Feed rate problem

[Rene Nuñez Paz]

Hello,

A year ago, I built a JGRO CNC Router, powered by a Hobby CNC Pro Card and 305 oz/in Unipolar Steppers, Power source are a 24VAC 10A transformer that gives me 34vdc. Hobby CNC controller can take 42vdc.

CNC Controller at 1/8 Microstepping.

The transmission are ½” 13TPI, Single Start Threated bar (Non ACME) .Configuration speed is 1000mm/min (aprox 40 IPM) for all axis. I can get that speed in rapids and in a Linear cuts along the axis , but when the cuts arn’t linear to the axis, the speed decreases at 200-300mm/min ( 7-15 IPM). For example, cutting pieces for dino’s schelettons, circles, ecc.

The PC are an old Asus P4D533 Motherboard with a 1.8Ghz P4 CPU, and 1Gba of RAM.

The MACH 3, Kernell speed are 35000 GHZ, but the PC only arrives at 33800Ghz.

What do you supposed that are the cause of that,,? Is normal??, Can I fix it in any way?

Excuse me my bad english, I hope you understand.

Thanks in advance for your answers,

Also I attach a file that had the problem.

Bye

Rene

[ger21]

What microstep setting are you using. I'd try 1/8 step, and set the kernel speed to 25Khz. That should still be good for 60+ ipm, and the PC might run better.

If you open Windows task manager, what is the CPU usage when both axis are moving?

[ger21]

After looking at your code, make sure you have constant velocity enabled in general config, or add G64 to the start of your g-code.

All the short line segments are probably not allowing Mach to get up to speed. Constant velocity should help. Increasing accel may also help, if possible.

[Rene Nuñez Paz]

Thanks Ger

I will check right now, and leter I'll tell you what happened.

Bye

Rene

[Rene Nuñez Paz]

Hello Gerry, thanks for your advice

My work step by step...

Check and set the Kernell speed at 25Khz
Check and set the G64 in Config/Initial State Settings/Initialization strings
Constant Velocity was ON--Ok
Microstepping was 1/8 Ok

Windows Task Manager--In all cut proccess the higgest use was 30%.

The real problem was the accell
the original setting were
Velocity----- 1000 mm/min---- 40IPM
Accel-----------70 mm/sec/sec

I put the accel to 200mm/sec/sec, and the slow cuts speed increases from 200-300mm/min to 500-600 mm/min, thats good for me now considering some misaligment in my axis, and the vibrations in my machine. I will check this part later. JGRO is good to learn but not for work.
Also was my first experience in Carpintery, Mechanical arrachments, and in CNC. I thinks thats perfect for the first time.

A last question

What's is the correct relationship btween Velocity and acceleration?

Thanks again, and excuseme my bad english

Bye

Rene