# Machining of re-bar on G4000 lathe



## prasad (Aug 11, 2014)

Guys, 

I want to turn a piece of re-bar on my Grizzly G4000 lathe. Please advice me on type of tool I must use. I have C2 and C6 tipped tools but not sure which one is better.  

Thank you
Prasad 
Wynnewood PA


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## Flammable_Solid (Aug 11, 2014)

Either one will work.  Be careful, as rebar is not great material to machine and has lots of inclusions, so it may have some odd pieces coming off of it.


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## Ulma Doctor (Aug 11, 2014)

the interrupted cuts on the rebar may be a little harsh on the cutter of any type. but if you got use carbide go kinda easy on it.
 HSS would be a little less prone to breakage and you can easily resharpen with a regular grinding wheel.
you chip a carbide tip you are not going to bring it back with a regular grinding wheel.


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## Walsheng (Aug 11, 2014)

I bet it would have more junk in it than late fall flea market on a Sunday afternoon. Just cutting it with a hack saw can be an adventure.  And with the interrupted cuts and hard spots it's going to bang away at whatever you throw at it.  I would not waste any good carbide inserts on it.
If I were to try it I think I would try a cheap brazed carbide bit and just resharpen whenever I hit a chunk of rock, piece of kryptonite or whatever is hiding in there.

John


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## darkzero (Aug 11, 2014)

Yup, because of the interupted cuts, C2 would be a better choice over C6.


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## pineyfolks (Aug 12, 2014)

Besides turning it, just chucking it to run somewhat true may be more hassle than its worth.


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## tripletap3 (Aug 12, 2014)

I don't know if this applies to your project or not, but here is a simple lesson that I learned for anyone that happens to come across this post. You can take a piece of FREE scrap rebar from your pile and spend $20+ on carbide inserts to make in the shape you want with a crummy finish or you can buy a good piece of metal for $10 and still have the original insert when you are finished. 

Just a little side note on rebar. Years ago we had a rebar manufacturer that was close by, and guys were constantly getting horribly burned and there even was a couple of fatalities until they ended up getting it shut down. The molten metal would just explode out of the ladle for no reason and singe everything around. During an inspection/tour of the plant I asked why there was so many serious burns and why don't they fix it. I was told that unlike normal metal, rebar was made inexpensively due to its limited application so they used a wide variety of scrap metal to make it with. This caused the molten mixture to become unstable at times and explode. I think OSHA shut them down and they moved the plant to China.


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## prasad (Aug 12, 2014)

John

You are right. It was acting strange and when I read your advice I understand its cause. Re-bar is certainly made of unknown material and has unpredictable behavior. I was using cheap brazed carbide tipped tool and one bit got chipped. I stopped at that and will not proceed. 

Time for me to order good stock from known trusted source. 

Thanks
Prasad
Wynnewood PA




Walsheng said:


> I bet it would have more junk in it than late fall flea market on a Sunday afternoon. Just cutting it with a hack saw can be an adventure.  And with the interrupted cuts and hard spots it's going to bang away at whatever you throw at it.  I would not waste any good carbide inserts on it.
> If I were to try it I think I would try a cheap brazed carbide bit and just resharpen whenever I hit a chunk of rock, piece of kryptonite or whatever is hiding in there.
> 
> John


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## Walsheng (Aug 12, 2014)

tripletap3 said:


> I don't know if this applies to your project or not, but here is a simple lesson that I learned for anyone that happens to come across this post. You can take a piece of FREE scrap rebar from your pile and spend $20+ on carbide inserts to make in the shape you want with a crummy finish or you can buy a good piece of metal for $10 and still have the original insert when you are finished.



Best advice I've seen yet for machining re-bar!!

John


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## prasad (Aug 15, 2014)

tripletap3 said:


> I don't know if this applies to your project or not, but here is a simple lesson that I learned for anyone that happens to come across this post. You can take a piece of FREE scrap rebar from your pile and spend $20+ on carbide inserts to make in the shape you want with a crummy finish or you can buy a good piece of metal for $10 and still have the original insert when you are finished.




That is a great advice. I have thrown away that piece of rebar. I am now looking for a regular mild steel or aluminum scrap. Thank you very much

Prasad 
Wynnewood PA


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## cwolfs69 (Aug 17, 2014)

a decent material from almost anywhere is better than trying to machine re-bar. the only reason i can think of to use re-bar is when you want the re-bar look in your final product. i have don that in making pens etc, but then the work on the rebar i mostly drill, tap chamfer etc. turning it is a night mare.


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## ericc (Aug 17, 2014)

Some people love the rebar look in forged items.  When I use rebar, I am very careful.  I don't think all rebar is bad.  There is enough bad rebar around to give it a bad name.  The master blacksmith in our organization told us to qualify all our raw material for making tools.  This saves you from wasting time.  The main toolmaking material that is used in the beginner workshop is sucker rod reused from central California oil wells.  This stuff is something like 25 cents per foot, and it really outperforms mild steel, even on hot cutting applications.  They buy this stuff by the truckload and I think that it was grade number cross referenced and spectro'ed as 4130.  It is not S-7, and you can tell the difference, but S-7 or Atlantic flutagon can cost real money.  I have a large stash of 5/8" rebar that I qualified as water quenching and uniform, and I save it in the rack as for tools only.  Everything else is suspect.  If you want to turn your rebar, heat it above critical, forge down the ridges, and normalize.  Test for hard spots with a file.  You will only have to do this once per lot.  Do not take shortcuts.  I have seen two students take shortcuts and end up with spectacular failures.  The shards will fly at supersonic speeds and penetrate polycarbonate safety glasses and leather aprons.  One of the guys told me he saw a guy just slump down.  He had an exit wound in his back that looked like a .38 special.  And this was factory certified 4140, the victim just goofed up the heat treat a little.


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