Setting Up TurboCNC

[Davedbq]

Hello once again,
I have set my CNC machine aside over the past month or more due to the fact that I have had more than my share of problems with it trying to make anything at all that is near accurate. I have had problems with all three axis changing or shifting locations and cutting images incorrectly. The depth of my cuts keep changing (getting deeper and deeper) as the part is being cut. The X and Y axis also seem to drift off of their correct location as though the machine looses track of where it is at in all three axis. I have been using KCAM4 software without a lot of success so I thought I would give TurboCNC another chance if someone could help me make sure I have everything set up correctly. I have it already on my computer and have managed to get it to jog all three axis and that it about as far as I could figure out how to make it work. What next? If this fails to make anything worth while my machine will be going up for sale on Ebay in short order.

Dave

[ger21]

It sounds like your losing steps. That's usually what causes the Z to get lower and lower. What kind of machine, drives, size motors? Do you know how to set the start speed, max speed and accel?

[Davedbq]

I am trying to run a 7th Sojourn designed by J. **********. This desktop machine is set up with a sp-3 controller and stepper motor from Stepperworld. These are unipolar steppers rated at 85oz in and 1.25 amp per phase. I know how to set the start speed, max speed and acceleration on the software. With what you tell me here I have set everything to high? What settings should I use.

Dave

[ger21]

What setting you use are really dependant on your machine. You should set the start speed first. Keep increasing the value until you notice it's missing steps, then back off about 25%. Do the same with max speed, and acceleration. A while back on the TCNC Yahoo group, there was some info showing that by lowering your start speed, you could increase your acceleration to much higher settings.

How fast are you moving the machine right now? And what are you using for leadscrews? What size power supply? From what I've heard, the SP-3 won't give you very much speed, and those motors are a little on the small side I think for that machine.

[Davedbq]

I am currently running the machine at 7 ipm. The leadscrews are 1/4 threaded rod. The power supply is 12 volt for running the motors and 5 volt for the circuitry. Top speed is approx 20,000 pulses per minute, which equals 100 rpm, no load condition. I know that I can never run at that speed as I am no where near it now and am having problems. I will try working with the start speed, max speed and acceleration and see if I can get the accuracy where I want it. Thanks.

[ger21]

If it's 1/4-20 rod, then 100 rpm is only 5 ipm? Try moving it at 2-3 ipm and see if it's more accurate.

A 24v power supply would double your top speed.

[jasminder]

Originally Posted by ger21 It sounds like your losing steps. That's usually what causes the Z to get lower and lower. What kind of machine, drives, size motors? Do you know how to set the start speed, max speed and accel?

hi ,
i am willing to run a stepper using an h-bridge through parallel port interface.
i am using turbocnc but i can't configure the phase definations
i don't have anycompany selling cnc kits in india so i am trying to make a simple two axis cnc lathe using an hbridge that drives upto 4A motors.

can i drive a stepper just using parallel port and h-Bridge
h-bridge takes 5V input to generate one pulse to the motor.

please help,
i tried talking to someother people here but no replies.