My new build!

[thejuggernaut]

I just placed an order for the XLE 1200 gantry, Reci 100 watt tube, X7 DSP and most of the things I think I'll need to make it work. I plan on using this as my build thread, and I'm sure I will have several questions along the way as well. I'm super excited about building my new laser and hope to have it operational in a few weeks.

My first question is about power supplies for the stepper motors. What kind of performance differences will I see going from 24V to 36V, and is it worth the trouble to run both 24v for the DSP and water pump and a second 36V PS for the steppers.

Regards,
Taylor

[Tech_Marco]

It is better to drive the motor with 36V or 40V as it is more efficiencies. The motor itself is running 2.8V. Current is limited by the motor driver so it won't burn the motor. In general, you use small current setting the motor specification. Say 4A motor, you should drive it by 3.5A or 3.8A. Don't ask me the detail about it as I am not design engineer. 36V is better than 24V, 40V is better than 36V, or 48V better than 40V ... but never go over drive limit (usually it is 24V~50V) but all depends.

I know you want to build 80W~100W system. Do not even try to cool it by water radiator. You MUST use water chiller unless you're super sure that the water temperature won't go over 30'C or so. In general, the laser tube should be running by cool water at temperature range from 18~25'C. I usually set my cooler to 22'C +/- 1'C


Marco

[thejuggernaut]

I plan on getting the CW5200 once I get it up and running. It will be in my garage and gets hot here during the summer, so the extra cooling capacity will be nice. While I'm setting it up and tuning it I was just planing on using cool water until I can spare the extra coin.

[Tech_Marco]

Taylor:

Try this post: http://www.rcgroups.com/forums/showthread.php?t=2243133

An excellence build log for a DIY laser by using our XY stage. Andy he knows well 'How to...'
I don't think he mind to answer you some question, right Andy?


Marco

[Tech_Marco]

I plan on getting the CW5200 once I get it up and running. It will be in my garage and gets hot here during the summer, so the extra cooling capacity will be nice. While I'm setting it up and tuning it I was just planing on using cool water until I can spare the extra coin.

I heard so many 'stories' so just be caution, OK. A Reci 80W cost $585 while a SP tube cost $400.
Only 60W or lower power tube a radiator could be considered (closed loop system. Open loop may work)
If you are thinking to build a 100W system, then you need to think "twice" about considering the radiator type cooling system. No fun if you found that your laser tube didn't last long or power output drop rapidly.

Marco

[thejuggernaut]

Thanks for the link, and you're right, I'll just go ahead and order a chiller while I'm getting the stand welded up for me.

[AndyKunz]

Taylor:

Try this post: http://www.rcgroups.com/forums/showthread.php?t=2243133

An excellence build log for a DIY laser by using our XY stage. Andy he knows well 'How to...'
I don't think he mind to answer you some question, right Andy?


Marco

I'm more than happy to answer questions, Marco.

The build thread even made you a sale, hopefully the first of many. http://www.rcgroups.com/forums/showthre ... st30414279

Andy

[MitchL]

I run the steppers in my build at 48V. The step motors I used were NEMA17s from automationtechnologiesinc.

I found this to be a good resource for stepper power supply sizing:

http://www.geckodrive.com/support.html

The AWC608 and 708 run just fine on 12V, so you don't need both a 24V and a 48V supply if you use a higher voltage for your steppers. (I think the 24V input voltage for the AWC is so that you can use the same supply for your steppers if you want to).

I have two small open-frame supplies in my machine, one beefy 48V for the motor drivers, and a 3A 12V one for the AWC, internal LEDs, small fans, etc.

/Mitch.

[thejuggernaut]

Thanks for the link. So let me make sure I have this right.

The inductance of the steppers in my kit are 1.35mH. So the max voltage I can use would be 32*sqrt1.35 = 37.18 Volt max. So a 36v PS is the max I should use.

The motors max out at 5.2A, so wiring them in full winding (series) they need 1/3 of the rating. That's about 1.75A, or 3.5A for both motors.

Did you wire your motors in full or half winding?

[MitchL]

Thanks for the link. So let me make sure I have this right.

The inductance of the steppers in my kit are 1.35mH. So the max voltage I can use would be 32*sqrt1.35 = 37.18 Volt max. So a 36v PS is the max I should use.

The motors max out at 5.2A, so wiring them in full winding (series) they need 1/3 of the rating. That's about 1.75A, or 3.5A for both motors.

Did you wire your motors in full or half winding?

Math seems reasonable to me. Do you have a datasheet for your motors?

My motors are little NEMA17s, these if I remember correctly:

http://www.automationtechnologiesinc.co ... pper-motor

They're 4-wire motors, so there's no full or half in this case. The current limit is done via the motor controller (Gecko 201X in my case).

My CNC machine uses some 906 oz/in NEMA34s - those are 8-wire motors and I wire them in parallel (so half winding). For those motors I use a 56V supply, though some people go as high as 70V.

The killer for stepper motors is current, not voltage - higher voltages will let you run faster. Too much current will burn out the windings. There's a limit of course, which is why the Gecko tutorial is a neat resource.

/Mitch.

[thejuggernaut]

The motors are spec'd on this link.

http://www.lightobject.com/XLE-18001200 ... -P739.aspx#

I believe there is a typo though. It says they are three wire, I pretty sure they are six.

[MitchL]

The motors are spec'd on this link.

http://www.lightobject.com/XLE-18001200 ... -P739.aspx#

Oh, interesting - those are 3-phase motors (not the regular bipolar motors I normally play with). I'll need to read up on those; the coil currents should be similar calculations, but I don't know the performance implications.

I'll read up, aways fun to learn new stuff.

/Mitch

[thejuggernaut]

LOL. You sound like me. My wife can't understand how I can sit on a computer for hours reading about stuff. Well my gantry should be arriving today. If I have time today, I'm going to draw out the frame in solidworks so that I can get a few quotes on getting something welded up and powdercoated for me.

[Tech_Marco]

Just for your info, a three phase motor could have 3 wires or 6 wires. The connection is "U, V, W" and you can wire in any sequence you want. It doesn't matter as you can change the direction of turning in the LaserCad. For 6 wires, it is just 'center tap' and you can ignore the center wire. Use a ohm meter and you can pair it out.

Marco

[thejuggernaut]

I'm drawing out the stand for my gantry and have one question. How much vertical clearance do I need so that the cable chains don't hit the lid. The drawings I got off of this form shows the total overall height to be right under 8 inches. Is 10" going to be enough or should I be safe and go with a foot of clearance?