Author Topic: Prima Lathe conversion  (Read 26531 times)

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Offline zafarsalam

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Re: Prima Lathe conversion
« Reply #20 on: November 30, 2013, 11:05:13 AM »
I would select the ball screws first. For a machine this size, 25 - 30 mm dia ball screws would be suitable. A pitch of 5 to 10 mm would fine too. Install the ball screws on your x and z slides and then measure the torque that is needed to turn the screws. Servo motors are selected after you have the required torque and the desired max. rapid feed. For conventional slides that have metal to metal contact, I normally don't go above 5000 mm/min. So if you have 3000 rpm servo motors and a 5 mm pitch ball screw, the timing pulley reduction to get 5000 mm/min rapids would be 1:3. And if the calculated torque is 6 N-m then for a 1:3 gear reduction you'll need 2 N-m on the motor shaft. A 2 N-m, 3000 rpm servo motor would be roughly 750W. This is normally the size of motors on machines this big. The spindle encoder mach3 needs is single pulse per revolution. If you are going for the parallel port setup then make sure that your index signal is long enough for mach to read. With external motion controllers you normally don't have to worry about the index pulse width.

Offline vre

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Re: Prima Lathe conversion
« Reply #21 on: November 30, 2013, 08:11:30 PM »
Thank you very much for your reply.
Because is not easy for me to make torque tests because if i disassemble the lathe and install ballscrews i will not have machine to make the modifications so from your experience this selection will be ok ?
for z axis: 32mm diameter 5mm pitch ballscrew 750w/3000rpm yaskawa/mitsubishi servo with reduction 1:3
for x axis:16mm diameter 5mm pitch ballscrew 400w/3000rpm yaskawa/mitsubishi servo with reduction 1:3

If i put steppers this will be ok?
for z axis: 32mm diameter 5mm pitch ballscrew nema42 4200oz with reduction 1:2
for x axis:16mm diameter 5mm pitch ballscrew nema34 1600oz with reduction 1:2

On your machine how much is the torque for z and x axis ? I will suppose that in my machine the torque will be 1.5 times higher than yours...

I will go with parallel port this encoder will be ok ?
http://www.ebay.com/itm/Optical-Endstop-Switch-for-CNC-3D-Printer-RepRap-Makerbot-Prusa-Mendel-RAMPS-1-4-/400545910883?pt=LH_DefaultDomain_0&hash=item5d42659063
Can i put with some hack to mach3 an incremental optical rotary encoder for better resolution or not ?
« Last Edit: November 30, 2013, 08:13:15 PM by vre »

Offline zafarsalam

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Re: Prima Lathe conversion
« Reply #22 on: November 30, 2013, 09:23:05 PM »
Your selected hardware seems ok. The motors on my machine are both 750 W with 1:2 reduction. They run fine with 3000 acceleration in Mach3. I didn't calculate the torque on the screws on this one. Your selected encoder will work fine. Just use a single slotted disk and make sure that the slot is wide enough for parallel port to read. For a spindle running at 1500 rpm max. the slot should be at least 45 degrees wide. You'll have to experiment with it a little. Mach3 won't read the optical incremental encoder at high speeds if it's a fine pitch. And the threading option in Mach requires single pulse per revolution.

Offline vre

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Re: Prima Lathe conversion
« Reply #23 on: December 11, 2013, 02:39:23 PM »
Iam planning to use these drives with matched servos without reduction
http://www.ibuyla.com/Product/14836946575/

What breakout board to suggest me supporting
>=4 axis
>=6 optical endstops
1 optical spindle sync endstop
option to control spindle speed with vfd
manual operation with joystick & jog speed control
option to switch on/off cooling fluid (to switch oil solenoid electric valve )
emergency stop
points in cutting tool
pause or reset cutting operation
ability to control tool turret

It doesn't matter the if is parallel or usb
Are these ok ?
http://www.ebay.com/itm/USB-5-Axis-CNC-Breakout-Board-Interface-Adapter-For-Stepper-Motor-Driver-/321133023129
http://www.aliexpress.com/item/4-axis-USBCNC-breakout-board-interface-board/1015011998.html

Iam planing to buy from ebay or aliexpress.

thank you
« Last Edit: December 11, 2013, 02:53:26 PM by vre »

Offline zafarsalam

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Re: Prima Lathe conversion
« Reply #24 on: December 12, 2013, 01:59:13 AM »
Sorry, I don't have experience with commercial break out boards. I design my own break out boards for each project I make.

Zafar

Offline vre

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Re: Prima Lathe conversion
« Reply #25 on: December 12, 2013, 02:06:58 AM »
the breakouts witch is for stepper drivers work with servo drivers ?

Offline zafarsalam

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Re: Prima Lathe conversion
« Reply #26 on: December 12, 2013, 05:08:49 AM »
Yes they will work for steppers too. Just make sure that you can connect the drive error signals through the BOB too. Normally we connect it to the external e-stop.

Zafar

Offline khalid

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Re: Prima Lathe conversion
« Reply #27 on: December 12, 2013, 06:31:31 AM »
Zafar Brother.. You are a legend:).. Really love your skills and knowledge. You are a true engineer:)

Offline khalid

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Re: Prima Lathe conversion
« Reply #28 on: December 16, 2013, 08:56:02 AM »
Zafar Brother, do you have UC100 available. I want to test it with my G540.

Offline zafarsalam

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Re: Prima Lathe conversion
« Reply #29 on: December 16, 2013, 09:42:42 AM »
Zafar Brother, do you have UC100 available. I want to test it with my G540.

Sorry Khalid. It got installed in a machine last month. I'll let you know when I get a few more. UC-300 are available at this time though.

Zafar