Open Collet While Main Spindle Spins

[danrudolph]

Quick question-- just wondering when you can and can not open the main spindle collet at the end of the cycle to regrip when the main spindle is running?

Pro's/Con's?

I have a small job, .150 OAL, using a front turn and a cut off, would like to just keep the main spindle running at 4k while the cycle restarts. Using a Citizen A20 with .125" dia stock.

Thanks--

[tobyaxis]

Originally Posted by danrudolph Quick question-- just wondering when you can and can not open the main spindle collet at the end of the cycle to regrip when the main spindle is running? Pro's/Con's? I have a small job, .150 OAL, using a front turn and a cut off, would like to just keep the main spindle running at 4k while the cycle restarts. Using a Citizen A20 with .125" dia stock. Thanks--

Not wise, Do an M5 then proceed with your transfer to the sub-spindle.

The machine should alarm if you try to open the collet while running anyway.

[ProProcess]

On a Citizen L series with Mitsubishi control MCVar #923 is Main Spindle Check speed, normally set a 2,000 RPM.
This is the Max RPM that M6 will still execute i.e. you can collet open at or below the value of #923.
I'm not sure if this is the case on the (I believe) Fanuc Controlled A series.
You could do a simple MDI test to see how fast the spindle can be running and still open.

They have set this speed based on what the feel is safe and operable for the collet open/close mechanism.
If you change to a higer speed [NOT RECOMMENDED!!], it may work but it may not work consistently i.e. you may have cases when the collet open signal is reached but mechanically the collet is not actually open, cause by inertia.
This would be an obvious bad thing and at the very least yield short parts.
The small may cause you problems as well.
Good luck!

[tobyaxis]

I just noticed your Signature, How True!

"Control the process, not the product!
Machining is more science than art, master the science and the artistry will be evident."

[cogsman1]

The NORMAL proceedure is to leave the spindle running in a swiss machine during "Start Position" at the end of the program. The "A" machine is no different. You have two choices. ***Be sure the cutoff is in front of the stock and the barfeeder is in AUTOMATIC to contain the stock.


M07-
M7- (macro) Collet open (main spindle). Use it alone on the line!
M7 will not open until the spindle is running less than 800RPM
Use M700 to open at any spindle speed.

M7M5(M5 won't work)

M5
M7(Will work)

M7U.5 (U argument added to dwell after chuck opened for barfeeders)

M700-(macro) Like M7 but open the collet at any RPM.

M700U.5 (U argument can be added to dwell after chuck opened)

[MikeMc]

Am I missing something? I have been opening and closing the chucks at high speed for years and never had a problem.

What do you think happens when you pick-off the part at cut-off........? Since the main and the sub are the same animal (on an L anyway), why would it make a differance? Someone please enlighten me.

[ProProcess]

Originally Posted by MikeMc Am I missing something? I have been opening and closing the chucks at high speed for years and never had a problem....

Since the L5, there has been the spindle check speed for the Main spindle.

Originally Posted by MikeMc What do you think happens when you pick-off the part at cut-off........?...

Usually when you pick off, the sub is open from knocking out.

Originally Posted by MikeMc ... Since the main and the sub are the same animal (on an L anyway), why would it make a differance? Someone please enlighten me....

One of the reason for regulating the M6 max speed is because of the weight of the bar stock.
At higher speeds, the centrifugal force would cause the bar to hang on the collet and move back with the head stock while returning to Start position.

[cogsman1]

The original question was for an A20 model. That has Fanuc control and a few codes are different. Openning and closing the collet at high speed is NOT reccomended on that machine, open at lower speed then go hogher if you need. During pickoff you should increase the speed AFTER you clamp on the part. This is better for the clamping devise and will prevent pre-mature wearing of the components.
Just because you can do it does NOT mean it is the correct way. Treat the machine nice and it will treat you nice.

Merry Christmas to ALL.

[tobyaxis]

Originally Posted by cogsman1 Treat the machine nice and it will treat you nice. Merry Christmas to ALL.

This is the Number One Rule in proper machine care!!! In other words"Do Not Bite the Hand that Feeds You", LOL.