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Author Topic: Spindle orientation on a Bridgeport...  (Read 3017 times)

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Offline Davek0974

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Spindle orientation on a Bridgeport...
« on: February 21, 2018, 06:31:46 AM »
I'm slowly making my way to an ATC project only BP conversion, got tool length on the knee, will be fitting a BT30 spindle this weekend, got new tooling etc,

Have read many great threads on here about ATC's but can find nothing on spindle orientation - seems with the BT30 having dogs, without this in place the ATC is a non-starter??

Now, I have an encoder on my spindle as it does rigid tapping, my first thought was can Mach read the Index pulse on this? Maybe that would be a way forwards, i just have no idea, the spindle drive is a standard 3Hp VFD driven AC motor the VFD has an "Inching" input option IIRC.

Whats the way forwards here?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives.
Plasma table, Mach3 V062, Step motors, C&CNC THC.
Re: Spindle orientation on a Bridgeport...
« Reply #1 on: February 21, 2018, 06:42:55 AM »
The way my BTC-1 does it is to inch the spindle and drop a shot pin into a ramped slot and when the shot pin reaches the bottom of the ramp/can't rotate anymore it sends a signal to stop inching and the spindle is orientated properly.


Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.

Offline TPS

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Re: Spindle orientation on a Bridgeport...
« Reply #2 on: February 21, 2018, 06:49:02 AM »
Hello Dave,

i am also stuck on exact the same point on by TonGIL TNV40 retrofit.
i also have CSLab,Encoder on spindle to a ENC module and VFD 0-10V for 0-6000 RPM as spindle drive.

i worked on the spindle orientation for hour's without any succes.

on one of my other machines i have a step/dir driven spindle, on problem there.

so let's see somebody has a good idea, but i think there is no way to get a 0-10V spindle to do exact positioning.

on a other machine i have a lenze VFD witch allows me to do the positiong on the driver.

Thomas
anything is possible, just try to do it.
if you find some mistakes, in my bad bavarian english,they are yours.

Offline TPS

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Re: Spindle orientation on a Bridgeport...
« Reply #3 on: February 21, 2018, 06:50:16 AM »
The way my BTC-1 does it is to inch the spindle and drop a shot pin into a ramped slot and when the shot pin reaches the bottom of the ramp/can't rotate anymore it sends a signal to stop inching and the spindle is orientated properly.


Mike

that is also a way i was thinking about. any photos ?
anything is possible, just try to do it.
if you find some mistakes, in my bad bavarian english,they are yours.

Offline Davek0974

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Re: Spindle orientation on a Bridgeport...
« Reply #4 on: February 21, 2018, 06:53:45 AM »
Yep, this point could be a major go/no-go point as changing controllers etc is out for the present due to funds and the fact that its all new anyway :(

I have see mechanical methods but i dislike those so far - cams, shoot-bolts etc.

There are also many mentions that on a BT30 size spindle the dogs are not needed anyway as the drive is taken by the taper, no idea if that is so or a good idea but it would certainly fix the issue cheaply !
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives.
Plasma table, Mach3 V062, Step motors, C&CNC THC.
Re: Spindle orientation on a Bridgeport...
« Reply #5 on: February 21, 2018, 07:14:43 AM »
Hi Dave,
this is from smurph:

http://www.machsupport.com/forum/index.php/topic,35694.msg248927.html#msg248927

The spindle dogs have to engage, a BT spindle taper is to steep to take the cutting torque like a Morse taper. Additionally if the dogs did not
line up the taper would not meet anyway.

Craig
My wife left with my best friend...
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Offline Chaoticone

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Re: Spindle orientation on a Bridgeport...
« Reply #6 on: February 21, 2018, 07:42:54 AM »
Not sure how you will line it up accurately enough without mechanical or electrical control capable of the required accuracy.

I have a Hurco with a BT 30 I was hoping to get going one day. I was going to drive the spindle with a servo and use the homing in the drive to orient the spindle for tool changes. Originally it used a shot pin.
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Offline Davek0974

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Re: Spindle orientation on a Bridgeport...
« Reply #7 on: February 21, 2018, 07:52:45 AM »
Hmm, ok a shot-pin or bolt seems it may be the only way then with my motor/drive setup.

I'll need to get the jog function programmed and working off a push-button in the drive first to do some tests it seems.

I knew i should have gone for a servo drive when i rebuilt ;)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives.
Plasma table, Mach3 V062, Step motors, C&CNC THC.

Offline Davek0974

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Re: Spindle orientation on a Bridgeport...
« Reply #8 on: February 21, 2018, 08:09:14 AM »
Ok, before i go too deep on mechanical indexing etc - all of this is a way off yet, lets have a re-visit to my setup..

I have a Bridgeport Knee mill with CNC everything :) It has recently been tagged as a KMVMC (knee mill vmc) :)

It has a 3Hp AC motor running sensorless vector drive with VFD at a 1:1 ratio, max speed is wound up to 125Hz to give me 4000rpm.

Is there a way to calculate a size of AC servo motor that would slot in and give me the same (or better) performance??

It seems most common ones only go to 2500rpm so would need to run at 1:1.6 ratio.

Just as a cost effectiveness exercise.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives.
Plasma table, Mach3 V062, Step motors, C&CNC THC.

Offline Chaoticone

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Re: Spindle orientation on a Bridgeport...
« Reply #9 on: February 21, 2018, 08:10:18 AM »
I'm pretty sure the Hurco did a slow run of the spindle then killed the spindle (will free wheel for a little bit). After killing the spindle and some set time it would trigger the shot pin. When the spindle coasted into position so that the shot pin and hole lined up it would bring the spindle to a stop at the correct position. After tool was changed, shot pin would retract. Be sure to think about fail safes if you go this route. Shot pin would ideally be gravity return. I would also want to be able to check that the shot pin is at home position before continuing.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!