Please Review My Plan

jbmauser said:
I have a SB48 lathe, a steel bar 1 1/2 in. Dia. that is to long to cut down for working stock with the tailstock in place. I am going to chuck it up and support it with the steady rest and cut it in half. I saw a video on youtube and the guy was doing exactly what I plan to do but he was cutting a hollow AL tube. he ran his cut off tool behind the rest and handled the cut off stock by hand. this bar is heavy and I am sure it will sag as the cut nears the center and it will bind on the tool, (my estimation anyway) I think I will support the stock and cut inside the rest on the chuck side and cut it in thirds or even quarters and balance the waste side and perhaps place support on the ways so the waste will stay level as it is cut free. Or I could cut to 1/2 in. and move to a hacksaw. My concern is binding on the tool and having a bit of excitement I don't meed. This bar is salvage from a yard for the purpose of cutting nothing in particular, practice, do dads and what nots.
Click to expand...
I'd find someone in the metal trades with a bandsaw or a torch and slip him a 6- pack.
 
jbmauser said:
Looking for plan C or to just retire this unknown steel and buy some known stock. I did not cut 1/8 into the shaft with a new Starrett hack saw blade and it quite cutting. lube and all. This metal is very hard. I think I will order some AL stock to start and work on developing a feel for the lathe then move on to stock of known material. Thanks all but I am out of tools.
Click to expand...

If that steel is too hard for a quality hacksaw blade then you will definitely not have much fun turning it especially with HSS tools. Bear in mind that all aluminum alloys are not equal in machinability either. Some are very gummy to cut.
Your idea to buy some known steel that is easy cutting sounds like the best option to get you started.
 
6061 Aluminum is easy so you will not learn much, the most common steel material that you will end up turning is 1018 because it is the least expensive. It is often difficult to achieve a nice finish with 1018 yet learning how will teach you a good deal, free machining steels will also not teach you much, as an experiment buy a piece of plain old 1018 CRS/A36 HRS and a piece of 12L14 of the same size and turn them one after the other using the same set up, this will give some idea of what "Free Machining" means.

Today's awful job, two parts from 6" Dia. X 1/4" wall steel tubing 64" long, the OD finishes at 5.870-5.875", this means it is only 3/16" wall at the finish cut, this was chatter waiting to happen and it did. I had to finish a 90 RPMs, .012 DOC and a .009 IPR feed rate using a TIN coated 321 triangular insert. This took roughly all day.

64" / .009 feed per revolution is 7111 revolutions, 7000 revolutions / 90 revolutions per minute is 79 minutes for the finish cut, the 3 roughing cuts were a bit faster.

On the bright side the finish was better then I had expected when turning so slowly.

6inchtube_zpszeer8sge.jpg

Good Luck
 
Last edited:
All my purchases come from a local metal supplier or from left overs at local machine shops. Fortunately our town is big on metal fabrication and machining.
It sounds like you are just starting out so the 6061 or the 12L14 would be good confidence boosters.
Once you have a bit of practise and have made a few do-dads and what-nots successfully then maybe cutting a less cooperative metal won't be so frustrating to figure out.
 
Thanks all for the replies. I took the piece to a man who knows about metal and tools. He told me the shaft is hardened and it was the piston rod of a hidrolic uy cylinder. It gave me 50 lbs of cut offs and told me to buy a HF portable band saw and then order some quality blades which I did. I hope I am good to go and I am working on drawing up some projects. Thanks again.
 
My thinking is, If it is too hard for a hand hacksaw, I don't want it ruining my bandsaw blade. I use abrasive cutting for hard stuff.
 
jbmauser said:
I have a SB48 lathe, a steel bar 1 1/2 in. Dia. that is to long to cut down for working stock with the tailstock in place. I am going to chuck it up and support it with the steady rest and cut it in half. I saw a video on youtube and the guy was doing exactly what I plan to do but he was cutting a hollow AL tube. he ran his cut off tool behind the rest and handled the cut off stock by hand. this bar is heavy and I am sure it will sag as the cut nears the center and it will bind on the tool, (my estimation anyway) I think I will support the stock and cut inside the rest on the chuck side and cut it in thirds or even quarters and balance the waste side and perhaps place support on the ways so the waste will stay level as it is cut free. Or I could cut to 1/2 in. and move to a hacksaw. My concern is binding on the tool and having a bit of excitement I don't meed. This bar is salvage from a yard for the purpose of cutting nothing in particular, practice, do dads and what nots.
Click to expand...
Yes, I see too hard anyway so sounds like you're on the right path now for just practicing and using for whatnot...I recommend Ledloy (if yoose' are wanting steel)
PS Your original plan though, even if the bar was soft, was an accident looking for a place to happen!...
...Saying that: If the bar was softer, maybe shorter, you would part shorter pcs. off on the tailstock side of the steady rest while holding/supporting (catching) the shorter part with your right hand while feeding the crosslide with your left hand (NOT the chuck side!)

Add: Remember when parting off in a manual lathe, once you get your spindle speed and your feed "dialed in" (slower), and usually with coolant or squirting/brushing on cutting oil in the ever deepening slot, keep going once you get the chip peeling and don't stop until you have cut it off (or finish cutting the last 1/4" or less with a hacksaw)
 
Last edited:
Ahh, the 'ol parting tool. Misuse will maim or kill.

I have had lathes and mills for over 50 years but the best addition to the shop was a big Wells Metal Band Saw that will cut up to a 9" X 18" cross section. New cost was $14,000 with a hydraulic feed 20 foot table.

I obtained it for $250 from a Machine Shop that was abandoned and being torn down. My best find ever. It did not run when I found it: A set of fuses and it was off to the races. It is 3 phase but I already had 3 phase power in the shop. Hydraulic feed up and down. Pressure coolant.

upload_2016-11-17_18-0-56.png
 
You must log in or register to reply here.
Back
Top