Aluminium CNC log.

[JAZZCNC]

They let you do that? I often say that to eBay sellers, didn't occur to me to try it on a proper company.

Yep it's just the same as collecting in person. Only your getting someone else to collect for you.!

I find P2GO ok thou I very rarely send light stuff or have it collected.

[motoxy]

Jonathan. quite often good courier deals on ebay. Not been let down yet.

[jcb121]

So, Even though I have steppers, I'm going to upgrade them to something a bit more powerful. 4.2Amp Steppers

But, How do I power this? I could get a 600watt power supply or I could get a transformer from Farnell and risk blowing myself up.

Just wondering the best way to power it, I'm guessing a few of you guys have them.

so how have you guys done it?

[JAZZCNC]

So, Even though I have steppers, I'm going to upgrade them to something a bit more powerful. 4.2Amp Steppers

But, How do I power this? I could get a 600watt power supply or I could get a transformer from Farnell and risk blowing myself up.

Just wondering the best way to power it, I'm guessing a few of you guys have them.

so how have you guys done it?

Build your own it's not hard, just need toroidal transformer, capacitors and bridge rectifier. . . there also prefered because Unregulated supplys are simple and more forgiving regards back EMF.
Steppers when decelerating from high speeds can become alternators sending power back into the drives which gets passed back to the supply. Linear regulated type supplys struggle to handle this and can tripout because often they have protection circuits. Where as unregulated supply's just absorb most of it in there filter caps.

Usually works out a bit cheaper as well if you want high volts & amps.

How many volts & Amps are you looking for.?

[Lee Roberts]

You could try Philip Lambert over at http://www.metallin.co.uk/shop/ as well he may be able to help.

[jcb121]

So the steppers run at 50v and 4.2A. so i will need something that can output 50v at 12.6 Amps. Multiply those to together, so I need over 630 watts/VA? A lot of the transformers I've seen run off 230v instead of 240v,

would this be ok?
http://www.rapidonline.com/Electrica...-0-50v-88-3848

I know hardly anything about electronics,

or could I use one of these http://www.rapidonline.com/Electrica...-0-50v-88-3844 and run the steppers at 4A. :S

Is there a circuit diagram I can base this PSU on?

[Jonathan]

So the steppers run at 50v and 4.2A. so i will need something that can output 50v at 12.6 Amps. Multiply those to together, so I need over 630 watts/VA?

The steppers run on 50V, but a transformer rated for 50V is 50V rms and you're rectifying the output and storing in a capacitor so the output voltage is actually close to the peak voltage, i.e. 50*2^0.5=70.7V. In reality you get a bit less than that due to the forward voltage of the diodes and numerous other factors. This means you can actually use no greater than 50/2^0.5=35.4V. A 36V (or one with two 18V secondariness placed in series) might be fine, but really it's too close to the limit so from Rapid the nearest is 30V, 88-3838. 32V (or 16+16) would be good too.

Next consideration is the current. For 3 motor a 500VA (or greater) transformer will be fine as it's actually a lot less current than you'd intitially expect. I recently tested with the same motor on 48V and the maximum continuous current (with the motor at full power) was just over 1 amp. You need more than that in reality for the peaks, hence 500VA is fine.

A lot of the transformers I've seen run off 230v instead of 240v,

Don't worry about the difference between 230v and 240v - it's insignificant as the 10% tolerance on the UK mains voltage encompasses that range. Often the transformers have two primary windings so you can put them in series to get 230V or in parallel for operation from 115V.

The circuit is widely available. Just the transformer, a bridge rectifier and electrolytic capacitor. For example:

http://www.cnccookbook.com/img/Lathe...ySchematic.jpg

[jcb121]

This Is progress so far, sorry I haven't been updating it too much.

Big thanks to John S and I2I for helping me out.

All that is left to do is secure the Y motor, and attach the 20mm plate to the 10mm plate floor bit.


And get loads of screws.

[motoxy]

Lots of success on the sites machines at the moment. Well done and looking good. (machine not you):lol:

bruce

[jcb121]

Bugger,if you see the panel that holds the rails for the Y axis, the motor mount secures onto that on top. but it's a bugger to drill and I just screwed up it!So I'm going to need to get those two panels remade. the motor mount and the panel itself.I've drawn a drawringon the right is how I've done it, this means it's super difficult to drill the hole down properly as I have to do it with a cordless. on the left is how it should have been done and how it is done on my X axis.I will probably post up a RFQ post after this, but this really is a Pain. I was so close to finishing.