DIY CNC

IIRC the original parallel port could switch up to 1,000,000 times a second. Assuming two switches per pulse, 8000 pulses per rotation, that's 3750 RPM, which is way more resolution than you need (steppers are 200 steps/rot, or 3200 with microstepping), and way faster than big steppers can probably run anyway.
When I was using steppers and a breakout, it was the steppers that were the limitataion.

So I should probably start with my Dell first and then get a Mesa card once I feel up to it? Just to confirm, you are saying that you don't think it'll be an issue for making that part (assuming the jitter is not a problem)?

Logthor wrote:

 

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My only concern regarding using my parallel port computer with a breakout board is the delay (hence why I was considering the mesa card). Hypothetically, let's say my jitter isn't a problem. Will my experience making chips be the same as with a mesa card? I want to make some pretty complex parts and am concerned that any amount of jitter could make that impossible. I've attached an STL file of a part that I want to make for a friend. Could this be possible using a parallel port, or should I just spring for the more expensive card?
 

The main difference between a parallel port based system and a system with external Step/Dir generation
hardware is the maximum step rate, This speed will be limited by the real time jitter on the parallel port system.

The output hardware does not limit the complexity of the created shapes just the maximum speed.

 

I'm aware. I just was wondering, based upon your knowledge, if it will affect me making that part.

As Peter said,

PCW wrote:

The output hardware does not limit the complexity of the created shapes just the maximum speed.

I suspect however you will find limitations due to the part geometry on any machine.

Things a machine can physically do are absolutely the same for parallel port and Mesa card, so there are no limitations either way.
Things that are the same:
-you can make whatever you, your CAM, and your machine can do
-any machine, 3, 4, 5 or more axis, robot, lathe all will work
-you can use more than one of any of those, and you can combine them as you need.
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Things that are not the same:
-pulse speed and subsequently the machine speed
-Parallel port can do approx. 20000-50000 pulses or encoder reads per second
-Mesa can do over 1000000 (1 million, some even 10 million) pulses per second
-Parallel port can have 12 outputs and 5 inputs in OUT mode, 4 outputs and 13 inputs in IN mode, 8 outputs and 9 inputs in mode X. Not all ports can do this, but all built in ones do.
-Mesa can have any of the 34 pins (some cards have more IO) set as input or output in hal, granted it is not used as Stepgen or PWM or encoder or sserial.
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Or in short, parallel port with LinuxCNC will be enough for any hobby machine and most 24/7 use machines, even for some industrial machines that are not to complex
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Yes, i do have a lot of Mesa boards/machines (probably over 70 or 80 or more), and yes i still use parallel ports and still have machines in daily use with both for over 15 years (i am fuzzy on the exact numbers and timelines)