# Tips For Turning A36 Hot Rolled Steel



## mrjbinok (Aug 20, 2016)

Learning things every day as I start using my Craftsman 12x36 more and more.

I had purchased some 1 1/4" A36 Hot Rolled round bar for a drill jig project and soon found out that this isn't the easiest material to work with on the lathe.  Problem being the hard outer surface of the stock plays hell with my cutting bits.

I am wanting to smooth the outer surface of the stock, and want to keep as much of the material as possible... not a critical diameter... more for esthetics.  I mainly use the 3/8" indexable carbide tools but have tried 3/8" HSS ground to a little larger tip radius as well as the sharp tip.  I've tried various lathe speeds and feed rates, using cutting fluid and not.  What I end up with is dulling the cutter within 30 minutes and having to either re-grind the HSS or changing the carbide inserts.  I have several pieces to make so it's getting frustrating to have so much down time

Last night I ordered some Cold Rolled TGP that should eliminate the problem, I hope... but I have enough of the hot rolled material that I would still like to use it up.

Can I get some tips and/or suggestions on machine setup and/or cutting techniques that will improve the life of my cutting tools?


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## chips&more (Aug 20, 2016)

On your next material purchase, try some “12L14”. Machines like butter…Dave.


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## Bob Korves (Aug 20, 2016)

Use a deep enough first cut to get under the scale, then turn up the speed until you get yellow to blue chips and you will get a better finish.  A36 is not the best steel to machine, as I guess you have already discovered.


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## 4GSR (Aug 20, 2016)

You said you bought some cold rolled T, G, & P..    T, G, & P is not really cold rolled.  It's actually specially processed hot rolled that is rough turned, centerless ground to size, and polished.  The most common one is La Salle 1144 which is sometimes referred to as "Stressproof" material.  You will find it to cut like a dream.  Unless you need the T, G, & P finish, go with one of the other material grades out there like 12L14, 1215 (which I prefer), 1144, for free machining grades.  1018, 1020, 1040/45, are not free machining grades, but are ok for certain needs.  A36 grade is mainly for any welding project you may want to do in the future, but not for machining parts out of.


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## francist (Aug 20, 2016)

Yeah, the mill scale is a pain. As others have said, a deep first cut to get past it works, but that might be a problem for some of the smaller lathes to manage. I've taken to immersing any hot-rolled pieces in a bath of muriatic acid prior to turning. It throws the scale off right quick, leaving just the fresh steel surface. The vapours are not good for you, so I do it outside in a plastic tub and use full face shield/ gloves. I've heard vinegar works for this too, probably a bit slower, but I've not tried it myself.

-frank


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## Wreck™Wreck (Aug 20, 2016)

Flood coolant, use negative rake carbide tooling meant for steel with a large nose radius and as mentioned above use a large depth of cut and spin as fast as you are comfortable with.

Cutting oil is not coolant as it doesn't remove the heat. Above all try not to use hot rolled bars whenever possible, also take note that 12L14 is mostly un-weldable due to the lead content, it was developed for automatic screw machine products but has been largely replaced by 1215 due to the toxicity of lead.


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## mrjbinok (Aug 20, 2016)

Thanks for the info.  The parts I am making will end up as drill jigs to insert into a bushing and give a reproducible line up for drilling for a locking dowel pin through the shoulder.  I will be heat treating to add some durability so my question (since I don't have time right now to research).... are the 2L14, 1215, 1144, and the 1018, 1020, 1040/45 grades heat treatable?


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## Wreck™Wreck (Aug 20, 2016)

mrjbinok said:


> Thanks for the info.  The parts I am making will end up as drill jigs to insert into a bushing and give a reproducible line up for drilling for a locking dowel pin through the shoulder.  I will be heat treating to add some durability so my question (since I don't have time right now to research).... are the 2L14, 1215, 1144, and the 1018, 1020, 1040/45 grades heat treatable?



I believe that 1045 is heat treatable, however common practice is to buy thin walled drill bushings and press them into the jig, these are easily replaced when worn and are inexpensive.

As seen here http://www.mcmaster.com/#drill-bushings/=13t59i6


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## T Bredehoft (Aug 20, 2016)

Wreck™Wreck said:


> buy thin walled drill bushings



Thanks for the link, Wreck, I was wondering....


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## Wreck™Wreck (Aug 20, 2016)

T Bredehoft said:


> Thanks for the link, Wreck, I was wondering....


You are welcome, if you have a relationship with a tool supplier they can sell you the bushings at about 1/2 the cost of M-C


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## T Bredehoft (Aug 20, 2016)

Wreck™Wreck said:


> if you have a relationship with a tool supplier



Unfortunately, I don't, never worked under my own name, I could always talk the boss into what ever was needed. 
Now my needs are one or two at a time, anyway.


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## Tony Wells (Aug 20, 2016)

You could look at one of the mfg catalogs, then find a distributor. It's not uncommon to have small orders, so I doubt you'd have trouble getting them to sell to you.

https://www.carrlane.com/catalog/in...D020609090C0015480013180B041D1E173C1B08535246

Or order direct:
http://www.drill-bushings.com/


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## mrjbinok (Aug 21, 2016)

I guess I didn't explain exactly what I was making with my jigs and is causing some confusion.  I am making jigs that will slip inside a newly installed bushing, which require a dowel pin to keep the bushing from twisting in a aluminum housing.  A hole is drilled through the bushing shoulder at a specific distance from center and needs to be perpendicular to the shoulder.  My jig allows you to line up the drill at the proper bushing radius and guide the drill bit straight in.  With a drill stop set to the proper length on the drill bit, you end up with a straight hole that is the proper depth which will then accept a dowel pin to be pressed in. 

I plan to sell these at a low cost to the end user, in various sizes for a specific application.  Adding a drill bushing would increase both cost and the time required to make the jig.  In most cases the end user won't be using the jigs for high volume production, so I believe that heat treating will be all that is needed and allow me to sell at an affordable price.


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## mrjbinok (Aug 21, 2016)

Bob Korves said:


> Use a deep enough first cut to get under the scale, then turn up the speed until you get yellow to blue chips and you will get a better finish.



How much of a cut would be considered typical for a "deep cut" to try in situations like this?  I am waiting till my TGP order gets here to continue with my project, but since I have the hot rolled, eventually I will probably want to use it up.


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## JimDawson (Aug 21, 2016)

mrjbinok said:


> How much of a cut would be considered typical for a "deep cut" to try in situations like this?  I am waiting till my TGP order gets here to continue with my project, but since I have the hot rolled, eventually I will probably want to use it up.



Given the size of your lathe, I might try 0.020 and see if it is happy there, maybe a bit more or less.  You are somewhat limited by power and rigidity, so you just have to figure out what works best for you and your machine.  Experiment a bit.  Maybe you can take 0.100 per pass, but slowly work up to that!


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## Bob Korves (Aug 21, 2016)

mrjbinok said:


> How much of a cut would be considered typical for a "deep cut" to try in situations like this?  I am waiting till my TGP order gets here to continue with my project, but since I have the hot rolled, eventually I will probably want to use it up.


It depends on how much scale is on the metal, but I agree with Jim Dawson on perhaps starting at about .020" with your lathe.  The feed depth also comes into the equation, you would really like to keep both pretty deep.  The idea is to expose the sharp cutting edges to as little of the scale as possible, which will tear them up.


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## mrjbinok (Aug 21, 2016)

Thanks for the suggestions.  I should have my new QCTP ready to install tomorrow and maybe I can do some experimenting.  Today is a different story..... weather is beautiful outside and a perfect day to get out and ride!!  Haven't been able to do this in a while so I'm going to enjoy the breeze in my face.


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## intjonmiller (Aug 21, 2016)

I have hundreds of pounds of A36, as a shop where I worked threw out substantial scraps like lawn clippings. As far as I understand it, the main difference between A36 and 1018-ish is that 1018 has a clearly defined standard composition, whereas A36 is more like pot/mystery metal. Lots of recycled content of unknown composition, with different sections of the same piece behaving differently (some hard, some soft; some machining easily while most is gummy). As has been mentioned, it is better suited to welding up machine stands and shelf brackets and so forth than it is to machining. That said...

I have turned a bit of it, as I wanted something I didn't mind using up for the first while on my first lathe. I hate using good material for practice, even though it means imperfect practice, but I just keep in mind that I'm practicing using the controls of the lathe, turning to a certain diameter, etc., not practicing getting ideal finish. 

And then there were a couple things where what I was doing worked well enough that I wanted to make it look good. I found that a vertical sheer bit (HSS ground very differently from other types; search on here and YouTube for plenty of examples, including how to grind it) cleans it up rather well. But you're only going to take off up to ~0.001" at a time with that tool, and it is impractical to use it right up to a shoulder. But it is a useful option to keep in mind.


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## Doubleeboy (Aug 21, 2016)

Wreck™Wreck said:


> Flood coolant, use negative rake carbide tooling meant for steel with a large nose radius and as mentioned above use a large depth of cut and spin as fast as you are comfortable with.
> 
> Cutting oil is not coolant as it doesn't remove the heat. Above all try not to use hot rolled bars whenever possible, also take note that 12L14 is mostly un-weldable due to the lead content, it was developed for automatic screw machine products but has been largely replaced by 1215 due to the toxicity of lead.



For decades I heard this about 12L14 and repeated it cause I had heard it.  Then a 75 year old, life long machinist called BS when he heard me repeat it.  Drug me over to his shop welded up 2 pieces of 12L14 flat stock, took them over to the press, 50T and the weld started to give about the same time as material.    Its not allowed for certain jobs that need to be welded, but it can certainly be welded even by a hack like me.  

cheers
michael


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## intjonmiller (Aug 21, 2016)

Doubleeboy said:


> For decades I heard this about 12L14 and repeated it cause I had heard it.  Then a 75 year old, life long machinist called BS when he heard me repeat it.  Drug me over to his shop welded up 2 pieces of 12L14 flat stock, took them over to the press, 50T and the weld started to give about the same time as material.    Its not allowed for certain jobs that need to be welded, but it can certainly be welded even by a hack like me.
> 
> cheers
> michael



Welded with what process and filler?


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## chips&more (Aug 21, 2016)

mrjbinok said:


> Thanks for the info.  The parts I am making will end up as drill jigs to insert into a bushing and give a reproducible line up for drilling for a locking dowel pin through the shoulder.  I will be heat treating to add some durability so my question (since I don't have time right now to research).... are the 2L14, 1215, 1144, and the 1018, 1020, 1040/45 grades heat treatable?


For what you have listed. They can all be case hardened. But only the 1144 and 1040/45 can be heat treated. To make the bushings, I would try the 1144.

And on another note. I did try many years ago to heat treat low carbon steel like 1018 with I think a salt/soapy water solution. I heard about it and tried it for the fun of it and it did work. For what I do in my shop though, it was not a viable plan, just a trick to remember (huh that sounds easy enough!). It’s probably all over the internet now.


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## Doubleeboy (Aug 21, 2016)

intjonmiller said:


> Welded with what process and filler?



It was stick, 6011


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## Wreck™Wreck (Aug 22, 2016)

Doubleeboy said:


> For decades I heard this about 12L14 and repeated it cause I had heard it.  Then a 75 year old, life long machinist called BS when he heard me repeat it.  Drug me over to his shop welded up 2 pieces of 12L14 flat stock, took them over to the press, 50T and the weld started to give about the same time as material.    Its not allowed for certain jobs that need to be welded, but it can certainly be welded even by a hack like me.
> 
> cheers
> michael


Agree, should have said that is doesn't weld well, have done it often in the past.


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## mrjbinok (Aug 22, 2016)

intjonmiller said:


> with different sections of the same piece behaving differently (some hard, some soft; some machining easily while most is gummy).
> 
> I have notice this on the pieces that I have turned. I have however been able to get a decent finish with emery cloth on the last .001 or so.
> 
> ...



I really do appreciate all the good info given here.  I asked for tips and suggestions and I got a whole lot more that I can file away for future reference.  I had come up with my own version of the "vertical sheer" that you suggested.... It worked somewhat, but I think I was trying to push it a bit too hard and the cutting edge didn't last long.  I didn't know what it was called, but decided to try the tool shape to see what it would do.  I'll do some research now and see if I can fine tune it for other projects.


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## intjonmiller (Aug 22, 2016)

Either the geometry was wrong, you were cutting too deep, you were feeding too fast, or you were using it on the mill scale. Those usually hold an edge very well. As my father always told me while teaching me to shoot free-throws, "Never end on a miss." It's a very cool and useful bit geometry, so don't let your experience with it become a lasting impression.


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## mrjbinok (Aug 22, 2016)

I think I was trying to push too fast and too deep.  I did come across this video on youtube where the guy is using the VS for exactly what I am trying to do with the Hot Rolled stock.  I picked up my QCTP this morning from my brother (he has the mill to make the TeeNut to fit) so I plan to do the VS first... using the new tool post.  I think I am close on the geometry, but I'll touch it up a bit before I start so that I know I have a good cutting edge.


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## Wreck™Wreck (Aug 22, 2016)

mrjbinok said:


> I think I was trying to push too fast and too deep.  I did come across this video on youtube where the guy is using the VS for exactly what I am trying to do with the Hot Rolled stock.  I picked up my QCTP this morning from my brother (he has the mill to make the TeeNut to fit) so I plan to do the VS first... using the new tool post.  I think I am close on the geometry, but I'll touch it up a bit before I start so that I know I have a good cutting edge.


What is the "VS"?


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## Tony Wells (Aug 22, 2016)

Thinking he is talking about that vertical shear tool people go on about. Never used one myself.


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## mrjbinok (Aug 23, 2016)

Yes my reference to VS is for the "Vertical Sheer".  Sometimes I look for abbreviations 'cause I'm lazy when it comes to typing!  I guess that is a carry over from years of computer programming.  Sorry for the confusion.


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## sanddan (Aug 23, 2016)

Doubleeboy said:


> For decades I heard this about 12L14 and repeated it cause I had heard it.  Then a 75 year old, life long machinist called BS when he heard me repeat it.  Drug me over to his shop welded up 2 pieces of 12L14 flat stock, took them over to the press, 50T and the weld started to give about the same time as material.    Its not allowed for certain jobs that need to be welded, but it can certainly be welded even by a hack like me.
> 
> cheers
> michael



Not a good idea to weld something that has lead in it. The smoke coming off the weld could be somewhat toxic. I'd use other materials if I was going to weld them.


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## sanddan (Aug 23, 2016)

I also did my early practice on the lathe using HRS as it was what I had on hand. It was discouraging due to the crappy finish until I realized what was happening.

A good source of material for practice is old bolts. If you are like me, you have a stash of old bolts in a bucket/drawer. Most will be made of pretty decent material and will give you a good finish. It might require you to do light cuts but it's practice right?


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## Wreck™Wreck (Aug 23, 2016)

Today's job, cams made from 1018 hot rolled stock 1 1/4" OD, they are 5" overall length, .498" +0 - .003" with a 1/2-13 thread .75" long.
The head diameter is .960" offset by .105" and is 5/8" long. I faced them to length in hard jaws and drilled a center in one end, changed to pocketed soft jaws and a live center then turned the .498-.495 X 4 3/8 shank.

Changed chuck jaws again to 1/2" soft jaws (in order to not mar the finished surface), put the large end inside the chuck against a spindle stop and did the chamfer, undercut and thread. 

Then made a fixture in the lathe and drilled and reamed it in a mill with the offset which looked like this:




Changed jaws again to hard jaws to hold the fixture, the shoulder is to give a fixed position in the Z axis when changing parts. Used the thread to hold them and turned the offset diameter of .960".

Used a DCMT insert at 750 RPM's, .032 DOC and .008 IPM feed for roughing, 750 RPM's, .004 DOC and .004 IPM for finishing and the finish and repeatability were excellent, flood coolant is essential. I did 12 parts with one insert.

As a sidenote these parts do not control the wings on aircraft so the typical hobbyist penchant for accuracy to 2 tenths does not apply. I did however use a set of thread ring gauges only because we had them.

You can get a reasonable finish on that material with careful tool choice and practices.
Also machine work is not as hard to learn as you might think, plan ahead a bit and do what works for you and your particular machine and job.

Good Luck


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