Yearly Archives: 2016

How far can it go?

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Summary: I drove my truck 46 miles on one charge (and had some juice left over).
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When you have an electric vehicle, everybody wants to know how far it can go.
I typically tell them “19,800 miles so far.”

But then you have to answer their real question, which is “What’s your range on a single charge?”. If you have a commercial EV like the Leaf or a Tesla, you can just refer to the EPA range figure for a nice apples to apples comparison. But when you have a conversion EV, the number is unique to your particular vehicle, motor, controller, battery pack and testing methodology. (And changes as the pack ages…)

I used to know the answer to that question for my truck with a (new) lead acid battery pack (“25-30 miles without killing the pack”), but I haven’t fully characterized the trucks’ power usage and range with the new (lighter weight, more powerful) pack made up of Nissan Leaf cell modules. My truck is heavier and has more air resistance than a stock Nissan leaf,   the motor/controller is slightly less efficient, and the (big fat!) tires have quite a bit more rolling resistance. I figured “half the range of a Leaf” would be a good ballpark estimate.

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Upgrading a 5 gallon portable compressed air tank

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I was given this 5 gallon portable air tank, but you can purchase them from Harbor Freight or Northern Industrial in the $30-35 price range. It is filled with a car tire (Schrader) valve and has a built in pressure gauge, overpressure release valve and car tire fill hose.

I have a small garage compressor. It is a 1.3 HP compressor that provides 2.4 SCFM at 90 psi, which is reasonable if you need to blow stuff off, drive the occasional air wrench, or do some light spray painting, but not a very high output. It only has a 1.5 gallon tank, so if you start using a lot of air it doesn’t last long.

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My plasma cutter wants 6 SCFM, which is more than the compressor can provide, but I only need about a 10% duty cycle.   (make a cut, then move the metal, re-clamp it, set up a straightedge or jig for the next cut, etc…)

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I bought some items in the tools / air-compressor isle at Home Depot to add the ability to attach the 5 gallon tank between my small compressor and the plasma cutter using standard quick connect fittings. The air fill hose that comes with the tank is mounted with a standard 1/4″ NPT connector, so all I need to buy was a T, a ball valve, a quick connection package, and a male to male adapter. I had to screw the pressure gauge 90 degrees to get room for both ends of the T.

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One end of the T goes to the ball valve and the quick connect fill connector. This side is connected to the air compressor and allows the tank to be filled by my small compressor and to act as an air buffer. The other end of the T goes to the female quick connect adapter, allowing me to plug in any standard QC hose. I included the ball valve so that I could close it and disconnect the tank from the compressor and have it remain full, although primarily I’ll be using the tank “in-line”. The cost of these parts was $15, or about half the cost of the tank if you bought it new.

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Here is a video:

Why you should NOT buy FOSCAM cameras

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I used to own two FOSCAM cameras, which used to (mostly) work with Linux. They would ask you to install a proprietary plugin (that doesn’t work in Linux) to view their camera feed, but if you selected the MJPEG feed everything would still work with Linux or other OS’s without installing the plugin.   (And you could manage them via the web interface with no problems.)

HOWEVER, after their latest firmware upgrade, their web management interface will NOT allow you to log in unless their proprietary plugins are detected. This means that you can not manage them from Linux. I asked them for a way to downgrade the firmware and they refused.

These cameras are now useless for use with Linux, and they are also useless unless you are willing to install foscam’s proprietary software on our (windows/mac) system.   And if you trust FOSCAM to put code on your computer, you should read this: Bug Exposes IP Cameras, Baby Monitors or look here: Foscam : Security Vulnerabilities and reconsider letting them install software on your computers.

And then there are things like this:This is Why People Fear the “˜Internet of Things’

ScanTek / Denford Micromill 2000 bent spindle motor bracket

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spindle_motor_at_angleWhen I purchased the ScanTek 2000 Scan Mill (A rebranded Denford Micromill) from a surplus supply house, the spindle motor was at an odd angle and the drive belt had frayed (probably due to the angle).

When   I took the motor off, it was clear that the problem was a bent bracket.
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Since I needed to purchase a new drive belt ( Sherline PN 40040   – $9) I decided to just buy a new Sherline spindle motor support bracket (PN 40020 – $7 ) at the same time because it was relatively inexpensive.
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How to convert a Denford / ScanTek 2000 Micromill to LinuxCNC / Mach3 control: Part 4 — Spindle Speed Control

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In part 1 of this series I showed how to get the X/Y/Z steppers moving. In part 2 I hooked up the home and estop switches. In part 3 I got the spindle go relay working so that I could turn the spindle on (at full speed) or off. In this post, I will show how to get PWM speed control of the spindle working.

The Balfor NextMove ST card has an output (SOUT & SGND) line that provides an isolated 0-10 volt signal (at low current) suitable for controlling a spindle motor driver board. (0 volts is stopped, 10 volts is full power) In the bottom left of the picture below you can see the small blue and red wire leading away from SOUT & SGND.

It does this by using a DC/DC converter (NME0512D) to provide an isolated (floating) 12 volts, referenced to the SGND connector. A TLC272C OpAmp chip integrates a PWM signal (taking into account an offset adjustment from R35, the boxy blue variable resistor near the SGND/SOUT pins) into a 0-10 volt signal.
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Micromill test run with G-code

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Now that I have the hardware in place, I’m working on the software side of things. I installed and configured LinuxCNC to control the Mill. (Mach3 was easier to get set up and running initially on the trial license, but they do require you to run windows…and the GUI is a bit garish.) In this video you can see the mill cutting out a circular pocket (in the middle of the air, as I’m testing CAM software, software limits, etc as well.)

You might notice that the belt has been removed between my spindle and spindle motor. When I purchased the machine the spindle motor was at a slight angle, which I traced to a bent spindle motor bracket.   As a new bracket costs under $7, I decided to buy a new one instead of trying to bend my existing one back into shape. The replacement bracket appears to be machined slightly better overall anyways. Until it arrives, I don’t have the spindle hooked up.

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J1772 to 120 volt opportunity charging auto-switchover

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My truck’s charge controller supports the J1772 protocol, and I have added a J1772 inlet I took out of the same salvage Nissan leaf that provided my LiIon battery pack.

I added the J1772 port, the “start charging” button, and a rotary switch to select between different charging profiles, as well as a 120 volt, 15 Amp RV inlet behind a flip up license plate.

When you have one charging inlet, things are simple and safe. When you have more than one, things can get complicated. In my case, I wanted to use the same charger(s) with both inlets. But I shouldn’t just wire them both up in parallel, because that would mean that the (male pins on the) RV inlet would be energized at 240 volts when charging via the J1772 plug, and it wouldn’t be good for somebody to reach in and touch them. Also, if somebody were to try and plug in the J1772 AND a 120 volt extension cable at the same time, they would be connecting a HOT (from the J1772) line directly to the Neutral line on the 120 volts (causing a short circuit). [Having the J1772 inlet energized with 120 volts is also undesirable, although slightly less dangerous, as the J1772 inlet is designed to be “finger safe”.]

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How to convert a Denford / ScanTek 2000 Micromill to LinuxCNC / Mach3 control: Part 3 — Spindle Motor Control

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In part 1 of this series I got the stepper motors for the 3 axes moving. In part 2 I hooked up the home and E-Stop switches. In this post I will describe getting the spindle motor to turn on (and off!) controlled via the parallel port break out card (I’m using Pin 1).

You can watch the video here, or read the text and see the photos below:

To enable the spindle motor, two things have to be done. First, the Spindle Go Relay (SGR) must be turned on, which provides 120 volts AC to the spindle driver board. Second, the spindle driver board input needs a 10 volt input to turn on the output (to the spindle motor) at full blast. The photos below are of my Dispatch Date 2005 mill, but other mills from Denford are similar in their general operation. [If you have an earlier dispatch date mill, you may have a DIN rail of relays mounted individually instead of this custom PCB of relays. Check out this post for a few photos and info about the SGR in that situation.]
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