Sandblasting thoughts & recommendations

[Mike Manning]

I am doing my first OWWM (Old WoodWorking Machine) restoration. I've also got two other OWWMs to do. My table saw and jointer are rust free for the most part but there is some surface rust on the CI body of my band saw that I feel like I need to get down to bare metal then prime and repaint it. I see a Jobsmart sandblaster advertised here on CL for $50. I have a PC pancake compressor. I'm wondering if you folks think that PC air compressor would drive the sand blaster? It looks like Jobsmart is a low end brand. It would be nice to have the ability to blast with different types of media, like glass beads, walnut shells, sand, etc. Any thoughts, shared experiences or recommendations on going in this direction for restorations would be appreciated?

[Doug Ladendorf]

With a pancake compressor you will get maybe 30 seconds of sand blasting then wait two minutes for it to fill up. My neighbor has a 60 gal Husky from the BORG on his blast cabinet and I still have to stop and wait for the compressor to catch up if I'm going more than five minutes. Where are you located? Post some pictures of your bandsaw!

Doug

[David Kumm]

Spend your money for a grinder with a knotted wire wheel and or a needle scaler. I sandblast once in a while and use a 25 hp compressor when I do. You are talking helmet, air, and the rig itself to have something better than the grinder or scaler. To really set up for sandblasting you will spend 5K easily including a compressor or you will have frustration. Eventually you will want to rehab a Quincy compressor and then use it with air grinders. Much better than electric ones. You will also eventually want a decent floor standing 12-14" wire wheel to clean up the small stuff. Slippery slope but fun. Dave

[John K Jordan]

With a pancake compressor you will get maybe 30 seconds of sand blasting then wait two minutes for it to fill up. My neighbor has a 60 gal Husky from the BORG on his blast cabinet and I still have to stop and wait for the compressor to catch up if I'm going more than five minutes. Where are you located? Post some pictures of your bandsaw!

Doug

Even my 5hp 60 gallon compressor won't keep up with the sand blaster. It will work fine with the small sand blasting guns with an attached canister but these are pretty limited in speed and power. (If sand blasting outside a cabinet don't forget the dust protection.)

For automotive and farm things I reach for the needle scaler and two kinds of twisted wire brushes in a 4" angle grinder - one flat like a disk and the other a cup - each has it's uses. I also use a wire brush wheel on a powerful bench grinder - you definitely do not want a wimpy grinder when wire brushing. (Also be REAL careful with hands and eyes! The wheels are "grabby" and throw steel wires across the room.)

I also use a flap wheels in the angle grinder for removing paint, rust, weld spatter, hot-roll mill scale, etc. - they work extremely well. These are overlapping petals of sandpaper which wear away as used, sometimes called flap sanding disks to distinguish them from flap wheels.

The inexpensive needle scaler works very well but I haven't tried it on sheet metal. The one I use also accepts chisels which are handy at times.

Good ol' hand wire brush is needed in tight spots at times. You can also use a wire brush that mounts on a reciprocating saw (sawzall). I'd like to try one of those.

JKJ

[Wayne Lomman]

Firstly, don't blast with sand! It is outlawed in the developed world. Google silicosis and you will understand why. This is not a joke. Sandblasters used to have a very short life span before silicosis was understood. Use garnet, staurolite, soda, ilmenite, glass beads, steel grit, aluminium oxide etc etc instead.

To make a blast pot work, find out what it's specified air consumption is and match the compressor to it. If yours isn't up to it, hire one. Half a day's hire won't be too bad. Or borrow 2 or 3 and manifold them to your pot.

Wire brushing etc is ok except for the tendency to burnish the surface. Paint doesn't like sticking to burnished steel. Blasted steel however provides excellent adhesion.

Wear a respirator and eye protection.
Cheers

[Mike Manning]

With a pancake compressor you will get maybe 30 seconds of sand blasting then wait two minutes for it to fill up. My neighbor has a 60 gal Husky from the BORG on his blast cabinet and I still have to stop and wait for the compressor to catch up if I'm going more than five minutes. Where are you located? Post some pictures of your bandsaw!

Doug

Doug,
I live in Austin, TX. Pics as requested...

Delta 28-290 Before
355521

Delta 28-290 during...
355522
Delta 28-290 after?

Not sure I will repaint it. I'm fine with the used look but I do care about protecting it. Thus the consideration to get rid of surface rust and old paint then priming it and repainting.



Firstly, don't blast with sand! It is outlawed in the developed world. Google silicosis and you will understand why. This is not a joke. Sandblasters used to have a very short life span before silicosis was understood. Use garnet, staurolite, soda, ilmenite, glass beads, steel grit, aluminium oxide etc etc instead.


To make a blast pot work, find out what it's specified air consumption is and match the compressor to it. If yours isn't up to it, hire one. Half a day's hire won't be too bad. Or borrow 2 or 3 and manifold them to your pot.


Wire brushing etc is ok except for the tendency to burnish the surface. Paint doesn't like sticking to burnished steel. Blasted steel however provides excellent adhesion.


Wear a respirator and eye protection.
Cheers

Wayne,
I've read that blasted steel provides much better adhesion for paint as well. Which was a big part of why I was considering it.

Mike

[CPeter James]

As I read through this thread, I noticed a common misconception. It is not the size of the tank, but the size of the compressor that matters. And as for the compressor, it is not the "rated" horse power, but the actual output in cubic feet per minute at what PSI (pounds per square inch) that matters. Compressors sold by the big box stores and the like use the same methodology in rating the compressors as they do routers. THEY LIE! You can not plug a 3 or 5 horse power compressor into a 120V outlet! Read the fine print and see what the actual air output is.

I do a fair amount of blasting and with my pressure pot blaster, I have switched to crushed glass, imported from Canada. It works great and leave a surface ideal for paint. I am running a 5 hp Ingersol Rand compressor that will put put out 17 cubic feet per minute at 175 PSI This used 28 amps at 240 volts. and is wired to the breaker panel with number 8 wire. It is a short run or I would have upgraded the wire to number 6. I run a small carbide nozzle and use very fine grade grit.
CPeter

[Doug Ladendorf]

Given Wayne's comment I'll clarify that I use glass beads for blasting. Has worked great on a number of vintage machines.

Mike, it looks pretty good. It seems the feet are always a bit rusty unless the PO had it on wheels or off the concrete. Good luck with it.

Doug

[Mike Manning]

Given Wayne's comment I'll clarify that I use glass beads for blasting. Has worked great on a number of vintage machines.

Mike, it looks pretty good. It seems the feet are always a bit rusty unless the PO had it on wheels or off the concrete. Good luck with it.

Doug

Doug,
Are you thinking it's not rusty enough to warrant strip down, prime and paint given my reasons for considering doing that?
Thanks, Mike

[Ed Labadie]

FWIW...when it comes to sandblasting, I feed both my cabinet blaster and pressurized tank blaster with a 100cfm Ingersol gas powered compressor.

I do not lack for air volume.

Ed

[Doug Ladendorf]

Mike if you have the time and inclination go for it. You will have a like-new or better-than-new machine to enjoy. If you are going to the trouble change the bearings and belts too.

Doug

[Ole Anderson]

I have a small Grainger gun with a 3 gallon pot running off my old 1 hp craftsman compressor. Very slow, but blasting will do things you simply can't do with any other method, getting the rust out of pitted iron and getting it to the ideal substrate: white metal. On the other end of the spectrum, I watched guys sandblast water towers prepping for paint using 300 hp compressors. They could blast metal from 4 feet away. Dealing with the moisture generated by the compressor is a separate problem.

[Peter Aeschliman]

First, I will challenge your assumption that it needs to be protected with a strip-down and paint. That's just surface rust, and assuming the machine will live indoors, it's not as if it is going to rot away like a body panel on a car. I would just give it a light rub-down with WD40 or a light machine oil from time to time. You say you don't mind the patina, so I really don't see a need to do a re-spray.

Second, there are some primers that claim to work well on very light surface rust. So I'd recommend looking into that. Just make sure it's de-greased and is free of any loose debris or rust dust.

Third, If you do want to do a serious paint job, I'll add to the chorus of those who say to save your money and find another method of removing the rust. Try a chemical process first (like evaporust). I have a 2 stage, 5 HP, 80 gallon compressor that I use for cleaning up parts for the restoration on my old landcruiser. It works well, but even then I still have to wait every 10 minutes or so for it to catch up. I can't imagine trying to sandblast anything with a pancake compressor. I think you'll waste your $50 trying. If you really want to sand blast, then you might want to look into having a professional blasting shop do it for you. I bet they could get that sucker cleaned up in less than an hour.

Good luck!

[Keith Weber]

Mike,

A few comments:

1) Pancake compressors are good for nail guns. They won't even begin to cut it for media blasting. Trying will only frustrate you, and might even burn out the motor on your compressor. My 7.5hp/80 gal compressor outputs 27cfm at 90psi and it keeps up to my blaster.

2) The blaster works great for OWWM restorations, but DO NOT under any circumstances blast tables, bearing surfaces, cutterheads, or anything similar with it. You'll wreck your machine. Keep the blasting for parts that will be painted. Tabletops should be scraped with a razor blade to remove surface rust, then use a green ScotchBrite pad by hand on a WD-40-doused table top. It'll shine with a little effort, and you tables will remain flat.

3) I like Aluminum Oxide media as you get the most use/$ with it, and it's aggressive enough to not take all day. Glass bead does a good job, too. It is less aggressive, but watch your pressure, or you'll obliterate your glass beads into dust and it will get expensive. Some people use walnut shells but it doesn't last long, and it'll take all day to get rid of stubborn stuff.

[Mike Cutler]

Mike

I'm sorry, but your PC compressor is really too small, but what you want to do can be done on a limited basis of you're willing to be patient., just not with that particular blaster tank. The air requirements are too high.
Harbor Freight sells a small portable media blaster ( http://www.harborfreight.com/portable-abrasive-blaster-kit-37025.html ) that you could. This along with an air receiver tank might get you where you want to go. You'd only get about 20-30 seconds of continuous blasting at a time though. But, it's a small project. (This setup is used by motoring enthusiasts to clean the carbon fouling from the backs of intake and exhaust valves with the engine in place. They use the fine walnut media. So yes, it does work in a limited application. Some specific BMW/MINI engines are notorious for this problem. )
You could do the hard to reach nooks and crannies, but the bulk would have to be done another way.

You don't need a huge setup for a one time only, very small, project like you're doing.

[Cary Falk]

I bought one of theses for <$20. I have a 60 gallon compressor and it runs continuously. I don't use it much because it makes a mess. I have switched over to soda for the medium. I do it outside in the driveway. What I can't sweep up, I just wash off. Don't do it on you grass because it will kill it

https://www.amazon.com/Campbell-Hausfeld-Sand-Blaster-AT122601AV/dp/B0007D30DO/ref=sr_1_3?ie=UTF8&qid=1489842267&sr=8-3&keywords=sandblaster

[Alex Tzoulis]

What about these nozzles ?
https://www.aliexpress.com/item/32984654896.html
I have lathe & mill is there any good plan to build myself a gun that accepts those boron carbide nozzles ?

[Alex Zeller]

Years ago I worked for a glass company. Every so often we would make a sign out of a mirror by masking the back and sand blasting the exposed part. It was a neat effect. The blasted area looked white and if you put a light source behind it it would light up. We never did our own blasting though. It was much cheaper to just pay someone (we had a welding shop who could do it) to do it for us. If you really want to S blast it I would make a few calls.

[John K Jordan]

Years ago I worked for a glass company. Every so often we would make a sign out of a mirror by masking the back and sand blasting the exposed part. It was a neat effect. The blasted area looked white and if you put a light source behind it it would light up. We never did our own blasting though. It was much cheaper to just pay someone (we had a welding shop who could do it) to do it for us. If you really want to S blast it I would make a few calls.

That sounds like fun. I have a huge antique mirror I need to get rid of - maybe someone would like to blast some of the sliver off the back!

Many years ago I would etch glass by blasting with silicon carbide grit. Using an idea in (I think) a Popular Mechanics magazine in the '80s I made masks by using an xacto knife to cut through paper attached to the glass with double sided tape. I made a hopper with a nozzle that forced grit upwards through a hole cut in a foam rubber sheet where it abraded the glass not covered by the mask. The grit just bounced off the mask. (That nozzle was brass but didn't wear since it was just supplying a stream of air.) It was very effective, especially at putting designs or monograms on round glassware for gifts.

426831 426832

[Alex Zeller]

We used a single sided sticky foam to mask the parts of the mirror off. There's a vinyl sticker place that has a printer (used for cutting the vinyl) that could cut the foam. The image had to be reversed since it was on the back side. That popular mechanic's idea looks interesting but I think it wouldn't work well for larger items. Often the mirrors we were doing were large, like 5'x10', and went into malls. the person doing the blasting had to carefully do each letter to make sure they miss any of the edges. With malls kind of fading away I'm not sure if there's still a demand for it.

[John K Jordan]

... That popular mechanic's idea looks interesting but I think it wouldn't work well for larger items. Often the mirrors we were doing were large, like 5'x10', and went into malls. the person doing the blasting had to carefully do each letter to make sure they miss any of the edges.

Yes, I can't imagine working on a large piece of anything with this method. Even with drinking glasses and glass canisters I had to work carefully to not miss anything.

The hopper method also worked for sandblasting a few other things. I threaded a small plywood square to hold spark plugs for cleaning. It wouldn't be practical for anything which didn't seal the hole in the foam completely.

For occasional sandblasting of small parts I bought a kit from Northern Tool with tank and gun. It's fine for occasional use but without a containment cabinet it wastes a lot of grit and can make a big mess.

[Bill Dufour]

The hopper idea is how the commercial spark plug cleaners work. You have to be careful and get all the grit out between the ceramic and the steel body. You do not want to add sand into a cylinder.
Bil lD