View Full Version : Turning square stock on a lathe?

02-10-2005, 09:40 AM
I have a question about turning square stock on lathes. I was wondering if turning square stock was hard on the motor?

I was wondering becuase of the instant shock forces on the motor when the edge of the stock hits the tool.

Thanks, and sorry for all the questions, just trying to learn...without learning the expensive way.

EDIT: Im getting a 7x12 lathe.

02-10-2005, 11:26 AM
You shouldn't have to worry about the motor. What you might have to watch is your tool bit chipping if you're using a cemented carbide type. They don't like intermittent cuts.


02-10-2005, 11:44 AM
You shouldn't have to worry about the motor. What you might have to watch is your tool bit chipping if you're using a cemented carbide type. They don't like intermittent cuts.

J.I'll just be using C-6 and C-5 bits to start with. And the stock is aluminum. I also forgot to mention that its a 7x12 lathe. Do those adversly affect anything?

02-10-2005, 03:01 PM
Hi Mike
I use a high speed steel bit when I turn square stock. Take it slow!
It will chatter, and the chips are red hot, so wear a face shield!
The motor should be fine, as the drive belts will take most of the shock. I don't use inserts, unless they are the type held by a screw.

Just my 2c

02-10-2005, 04:14 PM
There shouldnt be much turning on it. Basically I need to make a round area, probably 1.5" dia, and 1/8 deep on some square bar for a piece to bolt to correctly.

The other thing I will be doing is facing some square bar. So I hope it works and doesnt screw me out of $500. Because if that happens, the metal wont be the only thing thats red hot.

Which Axis is considered the X-axis?

02-10-2005, 06:51 PM
I remember seeing a guy turning a square stock that he had filed the edges down to ease the cutting.

Brandon M.

03-29-2005, 02:53 PM
Having done things like this for almost 40 yrs here is a suggestion. When making your first pass turn your tool in far enough to make it round on your first pass. I know it sounds like a lot but it will get rid of the intermitent cut. I've cut alot of 3/4 x 1.0 4130 steel to 3/4 round in 1 pass for Cessna Aircraft

03-29-2005, 05:12 PM
68Vert is right.
I have been cuting down some 3in 5 sided bars. and I found that if I take one big bite I can avoid a lot of banging on my rest. I start the cut from the end and my tool is angled just a bit . I allso use a live center as the bars are about four feet long.
good luck

03-29-2005, 06:20 PM
Ive been doing this for a while too, but guys, its a 7x12 lathe... a 1/2hp motor probably wont have the guts to turn down a chunk of anything unless its wood in a large cut like that.. Were use to the great big 14x40 or whatever, with power to spare, these little machines arnt the greatest and probably wont make the cut in 1 pass like that.


Mike Malott
03-29-2005, 09:07 PM
Many years ago, I recall making some special square headed steel bolts. These were turned from perhaps 2" square stock x 12" long and the turned & threaded portion was 1-1/2" diameter x 10" long.

The stock was center drilled on one end and held in a four-jaw chuck. The tailstock supported the center drilled end.

We has a HSS tool that was 1-1/2" tall x 1" wide with a tremendous positive top rake; perhaps 30 degrees or so.

As 68vert suggested, we would take one rough pass to get the stock round, at about 50SFM and a light feed .002IPR. This tool would just shear off little triangles of steel connected by a thin web; if you can visualize this. I was always impressed at how well this worked. No fuss, no hammering, just nice, smooth cutting. We'd only brush on a little cutting oil from time to time.

After the steel was round in one cut, we would finish turn with carbide, then chase the threads.


Jeff Parker
03-30-2005, 08:28 AM
Are you turning the center, or just one end? I can see their ideas on the end, but in the middle... If it were me, I would fire up the lathe and knock the corners down with a 4-1/2" grinder first.

03-30-2005, 07:33 PM
I did try using my grinder to knock down the hard edges but it dident work all that well I think I had poor results due to the fact that I was turning at to high of a speed.. I think I was turning at about 360. Hmmm now that I think about it a higher speed might work better. Anyway the next time I turn down some square stock I will give the grinder a try and I will report the results.
Good luck

04-01-2005, 04:10 PM
Turning square aluminum down to round in one cut is sound if you have a power feed.
Use the lightest feed possible and a little coolant to stop the chips welding to the tool. High speed steel is fine. Grind a nice top hook to reduce cutting pressure.
x Axis is Front to back. Really is more referred to on a Lathe as cross slide.
X axis on a cnc lathe.
Hope this helps

04-01-2005, 08:14 PM
Long sleeves buttoned up!!!! Not on a lathe please.(no gloves either)
You guys are making this way too hard. Sure everything thats been said is true (execept the sleeves),but come on just do it. You wont hurt the machine,and a small lathe will tell you if it does'nt like what you're doing.