Liberty4Ever's Laser Build Log

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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 06, 2012 11:35 am

canadianavenger wrote:That's not a color graphical LCD. It's a mono segment LCD with a colored graphical inlay. You can see the meter segments faintly in the picture under the red part. So you have a fixed number if digits and fixed resolution of where the meter shows its position.

I can see that now that you pointed it out. I hadn't noticed the meter segments. The C at the end of the numerical display is raised, and it looks like there could be another vertical segment that could change the superscript C into a full sized F. I was thinking it was a graphical display because the analog-ish scale could switch from C to F, but on closer inspection, maybe the Fahrenheit scale values are interspersed with the Celsius numbers and only one set is displayed at a time. Good catch!

It's still cheap looking for my $3500 laser build, but what do I expect for a $5.50 panel mounted digital thermometer?

I'm tempted to buy a 7-segment LED digital thermometer, so I can try them both to see which looks best. Oh the joys (and extra expenses) of a custom one-of-a-kind project.
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Re: Liberty4Ever's Laser Build Log

Postby Techgraphix » Sat Oct 06, 2012 11:48 am

Liberty4Ever wrote:I guess they don't call it a Quarter Pounder With Cheese in Europe, because of the metric system.

The Quarter Pounder has become more of a name than a measure of it's weight.. We are familiar to this "name".
We still have the English nearby.. they also do drive on the left side of the road..

Kees
Techgraphix
 
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Re: Liberty4Ever's Laser Build Log

Postby canadianavenger » Sat Oct 06, 2012 12:06 pm

Liberty4Ever wrote:The C at the end of the numerical display is raised, and it looks like there could be another vertical segment that could change the superscript C into a full sized F. I was thinking it was a graphical display because the analog-ish scale could switch from C to F, but on closer inspection, maybe the Fahrenheit scale values are interspersed with the Celsius numbers and only one set is displayed at a time.


There is another horizontal segment in the middle of the C, so the bottom segment switches off, and the middle one on to form the F. And yes the farenheit values are interspaced between the Celsius values shown in the pic for the analog section. The picture at the eBay link you posted actually shows it all more clearly.
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 06, 2012 7:34 pm

Second Order Arrived - Cooling System, Stepper Drivers, Laser Current Meter, Targeting Lasers, Etc.

My second order arrived from LightObject.com. It's possible to buy most of the items needed to build a laser from their website.

Here's the coolant pump. It's about half the size I expected, based on the 565 gallons per hour flow rate. That's almost certainly an unrestricted free flow rate and the rate will be much less through the cooling system, but it should still do a very good job of cooling the laser tube. It has a brushless DC motor, so I don't expect any maintenance issues.

Image

http://www.lightobject.com/High-volume-35Lm-565GPH-DC24V-Brushless-Water-Oil-Gasoline-pump-P571.aspx


Here is the 120mm X 240mm radiator along with the two "ultra strong" 12V fans. I'll wire the 12V fans in series and run them both from 24V. It's about a third the size of the radiator that's used for many small cars, but they run hotter pressurized water and higher mass flows for greater cooling, but this should still be more than adequate to cool the 80W laser tube. I'll be monitoring coolant level, minimal flow rate and coolant temperature, so I'll have a good idea of how well the radiator is working based on the steady state coolant temperature. I already tested the silicone tubing, and it seems like a very good fit on the radiator inlet and outlet. I guess all of this stuff is made to work together. I haven't been that fortunate when sourcing high quality surplus items from various sources. Sometimes, I spend as much money on fittings and connectors making stuff work with other stuff.

Image

http://www.lightobject.com/240mm-Water-Evaporator-Cooler-for-spindle-or-CO2-Laser-Cooling-P698.aspx

http://www.lightobject.com/Ultra-Strong-12cm-DC12V-Cooling-fan-200CFM-P605.aspx


Here's the coolant flow switch. If you're going for a less complicated system, you could avoid the coolant level switch and/or the coolant temperature monitoring, but you need a coolant flow switch at the bare minimum to protect the laser tube. I have a control philosophy that attempts to measure what matters, rather than indirectly inferring it from some other measurement. In this case, I'm planning on putting the flow switch immediately after the laser tube to ensure that there is a flow of coolant through the laser. I'm planning on putting the pump on the inlet side of the laser tube. I'm trying to make it as fault tolerant as possible. I don't want to measure the flow through the pump or out of the reservoir if the tubing has slipped off the laser tube inlet and I'm measuring the coolant that's spilling out underneath the laser cutter as the laser tube overheats. In my case, it probably wouldn't matter much because losing more than a few ounces of coolant would trip the coolant level switch and shut down the laser. I've built in some fault tolerance there as well, but I still like to measure what matters, and that's the coolant flowing through the laser tube.

Image

http://www.lightobject.com/Water-flow-OnOff-Sensor-G12-P680.aspx


Here's the coolant level switch. I want to shut down the laser if the coolant level isn't very close to being topped off. I plan on having the coolant tank, the coolant pump and the laser tube on close to the same level, with all of these items and the radiator and fans and laser power supply housed in a self contained laser box that hangs off the back of the laser cutter/engraver. I'd like to have a coolant fill tube flush with or protruding slightly from the top of the laser box so the entire coolant system is flooded and it's unlikely that air bubbles could form anywhere. The coolant switch would ensure that the coolant level is up in the filler neck to keep the coolant system from ingesting any air. It's probably obvious, but you can select normally open or normally closed contacts on the float switch by flipping the switch over when mounting it, so the float rises with fluid level to open the contacts, or to close the contacts.

Image

http://www.lightobject.com/Water-Level-Sensor-P138.aspx


The stepper driver is a 2 phase, 1.0 A to 4.2A single axis stepper driver with optically isolated inputs for ENABLE, PULSE, and DIRECTION. It's a sinusoidal drive that is reputed to be almost as smooth as a servo drive. I'll reserve judgment on that until I see it, but I know Leadshine is a Chinese manufacturer that has done a very good job at blurring the line between steppers and servos. There is no printed manual, although I think I saw a datasheet online somewhere. All of the information needed to connect the PSD5042-2P drive is printed on the side of the stepper driver. Wiring a four wire stepper motor should be obvious, but some people may struggle with wiring stepper motors with six or eight wires. Otherwise, this stepper driver looks very logical and simple to install, unlike the Hall Effect sensors on the circa 1985 Siemens brushless DC servo motor I was trying to interface to the servo drive on my other project last night - three different diagrams and it wasn't wired per any of them, so I had to ring out the cabling, make some guesses, and eventually figure it out. A couple of hours of that makes me appreciate simple and well documented designs. I was a bit surprised that the microstepping table of DIP settings includes a lot of options and none of them are the standard 200 steps per revolution. I'm probably missing something there, so maybe it's not as intuitive as I thought. 1111 is the missing code in that table. Maybe 1111 disables microstepping? I looked online and saw what appears to be an updated screen printing with 1111 designated as "Not Used". The #4 DIP switch selects half current mode, so the motor is held at half current when not in motion. That should be very handy in my application to increase efficiency and decrease the size of the power supply that's needed. I assume the 5042-2P portion of the part number refers to 50V maximum power supply voltage, 4.2A maximum motor current and 2 phase. I saw online descriptions of this stepper drive as "credit card sized". They must have some goofy big credit cards in China! There are 1.5A, 5.6A and 7.8A versions of this stepper driver as well. I bought three of the 4.2A version for the X, Y and Z stages.

Image

http://www.lightobject.com/2-Phase-45A-1-axis-Stepping-Motor-Driver-Support-to-Nema-1634-Leetro-replacement-P453.aspx

The Wikipedia article on stepper motors is good, but the following is a more thorough introduction to stepper motors and is written more from the applications perspective than the theoretical or academic Wikipedia entry:

http://www.ams2000.com/pdf/step101.pdf

It also mentions that power supplies rated for half the motor phase current will generally be acceptable, and the higher the power supply voltage, the lower the power supply current rating needs to be, so I'm probably OK with my 48V @ 7.3A switching power supply. I might need to add a large capacitor on the power supply output to increase its reserve current capacity for optimal stepper motor performance, but I'll wait to see on that.


Here's the laser mA current meter with the 7 segment green LED display and the shunt resistor to sample mA and convert them into mV for the display. Obviously, the shunt is attached on the low voltage side of the laser tube! These are available in blue for $2 more.

Image

http://www.lightobject.com/3-digit-Mini-Green-LED-100mA-Current-Meter-for-CO2-laser-machine-P595.aspx


Here are the two targeting laser diodes. I plan on mounting these on opposing sides of the laser head mount and aiming both lasers at an intersecting angle so both beams coincide at the CO2 laser focal point and the two targeting beams diverge above and below the focal point. I may not need a focus gauge if this is accurate enough. I think it will be. I wish I could take credit for this clever idea, but after I hatched the idea, I saw where someone else on BuildLog.net was already doing it.

Image

http://www.lightobject.com/5mW-650nm-Red-Laser-with-adjustable-focus-P585.aspx


I needed some red high voltage wire to connect the output of the laser power supply to the high voltage side of the laser tube. It looks like this would ship with the laser tube and power supply given that I bought them together, but it wasn't mentioned, so I assume it wasn't included. I saw a laser installation video where the Chinese manufacturer seemed to be using plastic spiral wrap (typically used to organize bundles of wire) as a high voltage dielectric material over standard wire with probably a 300V or 600V insulation rating. I like cheap, but when the good stuff is 85 cents a foot, that seemed a little too cheap for me.

Image

http://www.lightobject.com/High-Voltage-HV-Cable-for-CO2-Laser-Power-Supply-P748.aspx


LightObject.com offers different versions of these limit switches and all are inexpensive. I opted for the version with the little rollers for the contact point. Not a very good picture, but I've since cut open the packaging and they're nice little micro switches. If I don't use them on the laser, I'll surely use them for some 3D printers.

Image

http://www.lightobject.com/A-pack-of-5-Micro-Limit-Sensor-Switch-C1-P287.aspx
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 06, 2012 9:39 pm

Power Supply For The Stepper Motors, Part I

The USPS delivered my 48V @ 7.3A power supply today. I could tell as soon as I picked it up in the mailbox that there was a problem. Here's the message I sent to the eBay seller:

I received the power supply today. I could tell without opening the plastic bag that it was damaged. Something heavy, probably a transformer, is rattling around inside. I opened the plastic shipping bag and the thin "gift box" cardboard box (NOT a shipping box), and some blobs of white plastic fell out from inside the power supply. It looks like a hard hot glue was used to mount a transformer? I haven't applied power, as it wouldn't be safe to do so, given that there is obvious serious internal damage. Should I mail this back to you? Can you mail a replacement, hopefully in a REAL shipping box with a little bit of packing material? I've ordered a few of these power supplies from China, and they always arrived with the metal ears bent in, but otherwise intact, and their only packaging is a little bit of bubble wrap. I wish someone would spend 50 cents more on the packaging materials needed to ship these properly, and charge me $5 more.


Silence Of The EBay - It puts the item in the box with packing material or it gets the bad feedback again!

Image
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Re: Liberty4Ever's Laser Build Log

Postby Techgraphix » Sat Oct 06, 2012 10:01 pm

Seems like thermal-glue to me, like you wrote..
My supply didn't realy "bang" inside (just a bit) but it didn't work (the green light just flashed on and dimmed right after to stay off).. So i opened it and soldered some points and now it's working fine.. Else i had to wait another few weeks, send it back and hope for better..You can take the warranty sticker of with a sharp knive. Some hot air from a hairdryer also makes the glue from the sticker become weak..
Visual inspection of the PCB (mainly at the solder side) is necessary for most Chinese electronics after transport..

Kees
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 06, 2012 10:19 pm

The engineer in me is frustrated by the inefficiency... the lack of economy... in the way these power supplies are shipped. Saving a few cents on packing supplies and additional shipping weight is a false economy. It MUST be cheaper overall to pay for adequate shipping materials rather than waste time with angry customers, replacing their damaged merchandise.

The real irony was this little gem from the OTHER eBay seller in the US who stocks this Chinese power supply:

High quality product shipped from USA - Not From China that can get damaged!


Maybe I should have bought from them, but I chose the Jew Jersey seller over the California seller because they were closer and I thought I'd get the power supply faster and with less chance of damage in transit.
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 06, 2012 10:38 pm

Stepper Motor Test Signal Generator

I just ordered an inexpensive board to generate step and direction signals for a stepper motor and stepper motor drive, so I can test the stepper motor, stepper motor drive, and the connected motion control hardware without connecting a PC. This way, I can get the phasing of the motors established (hit or miss without good motor documentation) and drive the axes around to make sure the motion control hardware is properly aligned and not binding, without dragging the PC to the remote location where I'm building and aligning my laser. It'll also allow me to test the motion control system before I have a PC ready to go, although that's often something I do early in the process so I can integrate as I go, and test as I go. It could also be handy to get close on the microstepping setting for the motor drive to achieve optimal performance based on mechanical gear ratio, and torque roll off with step frequency, although it may require some final optimizing once the PC is controlling everything.

The board is powered by 12VDC, or the 15V to 80V that you'd use to power the stepper motor drives. It has an ON/OFF button to control the ENABLE signal to the stepper motor drive, a FORWARD/REVERSE button to control the motor direction, and the PULSE output to step the motor. There is a potentiometer to control the pulse frequency, which controls the motor speed.

Image

http://www.ebay.com/itm/180974203000

I hope the Chinese seller packages it well before shipping! :mrgreen:

The Chinese communists are some of the best capitalists on eBay!
Apparently, I didn't build that! :-)
Liberty4Ever
 
Posts: 274
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby Techgraphix » Sun Oct 07, 2012 10:08 am

The problem with a few wholesalers is that they realy don't know what they are selling. For them it is just another box that needs to be shipped.
They don't have answers to technical questions.
Unfortunately this number is increasing because it's a booming business there..
Have you opened the supply and inspected it already?

Kees
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sun Oct 07, 2012 1:14 pm

Free Market For The Win!

Techgraphix wrote:Have you opened the supply and inspected it already?

I have not opened the DOA power supply, for a couple of reasons:

1) It's not my job. Yes, I could probably fix it. I are an electrical engineer. :ugeek: As geeks we typically have the natural tendency to open it up to see what's wrong and fix it, but I didn't buy a Used, Not Working, For Parts Only power supply on eBay. If I open it, even by heating the tamper resistant warranty assurance sticker to peel it off without tearing it, I've substantially degraded my warranty claim and complicated the issue. Right now, the responsibility for this is on the seller, as it should be. I don't want to get into an argument over the fact that I opened the power supply and now it's somehow not their responsibility.

2) I'm inclined to fix things, but I'm trying to fix the bigger problem. From my perspective, the problem isn't a broken power supply. The problem isn't even a power supply that was broken in transit. The problem I'm trying to fix is an eBay seller with a good feedback rating who put a power supply in a plastic bag and dropped it in the mail. Of course the power supply is trashed. It was almost inevitable. If I drop a hammer on my toe, I don't blame the hammer and I don't try to fix the hammer. If I fix the power supply, there is no incentive for the seller to fix the real problem, which is their epic fail shipping process. The free market works, because everyone acts in their own enlightened self interest, and that's a good thing. If I don't insist that the seller fix this problem, then you guys are likely to order a power supply and have the same exact problem. Ultimately, making the seller fix this problem even benefits the seller, although I doubt he sees it that way. Free markets are incredibly efficient, self correcting, and they even have an intelligence that is greater than all of the participants.

Anticipating your next question... free market capitalism is close to being a religion to me, even to the point that I'll spend more of my time on the free market solution by making sure the seller incurs the cost of fixing his mistake so he'll prevent that mistake in the future, even when I could have pursued the technical solution, fixed it myself, and had a working power supply sooner.

Regardless of how this matter is resolved, I've already spent an hour documenting the problem and engaging the seller. The less geeky and more practical business decision would have been to throw the power supply paperweight in the trash, leave decent eBay feedback to avoid retaliatory feedback that would endanger my 100% eBay feedback rating, and order the 36V/24V supply from LightObject.com, because I know they'll ship it properly. I'm sure a lot of people do exactly that, the problem is never fixed, and the seller continues to save 50 cents on packaging and destroys power supplies in the process.

It probably seems that I'm all worked up about this, but I'm not. I'm at worst mildly perturbed. Every project has these little hassles, and I consider them the cost of playing the game. These little aggravations are background noise in the symphony that is my project. :P I am somewhat frustrated that someone thinks that putting a power supply in a bag is an acceptable shipping practice and it's somehow my job to educate them. I feel that I've been thrust into the role of teaching Remedial Life Lessons To The Perpetually Clueless, and that's not a job I would ever aspire to, but it's not a job that I can shirk in good conscience, either.

If the laser tube that I ordered from China arrives damaged, as so many apparently do, then I'll probably be more than a little perturbed. :P

The seller responded to my eBay inquiry last night, had me email pictures, and this is probably well on it's way to being fixed, hopefully with only minor additional aggravation to me.

This episode and similar episodes continue to reinforce the value of having good suppliers. I see this daily in my small business. I know if I order stuff from McMaster-Carr or Digi-Key, there is a very good chance that I'll get exactly what I ordered and no hassles. I've flirted with shipping supplies from other vendors to save some of the shipping costs I pay with U-Line, but the messed up orders and lower quality continue to make U-Line the better deal. When building my laser and needing those specific parts, I was happy to learn that LightObject.com is a good supplier, and I've gladly shared that info in this build log (almost to the point of writing an infomercial!) because that info is critical to the free market. Most of us aren't going to build lasers on an ongoing basis, so we don't have the opportunity to learn by trial and error. We need to know up front which sellers provide good value and won't waste your time, and I felt that I was doing a service to the laser building community to share my good results. That's not to say that any of the other suppliers aren't equally good. I'm new at this and I haven't tried them, so for now, I'll leave that free market data point for someone else's build log.

I'm off to finally start the BOM spreadsheet for my laser that I promised you guys, so anyone wanting to go down a similar path has some bread crumbs to follow.

And maybe I'll make time today to cut the foot tall yard and file my quarterly sales tax form with the state. :evil:
Apparently, I didn't build that! :-)
Liberty4Ever
 
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