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Messages - jimpinder

661
I've nothing to run it with (yet).

Now you have the manual - can it be connected to computer control.

If so give me a price to think about

662
General Mach Discussion / Re: Stepper motor power supply
« on: April 30, 2008, 03:47:55 AM »
I just had a look at that site - the drives you are looking at seem to be 3 amp spec.

I  also started with 8 wires motors - rated at 2.5amp @7.5 volts and thus bought some 2.5 amp drives.

8 wire motors have two pairs of two windings, and can be wired together in series, or parrallel - or just using a single winding

I wired mine in series. Without going into a lot of maths which we did in the last post (see "how do I wire my steppers") - if you wire the motors in series you use roughly 1/2 the rated current.

If you wire up using just one of the two windings on each side - you use the rated current.

If you wire up in parrallel - I think we decided you use 1.666 x rated current.

The big thing about it is the power from the motors. I was satisfied in series (my first go) I was pleased to have everything work - but could not get the axis speeds up above 4 ins per minute (48,000 pulses per inch) no matter what I did.
I decided to wire them in parrallel - and the difference was amazing - I could get up to 10 times the speed. Even using a single winding, I was up to 5 times the speed.

The problem was - of course - that having done all this - my drives were not powerful enough to sustain about 4 amps continuously - and I have now moved on to Gecko drives - which are rated up to 7amp at about 80 volts.

CHECK THE RATING  of your motors and find out wether the quoted current is through one winding or two. If you measure the resistance of a single winding and check it against the spec that will tell you - E = IR  - mine were 3 ohms resistance - which gave me 7.5 = 2.5 x 3 which told me that the quoted rating was for only ONE winding in the motor and there were two.

The drives you are looking at seem relatively expensive - so I think you should be able to perhaps invest in some more powerful ones which will staisfy your needs for quite some time.

Drives cards can be limited in current, so buying too big is not a problem.

Sorry is you have already worked this out.



663
Forget the word "STEPS" - IT IS MISLEADING.

Mach 3 needs to know how many "PULSES" to send to your motor to move it one unit - in your case MM.

The first thing to do is check that you have the UNITS correctly ticked undet Config/Native Units.

Your motor is a 1.8 degree step - so you are right 200 pulses will turn the motor 1 rev.

Now read your Drive manual - and as Hood says the Gecko drive you are using ( I have the same ones) are 10 micro-step drives. Stepper motors can run is part steps using a combination of signals on the wires. As bought the Gecko is set at 10. This is done for smootness and power.

You say that your spindle moves 5mm per turn - and is a direct drive.

Your calculation is therefore 200 x 10 divided by 5 - which is 400 pulses per mm - not 40.



664
General Mach Discussion / Re: Reset - I was wrong
« on: April 30, 2008, 02:55:17 AM »
The switches you are using are multi-function. They are home switches and also limit switches.

If you use them as a limit switch - or access them whilst they are acting as a limit switch, they will, as you have found out, stop the whole system and require a reset.

If you access them as a homing switch, they do not cause the trip - they are programmed to take a hit, the axis reverses, the switch opens (or closes) again - BUT - THEY THEN BECOME LIMIT SWITCHES AGAIN - and as far as I understand - immediately.

What effect is it that you are trying to create - are you homing or what. I would not have thought it good practice to use LIMIT switches in a program as a positioning tool. I thought the idea was to use the homing facility and then use a G54 move to a position to start work.

As far as the syntax is concerned - see the post at the top of the main page by Hood - OEM codes
See also \Mach specific Subroutines-Functions grouped by purpose - MachCustomizeWiki.mht - which I think is attached to this forum
and also the attachment on the post "Re- Macros" where I attached VB Script commands.

665
Phil - you will have to excuse Hood and me.

Actually the inverter you have looks like a neat unit - and you say you have a manual. What sort of power does it give out - is it OK for running a drill press - or even a cross slide mounted drill of some sort.

666
Phil - You are not another Scot - or even Welsh - are you  ???

667
General Mach Discussion / Re: Stepper motor power supply
« on: April 28, 2008, 06:56:32 AM »
I didn't say financial advisor - I SAID FINANCIAL MASTER

668
General Mach Discussion / Re: Stepper motor power supply
« on: April 28, 2008, 05:11:08 AM »
I just read you post again - for your second project I WOULD NOT buy a three axis board.

Buy three seperate single axis boards - if anything goes wrong you can change the faulty board - and you do not have to change the whole thing.

A little more expensive to start with, but much more flexible in the end, particularly if like me, you start to uprate your system and want to replace single boards.

My motors are 220Ncm motors rated at 2.5amps at 7.5 volts - but they are 8 wire motors. I bought 24volt 2.5 amp drives and wired the motors in series. The result was reasonable (to my mind) - but my speeds were dissapointing. I wired the motors in parrallel and the results were much better - a 7 fold increase in speed (later cut to 4 to increase accuracy) - but then my drives were not powerful enough to drive the motors - which needed more CURRENT.

As I say, I have changed the two main axis to Gecko drives - which give me capability of 7 amps at (I think) 80 volts - but I still run the third motor on the old  Routout 24v 2.5amp drive.

I had one Gecko given, I had to buy one, (and the financial master turned her nose up at that), so I am not quite sure when I am going to get the third axis done.


669
General Mach Discussion / Re: Stepper motor power supply
« on: April 28, 2008, 04:56:47 AM »
Stepper motors are normally run at several times their working voltage. It does not hurt them.

If your motors are rated at 2.0amps at 6 volts, then you would be better to run them at 24 volts, or even 30v. If your driver boards only go up to 24 volts them stick to that.

The driver board SHOULD have some way to limit the current output to each motor. Each driver board, therefore needs to be set at the motor rating - 2.0amps, so the current to the motor is not exceeded.

You therefore have your answer - your power supply needs to be 24volts - capable of giving 6.0amps. You needs a capability of 6.0amps just in case all motors are drawing 2,0amps simultaneously - perhaps not likely, but possible.

Your problem will be to ensure that, when the motors are not drawing full current, the voltage on your power supply will not rise above 24 volts and therefore damage your drivers.

On my system I use 2 x 12volt batteries in series to give 24 volts and as much current as I need - without any danger of exceeding the "safe" voltage of my drives. I have just replaced two of the drives with Gecko drives which are OK up to I think it is 70 volts, so really the problem does not arise - but my third driver, for my Z axis is a 24 volt 2.5 amp drive - so I have to keep within those limits.

I charge the batteries up overnight - no problem

670
General Mach Discussion / Re: Macros
« on: April 28, 2008, 04:39:57 AM »
For anybody who is interested the post attached is the Mach3 specific part of Vis Basic - how to access and post to Mach3 from Vis Basic. It is available on this site (but I can't remember where)

Found another file re Mach specific sub routines  - it is on this forum as a wikki - cnc tutorials\Mach specific Subroutines-Functions grouped by purpose - MachCustomizeWiki.mht