For those who have converted to a different controller and high powered drivers, what is the maximum feed for stock Langmuir steppers?
I am gonna interested in some replies here as well BECAUSE you don’t need to change the controller to get more speed out of the stock steppers.
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It will depend a lot on the physical machine build, because the resistance will vary depending on how accurately the rails and lead screws are aligned.
I think around 200ipm worked for me. I switched to different drives with the stock steppers almost immediately and ran those at over 300ipm reliably on X and Y. I got a good deal on some servos later, and now run at 500ipm rapids.
Are you talking about the high power drivers from langmuir or something equivelent maybe?
The real question should be, how fast can the stock Z stepper be run. Even at 100IPM my machining limitation is in Z at 40IPM.
I was missing steps from time to time at 100 IPM when machining with the factory high-power drives and stock steppers. While a lower ramp rate allows for higher rapids, stable machining was my primary target. I currently run 5A NEMA 23 steppers with factory high-power drives and an 80V, 1500W PSU. I have them capped at 230 IPM just to ensure I don’t miss any steps. I hit around 330 IPM with rapid moves, but my focus is on avoiding missed steps. I normally crank the speed up until it misses steps, then back it down until it is consistently stable. This is how I settled on 230 ipm.
Edit: I guess I should clarify. I was missing steps about 1% or less while running 10mm cutter, at .060” WOC .75” DOC. So it wasn’t all the time. It was rare but I wanted it to be “never”. I don’t want people to get the idea I was missing steps all the time with factory motors and drives. That was not the case… I just wanted more performance.
I also don’t have a problem with the factory controller now that most of the bugs are fixed. I do wish the probe was more dependable but it’s not a Renishaw so I should lower my expectations and stop complaining. 
I switched to some drives by Leadshine. I think they were EM542S or something like that, if you search my old posts you’ll see it. I used these under LinuxCNC, but others have used them with CutControl.
AlexW, not to hijack the thread, but, I’ve been looking through your posts about these Leadshine drives. I found a couple of things pretty intriguing.
I know you’d mentioned you’d changed controllers, but did you ever find out if the upgraded drives would allow CutControl to run beyond the 100ipm?
If I went with the Leadshine drives, would I need 3 of them?
And did you have a few pictures of the wiring and switches settings?
I never used them under Cut Control. Richard Beck (also in this thread) has posted a few times about how he changed GRBL/CutControl to get faster speeds.
I had 4 of them, for X, Y1, Y2, and Z.
I don’t have photos of the switch configuration, but they are in my notes at GitHub - alexphredorg/mr1: Langmuir MR-1 configuration for LinuxCNC · GitHub. Look all the way at the bottom.
I’m not using steppers anymore, but those drives worked well for me.
yeah it’s not the drives or cut control that is setting the speed limit. It’s the Langmuir Control board’s firmware. You can change that firmware using Universal G-Code Sender. Now… Just because you tell it to go 300 ipm doesn’t mean the motors, drives, or PSU can support that. If you upgrade those you can change all the firmware settings, and go faster without and controller upgrade.
Here is a link to the software I used to mode the factory firmware. Download - UGS
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Whats the practical limit in Z? Everyone always talks about rapids and high feed rates in x and y but Z with all the unbalanced spindle head weight on an ACME screw seem to be the biggest limit. LS slowed Z down to 40IPM which on a stock machine is the limit during operations. I can’t 3dm any faster than 40 since thats the stock limit.
I’m perfectly happy with the X, Y rapids/feed but 40IPM sucks the life out of the machine.
I can hit 140 ipm in the Z axis with my upgraded motors and modified firmware but to be super stable I backed it down to only 100 ipm. This way I never miss steps in the Z.
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The Z is an acme threaded leadscrew with a finer pitch than the ballscrews on X and Y. This the leadscrew has more friction which is good because it holds the axis in place when the motor is off, but it slows it down.
I do run mine at 240ipm, but my machine is far from stock and has servos instead of steppers. It can run faster with the servo that I’m using, but acceleration lengths get too long.