Polishing Small Curvy Pieces

[SpankySmith]

I mostly make very small pieces, think keychains, necklaces, letter openers, etc.  Many of them between the size of a gambling token and a largish keychain, typically from 5/16" round stock.   I have done a few pieces where I'd really like to polish them to a shiny finish, but I'm stumbling over what tool or method to best accomplish that.   I've tried sandpaper, can't effectively get into small bends and such with it.  Tried fine disc on a grinder, decent but uneven and again can't get into the smallish places.  A bench grinder would be the same effect.  

 

I've researched here and on other boards/forums casting about for ideas.  When I had a recent class with a master blacksmith he was using a ScotchBrite multi-finish wheel on a grinder that did an exceptional job - the finish was like glass when using it - but again it's limitation is the small places in a piece, the wheel is semi-flexible but it can't get in there.  I've tried the small wheels available for a Dremel - that actually works, but the wheels don't last, each wheel is only good for about one piece!  That local blacksmith also used a belt sander for some finish grinding, but again, limitation of not being able to get into small curves and such.  About the only technique I've read about that I HAVEN'T yet tried is a small parts tumbler, but I have no experience with them outside of my childhood fascination with rock tumbling to know if the medium used in the tumblers would work out the small places? 

 

Any of you who work in small pieces have any ideas?   

[bigfootnampa]

Two ways you could go... tumbler as you mentioned and sandblaster.  An enclosed sandblaster for auto parts would do the job quite quickly.  These are commonly used for such things as cleaning spark plugs... so just about what you need!

[SpankySmith]

Bigfoot, it'd be more economical for me to get a tumbler over a sandblasting setup - WILL a tumbler shiny up these small pieces?   I've not used one since childhood, and the only thing I remember about them was it took days on end to work.  

[ThomasPowers]

1: remove scale chemically 

2: use a Sisal buff with black compound

 

Danger Will Robinson DANGER   buffers stay up all night every night figuring new methods to maim you---we would never use them except they are the only way to get the results wanted.  Learn the safety rules AND FOLLOW THEM!

[SpankySmith]

Hmmmm... I've never even seen a "sisal wheel," had to just go look it up.  Does it have any flexibility in the wheel that allows it to get into small places?  I can't tell from the description and some online reviews I read. 

 

No worries Thomas, I'm rather a fanatic about safety - as with most life lessons, learned that one the hard way.  No loss of limbs or digits (so far), but I've had too many scary moments.  I'm a powerful respecter of loud, twirly, fast-moving machines and equipment.  Love 'em all dearly and I have quite the collection, but I respect them greatly. 

[ThomasPowers]

Actually I should have mentioned that both 1&2 should be done in that order.  If you can find some bristle wheel that can be used with black compound it would be even better; but we never used anything coarser than sisal.

 

If you forge them in stainless look up electro polishing as a possibly possible method...

[Ohio Rusty]

I use a vibratory bowl unit to polish the brass for my pistol shells. They come out beautiful like brand new. The media I use is plain ground up walnut media.  I add a tablespoon of Nu-finish car polish to the media to make the shells 'slick' so they easily go in and out of the resizing and loading dies .......   That being said, you could use the same kind of vibrating bowl with what ever polishing media you want to use. You can use walnut media, crush up corn cobs, there is also a fine stainless steel media that does a great job of polishing. You can add a liquid polisher to the media to help in the final process. You may have to remove hard crusty scale first as that is difficult to get off by nature .......

Ohio Rusty ><>

The Ohio Frontier Forge

[SpankySmith]

Ohio, how long does it typically take in the tumbler?   Is that a couple hours... multiple days?

[Chinobi]

depending on how narrow the openings are that you are trying to get at you could look at an inside ring buff ( http://www.riogrande.com/Search/inside-ring-buff for example).  they mount on your average bench grinder/buffer and are indispensable for shining up the insides of rings and other things with hollow spaces.  just make sure you keep track of what compound you have on what buffer, and also mark them for use on steel only (vs sterling etc, if you also work with other metals)

 

if memory serves I have had some decent luck using the regular tiny cloth wheels that just screw onto the shank of my craftsman rotary tool (basically the same as the dremel) and feed it Tripoli.  you might chew up wheels faster on steel than on silver, but as long as you are not trying to buff out sharp corners and burrs you shouldn't consume too many in the process.  plus changing them out is as easy as twisting off the old one and twisting on the new one, provided the old one didn't catch, shred, and explode into a huge cloud of dust on you :)  there are also 'bullet' shaped or tapered tip cloth buffing bits for the same machines that are much stiffer than the cloth wheels and have narrower points, so they can get into tighter places.  but when they are chewed up you have to replace the entire bit, they don't just screw off like the wheels.

 

also, those 'sponge' looking abrasive wheels are bloody awful for metal!  they disintegrate WAY too quickly to be of any practical use!

 

if you do find any other good small wheels for rotary tools that are good for progressive grits of sanding and reach into small places please do share, I have been on the lookout for similar products off and on and theres not much out there besides the little interchangeable drums, and they don't last very long at all!  not to mention they are very rigid so they don't do really tight spaces, and wont conform to curves =/

[L Smith]

What about crocus or emery cloth it can be torn into long thin strips and use it like buffing your shoes

[jcornell]

I've had good luck with a brass wire wheel on a bench grinder (remove the abrasive disc and substitute the brass wire wheel).  Upon occasion you'll have the object being cleaned/polished flung somewhere at high speed if you get the wrong angle (forget about grip at that point) but there's a doable learning curve for this technique.  YMMV

[billyO]

Ohio, how long does it typically take in the tumbler?   Is that a couple hours... multiple days?

Let us know when you find out. We tumble large stuff in a tumbler that could give 4-5 college kids a good ride but 30-90 minutes usually does the job.  The media we're using is 1" +/- slugs.

 

I remember an article in an old Hot Iron News issue about a tumbler made with a number of tires all hanging from a shaft run by a small motor,  All parts cheap if not free (or already owned),  As far as getting into the tiny cracks, you just need a small enough media.  Sand would work, but may take a while. 

 

Oh yeah, and remember, you'll be tumbling a number of them at once, so they will knock against each other to speed the process of de-scaling. 

[Glenn]

I've had good luck with a brass wire wheel on a bench grinder (remove the abrasive disc and substitute the brass wire wheel).  Upon occasion you'll have the object being cleaned/polished flung somewhere at high speed if you get the wrong angle (forget about grip at that point) but there's a doable learning curve for this technique.  YMMV

Be careful of open wire wheels.  I know of one blacksmith that the open wheel grabbed a 3/8 inch square S hook and threw it back at him with enough force to shatter safety glasses and give him a concussion. He got the 2nd concussion when he fell to the ground and hit his head.

 

Small parts and wire wheels do not play nice together.

[rockstar.esq]

500 pistol cases come out looking new in about a half hour.  I used to use walnut shells until I heard dry rice works just as well. -If I'm in a hurry I use minute rice!   :P  I also read that putting a paper towel in attracts the grime - it does.  Case tumblers aren't really removing stock, they're removing powder fouling.  I still have to debur case mouths after cleaning.

 

I don't know that it's a comparable thing.

 

I have however seen machine shops using ceramic media with some kind of soapy solution for very light deburring / polishing.  Their tumblers were made waterproof and thicker walled than a case tumbler.

 

Depending on what you get, they can be powerfully loud.

[SpankySmith]

I share Glenn's deep respect for the damage a wire wheel can do, really would rather not go that route.  After all these great suggestions I'm going to have to decide which one to pull the trigger on and try ($$ make some of the decision, as usual, still haven't managed to win the lottery).  

[JNewman]

Depends on what you want as far as shiny goes.  A tumbler with scrap steel pieces will make things shiny similar to the shiny you get from a wire wheel but with much less effort and way more safely.   It will not give the same sort of shiny that you will get with multiple grits of sanpaper and buffing but it gives a nice "rustic shiny"

[SpankySmith]

Tried a sisal wheel tonight, the steel basically laughed at it. So my next move is EITHER order a scotchbrite and several of the Dremel 520's for the smaller places OR go with a tumbler. I like the turn it on/walk away aspect of a tumbler, I just have no experience with knowing if it will shine it up enough. Do y'all think it'll shine up basically untouched pieces after forging?

[ThomasPowers]

What compound did you use on the wheel?  I suggest black a coarse fast cutting compound that does a job on high grade knife alloys.

[L Smith]

The dangers noted above are why i recommend emery cloth by hand. You can't get hurt and you can immediatly see your progress and finish.

[ianinsa]

Depending on the part, shape etc. A 'split-pin' with a small strip of clothbacked sandpaper folded back on itself in a drill/dremell does an amassing job.

[Frosty]

Spanky: We're running into a matter of degree issue here. What do you mean by shiny? Wire brush finish, sand blasted finish, mill bright finish, mirror finish? The finish you want makes all the difference in the machine technique and time required.

 

I'd give the vibratory a shot. Descale the pieces first, it'll save time and hold the black crud down some. You can use all kinds of media in a vibratory. I like rice and maybe a series of grits. When I say I like, it's not from experience tumbling steel, Dad was a rock hound and we had rock tumblers stacked (literally) in the basement.

 

Just like tumbling rocks the grit will determine the finish and time. I'm not sure what to add to the rice to help keep the grits in suspension, there isn't a rotating drum in a vibratory so grits will tend to settle. I think the rice will pick up grit as it circulate through the bottom of the bowl, there may be something you can add to help that action.

 

If you have a drum tumbler I'd give that a shot. You'll want to keep the parts from falling in the action to prevent marring so you'll need the drum at leas 1/2 full of media. I'm thinking rice sounds good again, it's small to get into the nooks and crannies and will do a good job of cushioning the drop s it tumbles. You'll need buckets for different grits so you can progress to your desired finish.

 

I don't think you'll want to tumble wet. Wet tumbling does bring subjects to a finish quickly and superbly but it's . . .wet and freshly cut steel in water is going to rust the second it dries when you remove it. A water soluble oil might do the job but you'd then have the fun of cleaning the oil to apply the finishing product, wax, clear Krylon, etc.

 

Frosty The Lucky.

[SpankySmith]

I'm aiming for very shiny, similar to stainless, but the more I read on this thread the more I'm thinking (duh!) to just START with stainless, which is something I haven't worked with yet.  I also had rock tumblers as a kid, but if memory serves they took days to weeks of tumbling - worked well but really time (and energy) consuming.   I think I'll order the scotchbrite and the dremel 520's, and the next time I'm feeling flush with cash get a tumbler to try also.   One can never have too many tools, right?   

[Frosty]

Too many tools? NAW, too small a shop! Steel will polish much faster in a tumbler than rocks will. I have one I made from a 55gl. drum and it cleans and puts a coarse brushed finish on out of the forge pieces in half an hour or less.

 

Electro polishing SS is pretty easy and doesn't take special equipment. A battery charger and the right electrolyte, Citrus cleaners seem really popular compared to the acid solutions. I'll have to ask for particulars in the Sandbox unless you want to sub on and ask yourself, a number of the guys in the Sandbox do large public sculptures and other work in SS so have pretty extensive experience with electro polishing.

 

I know one at least visits here now and then, maybe he'll chime in or I'll just have to tag him.

 

Frosty The Lucky.

[SpankySmith]

Been awhile since I took the various pieces of advice given in this thread and gave 'em a go, so I thought I'd report back primarily because it might help some other Newbs. (you old timers (you know who you are Frosty!), just tolerate my ramblings.     Here are some of the various polishing/cleaning techniques I've tried on small pieces over the last couple months and my own experiences with them: 

 

Vinegar soak:  I found it does a very good job of basically softening &/or dissolving the scale in small places, which then gets removed easily enough with a wire brush or stiff tooth brush.  For getting it out of tiny places that I can't even approach getting a wheel into, it's proved invaluable.   If I go this route, I soak my pieces at least overnight, often two days and sift them out of the vinegar and drop them into a pan of soapy water.  Each one gets immediate scrubbing with said brush in more soapy water and dried off meticulously.   I tried muriatic acid.... once.... sure it worked faster, but it is also just NASTY stuff.   I'll stick with vinegar. 

 

Parts tumbler:  Besides being just about the coolest toy since my rock tumbling days when I was just a wee lass, I'm in love with what this does to my pieces.  If I got lazy and didn't wire brush my piece when finishing it, then nope, it won't remove every bit of scale on a small piece, but it does a very good job with most of it and I like the uniform finish it gives my pieces.  I've been happiest with pieces that have been tumbled, then dusted off, then polished with Stove Black to a glossy shine.  I used Kaybee Kay-Cobb for the bulk of my media, mixed with a bit of bb's and various tiny pieces of scrap off the floor under my band saw.  Parts come out clean with a uniform gray matte finish, which again the Stove Black or any other polish grabs onto nicely.   I haven't found a mix for the tumbler yet that actually POLISHES (like SHINY polishes) mild steel, still experimenting with that. 

 

Wire wheel:  I admit to not being brave/dumb enough to try this yet.  I've been around power tools my whole life (I was "enlisted" to help renovate the house I grew up in at age 5), and only a wire wheel actually scares me.  So I don't have one in my shop.  What I DID get was a Scotchbrite Multifininishing wheel and I absolutely ADORE it.  It's basically a big Scotchbrite pad for a bench grinder.  I love the fact that it has some small amount of "give" to it, so I can push a piece into it and get in some small places I couldn't with a sanding belt or standard grinding wheel.  Shines things up right purty, perfect for hearts and small crosses and other decorative pieces that look better shiny than black.   Pretty expensive wheel, but I think I will always have one in my shop. 

 

Dremel attachments for small places:  As someone else mentioned here, good luck with that.  The various dremel options - sanders, grinders, "diamond tip" attachments all do a good job in very small places... for very few pieces.  They simply don't last.  You can burn up a lot of these on just one small heart, for instance.  I will say that a variable speed dremel makes a difference, operating at low speed you get the job done and don't seem to burn out the attachment quite so quickly.  Dremel and all their knock off people need to work harder on this, there's got to be some attachments out there that last more than 5 minutes of work!

 

That's about it.  I've been enjoying the experimentation, figuring out what looks good on what types of pieces.   Still like a good wire brushing and then a quenching in vegetable oil for the dark almost gunmetal finish on a lot of parts.    Living and learning, it's all one great big learning process, isn't it?    One that I suspect will not end until the day I lay my hammer down for the last time. 

[Frank Turley]

Safety. What are we talking about? With a bench grinder and buff, the wheels are rotating so that the top of the wheel is coming 'toward you,' and the bottom of the wheel is 'going away.' The bench grinder has a tool rest, so you can place the tool against it if need be. Say you're sharpening a cold chisel, the grinder wheel is rotating toward the cutting edge.

 

NOT SO with a buff, wire wheel, or Scotch Brite wheel. The rotation is the same, but there is no tool rest. The work is held toward the bottom of the wheel, so if the workpiece gets hung up, you hope it rotates away, ie., flies away from you.

 

And with a belt sander, you don't want to hold a cutting-edge piece as you would with a bench grinder, or you'd tear the belt up.

 

Sayings and Cornpone

   "Common sense isn't so common."