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Types of metal

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Wolfie24/12/2011 23:35:05
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OK following on from the parting off post, I noticed that I struggled more with some metal than others. Now aluminium isn't a problem it parts off great.
 
But I have been collecting various chunks of metal where I find them (I'm a truck driver so I find myself in all sorts of strange yards!) and I picked something today which really didn't want to be parted off.
 
I thought it was mild steel, but it juddered and jumped and I gave up on it before I had another breakage and I'm wondering if it was cast iron cos I had that problem with a flywheel casting. I'm pretty sure its not silver steel or owt like that.
 
Its just that something one of my club members said made me think there was maybe a certain steel that was better for turning than others.

Edited By Wolfie on 24/12/2011 23:35:31

Brian Dickinson25/12/2011 06:29:49
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Have a look at this web page it gives you a description as well as a grade.
 
There are a great many types of - or alloys of metals.
 
 

Fred Dibnah, Collected all sorts of metals as he moved around, making things out of it. It's OK but never make a boiler component unless you know its correct specification. BANG!!!
 
Other parts made out of unsuitable material will either wear quick, break quick, or bend.
 
 
Merry Christmas
Terryd25/12/2011 07:01:37
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Posted by Wolfie on 24/12/2011 23:35:05:
OK following on from the parting off post, I noticed that I struggled more with some metal than others. Now aluminium isn't a problem it parts off great.
 
...................
 
Its just that something one of my club members said made me think there was maybe a certain steel that was better for turning than others.

Edited By Wolfie on 24/12/2011 23:35:31

Hi Wolfie,
 
In some steel alloys lead is added to make it more machineable, it is usually called FCMS - Free Cutting Mild Steel.
 
Regarding your chunk in question, when machining cast iron you will produce small chips rather than long coils of swarf. You will also get a lot of black dust especially from 'grey' cast iron as there is a lot of free carbon in the metal. most cast iron machines really well once under the hard skin (your first cut should be deep enough to achieve that). There can be hard spots usually caused by a chilling of the casting. The 'chilling' effect is caused by a rapid cooling of the casting in the mould after pouring. It can be accidental or deliberate in order to give a hardness to areas of the final casting.
 
I have some lumps of various alloy steels that were given to me by a friend years ago. He sold speciality alloys to the aircraft component industry. These alloys have resisted all of my attempts to machine them, even with carbide tooling. I now use them as doorstops and hammering blocks. Sometimes you have to give in and admit that some metals are so specialised as to not be worth bothering with.
 
As Brian says there are very many metal alloys, far too many to speak of here, but I also like to scrounge and 'liberate' large chunks when they are unwanted but be prepared to experiment and treat them appropriately.
 
Happy Yuletide to you ,
 
Terry
BERTO25/12/2011 07:53:50
46 forum posts
Hi Wolfie .
I too am a wheel man and know what it's like to take an opertunity when it presents itself !
I recently aquired some scrap from work that was a retaining hook for a rear load rubbish truck and boy it is a tuff bit of metal !
I have now cut it to a usefull size then machined to make a piece for my tool & cutter grinder that i am building .
There are some basic test to see what you have using a grinder and looking at the colour of the spark and this is reasonable for testing between steel and cast iron as the spark will be different but there are many alloy steels around and maybe you have one of the work hardening type which will cause you no end of trouble !
You could always ask the people from the yard where you got it and maybe they won't mind you going back to check thier scrap bin - maybe you have sourced a supply of alloy steel!
 
 
Ian
 
 
 
Gordon W25/12/2011 10:29:00
2011 forum posts
Always is hard to tell with scrap ends, just keep it ,a use will turn up. Round here a lot of oil related stuff is made, scrap is not easy to get hold of, the last lot was about 1" dia. and looked like black steel bar, but was very tough and difficult to turn, a good finish was impossible. So I made a set of tools for knocking in , and out, king pins and bushes. The finish did not matter, they work great, and some two years later are still shiny, so I guess are some kind of stainless steel alloy.
Mark P.25/12/2011 10:48:01
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Hi Wolfie I also collect bits of metal as I travel round mainly from skips,some finds are better than others,(shiney stuff think that I'm related to a magpie)
 
Regards Pailo.
Bazyle25/12/2011 16:44:18
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If you have a real live fire, stove or open, you might find a few days in the hearth will soften them up, but some might just get harder. If it melts into a shiney pool it was alloy
David Littlewood25/12/2011 23:25:38
533 forum posts
Wolfie,
 
When I started out I scrounged lots of bits of scrap, mostly steel, but the majority of it was rather horrible stringy stuff. It may be I could have found a way to treat it but I was too ignorant to know how.
 
After a while I got introduced to decent free-cutting mild steel, leaded EN1A. It turns beautifully, can give a mirror finish, and has perfectly adequate strength for almost every purpose an amateur engineer is likely to need. Its only disadvantage is that it is unsuitable for welding or case hardening, but as a relative beginner (which I assume you are) you are unlikely to do that for a while.
 
I soon realised that the most precious investment I was making was my time, and it was counter-productive to spend many hours making some piece of precision equipment out of a piece of poor steel from a scrap bin. My advice to you is to buy a selection of EN1A (I think its modern designation is 220M07) or, if you can find it, the leaded version of the same, and use that for your learning. When you get a little more experienced you will find a range of other steels which are rather better for some special purposes. Some are good for welding, some have enough carbon in them to be hardened, some are like EN1A but a bit stronger. One of my favourites for real strength and toughness is EN24T, an alloy steel which has a UTS of 2-3 times that of EN1A but turns reasonably well. A reputable supplier will always be able to tell you the precise grade of steel you are buying.
 
I would also be careful of scrap cast iron, a lot of it has a very hard skin and will emasculate even a carbide tip pretty quickly, and they also often contain hard spots and voids. Decent continuous-cast grey iron costs a little more but is vastly superior. Aluminium alloys are also very variable, some are soft as butter and some as hard as steel, but if you find any it's worth trying it (but beware of alloys containing magniesium, they can be inflammable). For more expensive metals like brass, there is perhaps more sense in saving any piece you get your hands on, you can always try it and see how it goes, most grades turn OK to very well.
 
One final piece of advice, always mark the grade of each purchase and don't get them mixed up - advice I haven't always followed myself, but regretted the fact.
 
Hope this helps,
 
David
Stub Mandrel27/12/2011 16:22:23
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When I started out I got sold aload of stainless steel as 'silver steel'. I couldn't work out what I was doing wrong as it got softer if I tried to harden it.
 
Funnily enough I used some to make a new countershaft yesterday to replace the stopgap one. It wis pretty tough compared to some steels but it doesn't show any sign of workhardening and gives a decent finish. I was even able to mill a 3mm x 11.5mm deep keyway in it in one pass
 
It's a very accurate 0.500" as well so It all woprked out OK in the end.
 
Neil
Terryd27/12/2011 23:10:18
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Posted by Stub Mandrel on 27/12/2011 16:22:23:
................................
 
Funnily enough I used some to make a new countershaft yesterday to replace the stopgap one. It wis pretty tough compared to some steels but it doesn't show any sign of workhardening and gives a decent finish. I was even able to mill a 3mm x 11.5mm deep keyway in it in one pass............................
 
Neil
 
 
Hi Neil,
 
Why on earth did you need a keyway nearly 7/16" deep?   and with a 3mm cutter in one pass - wow.
 
Regards
 
Terry

Edited By Terryd on 27/12/2011 23:15:00

Stub Mandrel28/12/2011 15:03:13
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> Why on earth did you need a keyway nearly 7/16" deep? and with a 3mm cutter in one pass - wow.
 
I find that if the key slot goes right through the shaft I get twice the grip. I forge my cutters from pure unobtanium in the heart of a volcano.
 
Sauron.
Terryd28/12/2011 15:20:36
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Posted by Stub Mandrel on 28/12/2011 15:03:13:
> Why on earth did you need a keyway nearly 7/16" deep? and with a 3mm cutter in one pass - wow.
 
I find that if the key slot goes right through the shaft I get twice the grip. I forge my cutters from pure unobtanium in the heart of a volcano.
 
Sauron.
 
 
Ah, I see, but only found on Pandora as long as you have sympathies with the Na'avi and are willing to be 'blued'
 
Kindest regards of the Season,
 
Terry

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