The Armour Archive

Greetings! I'm sorry if this has been covered before but after a quick search I found nothing. My question is if I can use the 4.5 inch angle grinder I already have to polish some mild steel pieces I've made. I have no shop to install a bench grinder or I'd go that route. Any info would be greatly appreciated!

You ~could~ If I were you though, I would find a way to mount the grinder temporarily so you can have both hands on the work piece. Trying to hold both can be deadly; all you have to do is catch an edge and serious injury will follow. Here's a quick list for ya: mild abrasions, pulled muscles, shallow cuts, broken fingers, deep lacerations, partial amputations... you want control over what you're working on.

Don't see why not. You'd just need to find buffing or sisal wheels that will work with an angle grinder, instead of an arbor.

http://www.ebay.com/sch/sis.html?_nkw=4 ... nder+100mm

Edit to add: Saftey-wise, I agree with Ckanite. Polishing is already a dodgy business when you don't have to hold two things. One or the other needs to be secure, so you can have two hands on the other.

You could, but you will hate yourself in the morning. Along with the safety concerns already mentioned the swirls left by a 4.5 polisher would be hard to keep even and look good. Maybe if you went to a low gloss finish and completed with hand sanding.

Can you make friends with some one local with polishing equip?

A good friend has a bench grinder set up for polishing but I really don't want to be "that guy" and come knocking every time I need to buff something. Looks like I may need to look into putting a roof over my outdoor work space. Thanks to all for the insights and links!

When Buffing Goes Bad: A lesson from the late Pawpaw Wilson: http://www.anvilfire.com/iForge/tutor.p ... afety/demo

(Frequently posted; worth repeating.)

<Well, polishing with a wire wheel; but buffers have an equally bad reputation!>

When I worked in a welding fab shop I saw a small piece that a journeyman welder was working on get torn out of his hands and flung into his foot. He made a full recovery but he was lucky since he wasn't wearing any eye protection or gloves. I've always had a very healthy regard for power tools but it's always worth reminding ourselves about what can go wrong.

What the other Johann said...
But, I have done it, either the grinder or the workpiece has to be secured, but the swirls are very hard to get rid of. I have also used a 7 1/2 auto buffer, but that was for a helm.

Either the tool or the work needs to be secured to a heafty bench.

I have a small 6" buffer thats mounted to a board. The board gets bolted to the bench when I need it and stored when I don't.

A lot of tools can be used this way.
Bench shear, sander, vice, and others.

Yeah... they can catch and throw things. Even the bench mounted ones. Once when I was finish polishing a knife it got caught and wound up stuck in my sternum.

Ouch. I always stand on the side of the buffer to lessen the chances of that happening, can't do that with a hand held angle grinder.

Yeah... anymore when polishing small items I wear a breastplate with several stop ribs.

Ckanite wrote:Yeah... they can catch and throw things. Even the bench mounted ones. Once when I was finish polishing a knife it got caught and wound up stuck in my sternum.

That is one of my phobias!

I may need to finish that breastplate after all!

HAHA Yeah, I've never had anything that crazy happen after that but I took it as the warning it should be.

I use an angle grinder with a coarse wire brush for gross polishing, usually after some metal work.
Otherwise I use a 6-inch buffing wheel with a fine wire brush.

What's worse, is trying to drill larger holes in small piece of metal. The drill bit catches and the metal chops your fingers to bits.

Harry you can use something like a bench cleat or even just a piece of scrap wood attached with C clamps.
throw in a toggle or heel/strap clamp and it holds the piece in place.
It also keeps your fingers out of the way so you can see what's going on.

I am not saying I endorse the idea, but from a previous post it looks like fellow archiver Scott Martin uses an angle grinder to polish. He claims it is a big time saver because of the very high speed.

Despite having two great buffers, I use angle grinders a lot for deburring, shaping, and removing rust from random pieces people bring into my shop. Sandpaper flap wheels do a quick job. I haven't been able to master the knack of using a wire wheel on an angle grinder though. They're more flesh hungry than I'm comfortable with. The Lowes near me carries Gator wheels, which is kind of a Scotchbrite wheel with a rubber backing. You have to be very careful about not catching an edge with them since the wheel is so thin, it can embed your metal well into its body and use the high torque of the angle grinder to hurl metal like a champ. But when they work, they make a decent finish. Just think of it as a zombie head on a stick. It's useful, but wants to kill you.
For real polishing, the bench mounted buffer is a better choice if you can manage it.

Hi Tom

I can confirm that I use a vice mounted angle grinder for polishing.

That said, I considered it "disposable" since the polish, buff material and the binding agent (generally wax) get sucked into the cooling vents of the grinder. I have had this build up catch fire (polishing a wee bit too hot with a coarse (grey) Tripoli, which threw a spark just right...) and make sure that the direction of the grinder is down so that when you invariably catch an edge it goes down. There are a few reasons to mount sideways for polishing access, if you do, have the "spinward" direction face a wall or other surface you don't care about. Notre that I generally only mount sideways to polish heavy tools that won't get thrown very far, or "fiddly bits" on large objects like breastplates.

Power wise my 5" "polishing" grinder" is comparable to an 8" or 10" bench grinder, so it's still a tool to respect, but I don't think that "fear" is appropriate (that's for power hammers)

ALWAYS wear safety glasses, gloves, hearing protection, a filter mask (cartridge type recommended - your lungs are worth more than $50) along with long sleeves and pants. A face shield can be a good idea, but with my Peltors (hard hearing protection) filter mask and glasses I find that a cap covers all that is left exposed of my face.

To secure the muslin, put a couple of washers on the "angle grinder" side, or the buff will eat through your grinder casing. I also remove the guard (bad me...) because that way I can mount a 6" buff. Note that this rapidly becomes a 4" buff. You will be limited in the thickness of the polishing buff that you can use (~1/2") because of the depth of the threading on the disk attachment. While you could add a longer attachment, if you are going to go to that level of effort, just get a dedicated (big) polishing motor instead.

You can see my (minimal) polishing setup here:
http://borealissteel.ca/planishing-stake-construction/
for polishing a planishing stake (along with the results - the stake was mild steel)

A note if anyone has been looking at borealissteel.com, I had a data corruption issue around the time that I moved (for a new job) so the "resurrected" site is currently borealissteel.ca. This includes "tools for the starting armourer" which might be worth a read if you are strapped for budget and space.

Scott Martin