Hobby CNC 4 axis CNC Chopper driver board build. - RC Groups
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May 17, 2004, 01:19 PM
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Hobby CNC 4 axis CNC Chopper driver board build.

HobbyCNC just came out with a new 4 axis chopper driver board, the 4AUPC Driver Board Kit. The board is easy to assemble and quick to build. This is my second electronics project and I was able to build it without major issue. I don't have any relationship with HobbyCNC other than that of a happy, satisfied customer.


Here are the specifications of the board.


3 or 4 Axis Unipolar Chopper control. NO "Ballast" resistors required!
Individual OR simultaneous control of 2/4 Phase Stepper Motors.
Accepts 5, 6, or 8 wire stepper motors only.
44VDC maximum input voltage, 12VDC or 24VDC minimum input voltage depends on fan voltage used.
3.0 Amps Maximum per Phase, 500ma (.5A) minimum. Adjustable throughout this range.
1/2,1/4, 1/8, and 1/16 Microstepping .
Step and Direction Control.
3.5" by 6.8" double sided with top silkscreen and thru plated holes PCB.
Power On Reset.
On board voltage regulation for 5-volt logic with 12VDC or 24VDC cooling fan from motor power supply.
On board connections for home and limit switches with 10K pullup resistor provided to each.

I forgot to take a picture of the kit before I began building. Here is the picture from Hobbycnc's website.
Last edited by bgriggs; May 17, 2004 at 02:22 PM.
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May 17, 2004, 01:53 PM
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The first step was to solder in the resisters. There were 12 of these to be identified and soldered in place. A magnifying glass was helpful but not absolutely necessary. I had the question with the kit on this step.

The board has many hole in it that are not marked. These are vias. The via connect one side of the board to the other electrically. I didn't know this and so I almost used the via instead of the solder pad hole. On closer examination I realized that the mounting holes for the resister were easy to spot. The mounting holes are on the outside of a silk screen rectangle which represents the resister position. The via is located inside the rectangle. Easy when you recognize it.

Next I soldered in the resister networks, current sensing resisters (big brown barrels) and the potentiometers (blue circles).
Last edited by bgriggs; May 18, 2004 at 07:42 AM.
May 17, 2004, 02:17 PM
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I will post the pictures later tonight after I reduce the size to comply with the rules.

May 18, 2004, 07:44 AM
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After I soldered in the resisters and pots, I added the header blocks. These were very easy to solder in place.
May 18, 2004, 07:48 AM
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The next step was to add the voltage regulators. These had to be orientated properly in order to have the circuit work. Fortuneately, the circuit board has a painted line which indicates how each component should be orientated. One faces forward and the other backwards. The regulators are at the bottom right of the board. I also added the DB25 and the jumper blocks at this time.
Last edited by bgriggs; May 18, 2004 at 07:50 AM.
May 18, 2004, 07:57 AM
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Volt test

All the major components have now been installed with the exception of the (expensive) Driver chips. Before putting these in place HobbyCnc has you check the rest of the circuit for proper function. Little solder pads are provide and marked on the board for this purpose. Using a digital voltmeter check that your voltage is between 5.0 and 5.2 volts DC. If the voltage is out of this range you have a short circuit somewhere.
May 18, 2004, 08:01 AM
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Next, we solder in the Driver chips. This can be a bear! It requires a good soldering technique because the pins on the chip are very close together. I found it easiest to pick a horizontal row of pins and solder them in sequence. After finishing that row, I moved on to the next. Double check your work with a magnifying glass under bright light.
May 18, 2004, 08:05 AM
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Current check

Now that the board is complete. You should check the current setting for each axis. Different stepper motors use differing current levels. Check the included chart to locate the current requirements of your motors. Adjust the potentiometer until you get the proper reading. My board has been set to operate at 2 amp. This requires the current to be set at .34 amps.
Last edited by bgriggs; May 18, 2004 at 08:08 AM.
May 18, 2004, 08:16 AM
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I have not yet tried the board on my router. I am waiting to get the stepper motors and power supply to match. I built a Routezilla from kleinbauer plans. http://www.kleinbauer.com. These are good plans, although they are not complete. I would recommend them to experienced builders only. They also have several other designs to choose from.

Hobbycnc also offers plans for a cnc router table. I have a friend who has built one of these and he is very happy with it. It is smaller than the Routezilla but should meet the needs of many people. There are plenty of plans out there to choose from. I don't think you can go wrong with either Kleinbauer or HobbyCNC plans. http://www.hobbycnc.com

I will post an update when the motors and supply arrive.

Jun 02, 2004, 12:43 PM
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Do you have any more info since the last post?

Jun 02, 2004, 09:20 PM
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I wasn't aware anyone was reading this post! Sorry no updates yet, I have been busy selling stuff so I can afford the rest of the components. I will PM you when I post some more.

Jun 02, 2004, 10:04 PM
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I bought the 3 axis version after reading this thread. Haven't started assembly yet as I'm still working on converting a reel type lawnmower sharping machine into a cnc mill.

Jun 04, 2004, 08:28 AM
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BGriggs I have been watching your progress too, so please keep posting!

Jun 05, 2004, 05:24 PM
Got CAD ?
This is GREAT stuff !

Just a small point on the soldering of integrated circuits onto a PCB.
You really have work carefully if you solder in a row. Excess heat can damage an small ic. It is safer to alternate sides of the chip and just randomly pick pins to solder so the heat does not build up.

Thats what we were taught in Electronics Engineering Technology.

Please keep up the posts
Jun 05, 2004, 05:40 PM
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That is great advice. I wouldn't have know that. This is my 2nd electronics project. Keep the good advice coming.

Last edited by bgriggs; Jun 05, 2004 at 05:43 PM.

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