Thinking about a 5i25 board only

Post pictures of the machine if you can, the config files are at /home/your_user_name_here/linuxcnc/configs/.......<the actual name of your config, right click on it and choose "compress", be it .zip or .rar or .tar.gz it does not matter. That zipped file you can attach here so we can have a look if it is the config limited to that speed.
We would also need to know if the machine has belts or ball screws or other, and gearing ratios if any.

I misspoke earlier. The max speed is not 40 MM/minute it's 55 MM/second. That's very adequate to do simple stuff. The "fast move" times are not terrible, but could be much better, I think. That's what we are really talking about. The machine will move fast enough to break a 30 degree V bit in MDF.

I have several configs. This one is the simplest one.
configuration file for 3 axis

Here are some pics of my machine. Right now, it's set up to do flat work. I built a platform of MDF and then "leveled" it with an end mill.
front side
control box
back side

This is just a cheap 3040 type machine with the 4th axis. ( see it here ) The hardware is okay. I had to tighten things up a bit and adjust it to get it to actually work. The ball screw for the X axis to the stepper was grossly misaligned and the Y axis guides were loose. All told, I am pretty happy with the quality of the machine. The controller box is another story. I rewired it because it was terrible. Frayed wire terrible. I also replaced the power supply because it was under powered. The steppers are 2A each and the PS was a 6A supply. It would not power up the system if all of the motors were connected. I put a 15A supply in it and that works now. I am not happy with the spindle. It's a cable drive spindle and I really need a direct drive. It also has a crappy speed regulator. I will be changing those at some point.

Edits: tried several different ways to link the tar file. You can view it, but you may not be able to download.

I actually think your speed is limited more by your step drivers than by the controller

A 5I25 (or any fast external step generation hardware) will make the most difference with
higher end drives, (Gecko or Leadshine for example) higher ustep ratios, or step/dir driven servos

What leadscrew pitch and ustep ratio are you using?

PCW wrote: I actually think your speed is limited more by your step drivers than by the controller

That may very well be true. Is there some way to definitively tell? For example, if I jog the X axis (the heaviest one) at too high a speed, it will start to move, but then when the steps ramp up to a certain point, with acceleration set pretty slow, it freezes and just hums as me.

This is pretty typical of step motors driven past their torque limits

This why I asked about the lead pitch and step drive ustep ratio
( To see if the parallel port step rate is likely to a limiting factor )

also what is you power supply voltage?

I just looked up the datasheet for the TB6560, which is the chip that my drivers are based upon. It has a maximum clock rate of 15KHz. Compared to a maximum rate of 300KHz for a Leadshine driver. think I will get some drivers that are based on the TB6600. It has a max clock rate of 200KHz. Maybe I need to give that a try.

I have been taking a look at other drivers such as Leadshine and Wantai. They sure do look similar. Same specs and part numbers and everything. I wonder who -actually- makes them. Specifically, I am looking at the Wantai M542MA. here

edit: I failed to mention that Wantai is 1/2 the price of Leadshine.