To Sandblast or not?

[tmuir]

The one job I really hate is removing lots of rust of odd shaped objects.
I usually use a couple of different sizes of wire brushes in my cordless drill followed by small wire brushes in my dremel to get right into the hard spots and finish with a coat of rust converter to get the last bits I can't reach but today I saw a small sandblaster attachment for under $50 for an air compressor.
At that price it obviously doesn't come with nice little box to use it in and to catch the garnet for reuse but for the small objects I do I'm happy just doing it outside with the appropriate PPE.

My question is how harsh are they?
Am I in danger of blowing a hole through mild steel sheet metal or would it be fine as I can see it saving me a lot of time.

The type of items I would be using it on are like the sheet metal base on the toy steam engine.

and the cast iron base of my watch makers lathe which is bolted to the wood in this photo.

Thanks
Tony

 

[compound driver 2]

HI
The kind of sand blaster your looking at wont do a vast amount of damage to mild steel unless you go daft with it. Id look to using glass beads rather than sand bit better finish with a slightly easier clean up.

What it will do is bung up every hole with fine abrasive grit even with glass beads thats a real bugger to get out.
That said I grit blast full size boilers with out thought simply for the speed.

In short yes blasting works but its a real mess to clean from ports and bearings.

Cheers Kevin

 

[Mcgyver]

you guys need to try electrolytic rust removal. there's a lot written on the hsm bbs, search there. I just tried it this past weekend, neat stuff. make sure you only do steel though, don't drop the copper boiler in. There is the potential for hydrogen embrittlement so probably not suitable for chains, pressure vessels etc

 

[Bernd]

Walnut hules and baking soda are two other options. They aren't as abrasive and leave a better finish.

Bernd

 

[tmuir]

I've heard of baking soda been used before but never really looked into it.
Excuse my ignorance but is it just regular baking soda they use or is it different and how is it at getting off the rust.

Mcgyver I've once used electrolytic rust removal and I agree it worked very well the only thing you must be careful with that process is to dry the part immediately after removing from the water as the surface is partly porous and will rust quickly afterwords.

 

[Bogstandard]

Tony,

If you don't protect the metal straight after blasting, I think you will find it will try to start rusting very quickly anyway. So use gloves for handling the cleaned parts, the sweat from your hands will start the rusting process in no time.

Baking soda or walnut husks are very fine. In fact the walnut husks are fired thru running jet turbines to clean the carbon off the internal blades (it is called Turcoblast). Baking soda is used for blasting ceramic transfer rollers used in printing, to clean out the laser etched pockets. I don't think either would be very efficient rust removers, it would do it, but hi pressure and a long time would be required, but there would be no damage to the parent metal.

As previously suggested, glass beads would be the ideal choice, but on a fairly low pressure to protect against damage to valuable old parts.

John

 

[compound driver 2]

HI
The walnut husks work well on very lite rust but are almost pointless on anything else.
Its also worth thinking about the muck that comes away with the blasting medium, this certainly is
abrasive and if left in bearings or moving parts will cause wear.

Go with glass beads but be prepared to do a realy good clean up afterwards.

Cheers Kevin

 

[13AL]

I do more sandblasting in a week than.........uh well i do alot!
You need a small/hobby sized blast cabinet, you will use it more than you think, the medium stays in the cabinet, pop the piece in, blast and remove, no mess!
I have a small store bought cabinet that has baking soda in it (yes it is just normal old baking soda) and a large home-made cabinet that normally has glass bead but is easily changed to other types of media and can handle 18' long items.
Check out tptools.com, they also have parts like gloves, windows and such to build your own, and alot of different types of media.
I am in the US and paid $110.00 for a complete ready to go bench top blaster at Tractor supply Co.
I personally use glass bead for steel and aluminum, the air pressure has alot to do with it, a little less psi for aluminum.
I have used wallnut shells but found they pack tightly into small areas like screw holes and orifices, I switched to baking soda and like it. The backing soda is also the last step before I start polishing, it leaves a smooth mat type finish.
I started years ago with a $12.00 Wall-Mart siphon blaster and a bag of Childrens sand box sand, outside.....it's not fun!
I pay about $32.00 for 50 pounds of glass bead (about 5 gallons) it lasts me about two years in a cabinet, it would last a lifetime if used in a hobby enviroment.
13AL

 

[rake60]

Regardless of the blasting media, you create heat very quickly on the part
being blasted. On any thin metal that can lead to disaster.
I was fully aware of the heat issue when I started blasting a blower housing
off of a 1935 Briggs and Stratton Model Y engine with glass beads.
I kept the the nozzle moving and the pressure as low as possible.
Ended up with heat warp ripples that destroyed the look of the housing.
It took a skin coat of auto body filler and a whole lot of hand sanding to
recover from that mistake.

Rick

 

[Loose nut]

Blasting with glass beads or any hard abrasive on delicate material like that will probably distort the metal and remove fine detail, if you don't want to invest in equipment try and find a company that does dry ice blasting (this method removes material in a different manner) and see if they can do it with out damage other wise try something else, sandblasting is inherently damaging to the surface of the part, at the very least it will leave a matte finish that won't be any good as a polished surface without a lot of work.

 

[Hilmar]

No offense Tony ,
clean it up and let it be. Then put it on the mantel.
Any thing you do to it will take away from it for what it is.
I have never seen a 200 Year old item like new as just shipped from the factory.
Bling to antique don't sound right to me.
Hilmar

 

[Mcgyver]

I think Hilmar nailed it. the value of something old can be hurt by even taking a patina off let along sand blasting, I'd go with that advice.

 

[rake60]

I think Hilmar nailed it. the value of something old can be hurt by even taking a patina off let along sand blasting, I'd go with that advice.

Very Good Point in reference to Hilmar's post.
If you are looking at it from a collectors point of view it's best left untouched.
I have a dining room suite in my home that would be considered ruined because the chairs have been
reupholstered. It was bought at an auction for a ridiculous low price.
My wife refurbished it to make it a part of our home. That refurbishment took $5000 off it's
collectors value.

Could you buy it? Sure! The tooth and nail scars on the oak that are left from you taking it out
the door will be free of charge.

Rick

 

[tmuir]

No offense Tony ,
clean it up and let it be. Then put it on the mantel.
Any thing you do to it will take away from it for what it is.
I have never seen a 200 Year old item like new as just shipped from the factory.
Bling to antique don't sound right to me.
Hilmar

This is a debate that rages on and off again on another forum I'm on.
Normally I would agree with leave as original as possible but this one is too far gone.
It has no paint left on the top of the base, it is all just rust. I think the firebox has been repainted at some point and the safety valve had seized into the bush.
I have a rule, if I can't run the engine I can't keep it.
Saw I need to restore it to running condition and on this occasion I think a repaint is the only answer.
Given a choice I would rather leave it original but feel its past that point because if I don't repaint it in another 50 years it will be rusted away just due to the moisture in the air.

AS you say a very rare item left in original state is worth more than a very rare item heavily restored but I know for a fact that this engine would reach a high resale value restored by people who just want a steam engine to run than left in this state and sold to a collector.

Why am I so sure of this? Because in the last year only 2 of these engines have come up on ebay and both in similar states and I got them both for considerably less than a Mamod engine sells for of the same size second hand in running condition.

But lets not get involved with the to reatore or not debate as it gets too many peoples blood boiling. ;D

 

[Cedge]

Tony
This subject does tend to raise a few hackles in both camps.... eh? Restoration versus preservation is a really just personal choice. I tend to do as little as is required to preserve the engine, but will go to great lengths to restore one to "era". That includes retaining scars from children at play as well as normal wear and tear. I've even been known to distress paint or wood to keep an engine looking appropriate to its proper age under normal usage.

Either way, you go you've got quite a little project ahead of you.

How are things coming with your new shop and the lathe? I read where the water flow problem bit you solidly on the arse and I saw your first turning project. Seems like there has been a lot of emotion, good and bad, so far...LOL

Steve

 

[Mcgyver]

Tony, obviously you are very aware of the point, I didn't know that and had visions of yet another engine with the flywheel buffed to the point of looking like it belongs on the handle bars of an OCC product :big: :big:

 

[firebird]

Hi

Not sure if this is the right place to post this but it follows on. When I used to go shooting (before the ban) it was standard practice to reload used brass cartridge cases. After a while they would start to look a bit grubby. They were easily polished up using a "TUMBLER". This was a home made device knocked up by one of the members but worked very well. It comprised of a large sweet tin (the sort you buy at xmas, Roses/ quality street etc) fixed to an old record player turntable. A piece of wood 3x1x1 glued to the base inside. Tip in some walnut husks, add the brass cartridges, incline the whole thing by shoving a lump of wood under one corner and switch on with the speed set to its lowest speed which if memory serves me well was 16 RPM. 10 minutes would polish 100 brass cases. I've had it in mind to make one for polishing small components but haven't got round to it yet. Hope this helps.

Cheers

 

[tmuir]

Hi Cedge,

Yes the water that washed away about 1 cubic meter of fill and the last block on my reatining wall wasn't good but luckily my workshop wasn't damaged.
I still haven't finished fixing it yet as my wife has had me out looking at new flooring for the room all my workshop tools came out of but I really should get on with that repair.

Firebird I actually own a vibratory tumbler that I purchased to polish silver and gold jewellery I make.
I've never really given any though to use it to polish parts with non critical surfaces but it certainly would do a good job to get into the hard places.
This is my machine

I use stainless steel shot which does a great job at burnishing silver and gold and the amount I use it should last me a life time as long as I continue to wash and dry it after each use.