Newbie - what Mesa card to choose?

I received in the hard drive and built up the linux cnc pc last night. I ran into some issues with trying to get it going but it was me trying to load the iso on the hard drive and make the hard drive bootable from a windows box.

I ended up making a bootable usb stick and then ran into more issues where the installer wouldn't see the hard drive. Maybe the 5th try I booted from the usb stick, then connected the harddrive after at the install screen and the installer detected the harddrive and I was able to finish the build

I am seeing some breakdown of the graphics image when you have the screen resolution off, the driver only seems to show 60hz, I'll have to mess with that a bit.

My previous post where I mentioned I had the right parallel cable was wrong and I ordered up a new one. hopefully by mid week I am doing some demo cuts.

Congrats!

Before you get too deep, perform the latency test in this pc. It will determine if and how fast the computer base thread will be able to run step generation.

Latency test is not as important when using a mesa card as you will only need a decent servo thread.

The parallel port cable came in today and I went through the stepper config tool using the printed out manual the person selling me the cnc had and all I got were a bunch of clicks but each time it was the right axis and it was moving ever so slightly.

I found this post
forum.linuxcnc.org/16-stepconf-wizard/34...port-config-probably

and ran the command sudo cat /proc/ioports |grep parport and got the results of
0378-037a : Parport0
037b-037f : Parport0

I used 0378

Then it was still just clicking not not moving much so I researched a bit more and found this post
forum.linuxcnc.org/16-stepconf-wizard/39...iguring-6040z-issues

and from that I updated the following parameters and bingo I now have a config where I can move all 3 axis.
Step Time 10000 ns
Step Space 10000 ns
Direction Hold 10000
Direction Setup 10000

I've got to research some more as it is not moving the correct distance and the mach 3 parameters in the documentation seem too high at
Micro Steps/Rev 640
Driver microstepping 16

I did some RTFM here 360/1.8degree = 200 and then opened up the controller case and determined 8x multi stepping based upon the dip switches.

Seems to be doing better now. I did the jitter test and it was horrible, The PC is a 6-7 year old dell, 8GB Ram, new Sata SSD so it shouldn't be that bad. My next thoughts were about the graphics display sucking pond water, I removed the ati graphics card and went with the one built into the motherboard and when linux came back up the display was smooth. The max jitter still wasn't spectacular but it was 45,000ns.

For some reason after the display card was removed, I couldn't get the machine to jog yet if I went into the stepper config and tested each axis it would. After a few attempts I createx a new config and it seems to work. Putting a ruler on the x or y axis and jogging 5mm 2x seems to move it 10mm consistently.

since I do not have homing switches and don't know what I am doing, I ran into some issues with errors on joint size, after RTFM
on linuxcnc.org/docs/html/config/ini-homing.html I realized the software limitations set in the config file were getting me so I made all the sizes in the config file way too big ( I realize what that can do and won't step away from the machine )

any which way I was able to make sawdust - 3rd try this time I played with the height of z by setting the z height with a slip paper, removing the board, setting z 1mm lower and homing z
overall view of setup

photos.app.goo.gl/nLdvxD5udKHxSf368

I realize I've got a lot to learn on this and some of my actions are going to get me in trouble if I do not take the time to learn this homing setup as well as get some limit switches installed, but it was nice to see the machine make a cut and it turn out looking good.

That's a fair bit of progress in 6 days starting from zero.
The lack of Home switches doesn't prevent you from defining Home positions and having nice things like soft travel limits. If the motors are feeble enough you can buzz them against a hard travel limit and call it Home. A kinder method would use alignment marks. If the machine is returned to Home positions before powering down it's good to go next time (as long as the Z doesn't drop a bit). Not as accurate as switches but I get away with it for several consecutive power up cycles.