Could you guys offer any help please?

[barmybovine]

I have just built 4 picstep V4 20Mhz boards and the 4 axis interface by PMINMO.
I have all 4 working using a 35V supply and 2.8A powermaxII motors. I am using Turbocnc

I can run all 4 fine at low speeds but as I crank up the speed they run fine in one direction but loose steps and stop spinning all together in the opposite direction.

This is the same on all four boards I can get them running at up to 105 IPM in one direction before losing steps but only around 60 IPM in the opposite direction.

I have tried every combo of wiring up the steppers. I have tried in all step modes. I have tried a different computer and different software
all with the same results. I can get the motors to working well in both directions but only by changing the step active HI\LO option in Turbocnc but once again they will only run WELL in one direction.

Once I get these things working properly I can get my first CNC router table running so I am very eager to get this figured out. VERY frustrating

Thanks guys

[vacpress]

try simplfying the system down to 1 driver and motor with the PS... See if it still behaves the same way. If it does, then it wouldnt seem to be not enough current. Is this a switching power supply? Maybe the switching frequency and some emf generated by the motors going that direction creates missing step problems?

I would troubleshoot by simplifying.. Try and get a 555 timer circuit instead of Turbocnc to run a driver. a 555 'TTL' signal would pobably be more reliable troubleshooting tool than a parallel port...

[barmybovine]

Thanks for your reply.

Its a straight forward unswitched supply. Just your regular transformer\rectifier and a big cap.
The transformer is a 500VA 24V so should be able to do 20+Amps.

I will try to run it with an external oscillator as you suggest

Thanks

[barmybovine]

By the way....I also tried the 4Mhz version of the Firmware and still the same symptoms.

Here is a link to my motors info. I am wiring them as Bipolar Series for a pic....is this correct?

Going by the diagram could anyone tell me how they would wire the motors to a picstep. I have tried everycombo that makes any sense to me and still the same symptoms......spins good up to 100 IPM in one direction but only gets to about 50% of that speed in the opposite direction before it stops spinning...You can hear it still ttrying to spin but just acts as if its running to quick for the motor to keep up.

Thanks guys

[barmybovine]

ooopps forgot link

http://www.pacsci.com/support/docume...llbulletin.pdf

[pminmo]

Hi barmybovine,
Not knowing what screw pitch you are using, can you either provide the pitch or convert it to motor rpm. The fact that you get a speed in one direction but not the other would lend me to think a different mechanical load. vacpress is right, simplify to one axis, and work from there.

[barmybovine]

OK only one axis hooked up now and still the same symptoms.
I dont have the motors attached to a machine. They are just siting on the workbench with controllers hooked up. When I ave the IPM figures I am getting that from Turbocnc setup for 10tpi ACME.

Been trying for 3 days now and this is getting old. I know the motors are good because they came off of a CNC foam cutter I built and worked great.

Thanks for the replys guys

[pminmo]

What do you have for a step/microstep setting?
I assume you selected the appropriate current limit resistor for the lmd's?
You might try just using the step pulse and common for the pc and wiring a switch to control direction. Maybe you have marginal level's on the PC LTP port.
You have LPT1 set for SPP?

[barmybovine]

Thanks again for replying

when I am in full step I select 1 , half I select 2 etc...
I am trying in full step as I see the same symptoms whilst microsteping.
I have tried with a Fluke meter on the Dir pin and it swings from 0.06VDC to 5.01VDC as I jog in opposite directions.
On the current limiting resistor I went with 7.15K which was the closest 1% resistor I could find for my 2.8A motors.
In my BIOS I dont have an SPP option for the parallel port but I have tried it in every mode available and it acts the same regardless. Very weird little problem this turning out to be.

[Joe Petro]

Low current?
Is it possible that you are running those motors at half current?
Or, are you sure the resistor combo is giving the correct current?
Maybe an ammeter in line?
What exactly does the motor label say?


Joe Petro

[barmybovine]

Good news

Although I had tried it on another computer ,I had not tried adjusting the parallel port mode on the second computer. I have my motors running at around 100 IPM they spin good in both directions using this second machine and Mach2. I cannot try turbocnc on this machine as it is Windows 2000 with an NTFS drive so I can't run Turbocnc.
I will find another desktop and use it as a dedicated machine for my cnc table. Any idea where I could find one Joe

Thanks guys. I appreciate you taking the time to help me out with this

Scott

[Joe Petro]

I think you should send Phil your BMW for figuring it out.
Maybe he can understand the shift order is 1, 2, 3, 4, 5- not 1, 2, 3, 2, BANG!
Glad to hear the good news, mate!

Joe Petro