turning mandrels from rebar

A

alinwa

oft dis'd member
So I'm deeply engrossed in a BMG project, trying to make a series of accurate BMG's and the first thing that becomes apparent is that these things are BIG!!

Not BIG! but BIG!!

And I'm at the stage of making nice cases...... and I set out to turn some necks.

I say "set out" because this project is a sidebar not a commitment. I ain't spending 170 on a bullet puller, 230 on a primer pocket swedger nor over $250.00 for a single-use neckturner just to make a point about accuracy.

So off to the lathe.

I keep sticks of 1/4", 3/8" and 1/2" 12L14 at the lather just for making sacrificial turning mandrels....... but half inch ain't big enough!

P!$$ Poor Planning on my part. So I'm casting about for cheap easy-machining round scrap and I have literally tens of tons of rebar at the shop...... I jammed a hunk of 5/8 into the chuck, eyeballed it to center and whipped out a mandrel.....LIKE BUTTAHH!!

Mighta' just found my new (free) mandrel material )
 
It's the hotdog of steel...

...you never know what you'll get with rebar. It's made mostly from recycled material with little concern for alloy / etc. You might find a piece that turns well and another that defies a good finish. There might be some special purpose rebar that is more consistent, but I assume you'd know if you had such a thing. My luck with rebar was poor and I gave up on it as a general source of material outside of desperation. Bolts are more consistent - but an expensive way to go unless you have a bunch sitting on 'the pile'. I keep 12L14, 1018, 6061(al) and 4140 up to 1" for a very small investment (probably a bit more in the present economy). You're relatively near Onlinemetals which sells convenient 3' packs from 1/8" to 1" - probably get to you in a day.

GsT
 
Best price on metal ?

Is online metal the best/cheapest place on line, to purchase metal for lathe use ?

Hal
 
I'll have to agree with GeneT, the rebar I have turned was the crap-y-est steel I've ever seen. Maybe in the NW they make it better.
 
Hal said:
Is online metal the best/cheapest place on line, to purchase metal for lathe use ?

Hal
Click to expand...

It's the best I've found between price and delivery time (delivery may suffer if you're on the East Coast, I don't think they have anything out that way). If you have a good steel supplier locally (good meaning "carries what you want") they're probably a better bet. My 'local' steel yard is great for welding steel and delivers for a $10 gas surcharge, but they don't really carry specialty alloys (like 12L14 or 4140). Speaking of which, IIRC, I had to go with (not-so-)SpeedyMetals for 4140. If you do order from Online metals and 3' lengths work for you they seem to be much cheaper to ship than longer stock.

And if you find something better, I'm all ears!

GsT
 
Wayne Shaw said:
I'll have to agree with GeneT, the rebar I have turned was the crap-y-est steel I've ever seen. Maybe in the NW they make it better.
Click to expand...

The closer you get to Mexico the more varied the rebar becomes.

A few years ago a radioactive source was melted into a batch of steel and used to make rebar.
A radiation alarm went off when the truck pulled into a US lab facility, as opposed to leaving.
 
brickeyee said:
The closer you get to Mexico the more varied the rebar becomes.

A few years ago a radioactive source was melted into a batch of steel and used to make rebar.
A radiation alarm went off when the truck pulled into a US lab facility, as opposed to leaving.
Click to expand...

I don't know that being close to Mexico was a factor because there is a lot of oil and gas drilling pipe that is radioactive. It is contaminated by naturally occurring radio active drilling product. Most scrap yards check and reject the pipe, but apparently not all. Some farmers and ranchers will use it for fencing.
 
brickeyee said:
The closer you get to Mexico the more varied the rebar becomes.

A few years ago a radioactive source was melted into a batch of steel and used to make rebar.
A radiation alarm went off when the truck pulled into a US lab facility, as opposed to leaving.
Click to expand...

McMinnville, OR has a hotdog, errr, rebar plant. It's output is made, I believe, entirely from recycled steel and unsuited to machining. I'm not sure proximity to Mexico is a good heuristic. If you were referring to my comment and my shown location I should note that my experience trying to machine rebar occurred when I was an Oregonian.

GsT
 
Al Nyhus said:
Why not simply use some .625 round 303 or 316? :confused: -Al
Click to expand...

I THOUGHT I had plendy round stock in the hamper..... but had nothing suitable.

I live in the boonies an hour from town so the local 12L14 supplier is a 2.5-3.5hr round trip depending on traffic and gas is over a dollar.......and I wanted to go NOW :)

I'd heard of folks making tools from 40-grade and read of the guy who made a competitive barrel from a hunk of #11 60gr so I figgered I'd spend a minute.

I do have probably 10 brands and grades of rebar in the scrap, foreign and domestic and the first rusty staub I picked up just turned nice.

Next pc may well be bubble gum but this piece turned like 12L14 :)
 
Well.... I was wrong, I got lucky. The next two pieces machined terribly. I ended up making a mandrel from 1" stock
 
Just buy a gage pin and press into a holder, hardened so they don't gall and sized to what you want... if you want you can even buy carbide...
 
GeneT said:
...you never know what you'll get with rebar. It's made mostly from recycled material with little concern for alloy / etc. You might find a piece that turns well and another that defies a good finish. There might be some special purpose rebar that is more consistent, but I assume you'd know if you had such a thing. My luck with rebar was poor and I gave up on it as a general source of material outside of desperation. Bolts are more consistent - but an expensive way to go unless you have a bunch sitting on 'the pile'. I keep 12L14, 1018, 6061(al) and 4140 up to 1" for a very small investment (probably a bit more in the present economy). You're relatively near Onlinemetals which sells convenient 3' packs from 1/8" to 1" - probably get to you in a day.

GsT
Click to expand...

Listen to Gene. In a steel mill, Heats of steel that miss their alloy specifications badly enough that they cannot be salvaged, end up as rebar, Fence wire, and nails.
Joe
 
geo.ulrich said:
Just buy a gage pin and press into a holder, hardened so they don't gall and sized to what you want... if you want you can even buy carbide...
Click to expand...


What tool do you use to machine gage pin steel on a lathe ? Grinding add-on ??
Thanks,
Oliver.
 
I am not surprised by "your" (in USA) issues machining rebar.

Here in France, even ""regular"" or "new" construction steel aka A60, XC45 recently gave me qui a sweat. Very unpure, sandy portion, whatever your machining direction, vibration changes, chip changes, cutting depth changes several 0.01 mm on a 40 mm diameter. Even carbide bits cutting edge sometimes broke all of a sudden, just as if I had a stone in the steel.

That was my most hughly steel in life. After polishing, using a magnifying lens I could see """sand""" pockets at the surface.

Going to specific alloy, in my case S300Pb aka 12L14 was WAYYYYYYY much better at machining and polishing. The bad new is that I had to purchase 10 feets minimum.
So did I.
Never regret it.
Was able to control 0.01 mm on diameter again.
 
OliveOil said:
What tool do you use to machine gage pin steel on a lathe ? Grinding add-on ??
Thanks,
Oliver.
Click to expand...

Ceramic works fine or grind if you have that availability and you don't need to use the crappy free machining steels which are to soft for any real use....
 
geo.ulrich said:
Ceramic works fine or grind if you have that availability and you don't need to use the crappy free machining steels which are to soft for any real use....
Click to expand...
The softness of the 12L14 isn't an issue when turning in the lathe as I don't set for a slip-fit but instead I jam the case onto the mandrel with several thousandths interference and turn it on the spinning mandrel...... in fact, in this case I've even got a relief cut into the mandrel such that I'm turning and trimming to length in one setup.
 
jimsplce said:
I don't know that being close to Mexico was a factor because there is a lot of oil and gas drilling pipe that is radioactive. It is contaminated by naturally occurring radio active drilling product. Most scrap yards check and reject the pipe, but apparently not all. Some farmers and ranchers will use it for fencing.
Click to expand...

This was a 60Co source.
There is no naturally occurring 60Co
High energy gamma rays

https://en.wikipedia.org/wiki/Cobalt-60

There are other incidents around the world.
 
Last edited:
You must log in or register to reply here.
Back
Top