Do you run at 100%

C.Perkins · Jan 25, 2017

QT15, everyone knows it is old but a work horse.

Will it take running at 100% rapid all day long ?

Or would you run it at 100% rapid all day long ?

Would it make sense to lower it to 70% rapid to save maybe wear and tear cause the bottom line is that you only gain 6 seconds on a part that takes 2 min and 30 seconds to make ?

I want this machine to last with the less cost of wear and breakdown.
Maybe I am being too cautious.

Thanks;
Clarence

Gobo · Jan 25, 2017

If production numbers are important, of course you run at 100%. The question is somewhat ambiguous.

xa-mont · Jan 25, 2017

C.Perkins said:
QT15, everyone knows it is old but a work horse.

Will it take running at 100% rapid all day long ?

Or would you run it at 100% rapid all day long ?

Would it make sense to lower it to 70% rapid to save maybe wear and tear cause the bottom line is that you only gain 6 seconds on a part that takes 2 min and 30 seconds to make ?

I want this machine to last with the less cost of wear and breakdown.
Maybe I am being too cautious.

Thanks;
Clarence

I think your overthinking it.

Your not running at 100% rapid all the time, because you're not moving at rapid all the time.

When i saw the title i thought it might have been about running the spindle at 100% load. Pretty sure rapiding isn't going to ruin the servo, or the drive, or the ball screw (assuming it's well lubricated) any more than running at 70%.

Sent from my LG-H815 using Tapatalk

cwtoyota · Jan 25, 2017

Most of this old iron is well designed and so are the controls. Just because it's moving quickly doesn't necessarily mean it's taking a beating.
These machines accelerate and decelerate on each movement, so the forces applied to the ball-screws etc. are not that much different at 75% vs 100%.

Forces on the servos and ball screws are likely to be many times higher during time in cut than they ever are while moving rapid.

In terms of machine life, it's probably far better to run the machine wide open and use the time you saved to properly clean and lubricate the entire machine.

davehud · Jan 25, 2017

Yes.
The machines are designed to run 100% rapid.

benganboll · Jan 26, 2017

I have:
QT10N 1986
QT10N ATC m/c 1986 (New to me and still not in production)
ST30 ATC m/c 1988

I only go under 100% at test run of first piece...

Red James · Jan 26, 2017

I think it's all about your comfort level. If parts run in 2.5 minutes and 100% rapid saves 6 seconds, compare the 6 seconds to the part change time and see how much longer parts loading is than the savings at rapid travel. Then do what makes you more comfortable running the machine.

Pete Deal · Jan 26, 2017

When I got my QT15, still new to Mazatrol, I forgot to set the z zero for the end of a part and did a 100% rapid into the chuck which was luckily stopped. I read some posts on here that were much like Red's and I did some figuring what 100% rapids really save me and its not much of a time savings. So I set the 100% rapid max speed parameter(s) down to reduce it to a level that seemed to not give up much and might give me more chance to hit stop before a crash. If I get that 1,000,000 part job I may wind up putting it back to where it was.

wippin' boy · Jan 26, 2017

less than 100% on rapid will save wear and tear of the servo drives.
a drive is about $3k to rebuild plus down time.
same with the spindle drives, accel/decell reduction of a second or so saves a lot of spike in the drive.

DMF_TomB · Jan 26, 2017

always 1st run i run with rapids reduced. obviously will crash faster if something not right. drilling and slamming tools in and out at 100% rapids is harder on tooling.
.
many machines when they stop from 100% rapids they oscillate back and forth .001" for a few seconds. with short carbide drill any force sides ways will try to break snap drill off.
.
sometimes i add M0 or M1, i run at 100% rapids but have machine stop at tools i want to watch and run at slower rapids. then turn back up when i confirm everything ok
.
i have had jobs where tool is damaged and i had a extra 10 hours of rework. and high rapids and feeds and speeds that supposedly saved one hour cost me 10 hours in rework. like spending $10 trying to save $1

D.D.Machine · Jan 26, 2017

I think it has a lot to do with the machine I`m running .. my older fadal mills I run at 100% ( only 400 IPM ) my Haas mills I run at 50% in that the spindles are slow to get up speed 12K on most parts and there is no time saved moving fast if your just getting there and whiting for the spindle ... My Haas and mori lathe I run at 50% or they jump really bad on long moves.... my new doosan mill i run at 100% ... spindle gets up to speed fast and the machine never jumps on moves .

Bottom line is put your hand on the machine at 100% and see how bad its jumping around ,,,

Philabuster · Jan 26, 2017

wippin' boy said:
less than 100% on rapid will save wear and tear of the servo drives.
a drive is about $3k to rebuild plus down time.
same with the spindle drives, accel/decell reduction of a second or so saves a lot of spike in the drive.

Agree 100%

Slowing the down the spindle acceleration also saves a bunch on your power bill too if you are running the machines at home.

C.Perkins · Jan 26, 2017

Thank you all for the information.

The reason I ask is that I have retired from the automotive repair industry after 35 years.
Entered into CNC for almost a year now.

I run a QT15 that is 30+ years old and a QT200 that is about a couple years old.

No issues with the newer 200 running 100% after set up and first few good pieces.

The older 15, I am concerned about.
Forgive me cause I am new to this but was just wondering if turning down the rapid will extend the life of this aged machine, especially if the difference is only about 10 seconds for a completed part.
The powers to be want 100% on all machines, new or old.
It is just that my mechanical background says; "take it easy on the older machines".
Seems that trying to hold the bore and taper to .0009" on a .2511" x 1.020" bore gets tougher at a higher rapid rate than 70% which is why I go lower than 100% with certain parts.(is this normal ?)

Was just wanting to know what the "in the field" knowledge has to say.

Clarence

wippin' boy · Jan 26, 2017

my advice has always been
if you don't need it don't take it

machtool · Jan 27, 2017

wippin' boy said:
my advice has always been
if you don't need it don't take it

I never bother to argue with my other brother, born by a different mother, but this time I'm going to risk it.

Stay tuned.

machtool · Jan 27, 2017

C.Perkins said:
The older 15, I am concerned about.
Forgive me cause I am new to this but was just wondering if turning down the rapid will extend the life of this aged machine, especially if the difference is only about 10 seconds for a completed part.

Forgive me, I'm a heretic / metric. You can have a machine that does 8 -10 -12 metres per minute. Rapid rates and acceleration, are set by parameter. Changing the rapid feed knob 25 - 50 - 75 - 100, doesn't change the parameter, that sets acceleration. It will accelerate at the same rate, despite your best effort to screw it down.

It will always accelerate at the same rate. Its the same kick in the arse Zero to 50%, as Zero to 100% rapid. Turning it down, only means that it will top out sooner. It will stop at 50% of rapid. It would have accelerated just as fast in Acceleration at rapid if doing 4m/min or 8m/min. About 0.2G. There are no different rapid parameters for 25 - 50 -75 -100%

Just to be sure, we could solder, weld, and Jbweld your rapid over ride switch to 25%. Acceleration rates for 10 -25- 50- 75- 100, would still be the same. That's the same amount of power we are punching in until you hit flight attitude. (But we turned the engines off at 50%)

machtool · Jan 27, 2017

C.Perkins said:
Maybe I am being too cautious.

Pretty sure you are right on that count

Unless you are Dumb Mo Fu Tom. He's all about how to slow down a process 10:1 "Jerk" would be a wank off. And to others a Servo tuning term.

wippin' boy · Jan 27, 2017

I can't disagree with Machs analysis.
I have no history that say slowing down rapids has any real benefits.
but i do know some sick amplifiers will run all day at 70 or 80 and shut down on alarm at 100. this has always made me think there is some difference in the affect of rapid percentage on drive. I will have to agree with the accel/decell points as I only know of adjusting that on spindle drives not servo drives.
we'll just say looking at the scotch decanter I see half empty

wippin' boy · Jan 27, 2017

and wanking?
luckily for me I've spent the vast majority on the wanking side of manufacturing and it has served me well

DMF_TomB · Jan 27, 2017

i was a maintenance machinist too for over a decade. often machines slowed down do tend to need less maintenance. and occasionally a operator will have time to stop a crash from happening.
.
for example does a tool changer arm really need to rotate 180 in 0.5 seconds and slam the tool around possibly effects a probe sensor or boring bar settings ? or will taking a whole 1.0 seconds really going to cause business to fail ? and yes that is often a flow control or acceleration deceleration thing
.
i have seen many a time where company ends up spending $10. trying to save $1. i myself prefer to look at every machine break down and figure out why it happened and maybe change things so machine does not break down as often. as a maintenance machinist i started job 1st year working 5 days a week fixing things. after a few years i often only spent 2 or 3 days fixing (often just cleaning and oiling machine) machines and 2 or 3 days making parts in the shop so machines would run smoother.
.
i much preferred being the maytag repair man with nothing to do cause machines never broke down.

Do you run at 100%

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