Messages

261

Show"N"Tell ( Your Machines) / Re: 1987 Bridgeport Production Center Interact 412 to Mach3 Conversion

« on: August 13, 2010, 07:07:08 PM »

No problem, not like everyone in world should remember the current status of this project LOL

JH

262

Show"N"Tell ( Your Machines) / Re: 1987 Bridgeport Production Center Interact 412 to Mach3 Conversion

« on: August 13, 2010, 04:51:55 PM »

John,

Its long gone.....  3 phase is not an option for me.  This machine will run on 220VAC 30Amps Single Phase when we are done with it.

Thanks,
JH

263

Show"N"Tell ( Your Machines) / Spindle Orientation Part 1 of n

« on: August 13, 2010, 11:18:33 AM »

Been thinking a lot about how the spindle orientation will work.  The stock machine has a Spindle Encoder and Spindle Home Sensor connected off the spindle with a small pulley as shown in the picture below:

After doing some test attempting to stop to spindle and decelerate to the same spot each time, I have learned that this almost works.  I can get it to stop close to the same spot, but not good enough for a reliable tool change.  Its only off by a couple of degrees, enough to consider a different plan.  

The new plan:  replace the stock encoder mechanism with a small dc servo while keeping the mount and 1:1 pulley.  Add a home position notch and senor to the pulley.  Keeping the server motor disable while the spindle is on, the switch on the servo when the spindle if off, find home on the pulley and index to tool change orientation position.  

Concerns:  Q: the servo will turn into generator when the spindle is on and back drive the servo driver.  A: use a relay to disconnect the servo motor from the driver outputs and connect only during a tool change, make sure the servo driver is in reset when the outputs are connected and disconnected.

Some additional pictures below of the servo mount under construction:

264

Show"N"Tell ( Your Machines) / Programmable Gear Box

« on: August 11, 2010, 03:58:04 PM »

Step multipliers are common with high resolution encoders.  The ones that I have used before are typically programmable from 2x 4x 8x and 10x.  What is nice about the TSTA20C, is that you can select and ratio from 0.005x to 200x. 

On our VMC, we have 5 turns per inch ball screw and a 2:1 drive pulley for a total of 10:1 (10 turns on the servo will move the table 1 inch)  The encoder has 2500 lines with 10,000 pulses per revolution.  So with a target Mach3 Step/inch of 0.000125 (or 8000 Steps/Inch) I would need a 12.5x step multiplier.  My target max RPM is 2500 or 250 IPM (limited by the stock thrust bearing rating), therefore we can set the Mach3 kernel speed to 35Mhz.

Attached is a spread sheet that we used for the calculations.  There are 2 examples, the one described above and one with 0.0001 steps/inch target.  The Numerator and Denominator values is what the driver needs for the electronic gear box setting.  Based on that ratio, the Mach3 kernel speed required to generate the pulses for a target IPM is also calculated.

Screen shots of the kernel speed and motor tuning are in the spread sheet too.

Hope this helps,
JH

265

Show"N"Tell ( Your Machines) / AC Servos System

« on: August 09, 2010, 05:41:32 PM »

One of the cool things that I like about this system that is not advertised on the MachMotion site, is the electronic gear box parameters.  The servos have 2500 lines on the encoders that generate 10,000 pulses per revolution that would normally make for a very slow system.  However, the electronic gear box setting allow you select the resolution on the axis you want (ie: 0.0002 in/step), this allows for both accuracy and speed when connected Mach3.  It’s a programmable step multiplier with a scale from 0.005 to 200.

A second plus is the software CD from the manufacture.  This application allows you to dynamically monitor various parameters like Load, RPM, Current, etc in real-time.  You can also program and tweak all the parameters and setting on the user interface and save them off as a backup.  This makes setting up X and Z axis easy too.

Here are a couple of the software screens from the CD included with the servo driver:

266

Show"N"Tell ( Your Machines) / X Y Z Servo Motor Update

« on: August 09, 2010, 05:37:52 PM »

After setting for a several months, the Y Axis was faulting again.  I was generally pleased with the Gecko Drives and Stock Servos with the new digital encoders, however, the performance should be better on the this machine.  After slowing down the acceleration and speed profile again to prevent the fault, I have decided to scrap the current X Y Z plan… 

We been evaluating a NEW match set of 30 in/LB 750 Watt AC Servo/Driver from MachMotion.com  So far this system has been working great on the bench and we just connected it to the Y Axis.  Using the software provided by the Servo Driver Manufacture, we are able to move the Y Axis better than we have before.  Below is a picture of the new AC servo and the machining of the mounting bracket to fit it to the machine:

267

Show"N"Tell ( Your Machines) / Tool Changer Update

« on: August 09, 2010, 11:57:42 AM »

It’s been several months since I worked on the VMC.  The Tool Changer Carousel has been on my mind since we added the stepper to control it.  The stock changer used a large AC motor that was “broken” we got the machine…. or was it?  After doing some work this summer on some other AC motor systems, one having a bad starter capacitor, made me think, was the starting capacitor bad? 

After digging out the old Tool Changer Carousel Motor (pack rat) and getting a fresh 3uF starting cap… the old motor works great !!! 

The stepper motor used (3) digital outputs, Step, Dir and Enable and the AC motor only needed (2) Dir and Enable.  From the video below, the performance of much better than before and uses (1) less IO line.  We control the direction based on how the starting capacitor is wired during before it’s connected to power.

Thanks
JH

<a href="http://www.youtube.com/v/nvGSRYS_9nI&amp;hl=en&amp;fs=1&amp;rel=0&amp;color1=0x006699&amp;color2=0x54abd6&amp;border=1" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">http://www.youtube.com/v/nvGSRYS_9nI&amp;hl=en&amp;fs=1&amp;rel=0&amp;color1=0x006699&amp;color2=0x54abd6&amp;border=1</a>

268

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 04, 2010, 04:29:22 PM »

Looking good!

JH

269

Show"N"Tell ( Your Machines) / Re: New Project for the shop.

« on: July 03, 2010, 07:30:44 PM »

Cool, I like the poster hanging in the shop too

JH

270

Show"N"Tell ( Your Machines) / Re: 1987 Bridgeport Production Center Interact 412 to Mach3 Conversion

« on: June 14, 2010, 10:00:03 AM »

JH,
That sure is looking good. I'm following and taking notes.


JAckal

Thanks Jackal!   

Its been slow getting time to work on the BP 412 Project, Spring and Summer keeps me busy working on bike and parts.  I should get time as Summer starts to roll off.

Thanks,
JH