Emco PC120 Turn

[Chaz]

Are you using a charge pump?
If not, it sounds like the parallel port doing random things as things boot up.
If you've not got a charge pump, a quick fix would be an extra switch to keep the lathe powered of until the PC has booted. It's not ideal, but it would work, provided you remember to turn things on in the correct order.

Not sure what a charge pump is. It has a normal 24V contractor that fires up the coolant pump (single phase probably around 0.3KW). I may disconnect the main motor drivers and see if it still does it. Something seems to want to initialise. It could be the PC too, its not a good machine as such but we are fairly limited with the older interfaces (unless there are trust worthy add on cards for newer machines).

[Chaz]

Are you using a charge pump?
If not, it sounds like the parallel port doing random things as things boot up.
If you've not got a charge pump, a quick fix would be an extra switch to keep the lathe powered of until the PC has booted. It's not ideal, but it would work, provided you remember to turn things on in the correct order.

Actually, id go CS Labs for the simplicity however not value for money at present. I could look at something like one of the smoothieboards or something that is better than the BOB but less expensive than CS Labs.

[m_c]

A charge pump is a device that needs a fixed frequency input, at which point it then activates, and is typically used on BOBs to ensure no outputs are activated until the charge pump is active.

The problem with a parallel port, is the pins may switch on/off during power up/initialisation. By using a charge pump, it means the parallel port driver has to be full control, and generating a fixed frequency output, before any outputs get activated. It also provides some safety in the event the computer crashes, as it should cause the charge pump to fail and deactivate outputs.

If it's just the coolant switching on, I wouldn't worry too much. The big concern is if the spindle happens to activate, or anything else that could cause physical damage.

[cropwell]

I would only add that my experience of a charge pump on a Chinese BoB with no worthwhile knowledgeable support coming from the supplier (in Devon), I ended up disabling it and have a switch for my spindle (so I can change a tool without losing another finger end) and a switch for the air blower.

That was when I first started using Mach3, I probably could figure out how to enable it properly now, but it isn't on the BoBs I use now and I have got used to being without it

Cheers,

Rob

[Chaz]

My niggles continue. Latest one is really odd. After replacing my blown PSU, Ive had an el cheapo die and 2nd one seems to be holding up.

Z (stepper motor) moves when driven at slow feedrate. At higher feedrates it doesnt have torque and whilst it makes a noise, it doesnt move. I swapped the connectors, problem moved, so thought it was the connectors / BOB. However later when I tested it was inconsistent.

How do I test if I am getting the correct step / dir to each drive? Taking the steppers off is a pain, finding it difficult to figure out what else it could be. Wiring looks OK.

I did notice that a CSS value moves when I move one of the axis, turns out this is constant speed so should be OK. Anything else I Can look at? I dont like / trust these cheap controllers however I dont want to spend on the machine as Ill sell it at some point and get something larger for my needs (or just build one).

[Chaz]

Ok fixed.

I suspected the movement distance didn't look right. Turns out when I moved the 24V PSU and I had reconnected the drives, I had bumped a dipswitch on the drive which changed the steps.

Compared the drives, changed, sorted.

[Chaz]

So, since I have changed my PSU, my steppers dont seem to want to perform. It could be a cheap PSU however not sure.

If I am going to add in another PSU, should I try and increase the voltage? I cant see the exact number, I cant find these drives anywhere - but lets assume it will take 48V DC. I also need to check if the current settings are correct for the specific voltage. Currently everything runs off a 24V 10A supply.

Would it be 'good practice' to try and get the voltage as high as possible?

[Clive S]

Chaz its hard to see but if you look on the driver it gives the max voltage at bottom RH side (48V?) if so you could run them at say about 36V. Do yourself a favour and buy some decent drives like AM882 and run them at a higher voltage.

Also you don't say what PS you are using switch mode are not good for steppers.

[Chaz]

Chaz its hard to see but if you look on the driver it gives the max voltage at bottom RH side (48V?) if so you could run them at say about 36V. Do yourself a favour and buy some decent drives like AM882 and run them at a higher voltage.

Also you don't say what PS you are using switch mode are not good for steppers.

Ye, possibly around 50V.

They did work well before the previous set of PSUs died. The current PSU is one of them el cheapo ebay ones, I presume they are SMPS.

Id like to sell the lathe but need it to be 100% reliable before I do. Any suggestions on what PSU would suit if I was just going to upgrade this? Lets assume 36 or 48V max.

lll take a look at the AM882 anyways.

Thanks

[Chaz]

My best bet is probably something like this.

http://www.zappautomation.co.uk/elec...-supply-7.html

Move the drive power to this, leave the 24V supply to do the logic stuff only.