Acer Trump 1236 Vfd Conversion

[Bamban]

To appreciate the conversion, here is how the old set up was.




As I alluded on this thread, last entry, that the decision has been made, 3P and VFD is it. http://www.hobby-machinist.com/threads/3p-vfd-or-dc-motor.30710/ The conversion is done, done, but I will post in installment, will start with the details on what made up the conversion

First of all this conversion is a direct credit to a forum member. His generosity and kindness, and follow through by his daily email as I went through the installation, made it all possible. I am talking about one of own, mksj. Mark not only provided the guidance, he volunteered to build the kit and all I had to do was interface the boxes, and basically just run the cables and hook up the connectors. He put together a nice 16 page manual complete with theory of operations, schematic diagram, wiring diagram, parts breakdown, and VFD configuration set up optimized for maximum performance.

When I said he built the kit, I mean he built the entire kit, here are the pictures of the kit as it came in. I could not thank him enough for his work. Almost all the components he used are from Automation Direct, I defer to him if you folks are interested in knowing the detail components and the rationale for the selection.






















More pictures tomorrow, TinyPics is acting up on me and the site limited me to 20 pictures.

Enjoy.

 

[Bamban]

Mark and I exchanged a few emails discussing the lathe dimension, location of the VFD, size of the box housing the original logic control board so he can size the phenolic board properly. To allow the flexibility of the installation Mark added extra length to the wiring harness. You will see later on with the follow up pictures that his intuition is spot on. The cable lengths were just about perfect as if they were measured and fabricated on site.

Before I proceeded with the bolting down the major components I tested them for fit and best placement

VFD inside the enclosure


Logic control boards compared


Logic control board in the box


VFD enclosure resting on top of the portable heater, juts the right height to mock up the installation


Directional control box temporarily placed to figure out the optimum location for best operator reach.



The pre-work:

Prior to getting the VFD and the control system for it, I picked up this motor on Mark's recommendation, a Marathon inverter duty motor (still not sure I understand all I read about motors) on eBay. As described in the listing 221648873231, Marathon Electric Bluechip E2207-p 2HP HIGH PERFORMANCE INVERTER DUTY Series. The original motor is smaller in size compared to this one. Originally I was afraid it would not fit. The fit is tight, but I could only use on tensioning bar and the gap between the fan shroud and the splash fan is very narrow, appears to be fine though.




The motor directional control lever has always bugged me, due to the cramp space in my tool lay out I bumped on this thing a few times and turned on the motor. The week leading to the VFD conversion I just made it a habit to put the machine on eStop before I leave the work space. With the new directional control box for the VFD I decided to remove the manual lever and removed the 3rd rod. I kind of like the extra space to clean up under the bed.





Pulled out the front panel to see what kind of space there is behind it. Looks like there is but limited.




The initial fit up:

The relay logic control board though fits perfectly in the box, the old mounting holes were just free handed and not in the corners of the old board, the new one could not use the old holes. Instead of drilling new holes through the head stock I used an aluminum spacer which used the original holes, drilled and counter bored the holes, then drilled and tapped it to mount the new board.







I thought hard on how to run the interconnect cables from one end to the other. Options included plastic conduit, tie wrap hangers, plastic wire molds, or use the left over Unistruts I have after I installed Unistrut based frames to connect the2 cabinets after I removed the flimsy sheet metal that previously connected them. I end up using the Unistruts.

This first one houses all the power cables, you will see later the signal cables are running on a different Unistrut. The scheme worked out nicely in the final configuration. The white tie wraps are just to temporarily hold the cables in place.








More to follow later, reached my picture allocation,

Enjoy

 

[Bamban]

The installation did not go without any small inconvenience. When I sent the picture of the VFD input terminal strip I forgot to mention to Mark the bolt center, the spade terminals did not quite fit the slots. At first I modified a male quick disconnects connectors with hole in the middle to accommodate the hold down screws, got a couple of the spade connectors when Mark suggested just modify the spade connectors and squeeze them to fit. That saved some time






The motor did not come with studs to connect the wires and I did not want to use wire nuts so had to come up with a 3 wire terminal strip that I cut from 6 wire unit,





When I test fitted the front panel control, all the switches fit in the holes from the previous switches except for the new eStop, the original hole is 30MM while the new switch is 22MM. My plan was to machine adapter plates when Doctor Mark came to the rescue again. I did not know that HD sells 22MM to 30MM adapters that I just to flatten to use on the eStop hole. To cover the yellow color around the old function, I mounted the speed pot in that location.







As I mentioned I would end up running another Unistrut piece to house the signal cables. I do like these grown up Leggos.




The Final Hook Up.

The front panel control switches wiring had to pass through the headstock, the speed control had to pass through the headstock and on towards the VFD via the Unistrut channel, the interface between the relay control logic had to go through the same channel. The directional control box wiring had to be routed around the VFD enclosure and on to the relay control logic box.

Let the pictures do the talking.

 

[Bamban]

Functional testing the logic controller was the final verification to make sure I did not cross any signal wires. Prior to this test I made point to point continuity tests of the power cables just ensure I did not have any hot lines going to ground before I turned on the power. The front panel control configuration; top L is the eStop, right below it is the On switch to enable the logic controller. The top R is the Jog and below is the speed controller. Mark and I went around couple of times about the Jog button, at first when I pressed it, nothing happened. I was used to the old jog button that trips the forward contactor and was instantaneous.

During the testing we know the forward and reverse switches that activate relays and the circuits were good, so Mark suggested to swap the jog line and forward lines at the VFD. Pressed the jog switch, a momentary one, activated the spindle. The jog circuit is good. Pressed the forward switch, a latching one, nothing happened, but then a few seconds later the spindle started spinning at the low speed, which sort of reflects the programmed frequency for the jog. Turned off and repeated the test, same results. Reverted the wiring to normal and accepted the that the system will jog after a few seconds, something I can live with.

Did a clean pass on an aluminum stock I've been using to periodically test taper with







Finally, after verifying the correct spindle rotation, I Locktited the screws holding the motor wiring connections on the terminal strip and put the cover back on. Took some videos of the spindle at different RPMs to see how the speed controller works and how stable the it is. Uncovered that the 8 inch 6J Bison set thru has too much of a mass that when spinning hard and shut it down, its momentum will keep the spindle spinning, then the VFD faults out. Another consulting email to Mark. Switched to my Bison 6 inch 3J, I can spin it at 1000 RPMs or more, the system stays happy, no faults. Looks like I may just relegate the 8 inch 6J for slow rpm work or sell it and buy a 6 inch 6J set thru, even a Gator, or trade somebody for one.

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Done, done... Thank you, Mark!