z axis locked up

i have a problem i can't seem to overcome i'm using 2 vexta pk266-02a 1.8 deg stepping motors in my homemade lathe the driver boards consist of tip 31 transistors (just the basics no pcb yet until i know everything works) i have the x-axis running great but no matter what i change i cannot get any movement from the z axis.
i have switched motors to check for a bad one , both motors work the same on the x axis
i switched the transistor groups (x group for z group) to check for a bad transistor
no change, the z axis motor seems to be locked as soon as power is applied am i missing something with the parallel port? pins are
X
pin1
pin2
pin3
pin4

z
pin5
pin6
pin7
pin8

any help would be appreciated btw the transistors on the z axis get very hot i have double checked the connections and everything is correct
thanks in advance, i have checked the forum as best i could and tried everything i can think of so i must be missing something

it is normal for stepper motors to be locked on power up , and for them to become hot .
so essentialy all coils are energised in a stop condition , this is how they can hold a stationary point

if they become so hot that you cannot bare your hand on them , then you probably have too much current , so check your current limit resistor calculation and reduce the limit slightly

also check the mode of the parrell port pins , some are input only , they can not all be used as outputs , so check your circuits , and parrell port specs

it's also usual to use pins 2 through to 9 as data lines on a parrell port , i.e not use pin 1

Hello,

Have you checked that your parallel port pins are getting the signal all the way to your drivers? Cable good?
With a meter you can check if the direction signal goes from 0 one direction to around 5 volts the other direction.
With a scope you can check if the step pins is receiving a signal.
With power applied and no movement the motor should be "locked up" as pointed out above, however if the transistors are getting overly hot that sounds like too much current.

Rick G

Thank you for the help
i made a mistake in my post (probably from beating my head on the desk to hard) my pinout is actually 2-9
sorry about that. I agrre that the transistors getting hot sounds like to much current , however if i'm using two matching motors and 8 matching transistors (no diodes etc yet,just trying to get the basics working first) if i swap motors both work flawlessly on the x axis and if i swap transistor groups they too work flawlessly if current was an issue wouldn't it effect both axis the same? i'm using a converted computer ps and a multimeter so i know my voltage etc. i'm getting ready to leave for work but when i get home i'll build a quick led tester for the p-port
again thanks alot for the help

Might also want to look here...

wiki.linuxcnc.org/cgi-bin/wiki.pl?Parallel_Port_Tester

Rick G

okay... sorry for the delay
i have found that the original computer i was using had a fried p-port so built another the p-port checks out with the above script
i put some led's and resistors on a breadboard and put them on pins 6-9 (z-axis) and ran the Lathe-pawn-ngc
example the led's sometimes seemed to all be on all at once and stay on but only during long z-axis movements so i am assuming that they were powering the coils to fast to see any blinking (which would happen on shorter movements) my x-axis still works flawlessly but still no movement of my stepper on the z
i have checked my hal file so this leads me to believe i have missed something in the ini file(??)
i have tried changing some of the limits that have been mentioned in other posts , and in the doc's, such as ferror and velocity but still havn't figured this out and not really sure what would be considered normal for these settings (if there is a normal that is)
thanks again for the replies i am at the very least learning something

ok lets narrow it down , can you post your hal and ini files and also how you are connecting the steppers and the circuit you are using to do so and if your using a breakout board which one .
without that we realy are in the dark , not knowing your setup in detail

Here is my hal and ini files (i should have posted these first)
the motor's are hooked up using tip-31 transistors on a breadboard circuit nothing fancy right now for testing but this will later be a full circuit board with an aluminum housing that acts as a large heatsink (think car audio amplifier housing) both x and y are hooked up exactly the same except x uses pins 2-5 and z uses pins 6-9
i built another circuit as stated above and tested the port with the p-port test script and by running linuxcnc and i have gotten positive results until i try driving the motor

solved
thank you for all your help, it was my initiate file ,after coming home from work and taking some chances with different settings i now have full movement on both axis using the lathe-pawn example mostley it seemed to be my velocity settings that made things happen thanks again for all your help my next step is to investigate a little deeper into the changes i have made and hopefully gain some knowledge

Glad you got it sorted out!

Rick G