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Heavy Cut?

J

JOHN1

Aluminum
Joined
May 27, 2006
Location
SHREVEPORT, LA.
In general, on crs, what would be considered a "heavy cut" depth wise on my 17X60 Andrychow Lathe.

Manuel states the limit for "overload clutch slippage" is 11/32 ( .344 ) .0268 feed/ 45 rpm on 4" steel shaft.

Does this mean .344 on the carriage dial or half that?

Thanks
God Bless
John
 
I'd expect it to be the size of the chip. But more interesting would be the amount of HP the machine has, though at 45rpm it'll have some torque its also wayyyy too slow to be cutting 4" steel with these days. And if its anything like the one I just googled up with 7.5hp, it sure looks like it'll be running into trouble quick if anyone dials in a cut like that. 30hp machine, sure got for it.
 
Try it and see. That's a healthy cut but not a machine killer. Pretend its a drill cut. 11/16 drill at 0.014 feed per rev at 45 +/- feet per minute. It's only about 3/4 HP. A heavy feed to be sure but not a drill snapper. If the manual says it will take it then...

I've never tripped my overload clutch and I've doubled the motor HP my last upgrade. I regularly took up to 0.020 feeds at 350 FPM.

If you look it up in the literature the axial feed thrust varies widely for a given cut for any one particular material depending on DOC, tool geometry, tool mterial, SFM, and feed rate. It's a non-linear problem.

The overload clutch is to prevent damage to the feed mechanism in case of disaster not as a regularly used feed stop.
 
I love big high power machines and have taken some big cuts with them, but I see no sense in it. The risk of damaging the lathe just to see what is can do is silly. And the few extra minutes of cut time that come from making 2 passes instead of one is insignificant. Fixing a busted lathe is a pain so err on the side of too light rather than too heavy.
 
For setting the clutch.

SND said:
I'd expect it to be the size of the chip. But more interesting would be the amount of HP the machine has, though at 45rpm it'll have some torque its also wayyyy too slow to be cutting 4" steel with these days. And if its anything like the one I just googled up with 7.5hp, it sure looks like it'll be running into trouble quick if anyone dials in a cut like that. 30hp machine, sure got for it.
Click to expand...


This is from the Toolmex manual and that is the upper end when the clutch should start to slip. .197" starting cut without slip and the the 11/32" cut it should slip.

Thanks
John
 
I wouldn't think .344 would be much of an issue at that speed and feed. I'd just use HSS, because you aren't really running fast enough for carbide (45rpm on a 4" part is only 45ft/min). My old L&S with only 5hp can do that cut at double that speed, so I don't think it's going to max out your machine. Worst case, back the feed off a little.
 
kpotter said:
I love big high power machines and have taken some big cuts with them, but I see no sense in it. The risk of damaging the lathe just to see what is can do is silly. And the few extra minutes of cut time that come from making 2 passes instead of one is insignificant. Fixing a busted lathe is a pain so err on the side of too light rather than too heavy.
Click to expand...

AGREED! I could not have said it any better!
 
kpotter said:
I love big high power machines and have taken some big cuts with them, but I see no sense in it. The risk of damaging the lathe just to see what is can do is silly. And the few extra minutes of cut time that come from making 2 passes instead of one is insignificant. Fixing a busted lathe is a pain so err on the side of too light rather than too heavy.
Click to expand...

Although I respect your opinion and can see your point; if you are trying to make money, getting the most from the machines at all times is of importance.
If you take twice as many cuts as you need all day long it isn't very productive. There is no need to have a crash to get a lathe (or other machine tool) up close to it's limits if due care is taken in the setup and in general.
 
Im with Forrest on this, a cut, speed and feed like that is not going to bust anything, it will make the machine work and you will hear it!!

What you dont know is how the tool post will hold up. If you have a nice chunky tool block or 4 way you are probably good to go, some of the quick changes would be alot less forgiving.
 
When the factory states " a cutting depth of .344", do they mean .344 on the carriage dial, which in essence would be .688 diameter reduction or do they mean "dial in half that amount (.172"). Am I thinking right?

John
 
Fear Factory said:
I am a piece of shit and I know nothing compared to most, But Wouldn't the lathe stall way before you got to the stage of damaging the lathe, and if it didn't stall what's going to end up broken? feed mechanism?
Not being smart just curious.
Click to expand...

Well if the tool chips, there could be a sudden overload (not a lot of flywheel effect at 45 rpm) that shears off a key somewhere way back in the guts of the head or quick change. There are SO many variables as to the type of tool being used that the results would be highly variable wouldn't they ? "steel" is again a fairly generic term :-).
 
I have taken cuts that stall machines. The good machines like a lodge and shipley or an American tool works have clutches that slip and if that doesnt work they have pins that shear to protect the drive train. Chinese lathes for the most part have nothing and will self destruct. I earn a living with manual machines and taking an extra pass is much cheaper and cost effective than spending a week tearing down a busted lathe. If a couple extra passes on a job means the difference between you making a profit and not you are screwed. I cant compete with cnc and I dont even try. Manual lathes have their place but speed and efficiency is not their forte. Taking a full power cut for a couple of revolutions is no big deal or cutting a couple of inches so what. Taking a full power cut for a couple of feet now that will test your testicular fortitude. If the cutter goes dull for a second you wont have time to stop the lathe. The cutter will fail instantly if you are lucky, if the cutter doesnt fail the part needs to fly out if that doesnt happen clutches need to slip if they dont slip shear pins must break if the shear pins fail to break god help you if the belts dont slip on the motor. When that doesnt happen the apron blows up or the feed box. Blowin up a headstock is real hard to do that requires a collision.
 
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