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cuslog
06-16-2012, 07:16 PM
http://i726.photobucket.com/albums/ww262/cuslog/PICT0076640x480.jpg

Blade tensioning machanism from my sawmill. One side of a groove there has worn / broken away. The handwheel is definitely cast, I'm thinking cast iron by the way the last bits broke away (and it was full of black powder and crumbly bits when I took it apart).
Cast steel would be an easy fix, just turn up a bushing and weld it on the end, but I'm afraid its cast Iron and not so easily fixed.
Any easy way to identify Iron or steel ?
Any suggestions on repair if it is cast ??
Hope the picture works.
Thanks,

sasquatch
06-16-2012, 07:34 PM
Interesting question Cuslog, been wondering myself about identifying that.

Mcgyver
06-16-2012, 07:41 PM
I'd be thinkng spark test, cast steel should look similair to steel whereas cast iron is fairly different.

oldtiffie
06-16-2012, 07:43 PM
There might be an answer here:

http://www.google.com.au/#hl=en&output=search&sclient=psy-ab&q=compare+cast+iron+and+steel&rlz=1W1IRFC_enAU360&oq=compare+cast+i%5C&aq=2q&aqi=g-q3&aql=&gs_l=hp.1.2.0i22l3.3298.13358.0.20347.18.14.1.3.4. 1.396.4258.2-9j5.14.0...0.0.wBL3O39Rub0&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c0ba19284add315e&biw=1280&bih=545

radkins
06-16-2012, 08:10 PM
There is a huge difference between the sparks from an iron casting and any kind of steel, a steel casting of most common alloys will throw nearly the same sparks as mild steel. What I have heard suggested, and it works great, is to just hit a small piece of known steel with a grinder and compare the sparks, if similar the cast part is a steel casting but if it's an iron casting the sparks won't even be close to the same! Without trying to get into a confusing description of spark color and spark type (shape and description) from steel vs iron just suffice it to say if you compare the sparks from a piece of cast iron to a known piece of steel there will be no doubt if one is cast iron! Also if you can a tiny nick with an Oxy/Acetylene cutting torch will tell the tale, steel cuts easily of course while cast iron will not.

Forrest Addy
06-16-2012, 08:20 PM
Cast iron, definitely. Brittle crumbling fracture. No ductillity. No evidence of metal fatigue. A spark test is definitive. In deep shade touch it with a 4" disk sander with a fresh disk. Steel will produce bright yellow forked sparks, cast iron short red streaks.

There's a spark test tutorial on anvilfire.com

Might be a simple fix: silverbraze on a collar. Observe the usual silverbraze precautions: cleanlness, heat control, filler alloy, flux, and in the case of cast iron bead blasting the faying surface to removes surface graphite.

Bob Fisher
06-16-2012, 10:18 PM
Wheel is cast iron for sure by the look of the failure.Another option would be to machine a new hub, bore out the wheel, and pin/locktite the two together. I'm sure the flange was never intended to carry significant forces, probably only meant to keep the screw from unscrewing itself.Bob.

oldtiffie
06-17-2012, 12:20 AM
http://en.wikipedia.org/wiki/Spark_testing

http://www.google.com.au/#hl=en&gs_nf=1&cp=11&gs_id=1a&xhr=t&q=spark+testing&pf=p&rlz=1W1IRFC_enAU360&sclient=psy-ab&oq=spark+testi&aq=0&aqi=g4&aql=&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c0ba19284add315e&biw=1280&bih=545

Elninio
06-17-2012, 02:16 AM
if i'm not mistaken, they fracture differently too, and the blunt force impact site that cause the fracture should be deeper on steel, if there's any such indication on the piece ... also, cast iron is abrasive, they wouldn't make a nut out of that material.

10KPete
06-17-2012, 06:42 AM
This stuff

http://www.muggyweld.com/?view=castiron

is unlike all other electrodes for cast iron. No connection with me, just
a happy user.

Pete

HSS
06-17-2012, 08:48 AM
I was shown by an old machinist to take a very small cold chisel and in an inconspicuous area try to tap up a sliver with the hammer and chisel. If the sliver curls its steel if it chips its iron.

Pat

cuslog
06-17-2012, 11:39 AM
Cast iron, definitely. Brittle crumbling fracture. No ductillity. No evidence of metal fatigue. A spark test is definitive. In deep shade touch it with a 4" disk sander with a fresh disk. Steel will produce bright yellow forked sparks, cast iron short red streaks.

There's a spark test tutorial on anvilfire.com

Might be a simple fix: silverbraze on a collar. Observe the usual silverbraze precautions: cleanlness, heat control, filler alloy, flux, and in the case of cast iron bead blasting the faying surface to removes surface graphite.


I'm convinced that its Cast Iron. I think I'll try the Silver Braze.
I've done a bit of brazing but its been a few years.
I'm wondering how tight the fit should be on the new collar ?
Light press or should it be slightly loose so the braze can wick into the joint ??
This is a fairly large peice (handwheel is 12" dia., collar would be about 1.800 OD. Maybe I should pre-heat it all With a propane "tiger torch" first ?
If I pre-heat W/ a tiger torch, would a MAP torch give me enough heat to do the brazing ? (I have an OXY / Acet. set but I've let the cylinder lease go.):o

loose nut
06-17-2012, 04:06 PM
Take a 1/16" drill and drill the suspect material. If it comes out as dust it's cast iron, if you get curly's it's steel, of some kind???

cuslog
06-17-2012, 07:05 PM
Take a 1/16" drill and drill the suspect material. If it comes out as dust it's cast iron, if you get curly's it's steel, of some kind???

It's cast iron.

I gave up on the brazing idea, I wasn't so keen on the Map gas / brazing idea and didn't want to spend the $300 to lease a new set of O/A tanks plus pay to fill them just for this job. Nor was I all that keen on heating the whole thing.
So I just made a collar about .010 undersize on the ID and heated as hot as I could with the Map torch and slipped her on and let her cool / shrink in place.
Back on the mill and working, so far so good.
We'll see how long this "backwoods repair" lasts.:)

sasquatch
06-17-2012, 08:24 PM
There are times when "backwoods" repairs will outlast the life of the machine/vehichle.
A real Feeling of accomplishment!!

lowcountrycamo
06-17-2012, 09:20 PM
I am surprised no one else said it first. Sure fire way... take any steel object and ping unknown meterial, if it rings, it's steel. If it makes a thud sound, it's cast iron. Go try it on something of known material.

Hobbyman
06-17-2012, 10:39 PM
filings of cast iron have graphite so if you rub the filings between your fingers and your fingers go black you have cast iron.