CNC for a beginner

Nov 03, 2005 2 Replies
A

I am trying to get up to speed on CNC for home use and need a bit of help .....



The story so far is the intention to convert a micro mill as a cnc 4 axis project. The plan so far is to use stepper motors and their drivers as available from Arc Euro Trade or similar and software Partmaster for CAD to CAM and Mach2 for machine control. Now to the "I'm lost bit". The connection from PC to control the stepper motors is presumably via a controller board with built in or perhaps separate DC power supplies into which the stepper motors plug in. Are these boards available as a home built design? Do the stepper motors have their own position digitisers built in or is that feed back not required? Are commercially available controller boards suitable for any stepper motors , ie is there a "standard" to which these things work?



There are probably loads more questions that I have not thought of yet!



Buying a commercially modified mill or kit of parts defeats the object of the project which is to learn more about it ...... the hard way by doing it!



All help and pointers that put me in the right direction earn brownie points.



Alan


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A

try this link

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have had good results in building a machine and using one of the 3 axis boards there is a uk suplier

Andrew Bishop

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J

Alan you have it all about correct.

For the actual operation of the mill you will need 4 stepper motors, 4 stepper drivers, a power supply, a controller and it's advisable to use a breakout board.

Going thru this list it looks as if you have found a supply on motors and controllers with Arc Euro. These are very good value for money, the motors are the latest spec and very good. I like their drivers for a couple of reasons, one they are separates, if you do have any problems it's one drive to replace. The combined ones if you pop a drive then the whole board is toast. Also what's not made clear on Arc's site is the drivers do have protection circuits on them for motor shorts and disconnect.

I know people aren't looking for problems but when you are learning a miss connected motor equals a disconnected drive which can fry a driver immediately.

For a power supply you can but a ready made one from farnell or RS or roll your own. Arc again has a very good guide on their site under Projects and Articles for a power supply to match their drives.

The controller you have covered with Mach2 but may I recommend you go straight onto Mach3, same price but Mach3 has a lot more features and most importantly all the training video's are for mach3.

A good breakout board is available by post from Arturo Duncan in the States http:

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for about $31 inc postage to the UK. With the £ to $ rate it's good value

Build up is you take a printer cable from the parallel port to the CNC4PC card, This also needs 5v which can be got from the PC. From that card you need 8 wires to go to the 4 drivers from Arc, these control step and direction of each axis.

Your 30 odd volt DC power supply also goes to the drivers. So you have

5 wires going into the drivers, 2 power, 1 step, one direction and a return.

From the drivers you have 4 wires going to the stepper motors. There is no position feedback on steppers, with a good design running within it's limits it's not needed.

Hope this gets you going.

-- Regards,

John Stevenson Nottingham, England.

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