MY HobbyCNCPro Package Step by Step

[massajamesb]

Sorry for the delayed reply. The short end of the jumpers is soldered in to the board, it will be easier to slip the jumpers on like that. and if you are only running 3 axis, you will ignore the A axis placement. Just insert into X Y Z, not A. A is only for 4 axis boards

[redneck79]

Dave I have just purchased and built your 4 axis kit, Ihave done the initial 5volt test, everything checked out fine. My question is later on in the instructions it says to set Vref, is this the 5.02 volts I tested earlier?

[diarmaid]

Originally Posted by redneck79 Dave I have just purchased and built your 4 axis kit, Ihave done the initial 5volt test, everything checked out fine. My question is later on in the instructions it says to set Vref, is this the 5.02 volts I tested earlier?

Please do not ask random questions in this thread at this point, until Im finished my review. I want it to be a straightforward review of the assembly of my HobbyCNC kit that people can read through without having 30 pages of posts which they have to try and sift through. There are lots of other HobbyCNC threads just for asking questions. Thanks, its much appreciated.

Edit: I will continue to post information when I receive my Transformer and other items.

[tercero]

Originally Posted by redneck79 Dave I have just purchased and built your 4 axis kit, Ihave done the initial 5volt test, everything checked out fine. My question is later on in the instructions it says to set Vref, is this the 5.02 volts I tested earlier?

Wouldn't it be best if you asked this in the
http://groups.yahoo.com/group/HobbyCNC/
You'll probably get a quicker answer.

Hey diarmaid. Did you contact newarkinone.com regarding the Hammond transformer. I haven't read through all of the posts, but I'm curious why you're using a substitute transformer.

[diarmaid]

The exact equivalent transformer on that site to the one Im getting is Manufacturer Part Number E500E SOLA ELECTRIC and the Newarkinone Part Number is 65H4388. Its 240V Input 24V Output and 500VA. But it costs $126.57c and the one on e-bay is €35.15c. Although the seller on e-bay hasn't answered my 4 e-mails about postage price yet so I might still have to buy from newarkinone!

[HobbyCNC]

Originally Posted by diarmaid The exact equivalent transformer on that site to the one Im getting is Manufacturer Part Number E500E SOLA ELECTRIC and the Newarkinone Part Number is 65H4388. Its 240V Input 24V Output and 500VA. But it costs $126.57c and the one on e-bay is €35.15c. Although the seller on e-bay hasn't answered my 4 e-mails about postage price yet so I might still have to buy from newarkinone!

Have you looked at the HobbyCNC UK Transformer thread in our forum here on the Zone?

[tercero]

Originally Posted by diarmaid The exact equivalent transformer on that site to the one Im getting is Manufacturer Part Number E500E SOLA ELECTRIC and the Newarkinone Part Number is 65H4388. Its 240V Input 24V Output and 500VA. But it costs $126.57c and the one on e-bay is €35.15c. Although the seller on e-bay hasn't answered my 4 e-mails about postage price yet so I might still have to buy from newarkinone!

Not sure why it's so expensive (maybe the shipping), but it's only $58.00 CDN. I'd go with whatever's recommended by Dave Rigotti though. Keep us posted.

Tercero.

[diarmaid]

Originally Posted by hobbycnc Have you looked at the HobbyCNC UK Transformer thread in our forum here on the Zone?

Edited: Yes I have, my question in that thread remains unanswered. Its the last post.

Originally Posted by tercero Not sure why it's so expensive (maybe the shipping), but it's only $58.00 CDN. I'd go with whatever's recommended by Dave Rigotti though. Keep us posted. Tercero.

Unfortunately that price is excluding shipping. I might be looking at a different transformer. Maybe the one thats 300VA is $58, it would work too...

[diarmaid]

(Correct me if Im wrong anywhere here anyone)
Ok just in case anyone is reading this in future trying to figure out their transformer like I was. The relevant formulas are explained and highlighted in blue. Other essential points are highlighted in red

The transformer MUST convert your mains voltage down to approx 24V (42V DC Maximum Input for the 'Pro' Driver Board) from either:
110/120V (USA Area) or 220/240V (UK/Ireland Area)

Those values are approximate as mains voltage can vary either side of them, but they are used to select a transformer for your particular area.

In addition to this your transformer MUST output a current of about 10Amps so that each motor will have enough power.

The Measure 'VA' in the post above stands for 'VoltAmps', and in a Direct Current system (Which is what we use to power our cnc kit) it is just a different way of saying 'Watts' and has the exact same value. In an AC (Alternating Current) system the VA is higher than the actual Wattage, but thats not relevant here.

The 'Watt' is a measure of Power, the Amp is a measure of Current, and the Volt is a measure of the difference in electrical potential between two points. Ok...confused yet?!

Anyway, to compute 'VA' we multiply 'Volts x Amps'. In this case we want 24Volts at 10Amps because we need for my 3 Axis system 24V min and 10A min. Therefore 24Vx10A=240VA. So our transformer needs to be at least 240VA in order to get us 10A.

Using this simple calculation we can deduce for the transformer Im intending to buy that 24V x XA = 500VA. (Where 'X' represents the value of the Amperage). Switch the calculation around and we get:

Amps = VoltAmps / Volts
XA = 500VA/24V
XA = 20.83A

Therefore the 500VA Transformer I am buying puts out 20.83A at 24V. More than enough for my setup.

HOWEVER, Thats not the entire story!!

A regular transformer changes the voltage and puts out specified amperage, BUT it usually will not convert from AC to DC. You need to check this or else you will damage something trying to power up with AC. My transformer puts out AC, NOT the required DC.

To convert your transformer output to DC you connect a device called a 'rectifier'. Shown in the pic below is a 35A 50V Bridge rectifier for €5 which Im going to get. FYI, a rectifier is:

"A semiconductor diode, or group of diodes, that acts to change AC to pulsating DC"
A 'diode' is:
A device having two terminals and has a low resistance to electrical current in one direction and a high resistance in the other direction, thus allowing current to only flow in one direction and blocking it in the other direction.

You will notice that the definition mentions 'Pulsating DC'. We want our Direct Current to be smooth, not pulsating (Uugh! ), so we also have to add after the rectifier, a 'Smoothing Cap'. This is just a large capacitor or more than one slightly smaller capacitors. I still dont know what capacitor I need but will tell you when I find out.

The transformer Im getting puts out AC, therefore after we convert to DC and rectify we will have a different output voltage. Thanks to Mike Beck at the Yahoo HobbyCNC group I know that on a 24V AC transformer after I rectify and add a smoothing cap I have about 33.6V.

SUMMARY:
After all that I have a 220V transformer going down to 24V with 500VA output, which is equal to 20.83A. Then I rectify and smooth the output, which brings me up to my final 33.6V at 20.83A. Woohoo!

Plenty of power for my kit.
Hope this helps someone at some point. It took long enough to get straight in my head and write it all down as clearly as possible!

[HobbyCNC]

We recommend a 24VAC 10A transformer be used in all cases, 3 or 4 axis. We find the 10A cheaper than an 8A here in the States. This allows upgrading to a 4th axis in the future. 13A tranny is NOT required to operate 4 3A steppers. Lets not get too involved with the "numbers" as some are certianly misleading in the post above.

Keep it simple:

24VAC at 10A, 25A or more at 200V or more rectifier, and a filter cap rated at least 27,000uF at 50VDC.

[diarmaid]

Thankyou for the correction. I've changed it.

[toneV8]

Can someone explain to me what is AC and DC.