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Author Topic: Retrofit Recommendations for Sharp CNC Knee Mill Using Existing Components  (Read 3789 times)

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My wife left with my best friend...
     and I miss him!
I have a couple of corrcections.

The LattePanda 4/64G is $149 without Windows activation, $209 with activation.

DMM 400W 60V servo $147
DMM DYN2 drive to suit $138 for a total of $285

for the high voltage setup, ie 230V input, no power supplies etc
DMM 400W 200V servo $177
DMM DYN4 200V drive $218 for a total of $395

You'd also need a couple of BoBs so posibly as much as another $100 for good ones.

My wife left with my best friend...
     and I miss him!
Once I looked up the Galil DMC-1020, it was pretty clear that it’s really old and only 2 axis.

Here’s a better pic of one of the Glentek brushed DC servos:


Model: GM4020-39-02006301-6
Torque: 23 In-Lb/368 oz-in (not huge for such large motors)
Resistance: 1.3 ohms
V/1000RPM: 7
Max RPM: 3500
rough calculations:

23/12= 1.92 ft.lb approx 2.2Nm

3500/60 =58 revs/sec
58 X 2 x 3.141 = 364 radians/sec

POWER= torque x speed
           = 2.2 X 364
           = 801W

Hey, those servos have got some serious grunt.... you'll want 750W units to match them, a bit
more than I allowed for. You could run 400W units but may not have quite the sting as the
current configuration. Plenty of blokes dream of having 400W servos on their axes...750W will
really make that mill sing...probably well more than is required for hobby purposes.

My wife left with my best friend...
     and I miss him!
I just realized that i may have 2 or 3 G320 Geckodrives
those servos are going to suck current like no ones business, I came to 32A at rated power.

I think you are buying into trouble....ditch the DC servos and get the current thing, they will last the life of the
machine. Additionally they have control and reporting modes that DC servos have never had.

I would go for 400W 200V DMM servos and matching drives...$1200 and you're out of there! No shagging
around with old s*********t!

My wife left with my best friend...
     and I miss him!
Ok. Thanks!
I assume those drives are digital with step/direction control capabilities.
Have any opinions on pulse generators or how to interface with more modern computers since parallel ports are old and not been on PCs for some time? Or just try to buy an okd PC with a parallel port?

I wonder if I could sell off the existing components to offset the cost of the new components.
My inclination is to leave the Mitutoyo linear scales on the machine and either get a DRO or find a way to display it on same PC so I can have a DRO for manual work.
I also would like to retrofit the quill with a motor/drive to make it a 3rd axis.

I like the Ethernet SmoothStepper (ESS) by Warp9. Its not the only choice but it is a good one amongst other good ones!
It will give you up to six co-ordinated axes....enough?

One, or if you want some more inputs, two BoBs, the old parallel port types plugged into the ESS and your set to go.
They can pulse at 4Mhz, 160 times faster than a parallel port and it allows you to use a late model PC like the LattePanda
I linked to.

I think the Mitutoyo scales and counter unit can be run as a separate system. A little bit of electronic trickery might be
required to get the scale to talk to Mach but is possible.

I personally think Mach4 is appropriate for new projects. Mach3 afficionados will disagree (i used to be one myself) but its so much
more flexible and stable.
My wife left with my best friend...
     and I miss him!
once you get away from the parallel port and use an external motion controller like the ESS or a UC300 then
you can use just about ANY PC you like....you know the one that the kids have left in the dust because its
three years old....just perfect.

It does have to be a PC, that is a Windows operating system. ARM processors wont do it and at this stage
Linux is not a go either....although according to smurph it may happen yet!

The little LattePanda I linked to is about 4 inches square, has an Arduino built in and Windows 10 Enterprise
pre-installed and activated for $209.

My wife left with my best friend...
     and I miss him!
Is there an upgrade discount for people who bought Mach a long time ago?

Breakout board recommendations?
I don’t see a need for tons of inputs (famous last words?) on this mill.

The servo drive box has a pretty beefy looking transformer in it to step the voltage down (from 120V) for the existing Glentek servo drives.