinder, 9" angle grinder, drill). Put on a dust mask, some goggles, gloves, and have at it. It will work good and be much faster. You could also use the sand blaster just to get in the tight areas, after using the wire wheels.

 

[barneyrb]

In using my small blaster I purchase the finest grain sand I can and then put it through a fine wire mesh as a strainer. You'd be surprised at how many large grains there are in the fine stuff.

 

[RonMar]

Thanks, Ron - yeah, it was regular sand so sounds like that is one of my problems..takes a long time = OK. I have about thirty years left to live I think, so an extra hour or two is ok!!!

I have basically the same equipmnet you do and have used it to strip bike and auto frames and parts. It won't be an extra hour or two, it will be an extra DAY or 3... It is also not a very comfortable job and face shields abrade and fog quickly. Never again. If I have a big job to do as this sounds, I would at the least rent a large compressor. That has always been my limiting factor. I was working on building a large compressor for my PTO for this purpose, then the need(vehicle) went away, so I never got round to it.

One thing that might speed your process is if you have a pressure washer. Spray on a degreaser and clean and blast as much as possible. This will loosen and remove the loose paint and rust and get it out of your way as that will slow you down sandblasting. Also any grease built up around gearboxes and bearings will not easilly blast off with the sand, it will just catch the grains.

Once it is dry, then start with the sand.

Good luck

 

[teg]

andrewj, I want to thank you for bring this sandblasting up... I forgot about our el cheapo one and decided to put away the drill and wire wheel. Sandblaster worked great (ten year old sand). The unit got plugged up a couple times, twice with peanuts at the front of the hose. Once I was getting sand like you described... I blew air back into the nozzle and a half a piece of corn came out of the hose. I guess mice were playing tricks on me. Since the sand was 9 inches deep in the plastic holding area, the trash must have been there a while. I did most of the box blade before it started to rain to much. Thanks again for the idea.

 

[SPYDERLK]

Thanks, Ron - yeah, it was regular sand so sounds like that is one of my problems..takes a long time = OK. I have about thirty years left to live I think, so an extra hour or two is ok!!!

Sounds like your sand is suction feed via an aspirator tube you stick down into the sand bucket and you are also using regular sand. I have experience with this. A few arrangements will get around all the problems:

1. Sandblast in the sun on a large plastic tarp on as smooth a surface as you have,
2. Before blasting spread your sand out thinly on the tarp and let the sun beat on it to dry it.
3. In about 15min it will be thoroughly pulverized. Sweep it into a pile, scoop it up and filter it thru a wire window screen into a bucket of some sort.
4. Do your sandblasting with a good area of tarp in front of you to catch the sand. Wear gloves, a filter, faceshield, and a cap with bill backward. If you have any problem with clogging, put your finger over the nozzle for a second to blow it back.
5. After using the sand sweep it up and refilter back to your bucket.
6. Repeat. The sand grains should flow a little better the second time thru.

Moisture in the air on this type system is totally unimportant. A little water in the blown sand doesnt matter. Just make sure you are in the sun so the sand drys between each use.
larry

 

[ray66v]

Moisture in the air on this type system is totally unimportant.

It's important if your goal is get rid of rust.

You may not have seen metal rust from the moisture sprayed on by the sand blaster. But, I did this for a living, and I sure have.

A system like this, under the right conditions, can spray almost as much water as sand.

Yes, with the proper knowledge and products it can be treated. But, its not the best way to start out your new finish.