Isel CPM 3020 - run with mach3?

[JAZZCNC]

If I was going for a 40v supply, what sort of current would I need?

With a Toroidal PSU then around 7.5A will do it. Why 40V.?

[craynerd]

Someone suggested 40v but is 36v what I need?

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[AndrewMawson]

Chris,

It depends totally on which drivers you choose. Obviously (hopefully) the PSU voltage cannot be higher than the max spec on the drivers. The higher the voltage the faster rise time the driver can achieve pushing current through the windings of the steppers. If the voltage is too low the driver will give a sluggish performance. Although steppers have a nominal voltage rating they are essentially current operated devices.

[JAZZCNC]

Someone suggested 40v but is 36v what I need?

Well if your talking about those DM556 drives I suggested then they are 50V max so I'd be running them around 44-48Vdc provided your using a unregulated Toroidal transformer PSU. 44Vdc being what I'd size for.

I wouldn't run them at 36Vdc

[limpet]

To be fair there are lots of possible variables.I reckon that with unregulated PSU`s I would estimate getting smoothed output voltage of about 1.5 times the nominal transformer secondary voltage.
Although I would suggest that you check the load as an output of 44v under no load could easily drop 10 or 15% under load.
On the other hand if your power supply can provide more than 44v under load it could well give over 50v with no load which might give problems.
It all comes down to the resistance in the secondary winding and across the rectifier. As soon as a current is drawn there will be a voltage drop from the no load condition to under load condition.
To be fair there are lots of possible variables, and using a beefy PSU would help.

[Clive S]

Limpet First welcome to the forum. Not sure what you are saying here. Have you read the op's problem if you look back he says his power supply is only 24V unregulated and is asking what power supply and drives to get so as to get a decent running system. I think he has been advise to get some digital drives and about 45V unregulated power supply.

[limpet]

Limpet First welcome to the forum. Not sure what you are saying here. Have you read the op's problem if you look back he says his power supply is only 24V regulated and is asking what power supply and drives to get so as to get a decent running system. I think he has been advise to get some digital drives and about 45V unregulated power supply.

Hi Clive and thanks for the welcome.
Sorry I could have been clearer.
I was just saying that if he`s creating his own unregulated PSU then a nominal output of 45v with no load could drop to below 40v under load and if he goes for a 45v output under load then the PSU may well give more than 50v without a load which may be too much voltage for his drives. I`m not sure what protection they have.
This may or may not be an issue, but I thought I would just point out the possibility.
I apologise if I`ve clouded the issue, that was not my intention.

I`m no electronics expert but that is my experience with power supplies.

[craynerd]

Anyone lend advice regarding limit switches and homing.

I I have two limit switches at the extreme of each axis, so 6 switches in total. Considering I'll have spindle input on off, touch plate probe etc, am I best putting all limits in series on one pin?

Im still confused by home switches. I don't see why you need a home and you can't just hit the limit switches as a corner home. Or even hit the limit switches for position and then find a software based home. I must be missing something. Also, most people seem to home to the centre of the bed. What is the best way to mount these switches and have them triggered as I guess they will mechanically get triggered a lot when the machine is actually in action?

Cheers

[komatias]

limit switches can be home switches and they can all be put in series. Once the machine homes, you can tell it to move to a predefined distance from the switches. On gantry machines where you need to home both sides of the gantry, it is best to have separate pins for each side of the gantry. In your case, it is up to you.

Have you read the Mach3 Manual yet?

[Clive S]

I must be missing something. Also, most people seem to home to the centre of the bed. What is the best way to mount these switches and have them triggered as I guess they will mechanically get triggered a lot when the machine is actually in action?

Chris. Can you say where you are getting this info from because it certainly is not from this forum. I am sorry but I feel like I don't want to answer any more questions as you don't want to give any feed back on the answers you have had thus far. ( ie what did you do with the power supply etc) as that sort of info helps others.