CNC Compatibility
March 14, 2008 10:56AM
I've lurked around for quite some time now, after a short stint at building a reprap using lumber and drawer slides.

Personally, I think we might see better progress if we conform more closely to CNC standards rather than re-designing the wheel. It would also allow people who already have CNC (like myself) to focus on the extruder and utilise existing hardware for everything else.

Most stepper-based CNC machines are controlled via LPT port and a simple chip stepper controller. The flow-rate on reprap is almost identical to spindle speed PWM on CNC, just scaled down.
For those not proficient at soldering, they could skip these steps and get a professional stepper controller.

I suppose it would need special drivers to control, but the rest should be compatible as is.
Re: CNC Compatibility
March 14, 2008 11:37AM
Hi! Long time no see!

You might want to follow what nophead is doing at the if you already have CNC. He's doing some brilliant work in printing HDPE.
Re: CNC Compatibility
March 14, 2008 02:18PM
The problem is modern PCs don't have an LPT port and you can't use a USB to parallel converter to step steppers.

Re: CNC Compatibility
March 14, 2008 03:11PM
... my CNC-controller has a RS232-port, what's more suitable for actual PC's which have a Serial port or over a USB-to-Serial-converter-cable.

On the other side i have some discrete stepper-drivers with CLK/DIR-input, which i could wire to a parallel port, but it's much better to drive them with a microcontroller-board, which has an USB- or serial interface.

So i want an open and freely reconfigurable interface-layer between the host-software and different stepper-drivers or CNC-controllers.

I know, the PIC's and Arduinos do this task already, but why not rewrite the output so you can reprap with any hardware you have at hand?

Re: CNC Compatibility
March 16, 2008 06:32AM

I have built an Arduino shield that has 2 25 way D type sockets mimicking 2 LPTS.

Still testing with standard hardware that accepts MACH3 CNC commands. So far so good and very simple.

I believe Ian Adkins (Bits from Bytes) is working on something similar that may be available


Re: CNC Compatibility
March 16, 2008 07:08AM
Yes i hope to post information in the next few days it is designed to work with both Arduino or Parallel port or any other uC for that matter

Re: CNC Compatibility
March 18, 2008 07:48AM
Oh yeah, been busy with other projects. And work. Things tend to drift around, I might have to finally give a shot at making that darn extruder.
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