[Fyddler]

I have started my first Home built CNC router. I have most of the MDF pieces cut, just need to finish drilling holes. Hope to start puting things together this weekend.

HobbyCNC EZ Driver board is built, and tested. I have set up an older PC with EMC2 Machine Controller, but my latency is terible. I am going to install a video card in hopes that disabling the onboard video card will increase performance. Guess all that soldering as a kid finally paid off!

I also successfully set up two scrapped ATX power supplies in series to give me 24V-18Amps. I may add a 3rd, but I am woried that it will bring me above the 36V Max input voltage for the board. Any suggestions?

I am so thankful for finding a great forum!

[CarveOne]

Welcome Fyddler!

EMC2 does not require a hot rod video card. In fact, it doesn't work well with them. Just plug in a low budget PCI card and see if EMC2 likes it.

CarveOne

[archer3d]

I also successfully set up two scrapped ATX power supplies in series to give me 24V-18Amps. I may add a 3rd, but I am woried that it will bring me above the 36V Max input voltage for the board. Any suggestions?

looking good so far. I will be using the same board to control my machine and have been looking for a good power supply, never thought of this. How exactly did you wire it as I have lots of these kicking around

archer3d

[Fyddler]

CarvOne:
Thanks. I was hoping that was the case. From reading I had figgured that the important thing was to not use the on-board vid.

archer3d:
I plan on documenting the 3rd power supply retro, but until then here is instructions on converting AT and ATX power supplies http://www.hobbycnc.com/information/downloads/. FYI the power supplies require a load to remain powered up, this is why they put a resistor between ground and one of the 5V leads.

I found another unrelated article http://www.procooling.com/index.php?...s&disp=52&pg=1 that described how to connect the power supplies in series. The circuit board MUST be isolated from ground, which means removing the ground wire, and insulating the board from the chassie (I just used several layers of black electricians tape on the stand offs).

I will probabally clean them up by actually de-soldering the un-needed wires, and hard wiring the 115V to all 3 but I was in a rush to show proof of concept and now I am going back to my build.

Allen AKA Fyddler

[atwooddon]

Most PC power supplies don't really deliver 12V under load. Most are around 11.9 or so with any significant load. You might want to measure your 24V supply to see what it is delivering under load. If it is less than 24V, then the 3 power supplies in series will probably be less than 36V.

Having said that, I went the other way and bought a 36V 10A power supply on eBay for about $40 delivered. It even has adjustable voltage withink a 10% range. I turned my supply down to 34V for the HobbyCNC board and it is working great. I had been running at 27V and the extra speed/torque from the higher voltage is nice.

Don

[quadtech]

I went the other way and bought a 36V 10A power supply on eBay for about $40 delivered. It even has adjustable voltage withink a 10% range. I turned my supply down to 34V for the HobbyCNC board and it is working great.

Could you post the ebay item details?

TIA!

[atwooddon]

Here is a link to a similar power supply. There are many options out on eBay. Just do a search for '36V power supply'.

http://cgi.ebay.com/36V-DC-9-7A-350W...56927713559857

Don

[Fyddler]

I am definately a noob, so I am no expert, but the instructions that came with my HobbyCNC Driver board stated to make sure that my power supply was rated at 2X what my steppers were.

Even their smallest stepper is 2.1A, X3 X2 would be 12.6A. I will probabally go with one of the 3A motors, which would bring me to 18A recommended.

Is this overkill?

[Jesse B]

I am definately a noob, so I am no expert, but the instructions that came with my HobbyCNC Driver board stated to make sure that my power supply was rated at 2X what my steppers were.

Even their smallest stepper is 2.1A, X3 X2 would be 12.6A. I will probabally go with one of the 3A motors, which would bring me to 18A recommended.

Is this overkill?

They're talking about the Voltage rating, not the amperage. The ideal voltage for your steppers can be calculated using the formula 32 * sqrt(Motor's Inductance). You don't want to exceed this limit, or the limits of your drivers. Just go as high as you can. Your motors amperage ratings will not change; they require what they're listed as requiring.

[atwooddon]

I am definately a noob, so I am no expert, but the instructions that came with my HobbyCNC Driver board stated to make sure that my power supply was rated at 2X what my steppers were.

Even their smallest stepper is 2.1A, X3 X2 would be 12.6A. I will probabally go with one of the 3A motors, which would bring me to 18A recommended.

Is this overkill?

You could very well be correct but mine is running fine with this power supply. I have my motors set for 2.3A per axis and with an amp meter in line to the CNC board, I never see more than about 8A. Depending on which HobbyCNC board you have, the max amps are also listed for the board. The EZ board is listed as 10A max I believe. But then again, I could be wrong (again). ;-)

Don

[Fyddler]

The board has 18A max listed on it. I double checked the driver paper work and it clearly states that a stepper motor rated at 2.5A will draw 5A. I assume this is due to the rating being PER PHASE and with 1/2 stepping (or 1/4 or what ever) you have multiple coils energized at the same time.

[Fyddler]

Updated Pics!

Main assemply complete. Playing around with options for lead screw bearings. Ordered motors. Hope to be cutting in a week or so.

[Fyddler]

Motors mounted, end bearings in place. Ready to wire and test! Hope to be cutting wood tonight.

So excited I havnt finished the working table yet, just going to throw on a piece of particle board and start cutting!

[Fyddler]

IT CUTS!

I was so excited I thru some scrap lumber and a sheet of particle board on it to cut. It has been a few weeks and have had lots of fun. Now I need to start cutting parts for my Joes 2006.

The "Chris" was one of my first cuts. Table was way off level.
The last pic is my favorite. Cut out of scrap corian. Had some problems with chatter using an up-spiral bit. Think the problem is with my router mount. Plan on re-building it out of HDPE as soon as I can get some.

[CarveOne]

Nice job on your first cuts and JGRO build Fyddler.

Why not just build a 4x8 Joes Hybrid R&P instead of getting there incrementally. You know that's where this is all leading you to anyway.

It's official now, you've been hooked by The Zone....

CarveOne

[Fyddler]

Thanks! Unfortunately I couldn't justify a 4x8 to my wife. The way it is I am going to have to sneak the joes 2006 build, One piece at a time.

[CarveOne]

Thanks! Unfortunately I couldn't justify a 4x8 to my wife. The way it is I am going to have to sneak the joes 2006 build, One piece at a time.

I understand that. All of those parts are just "test samples" made from scraps of MDF. Don't store the parts all in one place neatly taped together or she'll get suspicious.

CarveOne

[R L Harris]

Keep bed sheet over it say your make her gift for next chritsmas and no peeking!

[Fyddler]

Hard to believe it's been 6 years. I have had other projects and the CNC has spent time off and on collecting dust. I ended up replacing the X and Y axis screws with real lead screws and anti-backlash nuts frumpy dumpster cnc. Recently I have been cutting tap handles for a local brewery, more than paid off the second machine, but the volume is outgrowing my current machine, so on to my next adventure building a Joe's Evo.

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[Fyddler]

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