Aluminium CNC log.

Looks good, except for one thing. You have put the rails for the Z-axis on the Y carriage. It's much stronger if you have the bearing blocks for the Z-axis on that carriage (in addition to the bearings for Y). I mentioned it in post #23 and #60. Although having said that with the way you've orientated it it wont make too much difference.

If you don't mind me asking, how much did it cost to get those bits cut?

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Originally Posted by jcb121

Also, What kind of wiring do I need? This will be used for my Steppers, Spindle to VFD, and generally all the wiring.

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Erm, post #53. Same wire for steppers and spindle to VFD.

What Steepers are you using? Shielded CY or SY wire is my best suggestion, as it really helps with reducing signal noise along the wiring.

Michael

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Originally Posted by m.marino

What Steepers are you using?

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3 Nm, Nema 24 according to post #46 (well, the picture).

Since it's quite a small machine the cable length wont be too great, so 1mm^2 should be fine. Same is fine for the VFD-spindle.

Quote:

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Originally Posted by Jonathan

Looks good, except for one thing. You have put the rails for the Z-axis on the Y carriage. It's much stronger if you have the bearing blocks for the Z-axis on that carriage (in addition to the bearings for Y). I mentioned it in post #23 and #60. Although having said that with the way you've orientated it it wont make too much difference.

If you don't mind me asking, how much did it cost to get those bits cut?



Erm, post #53. Same wire for steppers and spindle to VFD.

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Cost around £325 for the Aluminium and to get it cut perfectly, there are cheaper places but I was inpatient.

Mounting the rails behind the spindle plate in my Eyes isn't correct.
I don't know why it would be stronger and on our scale machines it may make no difference at all but I just prefer it that way.

Attachment 5199

I know this drawing is unfair but I'm provin a point here.

Also, Once apon a time, my college used to be the place people went for engineering apprentiships, While all the CNCs and most of the lathes are gone now. I managed to find about 40 brand new end mill bits in the sizes 6mm and 4mm. These fit perfectly into my Spindle and my tutors said i could have them :)

And I'm going to buy a reel of single core wire between 1mm^2 and just use it for everything. I would go multicore for the steppers and drivers but I don't need a reel of it costing nearly £100 from Farnell and don't know where else to get cable.

Quote:

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Originally Posted by jcb121

Mounting the rails behind the spindle plate in my Eyes isn't correct.
I don't know why it would be stronger and on our scale machines it may make no difference at all but I just prefer it that way.

Attachment 5199

I know this drawing is unfair but I'm provin a point here.

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The scale doesn't mean it makes no difference, just a little less. With profile rails it would make a lot less difference as they are so much more rigid. Unless the Z-axis travel is very short it will make a difference.
The reason why is most people start by mounting them like this:
Attachment 5201
So clearly there there is a large overhang = weak.

However you've mounted it like this:

Attachment 5200

Which is better than the previous, as at the bottom of the travel (where you'll use it most for thin materials i.e. cutting aluminium for which it is the most rigid). However further up you're relying on er... the spindle for rigidity instead of with the configuration I suggest the aluminium plate and rails.

EDIT: Actually the second diagram is just the same as the first except instead of using aluminium plate to hold the spindle you're relying on the strength of the spindle itself.

Chip did it like in the first drawing and unfortunately found out the hard way when he tried to cut aluminium. I started by drawing the same on my Z-axis (400mm travel), but fortunately someone pointed it out so I changed it.

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Originally Posted by jcb121

Cost around £325 for the Aluminium and to get it cut perfectly, there are cheaper places but I was inpatient.

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Rather you than me...I'd have cut it for less on my router but it would have taken longer.

Quote:

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Originally Posted by jcb121

And I'm going to buy a reel of single core wire between 1mm^2 and just use it for everything. I would go multicore for the steppers and drivers but I don't need a reel of it costing nearly £100 from Farnell and don't know where else to get cable.

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What length do you need for all the motors and the VFD to spindle?

Quote:

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Originally Posted by jcb121

And I'm going to buy a reel of single core wire between 1mm^2 and just use it for everything. I would go multicore for the steppers and drivers but I don't need a reel of it costing nearly £100 from Farnell and don't know where else to get cable.

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Here you go http://www.csecables.com/control-cab...trol-cable.asp buy just what you need.

Edit: Better link http://www.csecables.com/acatalog/Fl...rol-Cable.html

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Originally Posted by jcb121

Mounting the rails behind the spindle plate in my Eyes isn't correct.

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Well you need to go to Spec savers then. .:lol: . . Look closer and you'll figure out why.!! . . . It's quite obvious if you think about levers and lever length's.:question:

The rails mounted on the front plate make a big difference when it come to reducing chatter.!

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Originally Posted by JAZZCNC

Here you go http://www.csecables.com/control-cab...trol-cable.asp buy just what you need.

Edit: Better link http://www.csecables.com/acatalog/Fl...rol-Cable.html

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I just thought 'it's gone down in price since I bought the 100m reel', then I tried pretending to buy 10m of 1.5mm^2 and they want £9.50+vat for postage...extortionate!! That makes it £2.21 per meter for 10m.

Let me know how much you need as I'm happy to sell some of mine.

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Originally Posted by Jonathan

I just thought 'it's gone down in price since I bought the 100m reel', then I tried pretending to buy 10m of 1.5mm^2 and they want £9.50+vat for postage...extortionate!! That makes it £2.21 per meter for 10m.

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You can do what I do and tell them you're sending in your own courier, parcel to go about £4.50. . . . . Anyway how much do you think it would be to send heavy cabel via the post office.?

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Originally Posted by JAZZCNC

You can do what I do and tell them you're sending in your own courier, parcel to go about £4.50. . . . . Anyway how much do you think it would be to send heavy cabel via the post office.?

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They let you do that? I often say that to eBay sellers, didn't occur to me to try it on a proper company.
It's about 120 grams per meter, so can probably get 8m in 1kg for £3.15 2nd class. Or standard parcels is £4.41 for 2kg ... parcels2go probably less as they keep spamming me with emails about how cheap they are.

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Originally Posted by Jonathan

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

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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.

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

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?

Quote:

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Originally Posted by 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?

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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.?

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

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?

Quote:

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Originally Posted by 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?

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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.

Quote:

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Originally Posted by jcb121

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

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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

http://www.youtube.com/watch?v=F-rnR...ature=youtu.be

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.

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

bruce

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 drawringAttachment 5365on 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.

If you don't mind me asking what is your total build cost? And your estimated final build cost?

What is you're cut area?

Cutting Area is A3. with 100mm Z

Supported rails, ball screws, mounts, spindle, VFD, Bearing Blocks, Ball screw nuts, £530 incl P+P and Tax

Nema 23 motos: £81.60

Stepper Drivers: £45

Breakout board: £17.98

Power Supply: £35

Aluminium and Water Cutting: £331

Various screws from Screwfix £25

Pump and accesories £15

Steal Subframe and feet, £18

Can't think of what else of the top of my head. My budget was a grand that my Nan gave me.

Even with those cheap drivers I would expect higher acceleration than you are currently using. Keep increasing the acceleration setting until either it stall or the machine shakes about too much, then back off a little to be safe. Aiming for something like 500-1000mm/s^2.

If you put a cable tie round each stepper motor that'll stop the plastic wire guard things snapping off.

All i have done in mach is set the step per mm to 40 and set a speed of 2mps. I haven't even messed around with anything else so I will be doing that when it's all together.

So, I've finally got it all together.

I turned on the power supply for the steppers, then the VFD, turned the spindle on and the entire machine shakes, the Spindle is making the Steppers step.

My guess is to move the pc as far away as possible? wrap everything in tin foil :P? I'm using SY Cabling.

Jes Have you got the wiring earthed ?? and the machine earthed ??

James

Make sure the CY cable shielding is all earthed at just the driver end. Connect the earth wire from the VFD via the spindle wire to the spindle body/Z-axis. Also earth the machine frame.

Things to check.

Check VFD Shield wires goto ground, VFD is one of the few execptions where it's ok and even recommended by some manufacturers to ground both ends of the sheild.
No signal wires, so steppers,estop etc run along side VFD cables or even along side any power cables.
Don't cable tie signal wires together or along side power wires.
Use a Star grounding in control box.
Double check all connections for lose wires, Esp the earth.

Does it only do it when spindle starts or when you actually turn the VFD on.?

only when the spindle starts to turn. I just took out all of the cabling and wired up just the Z axis in a different way, and It's working fine now :)

must have been a bad earth.

It's all working :D!!!

but it's too late to do anything :(

big thanks to 2e0poz and i2i, Couldn't have done it without you guys!

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Originally Posted by jcb121

but it's too late to do anything :(

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Mine's currently running .. it's never too late!

Good hear JCB :thumsup: