Liberty4Ever's Laser Build Log

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Re: Liberty4Ever's Laser Build Log

Postby lasersafe1 » Fri Oct 12, 2012 12:00 am

Your stepper motor test signal generator is interesting and cheap. I have needed to test some steppers before and I simply used a normal optical encoder going into a normal stepper drive. The quadrature output signals can go directly to the step and direction input pins of the stepper driver. Since the motor driver looks for the direction pin at the moment the step signal is taken high (or low in some cases), it just "works" without any thought, because this is the way quadrature signals work. It's pretty cool to spin the knob of an encoder and watch the motor spin by the same amount. If you have your driver set for microstepping, then each turn of the encoder will give much smaller rotation increments. It makes it easy to think about those surgical situations where a doctor may be making large macroscopic movements of his hands holding controllers while the surgical instrument makes microscopic motions down in the tissue.
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Fri Oct 12, 2012 12:32 am

lasersafe1 wrote:Your stepper motor test signal generator is interesting and cheap. I have needed to test some steppers before and I simply used a normal optical encoder going into a normal stepper drive.

Your quadrature output optical encoder trick is slick (low cost, and something hackers are likely to have lying around so it's free and can be immediately put into use at 2:00 AM Sunday morning), but I wanted to be able to give the large XY table a good workout before I'm ready to have the PC control the stepper motors, and I wanted to be able to zip back and forth quickly over almost the entire working area with the microstepping set to the values I'd use with the PC control, so I'm testing the alignment of the XY stage as I'm assembling it (before tightening the screws) and then I'm testing the speed of the motors at various microstepping settings. Hopefully the stepper pulse generator will do that.

I'm planning on using stepper motors to drive the Z axis to raise and lower the bed. I may cheap out and use a fairly maxed out parallel port to drive the X and Y stepper motors, and simply use front panel push button switches wired to the stepper pulse generator to directly drive the Z axis stepper motor driver to raise and lower the bed to focus the laser before each job. There's really no need to put the PC in that control loop.

So maybe I'll use the stepper motor pulse generator to test the X and Y axes as I'm building and testing the XY table, then use it to test the Z axis, and then use it on the finished laser to drive the Z axis.
Apparently, I didn't build that! :-)
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Fri Oct 12, 2012 1:59 am

Still Shopping & Planning A Home For The Laser

The small orders I've placed should be coming in soon, although some are coming from China and that takes 1-3 weeks.

I've played Daily Email Tag with the eBay supplier that dropped my 48V power supply in a plastic bag and mailed it, destroying it in the process. We finally agreed that they'd send me a postage paid label that I can print to mail the power supply back to them and they'll refund my purchase price. What a time wasting hassle. It makes me appreciate good suppliers.

I added some more items to my LightObject.com wish list today, and I'll be placing my third order with them soon. I already had the 36V/24V power supply in my wishlist. I added a 24V to 5V buck converter to get the 5V I need for the digital thermometer and digital laser ammeter. Hopefully, this will be my last order with LightObject.com for this project, although I was thinking about cheap solar heating today and thought how nice the radiator and fans that I bought for the laser project would be for a solar heating project with a water antifreeze mix as the circulating fluid. Use a photovoltaic panel next to the solar thermal panel, and as long as the sun is shining, the water is being heated and the pump is circulating the water, and the fan is blowing air through the radiator to heat the house. The more heat that goes into the thermal panel, the more electricity that's generated by the PV panel, and the faster the pump and fans run. It's a simple control solution. No battery. No charge controller. Etc.

I spent some time this evening looking at the patio under the deck. I need to replace the floor of the deck (dufus contractors didn't use pressure treated lumber and the pine eventually rotted), and then I need to build a shallow sloping roof above the patio that's under the deck and wall in the open side of the 8' X 12' patio. The patio is just outside my walk-out basement workshop, and it's already enclosed by the house on three sides. Wall in the last side, and I'll have an 8' X 12' extension on my shop for smelly stuff like the 3D printers and the laser. The temperature should stay reasonable in there without any HVAC if I insulate the roof with 2" thick styrofoam sheet, and build an insulated wall to enclose the back of the patio. My laser is probably going to eat up 7' of the 12' wall, and I'll have a 3' wide door in there. The last 2' will be the 3D printer shelf on the other side of the door. But before I can enclose the patio, I need to build a simple lean-to yard closet on the chimney chaseway near the patio, so I have some place to store the lawn mower and the kayak that I'm currently storing on the patio! I'll also be able to get some shovels and post hole diggers and a weed eater out of the basement workshop to free up a little bit of much needed space.

I have a dedicated electrical circuit to an outside outlet on the patio, and there's a light on the patio. I'll need a lot more light out there if I use it as a workshop, but the lighting circuit won't have any problem with four to six 4' fluorescent shop lights. The 80W laser may use 800W of power, and the blower will probably use another 800W or so. That's starting to strain the single 120 VAC circuit. Hopefully, it's a 20A circuit and not a 15A circuit.

If I work out there a lot in the winter and I'm running the big laser exhaust blower, even if I'm circulating outside air through the laser instead of pumping 500 cfm of heated room air outside, I'll still need some heat in there. In that case, I'll get some radiant heaters, which are good for drafty areas where it's almost impossible to heat the air. Radiant heaters heat the objects (and people). My brother has a garage workshop with radiant heaters and they're amazing. They use electricity, which is a generally a lousy way to make heat. Electricity is one of the highest forms of energy and it can do all manner of amazing things, and heat is the lowest form of energy. Every energy conversion produces waste heat. It seems a shame to deliberately use electricity to produce heat, but the radiant heat works almost instantly. There's no need to run radiant heat for hours before using the shop to get it up to temperature, so that's a major offset to the efficiency issue and the high cost of electricity. I'll need to run power from another circuit for the heaters. But, one thing at a time.

I spent a couple of hours last night staring at a 3' X 5' granite surface plate. That's the size of the XY stage that I bought. That's a frickin' huge laser! I'm now thinking I'll chop the Y axis down to a bit over 2' and leave the X axis a little under 5'. The Y axis mod looks easy. I can cut a 2' X 4' piece of sheet stock if needed with room to spare.



Near Term Project Strategy And To Do List

Assemble the full size 3' X 5' XY table
Exercise the full size table with the stepper pulse generator to test the motors, micro stepping, and table alignment
Measure the true work area
Mark where to chop the Y axis for 24" of Y axis travel
Chop the Y axis
Reassemble the chopped table and test it again
Build the 24" X ??" laser bed
Finish designing the simple 4 stepper motor Z axis bed lift
Assemble the brackets, lead screws and Z axis motors
Design the frame to enclose the Z axis & laser bed and XY table
Design the rest of the frame to contain the exhaust and electronics
Design the module frame to enclose the laser tube, power supply and cooling system
Order the frame materials
Assemble the frame and install the stuff!

There are a lot of details not on this zoomed out timeline of the rest of the project, but I plan on designing it from the inside out. Remember, I don't have SolidWorks or Pro E. I'm even thinking of paying more and buying uncut aluminum extrusion, brackets and fasteners from McMaster-Carr. The advantages are, I could have it overnight for UPS ground shipping charges instead of waiting two weeks for Misumi, and I could chop the pieces to length and design as I go. That's usually a bad idea but I often do it anyway, because I can catch mistakes sooner and correct them as I go. Chopping the aluminum as I build is sort of the real world version of 3D parametric design software. If I can always think ahead, I should be OK. It'll all depend on how much more expensive the aluminum is from McMaster-Carr. I don't mind chopping it myself. It's not difficult with a power miter saw and a fine toothed carbide blade... even a good wood working blade.

I've been giving a lot of thought to the modular laser and cooling system that will mount to the back of the laser table assembly. The goal is to be able to drain the cooling system, remove six screws and unplug one Amp Mate-N-Lock connector and lift off the entire laser module for transport. It reassembles by pushing against a hard stop to precisely realign the entire module before bolting it back in place. A removable laser module makes the laser much easier to move by breaking it into two large assemblies. The XY table portion can then be as deep in the Y direction as possible (24"+) and the entire laser without the 10" deep laser module can still easily fit through the width of a residential door.

I started off wanting a true 1' X 2' working area, and now I'm building a laser with a working area that's 2' X 4.5'. I'll enjoy cutting 667 disks out of a 24" X 24" sheet of foam for one of the products I manufacture as a single job. Heck, I could throw down two 24" X 24" sheets and cut them both as a single job! I'm redesigning the fixture for another product to cut eight parts at once instead of one, for less laser time per part and less waste. These are tubes that are cut to length, and multiples allows them to share common end cuts. It'll also require a lot less manual operation of pre-cutting tube blanks and loading and unloading the laser, so I'll have more time to watch YouTube videos and read BuildLog.net. :) The throughput with a new water cooled 80W laser should kick butt compared to the old 40W air cooled laser I've been using. Finally, I'll be able to make the occasional large reverse engraved and laser cut machine panel or sign, and my brother might want to laser engrave some of his wood working, so that extra large area will come in handy at times. At lunch today, my wife asked if I'd be able to make rubber stamps on the laser. I was already planning to surprise her with that, but I guess it's no surprise.

Every home should have a laser cutter.
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby jofinneg » Fri Oct 12, 2012 1:37 pm

Go big or go home :D
I'm eager to see your BOM when you get the chance as I've already started my lightobject wish list.
We're in similar situations regarding work space. I've begun planning the conversion of half of my garage into the laser workshop.

John
Adorable laser cut kids clocks at www.LeLuni.com
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Fri Oct 12, 2012 1:49 pm

jofinneg wrote:I'm eager to see your BOM when you get the chance as I've already started my lightobject wish list.

I'm busy working on The Beast (giant CNC gantry machine) today. I started my preliminary laser BOM a couple of days ago, but didn't get very far. I hope to wrap up my 3rd and final LightObject order this weekend, and get those items onto the preliminary BOM, and get the preliminary BOB posted in the next 2-3 days.

If you have any questions about why I ordered this instead of that, or whatever, please don't hesitate to ask. I've gotten a lot of good info from BuildLog.net and I'd like to give back if I can.



jofinneg wrote:We're in similar situations regarding work space. I've begun planning the conversion of half of my garage into the laser workshop.

At one time, I thought of building a garage to use as a workshop. If I keep buying and building CNC machines, I may yet need to do that.

I'm not sure I have a move left in me, but my pseudo goal is to grow my business enough to buy some rural property for a geeky solar powered straw bale house, and have a nice shop, well organized, with lots of space.
Apparently, I didn't build that! :-)
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Fri Oct 12, 2012 8:17 pm

Mirror Reflective Efficiency - Smoke & Mirrors

Being a newbie noob, I ordered the molybdenum mirrors because they were tough and I wanted something that would better withstand cleaning or accidental overheating if the mirror became contaminated. Then I learned that the molybdenum mirror was less efficient. I could have guessed that, based on the fact that the molybdenum mirror is almost exactly the same price as the coated silicon mirror, but is much more durable. Why would anyone use the more common coated silicon mirror if it was the same efficiency, same cost, and more fragile?

I did a brief search and didn't find much about mirror efficiency. In a previous post in this build log, I provided some simple calculations based on a complete guess that the molybdenum mirror might be 97% efficient and the coated silicon mirror might be 99% efficient, and I calculated that I'd lose an additional 4.6W out of 80W using molybdenum mirrors instead of coated silicon mirrors.

I did some more online searching and found some real numbers.

http://www.eoc-inc.com/lbp/technical.pdf

General laser optics info: http://www.eoc-inc.com/co2_laser_optics_mirrors.htm

Silicon mirror info: http://www.eoc-inc.com/lbp/substrates_silicon.htm

MaxR reflective coating for silicon mirrors (nearly 100% reflective at 10.6 um!): http://www.eoc-inc.com/lbp/coating_MaxR.htm

Molybdenum mirrors: http://www.eoc-inc.com/lbp/substrates_molybdenum.htm

I guessed close with 97% for the molybdenum mirror efficiency. According to the above linked article, it's more like 98% efficient at CO2 laser frequencies. With differences in coatings, it's not possible to provide accurate efficiency numbers for the coated mirrors, but it seems that coated silicon mirrors could be as efficient as 99.9%! My 99% guess was probably a bit low.

I'm sticking by my revised plan to use the highest quality coated silicon mirrors for the #1 and #2 mirror, and use the more durable molybdenum mirror for the #3 mirror at the top of the flying optics where it's more likely to encounter smoke. Assuming 99.5% efficiency for the coated silicon mirrors and 98% efficiency for the molybdenum mirror, I should have 80W*.995*.995*.98 = 77.6W delivered to the focus lens. If I used all coated silicon mirrors I'd have 78.8W assuming 99.5% efficiency. If the mirrors were actually 99.8% efficient, I could have 79.6W.

Whatever. It's still going to be a LOT better than the old and tired 40W laser I've been using lately.

Here's a good datasheet with lots of info:
http://www.lasercomponents.com/fileadmin/user_upload/home/Datasheets/zubehoer/co2_laseroptik/mirrors_co2-laser.pdf
Si with protected silver coating: 99.2%
Si with enhanced silver coating: 99.5%
Si with dielectric MaxR coating: 99.8%
Mo: 98.5%

I have three of the high quality coated silicon mirrors in my LightObject.com wish list (one is a spare). The brief description lists them as "full reflection". I like the sound of that.

http://www.lightobject.com/25mm-High-quality-Si-Plated-Reflection-Mirror-P117.aspx

BTW - My plan to use the molybdenum mirror for the final mirror is apparently an industry strategy, according to the above linked article on molybdenum mirrors (although that's probably for metal cutting and other very nasty laser cutting operations):
In laser cutting the final mirror of the delivery system is often upgraded to a Molybdenum one, as this is the most exposed, and therefore most frequently damaged mirror.
Apparently, I didn't build that! :-)
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 13, 2012 2:17 pm

Still Shopping - The Little Stuff



Front Panel User Interface

As I think more about how the laser will work, I"m thinking of new parts I need, and I'm buying as I go. I still need to spend time this weekend to make a REAL bill of materials and a REAL schematic, to force me to fill in all of the remaining details.

Last night, I bought some very high quality Allen-Bradley 800 series industrial push buttons and an E-stop switch. These are the industry standard by which all others are measured. A simple push button costs something like $50 new. I could have bought lower quality imported switches. but they'd have only been slightly less expensive than the "like new" used eBay deals, and I was in the mood to go retro heavy duty industrial on the operator panel. I won't use all of these operators. I'm still not sure if I want to have a rocker switch for POWER ON-OFF, which looks more like an appliance, but given these recent purchases, I'll probably go with the more industrial push buttons for POWER ON and POWER OFF even though the momentary contact push button switches will require a control power relay. I'll probably have a green push button for CYCLE START. Most of my work is production work. I want to close the lid and press play. I don't want to close the lid and then go find a mouse or keyboard to run the job from the LinuxCNC user interface. I'd like to dedicate one input to the PC for CYCLE START. The user interface is rounded out by a couple of push buttons for TABLE UP and TABLE DOWN (probably driving the stepper motors through a pulse generator and not driven via LinuxCNC control because I'd probably need a second parallel port for the Z axis control), and of course, the big E-Stop mushroom switch.

http://www.ebay.com/itm/380361862495

http://www.ebay.com/itm/290785458014



Laser Door Interlock

This morning, I bought magnetic reed switches for the laser interlock when the door is opened. There were many versions to choose from and my initial inclination was to get some cylindrical magnets and cylindrical reed switches and drill some blind holes in the top rail of the frame for the switch, and matching blind holes in the door frame for the magnet. These are sold for residential security systems to detect when a door or window is opened. But after looking at the options, I decided on the old style reed switches I knew as a kid. They're cylindrical glass tubes with thin metal contacts inside. My plan is to hide the reed switches and magnets inside the black plastic T slot trim strips that fit into the T slot openings in the extruded aluminum frame. Make it look like magic. They're cheap, too. $3.53 for ten of them, including shipping.

http://www.ebay.com/itm/251125559130

Image

Reed Switch Glass N/O Low Voltage Current 2x14mm
Quantity:10pcs
Contact rating (max): 10W
Initial contact resistance (max): 100 mOhm
Switch voltage (max): 100V DC
Switch current (max): 0.5A
Contact capacitance (max): 0.5pF
Position: normally open
Pull in value: 10 - 20 AT
Drop out value (min): 5
Total length: 45mm
Glass section dimensions: 14 x 2.2mm
Electrical Life:100k times

I probably won't mess with a relay to enable the laser when the door is closed and turn on the red targeting lasers when the door is open and the CO2 laser is disabled. I'll probably leave the red lasers on all the time, and if the .5A max capacity of the reed switches are up to the task, I'll have them in series, directly in the path of the laser enable signal.

I'm going to work on the schematic and BOM today. Both have been percolating in my brain pan for almost a month, and it's past time to start documenting the ideas and filling in the last of the details.

I got word on 8OCT12 that the one week Chinese holiday had ended and my 80W RECI laser tube and power supply that I ordered on 3OCT12 would ship soon, but haven't heard anything since then. Not that I need the laser tube yet. Hopefully it'll ship soon. Maybe it shipped and they didn't tell me? Maybe DHL will show up with a big dog bone package for me next week?
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sun Oct 14, 2012 10:03 pm

Ordered MORE Parts

I just placed my third, and hopefully last order for this project from LightObject.com:

Qty SKU Item Price
3 LSR-MIR25SSH 25mm High quality Si Plated Reflection Mirror $85.50
4 EMOT-42HS02 NEMA 17 42HS02 Stepper motor $63.80
1 EPS-D3624V10A Dual DC 36V & 24V 10A Switching Power Supply. Ideal for DSP System $65.00
1 EPS-LM2576ADCVR Universal AC/DC LM2576 Buck (step down) adjustable Power Module/ Regulator $8.50
1 ECB-DB25MF4 4ft DB25 Male to Female Printer Port Cable $2.25
1 LSR-ZNSE2050HQ High quality 20mm ZnSe Focus lens (F50.8mm) $52.00
1 ESW-5MLMT-B1 A pack of 5 Micro Limit Sensor Switch B1 $5.00
1 ESW-5MLMT-A1 A pack of 5 Micro Limit Sensor Switch A1 $5.00
1 SHIPPING UPS Ground $18.03

Order Summary:
Item Subtotal: $287.05
Shipping: $18.03
Total: $305.08

The lens is a spare. The three mirrors will replace two of the lower efficiency molybdenum mirrors, leaving me with two spare molybdenum mirrors, one spare silicon mirror, and one spare lens. If I break some optics, I don't want to be waiting for replacements. Spares are good.

The power supply is a replacement for the FUBAR transaction on eBay. I've sent that bad supply back and am awaiting a full refund.

The buck regulator board will take some of the 24VDC output from the power supply and turn it into a 5V supply, so the laser will have 5V for a few display modules and maybe I/O, 24V for most of the control electronics, and 36V to power the stepper motor drivers. I hate that there are three DC voltages and 120VAC in the laser design, but it is what it is.

The parallel port cable is sort of a spare. I wanted to see if it was fully wired and IEEE 1284 compliant. I may decide to put a second parallel port on the PC for more I/O and the Z axis stepper motor controller.

The four NEMA 17 stepper motors are for the Z axis, raising and lowering the laser cutting bed. I could have used one or two larger stepper motors and some belts and pulleys, but the four smaller stepper motors were a conceptually simpler design that trades pulleys and belts for some wiring. I'm an ELECTRICAL engineer, so I opted for the wiring. :) If you think I spent too much on the four stepper motor design, at least I didn't buy a Z lift for $1000!
http://www.ebay.com/itm/200762998975

The two packages of limit switches are for my CNC junk box. It's cheap insurance. I hate it when I'm building something and I need a small item like this late at night and the project comes to a screeching halt. Of course, I probably have a few dozen similar micro switches buried in my old electronics junk box, so far down that I haven't seen them in a decade.

To date, I've ordered a bit under $2000 worth of stuff from LightObject.com, $940 including shipping for the 80W RECI laser tube and power supply from Bell Laser on eBay, and probably a couple of hundred dollars worth of miscellaneous stuff from eBay and Amazon.com. I'll have a more accurate and detailed accounting when I finish my BOM spreadsheet. I hope to be getting a scrap 120VAC approximately 1HP blower from my brother, who works in the HVAC industry. He says they scrap 2-3 of these a day. More on that later as it develops, but it might be a possibility if you're looking for a laser exhaust blower. I still need to buy the extruded aluminum frame and skins, acrylic or vandal resistant polycarbonate for the lid, etc. It's looking like I'll bust my $3500 estimate, but should bring it in under $4000. No doubt you could do it for less with some dedicated scrounging, but there were a few places where I opted for "nicer" rather than "cheaper". I should have a very nice and capable laser that puts the $12,000 laser I've been using to shame, and is nicer than an almost comparable used Chinese laser for twice the price.
http://www.ebay.com/itm/150890370007

I'm itchin' to get buildin'.
Apparently, I didn't build that! :-)
Liberty4Ever
 
Posts: 274
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby Speedythinker » Mon Oct 15, 2012 7:47 am

I spent some time this evening looking at the patio under the deck. I need to replace the floor of the deck (dufus contractors didn't use pressure treated lumber and the pine eventually rotted), and then I need to build a shallow sloping roof above the patio that's under the deck and wall in the open side of the 8' X 12' patio. The patio is just outside my walk-out basement workshop, and it's already enclosed by the house on three sides. Wall in the last side, and I'll have an 8' X 12' extension on my shop for smelly stuff like the 3D printers and the laser. The temperature should stay reasonable in there without any HVAC if I insulate the roof with 2" thick styrofoam sheet, and build an insulated wall to enclose the back of the patio. My laser is probably going to eat up 7' of the 12' wall, and I'll have a 3' wide door in there. The last 2' will be the 3D printer shelf on the other side of the door. But before I can enclose the patio, I need to build a simple lean-to yard closet on the chimney chaseway near the patio, so I have some place to store the lawn mower and the kayak that I'm currently storing on the patio! I'll also be able to get some shovels and post hole diggers and a weed eater out of the basement workshop to free up a little bit of much needed space.


Just let you know what I have 10 set high efficiency solar heater in stock. It's using 'heat transfer' super conductor instead of water pipe where water running throuhg each tube. Instead, each coated glass tube has a super heat transfer conductor insert and transfer heat to the main pipe. See picture attached.

FYI, regular US solar heater (flat type) is having about 42% efficiency but the one I have is running about 74%. The max temperature can go is 93'C and the extemly coolest temperate it can operate is -30'C. Plus, unlike regular solar heater than need water running all time or it may crack, our solar heater don't need 'running' water.

In case tue crack, it won't affect the other as no water passing through the glass tube.

Marco
Attachments
Series47-Fig2.jpg
Heat-transfer-tube.jpg
Series47-Fig1.JPG
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Mon Oct 15, 2012 1:35 pm

Hour Meter

I'm still imagineering the laser build and thinking of things I want to include. It's a haphazard process. I'm still trying to finish the BOM & schematic, but even then, I'll be editing in stuff I want as I think of it. About the only positive to this improvisation is that at least, for the most part, I'm not thinking of stuff to add and then forgetting to add it. With the internet so readily available, I don't even bother with a shopping list. I think of it, and I buy it. Instant geek gratification! Hopefully, I'll have a BOM that will allow other laser builders to browse and edit to make their own shopping list, which should trade a lot of dream time for build time!

This morning's purchase is an hour meter, aka a Hobbs meter. It's mostly for the laser tube,but it'll also be useful for other maintenance and preventative maintenance items such as cleaning filters. I hope I'll never be replacing the 8,000 hour laser tube (that's a LOT of lasing!), but if there is a problem, I'd like to be able to tell the supplier that "the laser tube only has 64.9 hours on it", which is a lot more compelling than telling them that I've had it less than six months and haven't used it much. While not essential, the hour meter seemed like a nice feature that's worth $8. Heck, at that price, maybe I should buy two, and use one for machine run time, and the other for laser tube time.

http://www.ebay.com/itm/330768712467

Image

I like the idea of PC based machines. I can keep the maintenance log as a text file on the PC that runs LinuxCNC and the build notes, component PDF datasheets, and maintenance records go with the machine. This information can be easily backed up to a USB thumb drive and the backup copy can be kept on my general purpose notebook PC.

When I was buying the hour meter on eBay, I was surprised that most of the hour meters were advertised the same way, to be used on a car/boat/tractor, but half of those required 220 VAC power. Who has a 220 VAC car, boat or tractor? Buyer beware! Read the description!
Apparently, I didn't build that! :-)
Liberty4Ever
 
Posts: 274
Joined: Wed May 30, 2012 1:49 am
Location: Lexington KY

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