Liberty4Ever's Laser Build Log

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Re: Liberty4Ever's Laser Build Log

Postby macona » Wed Oct 24, 2012 2:28 am

About a capful of chorine bleach to a couple gallons of water will prevent algae and not hurt anything else.

Water is the best coolant. Adding stuff just makes it less effective. If the machine is in a place where it will get below 32 then you have other things to worry about like condensation in the electronics.

I use Reverse Osmosis Deionozed water in the cooling systems on my laser, my tig machine, and vacuum system. The water has been in the tig machine for over 5 years and is perfectly clear. No nutrients, no microbes.
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Fri Oct 26, 2012 10:11 pm

I've been plugging away the last week, but insanely, I ordered a NEMA 34 stepper motor kit to CNC my cheap import bench top milling machine, so I diverted my attention from the laser build temporarily. I've been blowing a lot of money this week on new tooling for the little milling machine that'll be more appropriate to my new quick & dirty low cost CNC milling machine. I bought one of those cool Edge Technology vise stops, and my cheap import vise apparently has the same screw spacing, but it uses M12X30 screws instead of the SAE screws provided with the vise stop, and naturally Lowes has no metric button head cap screws. I don't think they have SAE cap screws either. I paid an outrageous price for five of them at McMaster-Carr, so I went ahead and bought the $100 worth of ACME screws for the laser Z axis bed lift at the same time. I probably could have used cheap threaded rod, but I decided to go for the fancy stuff. I did some due diligence, though. I surprisingly couldn't find left handed Acme rod on eBay, and Enco had it, but even though they're cheap on lots of other stuff, they were sky high on their threaded rod. I'm sure I could have found it cheaper somewhere, but I didn't want to spend two hours of searching in the hopes of saving $20.

Code: Select all
1 each     95061A810     18-8 SS General Purpose ACME Threaded Rod Right Hand, 3/8"-10 Thread, 3' Length  $46.82 each
1 each     95061A727     18-8 SS General Purpose ACME Threaded Rod Left Hand, 3/8"-10 ACME Size, 3' Length  $43.50 each
2 each     94815A018     Plain Steel ACME 2G Hex Nut Right-Hand, 3/8"-10 ACME Size  $2.82 each
2 each     91808A019     Plain Steel General Purpose ACME Hex Nut Left-Hand, 3/8"-10 ACME Size  $3.14 each


The left hand rod was in stock when I put it in my cart a week ago, but is now a one week lead time item. That's not a big deal. I still need to decide on the actual size of the laser bed so I can build the laser bed frame and the extruded aluminum frame around the laser bed where the stepper motors and bearing blocks will mount. I did buy some 608 skate bearings on eBay. I might turn down the acme rod ends in my lathe to fit the 85 cent bearings, but the smart money is probably on getting some bearings that fit the 3/8" rods.

I just noticed that I bought 3/8"-10 rods. I had been looking for 1/2"-10 rods lately. No wonder McMaster-Carr was cheaper! I'm sure 3/8" Acme rod will be stiff enough in this application, but I'd have preferred 1/2" rods for my TLAR engineering (That Looks About Right). In this design, the four rods are fixed by the stepper motors on the bottom and they're fixed by the bearings on top. The four rods are a bit over a foot long and they're turning slowly, about 5 RPM, so they aren't going to be whipping around. I expect the laser table to raise and lower very evenly, with no significant side to side motion. The table isn't raised or lowered while lasing, so it won't move once it's in place. I can laser engrave, remove the material, paint it, put it back on the table, and laser cut it with precise registration to the engraving.

I'm going to try again to get those four laser Z axis motors turning tonight under LinuxCNC and post a video, but first, I gotta go make a pizza for dinner.
Apparently, I didn't build that! :-)
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 27, 2012 3:39 am

I bought four inexpensive skateboard sealed bearings with a 3/8" ID to hopefully use on the top bearing blocks on the Z axis Acme screws. $11.60 including shipping.

http://www.ebay.com/itm/370674340416

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

Postby macona » Sat Oct 27, 2012 5:06 am

I noticed you ordered Stainless threaded rod. You might want to send that back. Stainless is notorious for galling if you look at it wrong. I used some rolled steel acme to replace the old worn out cross slide screw on my lathe. It was made by Nook and has less than .003" error per foot, bought from McMaster.

And since it is CNC controlled, who cares what the pitch of the threads is?
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Sat Oct 27, 2012 5:22 am

I'd be very surprised if there is any galling in this application. Very slow. Very infrequent use. Well lubed. If stainless Acme thread galls in this application, I don't think there is any application other than submersed in warm circulating filtered oil where it would work.

Also note that the nuts aren't stainless. Stainless on stainless is bad juju. Stainless and aluminum is also bad for galling. The nuts will be encapsulated enough to miss any condensing environment so they should never rust, although I doubt there would have been any problem with Acme screws that weren't stainless in this clean and hopefully non-condensing environment.
Apparently, I didn't build that! :-)
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Mon Nov 12, 2012 11:57 pm

The Laser Tube Arrived Today!

Well, this is a red letter day in my laser build log. The laser tube arrived today, apparently in good shape. I was surprised at how small the box was, having seen pictures of giant bubble wrapped dog bones.

I was also surprised that the ends were wrapped in open cell foam to fill the ends of the box on the sides, but there was no padding on the ends. The laser tube was attached to the foam on the inside with strips of masking tape to keep it from sliding and smashing the ends of the tube against the ends of the box. I guess they ship enough that they get good at it.

Image

I'll be testing the laser tube and power supply under power, hopefully in the next few days.

The laser tube is just slightly over four feet long.

Note from the label that it's actually a 90W laser tube that's been derated to 80W to extend the life.

Image

Also note the label's admonishment to read the manual before use. Pffft. I'm a guy. I ain't reading no manual. It's just a frickin' laser.
:D <--Because there are no smilies with eye patches.

Naturally, as soon as I opened the box and turned my back, George the cat peed on the box. Great. Now there's no way to return it. :) I'm thinking about unofficially changing George's name to R. Kelly. When I have my death star laser fully operational, he'll pay. Oh, how he'll pay. Bwa ha ha ha ha. (That's my evil mad scientist laugh)

I bought the laser power supply and the laser as a bundle on eBay, but there was a mix up on the shipping that caused me to receive the laser power supply soon after the one week Chinese holiday had concluded, but the laser tube was shipped to the eBay seller by mistake. That resulted in a few weeks of delay while another laser tube was shipped to me from China. Throughout all of this, Greg at Bell Laser was very professional. He kept me apprised every step of the way. That was very good service, considering that he had the lowest price I could find. He gets the Liberty4Ever seal of approval!

The delay in receiving the laser tube wasn't a problem for me, but I used it as an excuse to start the CNC conversion of my milling machine, even though there were plenty of tasks I could do to advance my laser project and none of them required the laser tube.

I'll post pictures and/or video when I do the laser testing.
Apparently, I didn't build that! :-)
Liberty4Ever
 
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Re: Liberty4Ever's Laser Build Log

Postby educa » Tue Nov 13, 2012 6:56 am

I don't know if they are derated. Its just that they make them and then measure what is the max they can get out of it.

They only promise you that the tube will give at least 80W.

This is a V2 80W RECI tube and yours is agreed at 80W and peaks at 90W. Mine is exactly the same, agreed at 80W but it peaks at 105W (if you may believe the label on the tube of course). So its more like good luck how much more you get for the price.

I would however not go higher then 25mA on these tubes to save life. 27mA is absolute max
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Tue Nov 13, 2012 2:39 pm

educa wrote:Mine is exactly the same, agreed at 80W but it peaks at 105W

That''s interesting. I assumed they designed it to be a 90W output tube, tested it to output 90W as a quality control, and labeled it 80W for maximum life. Apparently, they design it to be a 90W minimum tube, test it for actual maximum output, then derate it to 80W for maximum life.

I don't know how the power vs life curve looks, but it sounds like you might be able to get 90W out of yours and still get as much life as I'll get at 80W, or, if we both run at 80W, you'll get a lot longer life than I will.

I'm not too worried about it. The quality looks very good and the price was significantly lower than I was expecting to pay. I was initially considering a 60W tube and the extra 20W is a bonus to me. I guess I'm in a "glass is half full mood" today, which is unusual for a cold November morning.

The tube is rated for 4X the hours I expect to put on it in a lifetime, and I've been using an old weak 40W laser that probably outputs approximately 25W. Instead of driving across town and staying up all night making my parts, I'll soon be able to conveniently cut parts at home. Net: win.

The size and power of this laser both expanded once I started shopping for parts and making it up as I went. It seems that at every stage, once I achieved my minimum requirement, the extra capacity was free so I got an upgrade.



More Laser Bed Cutting Surface Musings

I spent an hour yesterday, once again looking at various cutting surfaces for the laser bed. I'm about ready to get back on that, and after some outside of the box thinking, I'm leaning back toward the traditional honeycomb. I'm still checking for other sources. All recommendations welcome!

I could have been (SHOULD have been) designing the laser bed and Z axis all along, but lost some mojo while waiting for the laser tube. I'm back on it, although far from full time. Slow and steady wins the race. I've also been heavily invested lately in the bigger project of building a storage shed in the back yard, to de-clutter the basement enough to have the space to build the laser, which is a far more daunting and far less enjoyable task that's not worthy of a build log.
Apparently, I didn't build that! :-)
Liberty4Ever
 
Posts: 274
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Location: Lexington KY

Re: Liberty4Ever's Laser Build Log

Postby educa » Tue Nov 13, 2012 3:07 pm

I would surely go for honeycomb
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Re: Liberty4Ever's Laser Build Log

Postby Liberty4Ever » Thu Nov 15, 2012 9:18 pm

educa wrote:I would surely go for honeycomb


Oops. I was just coming here to make the following post when I saw your reply. I didn't make the opposite choice just to defy you. :)

The Laser Bed Material

I finally decided on the laser bed material and placed the order for that yesterday. I calculated the 2'X4' perforated stainless was going to be about 42 pounds, but the UPS shipping notification said the package was 32 pounds. In my hasty calculations, I forgot it was perforated with 40% open area. Duh. Still, it's very heavy duty. I don't plan on ever replacing it.

http://www.ebay.com/itm/370663425685

Almost all of my production lasing is on flat carrier sheets of aluminum or on my own fixtures, so that's why I didn't get honeycomb or a grid. If I need honeycomb for a job, I'll get a 1'X2' piece to put on the 2'X4' laser bed. Or maybe I'll get a 2' X 2' piece of honeycomb and use that to cut the big sheets of material that I'm currently cutting on paper lined aluminum sheets.

As I was writing this, I did a different search, and found a YouTube video comparing a flat top to honeycomb. Apparently some materials char more on the bottom when air gets to them, although there will probably be plenty of air with the perforated stainless that I chose, but that's a good reason for me to continue using flat carrier sheets to cut my parts.

http://www.youtube.com/watch?v=Pfp9NAaI8rU

However, other sources indicate that the improved air flow from using egg crate or honeycomb result in less smoke lingering around the part and less soot deposited on the part.

I was tempted to get egg crate, but the best eBay option for me is a nominal 24" X 48" that probably includes the frame, and my 24" X 24" parts would probably BARELY not fit, which I hate. The "slightly too small" problem is what started me on the path that led to a much larger laser in the first place.

http://www.ebay.com/itm/190737296285

Here's a pretty good article describing the frustration and compromises for hobby scale laser builders when picking a laser bed material.

http://diylaser.midwestlaserarts.com/2011/09/searching-for-perfect-laser-cutting.html

My biggest problem was the few online sources for suitable laser beds, and with the exception of http://www.cuttinggrid.com, the complete lack of online pricing. That always makes me feel that I'm about to be ripped off. Even the low cost laser part supplier CNColeTech.com isn't listing prices.

http://cncoletech.com/honeycomb%20table.html

As soon as my perforated stainless arrives, I'll verify the exact dimensions (it had better be AT LEAST 24" X 48") and buy the extruded aluminum for the framework that surrounds the perforated stainless bed and supports it from underneath, and the mounting brackets for the Acme threaded rod nuts.

Then, I can get the Z axis working, and design the rest of the frame from the inside out, get the last parts on order and start building this sucka.

UPS is here with the drain plug I need for my NEW ultra quiet air compressor (Syclone air compressor, I bought it on Amazon) and the cathode plate material for the anodizing line I decided to build in my basement. I hope to finish some of these projects before I die.
Apparently, I didn't build that! :-)
Liberty4Ever
 
Posts: 274
Joined: Wed May 30, 2012 1:49 am
Location: Lexington KY

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