Turning Steel

[Chip Monkey]

I know mini lathes can cut steel. I don't have a lot of experience doing it, but have been able to hold decent size and finish on stuff of varying lengths and diameters. But, seems like more often than not that every steel session has to be followed up with a carriage adjustment. Light cuts, good tooling, proper speeds/feeds, etc., but so far I'm not impressed with its ability to stand up to 12L14.

What might I be doing wrong/what should I check? I'm all ears and would love to find out that I'm the problem and not the other way around. I think it's me, but at the same time I really think I'm doing things properly. I consider myself a novice on a lathe, but all my time has been on larger, domestic machines.

My machine is a LMS 7350 which I am not singling out. Talking generically about these Sieg based lathes. What's your experience?

PS

Not to gush, but I'm a new guy here and have REALLY appreciated the knowledgeable feedback I've received from other posts. Thank you all very much.

 

[Flyinfool]

When you say you are "using proper speeds and feeds", what is your source for "proper"?

Many small machines can not handle the speeds and feeds that are published, You might just be trying to cut more than a small machine can handle.

 

[SLK001]

A sharp HSS tool with the correct geometry should cut 12L14 like butter.

 

[WobblyHand]

I know mini lathes can cut steel. I don't have a lot of experience doing it, but have been able to hold decent size and finish on stuff of varying lengths and diameters. But, seems like more often than not that every steel session has to be followed up with a carriage adjustment. Light cuts, good tooling, proper speeds/feeds, etc., but so far I'm not impressed with its ability to stand up to 12L14.

What might I be doing wrong/what should I check? I'm all ears and would love to find out that I'm the problem and not the other way around. I think it's me, but at the same time I really think I'm doing things properly. I consider myself a novice on a lathe, but all my time has been on larger, domestic machines.

My machine is a LMS 7350 which I am not singling out. Talking generically about these Sieg based lathes. What's your experience?

PS

Not to gush, but I'm a new guy here and have REALLY appreciated the knowledgeable feedback I've received from other posts. Thank you all very much.

I have a 7350 from LMS. It is fairly capable. I have found the saddle retainer needs to be tightened more often than I like. They simply cannot be done while on the ways. That being said, it was fairly easy to slide off the apron and tighten the retainers once there is easy access. I have found a mod that can be done that allows the retainers to be adjusted from the top.

That being said, if you haven't adjusted your gibs and saddle retainer, you should do that according to the instructions. A 7350 will have no problem cutting 12L14 at all. (Or 1144) But your tool needs to be on center, it has to be sharp, and all the slop in the lathe adjusted out. Adjusting the gibs and retainer doesn't take long at all. Once you do that, it's pretty good for it's size.

 

[Chip Monkey]

When you say you are "using proper speeds and feeds", what is your source for "proper"?

Many small machines can not handle the speeds and feeds that are published, You might just be trying to cut more than a small machine can handle.

Below 80 sfpm, not more than .015 per pass

 

[DavidR8]

I know mini lathes can cut steel. I don't have a lot of experience doing it, but have been able to hold decent size and finish on stuff of varying lengths and diameters. But, seems like more often than not that every steel session has to be followed up with a carriage adjustment. Light cuts, good tooling, proper speeds/feeds, etc., but so far I'm not impressed with its ability to stand up to 12L14.

What might I be doing wrong/what should I check? I'm all ears and would love to find out that I'm the problem and not the other way around. I think it's me, but at the same time I really think I'm doing things properly. I consider myself a novice on a lathe, but all my time has been on larger, domestic machines.

My machine is a LMS 7350 which I am not singling out. Talking generically about these Sieg based lathes. What's your experience?

PS

Not to gush, but I'm a new guy here and have REALLY appreciated the knowledgeable feedback I've received from other posts. Thank you all very much.

What kind of tooling are you using?
As @SLK001 mentioned sharp HSS with the right geometry should cut 12L14 like butter.
Cheap import carbide will probably not do a great job.

 

[WobblyHand]

Below 80 sfpm, not more than .015 per pass

Carbide insert, brazed carbide, or high speed steel tooling? CCGT carbide inserts work well, or sharp HSS, or sharp brazed carbide are ok. If not sharp, not so good. I can easily cut 12L14 with your settings.

By sharp, I mean the tool is sharp enough to slice your thumb.

 

[Watchwatch]

A sharp HSS tool with the correct geometry should cut 12L14 like butter.

This. The geometry doesn’t even have to be that great. HSS, 500 rpm, a couple thou per rev feed rate, and .02ish max DOC.

I bet the OP is using the wrong carbide inserts for the size of lathe.


Sent from my iPhone using Tapatalk

 

[Chip Monkey]

I know gibbs/ways are routine maintenance, I meant that by "carriage adjustment". I can get things nice and snug from the ways to the tool post, I was just expecting them to stay that way longer.

BTW, using home ground hss and will absolutely brush up on geometry. I never really thought carbide would be much good. Should I try?

 

[WobblyHand]

I know gibbs/ways are routine maintenance, I meant that by "carriage adjustment". I can get things nice and snug from the ways to the tool post, I was just expecting them to stay that way longer.

If you are like me, those saddle retainers don't get looked at often enough. Tightening them really helps with lathe rigidity. Last time I looked at them (last week) all the retainer screws were loose. I've had the middle screw fall out before. The middle screw is totally inaccessible when the apron is on the lathe.