Which abrasive to use ?

[jpigg55]

I purchased a taper attachment for my lathe, but it's in need of a good clean-up before installing.
I want to remove the old paint and rust and thought sand blasting would be the way to go.
My question is which material would be best for this ? Walnut shell, glass & grit, aluminum oxide, Armex soda ?

[Jake Parker]

If you have a soda blaster, that's the way I would go

[jpigg55]

I don't, really haven't done any sand blasting since high school shop class.
A friend of mine has a sand blaster I can use and wondered what media I should purchase for the job.
I thought any media could be used in a sand blaster, guess I was wrong.

[woodchucker]

I purchased a taper attachment for my lathe, but it's in need of a good clean-up before installing.
I want to remove the old paint and rust and thought sand blasting would be the way to go.
My question is which material would be best for this ? Walnut shell, glass & grit, aluminum oxide, Armex soda ?

I have walnut, I don't find it works well. Glass does a better jobs, and certainly alum ox works great.


I don't have experience with soda.. it requires a pressurized vessel.

[kvt85]

No mater which media you use do not breath the dust.   Some the finer stuff takes a bit longer to get trough the paint, and also the rust, but it will not eat way on as much good stuff as quick. 
How much rust and stuff is on it.   It may be better to do something like rust remover, that does not harm the good metal.  Some of the abrasives if they hit a soft spot will dig in,   I have done some with standard Alum ox,  all the way up to the black diamond stuff and now do a lot a strip with a good stripper,  cleaned off with a pressure washer,  then either electrolysis, Molasses mix, or smaller pieces put into an evaporust soak.  That way I am not taking anything that is good down any.   

[f350ca]

I wouldn't media blast anything with machined surfaces.

Greg

[jpigg55]

Looks worse than it is.
Wanting to remove the rust and paint while either preventing or minimizing metal removal/pitting.
With the HF sand blaster I have access to, I'm thinking using either sand or aluminum oxide and control the pressure and time to clean it up.
Either that or use Evaporust, but wasn't sure if it would remove the paint since I want to re-paint it after cleaning.

[chips and more]

If you want to retain the original machined surfaces as best as possible, then blasting is not the way to go. And I’m in that group. I would use a paint stripper and the Evapo-Rust. When using Evapo-Rust it usually does not remove paint, just rust, gun metal blue, black oxide finish and maybe more than I’m not aware of.

[jpigg55]

Thanks for the advice guys.
Not a professional restoration by any means, but I'm satisfied with it. I opted to sand blast the non-machined areas with alum ox (covered and taped the critical areas) and used Evaporust afterwards.
I re-painted the areas that had paint, waiting for it to dry before final reassembly and installation.

[4GSR]

I'm late to the party as usual.  Any kind of blasting on long thin like parts like on this taper attachment, they will warp on you and cause havoc on you trying to get the surfaces flat again.  Evapo Rust and paint remover is the way to go.  I'm not really a fan of Evapo Rust,  I just like the good old steel wool and elbow grease myself.  A good carbide scraper, slightly dull works good for removing rust on bearing surfaces.  Ken

[woodchucker]

warp from what?
we are talking cast iron here...
sand blasting would warp that?

[Carpenter84]

The sandblasting creates a huge amount of heat as each particle impacts the metal. And depending on the abrasive, it can stretch or shrink the metal itself.

[4GSR]

Sandblasting creates "peening" of the surface.  This will cause it to warp or bend.  I kid you not, even in cast iron, it will warp.  How do you think I used to fine tune gibs.  Ken

[woodchucker]

that's interesting. I have sand blasted a few things, and never noticed.


good to know.

[RayH]

For any given workpiece, warpage from abrasive blasting can occur but the magnitude of warpage has to do with the magnitude of mechanical and thermal energy applied. "Magnitude" is the factor that hasn't been discussed so far.

On the taper attachment in question, I would use Evaporust and paint stripper. However, I'm sure the paint could be removed by abrasive blasting (by the appropriate process) without significant damage. I would only blast the precision surfaces with a relatively soft media (like walnut shells) but I don't know how well that works on significant rust.

Too much energy (too hard media, too high velocity, concentration of the flow) can damage your workpiece. Evaporust and paint stripper may be slower, but I think safer.