Buildlog.net Open Source Laser

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Re: Buildlog.net Open Source Laser

Postby bdring » Tue Feb 09, 2010 7:48 pm

Comment From Buildlog Author

buildsomething wrote:Something still doesn't make sense here. A smaller pulley does not increase resolution unless it works in conjuction with another pulley that is much larger. If the driver and driven are the same diam, no matter how small or how fine the pitch that is used, the resolution is still the same.

In my cutting laser I have a 3:1 reduction from stepper to the driven ass'y. This reduces my speed by 3X, increase my torque available by 3X and increases the resolution by 3X. In my case, I didn't need speed. I can move my 5lb gantry at speeds over 800 ipm which is way way to fast anyway for cutting.

Richard


In my simple system the motor is driving the pulley which drives the belt attached to the moving part. So all I care about is diameter of the pulley on the motor. It is actually calculated in teeth, so the fewer teeth per rev (smaller dia.), the higher the resolution.
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Re: Buildlog.net Open Source Laser

Postby Robert Williams » Thu Feb 11, 2010 12:15 pm

Will you post plans for this latest revision?
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Re: Buildlog.net Open Source Laser

Postby bdring » Thu Feb 11, 2010 12:29 pm

Comment From Buildlog Author

Yes, as soon as I test the changes. I will probably fabricate the parts on Saturday and install them before the end of the weekend.
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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Feb 12, 2010 4:15 am

I have all the changes ready and I programmed the router in Aspire. I have some Acrylic coming tomorrow (hopefully) and I will cut the parts. They nested pretty well. and won't take up too much material. It should take about 40 minutes to cut. I could easily optimize it to take a lot less time, but it is not worth it for one job.
.
cutout.png
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Re: Buildlog.net Open Source Laser

Postby lasersafe1 » Fri Feb 12, 2010 4:22 am

Are you CNC cutting or Laser cutting? The drawing looks nice! It's amazing how things that were once hard are now becoming a button press.

After I finish the ULS upgrade I will move on to build my gantry CNC mill that I have left in a half built stage. I am presently using a small mill from Harbor Freight that I upgraded to CNC.
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Re: Buildlog.net Open Source Laser

Postby bdring » Fri Feb 12, 2010 1:16 pm

Comment From Buildlog Author
I will use my CNC router. It is just easier at this point and can fit the full raw stock without cutting down. Ideally this would be lasered so a laser can make a complete set of parts for a new machine. I have a couple stepped areas where bearings drop in. That would need a slight change. Other than that, it looks good for a laser.

I will use a 1/16 solid carbide end mill from Precise Bits. I bought a couple of these a few years ago and they seem to last forever. I must have cut 100's of parts on them and I have yet to retire one. I have even cut some 6061 aluminum with them. I also have a 0.010 end mill that I use to mill PCBs.
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Re: Buildlog.net Open Source Laser

Postby 8bithack » Tue Feb 16, 2010 11:37 pm

I love the work you've done on this project. I would really like to build a laser cutter for just doing cutting, no etching right now. Are you planning on releasing a "final" drawing of all the laser cut parts for laser cutting? I don't have access to a CNC router or laser cutter right now so I will probably just have them cut at Pololu or Ponoko. I'll also probably have a bunch of questions for you once I get farther into the build. Thanks for any help you can give.
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Re: Buildlog.net Open Source Laser

Postby bdring » Tue Feb 16, 2010 11:50 pm

Comment From Buildlog Author

I have a drawing done, but I want to do a test cut on my router. Unfortunately the material did not arrive until today. I might be able to cut tonight. If the parts workout and the cut time is not too long, I may run an extra set or two later in the week.
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Re: Buildlog.net Open Source Laser

Postby 8bithack » Wed Feb 17, 2010 4:20 am

Have you thought about attempting to add a vacuum assist to your machine or have you found it unnecessary so far? It seems like it would be fairly easy to build a vacuum box to go on your Z platform. Have you had any problems when cutting with parts moving or are the cutting speeds slow enough to not get any movement on the parts?
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Re: Buildlog.net Open Source Laser

Postby bdring » Wed Feb 17, 2010 1:45 pm

Comment From Buildlog Author
A vacuum or downdraft system would be a great additon to any laser cutter for a lot of reasons, but not really a necessity. The laser cutting/engraving action does not affect the workpiece much. It does a good job of handling the smoke and keeps small pieces from flying around.

On my system the thing that affectes the work is the mostly the flushing fan and to a lesser extent the assist air. I could easily cut a playing card just by setting it down. If I were to try to cut a small piece of regular paper, it would probably move. Thin paper often tends to curl while cutting and small cutout pieces can blow around.

The buildsomething laser has a nice downdraft system.

FYI: I had some minor trouble with my router that will delay the cutting of the new laser cutter pieces a few days as I wait for a new part. I will try to post the files in the mean time.
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