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Author Topic: stepper drive cards.  (Read 3419 times)

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stepper drive cards.
« on: March 28, 2010, 08:37:14 AM »
Just fitted some new stepper drives on the X Y Z axis of my Denford Triac. They are the ones with lots of switches to allow you to select the steps range. Problem is I dont know how to start, I understand the Mach 3 tutorial on setting the accuracy but not sure where to start with the switches. The ballscrew pitches are 5mm and the pulley drive to them has a 2.5 to 1 ratio connecting them to the D34 motors. I'm an old engineer who is used to a hand wheel with division on it. How do I start, sorry if I appear a bit thick but I have the steppers working although very slowly on the switch settings the stepper drives came set at. Does the steps range selected affect the speed or am I barking up the wrong tree. I did a quick measure and asked the machine to move 20mm in G00 it moved 25mm very slow. Jim

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Re: stepper drive cards.
« Reply #1 on: March 28, 2010, 11:16:56 AM »
You really want to go for 8 or 10 microstepping, not sure what your drives will allow.
Ok so say you can change to 10 micro steps that would mean your steps per unit would be
10 x 200 = 2000 per motor rev
2,000 x 2.5 = 5000 per 5mm so steps per unit would be 1,000

Try an Vel of around 2,000mm/min  and an Accel of around 50mm/s/s and see how you go.

If you set to 8 microstepping then your steps per unit would be 800

Hood
Re: stepper drive cards.
« Reply #2 on: March 28, 2010, 11:29:13 AM »
Hi Hood its Jim again in Birmingham, Just had a go at setting the x axis I left the dil pins on the steppers at the setting they came at, adjusted the velocity to about the same as the speed with the Denford electronics. Did the calibration and it came out with 800, acepted it and tried it seems OK. Does that make sense. It the settings on the stepper card that i'm not sure about this is the stepper card im using

http://cgi.ebay.co.uk/Cnc-5-6-A-Bipolar-2ph-hybrid-Micro-stepper-motor-drive_W0QQitemZ320507138790QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item4a9fb6d2e6.

aint touched any of the dil switches do i need to set them, PS the X axis moves sweetly.
Jim

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Re: stepper drive cards.
« Reply #3 on: March 28, 2010, 11:36:48 AM »
Jim not sure what the default is on the drives but sounds like you have it at 8 micro step. Looking at that drive it would be the 1600 setting,
 Sw5 = Off
Sw6 = Off
Sw7 = On
Sw8 = On

If its all working and sounding good at that then its probably not worth trying anything else.

Hood
Re: stepper drive cards.
« Reply #4 on: March 28, 2010, 11:44:06 AM »
Cheers Hood, I've upgraded your medal to a knighthood. Thanks. Watch my posts I'm going to tackle the spindle drive, bound to have problems with it. Cheers Jim

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Re: stepper drive cards.
« Reply #5 on: March 28, 2010, 11:48:13 AM »
Ha ha well not much experience with spindle drives other than servo spindles but should get help from the others here :)

Hood
Re: stepper drive cards.
« Reply #6 on: March 30, 2010, 01:56:48 AM »
Hi Hood can you tell me how important it is to set the switches on the drive cards to 1600 steps per rev. I know its controls the accuracy but wondered what effect the higher steps selection has on the motor and the drives. The reason why I ask is that the 5 amp maximum drives cards are running NEMA 34 motors and was told not to load them at maximum as that is near the top of the 5 amp limit  (what ever that means?). I have set one them to what you recommended 1600 per rev and left the others on the settings that the drives came with 25000 per rev at the moment. There dosen't seem to be much difference in the action and sound of the axis moves. So just wondered why there dosen't appear to be any noticable diffence in the table actions and what will be the affect on leaving them on the higher setting. If i'm talking jibberish only this is my first step into electronics, I'm an old egineer (65) and if it aint got grease or oil on it I don't understand how it works.

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Re: stepper drive cards.
« Reply #7 on: March 30, 2010, 03:09:45 AM »
Jim,
 I am not an expert on steppers, in fact not an expert at anything :)
Geckodrive have some good articles on steppers and drives which might be worth a read but basically they say for CNC applications setting the microstepping higher than 10x (2,000 per motor rev) is a waste of time.
 I cant see how microstepping would affect current, there should be dip switches which will do that but if the drives are designed for 5 amps they should be capable of 5 amps. It will all depend on your motors current ratings as to what you need to set the dip switches to.

Hood
Re: stepper drive cards.
« Reply #8 on: March 30, 2010, 03:33:07 AM »
Cheers, Hood will have a look.